Volume 3 - Annexes 23.3-23.5

INTERNATIONAL COURT OF JUSTICE
DISPUTE OVER THE STATUS AND USE OF THE
WATERS OF THE SILALA
(CHILE v. BOLIVIA)
REJOINDER OF THE
PLURINATIONAL STATE OF BOLIVIA
ANNEXES 23.3 TO 23.5
VOLUME 3 OF 6
15 MAY 2019

LIST OF ANNEXES TO THE REJOINDER OF THE
PLURINATIONAL STATE OF BOLIVIA
VOLUME 3 OF 6
ANNEX N°
TITLE PAGE N°
TECHNICAL DOCUMENTS (ANNEXES 23.3 – 23.5)
Annex 23.3 FUNDECO, “Study of Evaluation of Environmental
Impacts in the Silala”, May 2018
(English Translation)
5
Annex 23.4 FUNDECO, “Study of Evaluation of Environmental
Impacts in the Silala, Palynology”, 2018
(English Translation)
131
Annex 23.5 F. Urquidi, “Technical analysis of geological,
hydrological, hydrogeological and hydrochemical surveys
completed for the Silala water system”, June 2018
(English Translation)
233
Annex 23.5
Appendix a
SERGEOMIN (National Service of Geology and Mining),
Study of the Geology, Hydrology, Hydrogeology and
Environment of the Area of the Silala Springs, June 2000-
2001, Final Edition 2003
(English Translation)
333

Annex 23.3
FUNDECO, “Study of Evaluation of Environmental Impacts in
the Silala”, May 2018
(English Translation)

7
ENVIRONMENTAL IMPACT
ASSESSMENT STUDY IN SI LALA
FUND-ECO
-~-Ca.
cclon •o11~1,-,_ ct.li•un.1
La Paz - Bolivia
May 2018
Lu is Pach eco D .Cs.
Coordinator
MNHN
M-llo'°""
dtt HlEMrla N1111nl
8
Authors:
Luis F. Pacheco, D.Cs. Coordinator. Director of the Institute of Ecology of the
Higher University of San Andres (UMSA).
Lic. Rosa Isela Meneses Specialist in high Andean ecosystems and wetlands.
Head of the botany unit of the National Museum of Natural History and
Researcher of the National Herbarium of Bolivia.
Eng. Lic. Gabriel Zeballos Specialist in Geographic Information Systems. Department
of Geography, Ohio State University.
M. Carolina Garcia Lino, PhD. Ecologist of plants of alpine environments.
Researcher associated with the National Herbarium of Bolivia.
Susi Loza Herrera, MSc. Biologist – ecologist. Researcher associated with the
National Herbarium of Bolivia.
Lic. Loly Vargas C. Socio-environmental biologist
Arely N. Palabral A., MSc. Botanical biologist. Researcher associated with the
National Herbarium of Bolivia.
Eng. Ariel Lliully A. Botanical specialist in grasses and graminoids. Re earcher
associated to the National Herbarium of Bolivia.
Lic. Jorge Molina Biologist of aquatic ecosystems. Researcher associated with
the Limnology Unit (IE-UMSA).
Biol. Jaime Sarmiento Ichthyologist. National Museum of Natural History.
Biol. Alberto Mariscal Ichthyologist.
Lic. James K. Aparicio E. Herpetologist. Head of the Zoology Unit of the National
Museum of Natural History. Head and Curator of the Reptile and Amphibian
Area of the Bolivian Wildlife Collection.
Lic. Leslie Zegada H. Herpetologist
Lic. M. Isabel Gomez U. Ornithologist. National Museum of Natural History.
Lic. Paola Velásquez Noriega Ornithologist.
Adriana Rico, PhD. Mammal Zoologist. Bolivian Wildlife Collection (IE-UMSA).
Biologist Virginia Sanchez Mammal Zoologist.
2
9
Glossary
Bofedal: Type of plant formation dependent on the constant contribution of
water and characterized by a high concentration of organic matter.
Ecological quality: The general expression of the structure and function of an
ecosystem.
Community: Set of animal populations, plants and/or living beings that share
a geographical area in a given time. When living in a territory, the populations
share space and other resources and establish different types of relationships.
The stability of a biological community is determined by the variety and quantity
of populations that form it.
Ecosystem: It is integrated by the community in interrelation with the area or
territory occupied by it. Then, in the ecosystem live components are distinguished,
which form the community and the lifeless components (abiotic elements).
Macro-invertebrates: They are aquatic invertebrates, larvae, nymphs, naiads or
adults that live in the substrate, the column or the surface of bodies of water,
which can be seen with the naked eye or through simple magnifying glasses.
When they are in the water they can give information about
the health of the ecosystems and the ecological quality of the water, in its physical-
chemical and morph-structural components.
Fluvial Habitat Index (FHI): Index designed to assess habitat quality based
on seven parameters including: the inclusion of rapids, frequency of rapids,
composition of the substrate, velocity/depth regime, percentage of shade in the
channel, elements of heterogeneity and coverage of aquatic vegetation.
Population: Set of individuals of the same species that share a geographical
space in a given time. A species is a set of beings with similar biological characteristics,
which can cross originating fertile offspring. Example: all the lapachos
of a certain area form a population. Example: all mice in a certain area.
Physiological unit: Community of plants similar in appearance. For example,
because of its growth pattern.
3
10
Authors
Glossary
Executive Summary
1. BACKGROUND
2. THEORETICAL FRAMEWORK
3. GENERAL OBJECTIVE
4. STUDY AREA
5. METHODOLOGY
5.1 Diagnosis of abiotic and biotic factors in the Silala area
5.2 Determination of the actual area of the bofedales
5.3 Vegetation map of the area and calculation of the bofedales area in the past
5.4 Current conditions of the bofedales: first line of analysis
Vegetation
Ichthyofauna
Herpetofauna
Avifauna
Mastofauna
DATA ANALYSIS
5.5 Environmental impacts to the bofedal caused by the artificial canal system
Vegetation
Aquatic macro-invertebrates
5.6 Fishes
6. RESULTS
6.1 Historical occupation in the territory of Silala (social area)
6.2 Diagnosis of biotic and abiotic factors
Climatic conditions
Physical-chemical parameters
Canals
Soil
Flora
Fauna
Macro-invertebrates
4
11
Ichthyofauna
Herpetofauna
Avifauna
Mastofauna
6.3 Determination of the actual area of the bofedales
6.4 Calculation of the bofedal area in the present and recent past
6.5 Current conditions of the Silala bofedales
Botanical description of the Silala bofedales
Fragments of the South Bofedal
North Bofedal (N)
Confluence between the South and North Bofedales (CONF)
Current status of the bofedales
6.6 Environmental impacts to the bofedal caused by the presence of artificial
canals
6.6.1 Ecological quality of the bofedales
6.6.1 Macro-invertebrates
Birds
Mammals
6.7 Planning of the restoration measures that must be carried out to guarantee
the conservation
of the ecosystem of bofedales
6.8 Development of an environmental monitoring program for Silala
6.9 Mitigation and control of impacts on the Silala bofedales
7. CONCLUSIONS
8. BIBLIOGRAPHIC REFERENCES
ANNEXES
1. Historical and social aspects
2. Codes and meanings of fragments and abbreviated species
3. Forward selection of PCA analysis with environmental variables that
significantly affect plant communities.
4. Photographic guide of the taxa found in the Silala wetlands
5. Physical-chemical parameters of the sampling stations in the Silala
wetlands
6. Habitat and morphological-structural parameters of the Silala wetlands
5
12
Executive Summary
The results of the report of the consultancy “Environmental Impact Assessment
Study in Silala” are presented. This report includes the assessment of the status of
bofedales (biotic and abiotic factors), the impacts caused by human activities (mainly
the canalization), an assessment of the diversity associated with bofedales, restoring,
mitigation and monitoring guidelines and, in addition some historical and social
aspects related to the area. The assessment was carried out through field visits between
March and April 2018 and analysis of satellite images.
Three zones were differentiated in the Silala bofedales: the South Bofedal, North
Bofedal and the Confluence Area. At a landscape level and based on the composition
and abundance of species, the three bofedales are described. The South Bofedal is
the most degraded and fragmented. In this area six fragments with different plant
communities are recognized, which correspond to meadows and grass with different
proportions of bare soil and saline outcrops (fragments A, B and C).
Species were found that are not typical of bofedales (such as Deyeuxia curvula), some
that are indicative of high soil moisture (such as Xenophyllum incisum), which are
usually found at the margins of bodies of water and bofedal margins. Desert and saline
areas were found that, due to the presence of the aforementioned species, would have
been a bofedal in the recent past (decades). Within the South Bofedal, the D and E
fragments represent the areas that still maintain a properly bofedal structure, with a
state of conservation from regular to degraded, with the E fragment having the highest
ecological quality in the Silala. The D and E fragments of the South Bofedal have a
total area of 4,822 m2.
In the North Bofedal, three units were identified: 1) areas with dominance of Oxychloe
andina (typical species of bofedales), 2) areas with a high density of open canals with
dominance of Deyeuxia eminens var. eminens and 3) semi-dry sectors of margins of
bofedales, with Festuca potosiana dominance. The North Bofedal has an area of 2,540
m2. This bofedal is degraded.
In the bofedal of the Confluence Area there is a higher frequency of Deyeuxia eminens
var. eminens (species associated with running waters) and to a lesser extent a mixture
of Festuca rigescens and Oychloe andina. This sector is much degraded and poorly
preserved.
The assessment at the level of quadrants (129 of 1 m2), shows a high heterogeneity
of the vegetation in the bofedales; mainly the North Bofedal, which has a wide range
of grasses such as Festuca potosiana. Since it is a species of the margins of bofedales,
the presence of Festuca potosiana suggests that the water availability of bofedales has
been reduced, compared to a typical bofedal.
The floristic composition indicates a high degree of compaction (which reduces the
porosity of the soil), by the dominance of gramineae and graminoid species, such as
Carex cf. maritima and frigid Puccinellia; species that form plaques, such as Plantago
tubulosa and herbaceous as Gentiana gayi. The North Bofedal and the fragment D of
the South Bofedal are the least compacted, although the presence of gramineae typical
of dry environments is common, even in the core part of the bofedal.
At the abiotic level, we observe that the physical and chemical characteristics of
the water, the relief characteristics (slope of <1 to 7%) and low density of camelid
cattle (inferred by the low presence of feces), the bofedales should be in very good
conservation conditions and
6
13
with very good ecological quality. However, the current status of the Silala bofedales
reflects a high degree of fragmentation and desiccation. Below, there is a diagram that
summarizes the main environmental impacts found in the components evaluated in the
Silala bofedales:
At the socio-cultural level, the Silala bofedales and its surroundings present
historical- archaeological and cultural value, given the evidence of human settlements
and seasonal occupation; possibly for grazing and/or hunting activities,
since Inca times. The geographical position of Silala, in the middle of a
desert area, makes its springs a place of great ecological relevance and temporary
refuge for several species of fauna; particularly migratory birds.
The Silala bofedales had several human interventions over time, such as: i)
the extraction of yareta (Azorella compacta), whose populations seem to have
been decimated several decades ago to supply vegetable fuel for human activities;
and ii) human settlements, temporary shelters of people and grazing sites,
especially by Quetena Chico community members. However, the canalization
of the waters at the beginning of the 20th century to supply the railway of the
Chilean Company “The Antofagasta and Bolivian Railway Company Limited”,
who carried out the canalization, is undoubtedly the activity with the greatest
impact on the Silala bofedales. These impacts continued with the maintenance
of canals throughout almost the last century.
The surface that has 100% clear evidence of having been a bofedal totals
117,934 m2 (11.79 hectares). For 2016 the bofedal covered an area of 7,679
m2 (0.76 hectares). This reinforces the evidence that the canalization was an
important factor of degradation of bofedales. The reduction of the bofedal area
as a consequence of the infrastructure was of approximately 94%.
7
IMPACT
Canali: ation
Si I a la
bofedal
GLOBAL
EFFECTS
(Results)
Bofedal
surface
reduction
Changes in
the riches and
coverage of
specific
bofedal plants
Reduction of
diversity and changes
in the composition of
aquatic macroin
vertebrates (Ml)
SPECIFIC
EFFECTS
(Results)
Reduct:iac. (dffl:at:ioo) of
96%of.bebof@dal Potential
atea:ll.79ba.R.esitmalare;a
ofbofedal fee 2016: 0.7h.a.
PD diVe[?ityreduttiOil:: In.
129 evalw:t:dquadram,
all)· lto lOcyed.es
Sajamapresai.ti lOto:28
~esin19qu::adnlts.
Hizh frumentation of the
bored.11: Due to ihe higb
rep:::esecut::inir:iess ofgas;;es
and gaminoid9 adap:.ed to cl'"'}'
sL~i.
Ca:ulizatiandwticilly
hamogenized tbe aqu:ztic
habiut, gioing rise to few
Ill3ao-i:Il\"ertetutesgrOJp5
and 1:im.irl!:Lg the growtih of
Scheme I: Own elaboration.
14
In conclusion, there are three areas of bofedal with different degrees of fragmentation
and drainage. The abundance of some surrounding plant species suggests a change in
the composition of the bofedal. The area has a wealth of 167 species, 86 of flora and
81 of fauna (including macro- invertebrates). The biodiversity of the Silala suggests
that this site is a regional oasis, due to the diversity it contains. However, the presence
of human activity from the settlements and in particular the canalization modified the
area and the typical composition of the bofedal, causing a strong fragmentation. Restoration,
mitigation and monitoring measures are suggested according to the assessment
carried out.
8
15
ENVIRONMENTAL IMPACT ASSESSMENT STUDY IN SILALA
1. BACKGROUND
The canals were built to make the water flow more efficient that, due to the geo-morphological
characteristics, has a slope towards Chile. The Bolivian State carried out
several studies on hydrological level, soils, temporal analysis of bofedales via images
(Normalized Difference Vegetation Index – NDVI), among others (see Table 1).
Table 1. Studies carried out in the Silala area requested by the Strategic Office for the
Maritime Claim, Silala and International Water Resources (DIREMAR).
Biological aspects of the Silala region are described in this report, which are of great
importance to assess the impact of the constructions on the bofedales. For this, a description
of the current vegetation and fauna is used, framed in a multi-temporal analysis
of the landscape and the most obvious changes, under the current knowledge of the
biota associated with bofedales.
9
].\fain Commentaries Source
Subject
Hydro geology It suggests that the groUOO\.-ater in the Silala area was recharged mainly by SERGEOTEC
glacial melting thousands of years ago. .MIN,2004
The Silala geomol]lhology consists of ravines fanned by fault action, giving
rise to a zone of weakness and erosive action combined fluviog)acial water and
mechanical weathering. The fluv~oglacial flow derives from the melting that
occurred more than 10,000 years BP. Currently no natural f!U\~al activity is
manifested.
Geology They present a detailed geological map for the Silala bofedales, \\here the SERGEOMIN,
volcanic events and the alluvial and colluv~al contributions of the glacial 2017
events stand out as a basis for the formation of the ecosystems in the area.
The rocks that stand out from the area are of the ignimbrite type Silala 1, 2
and 3, "hich is the place where the springs are formed.
Soil The soils in the Silala area have a typical granulometry of f!U\~og)acial SERGEOMIN
soils with clasts and angular grains. They were able to organize 2017
themselves in the natural bed of a river along hollows.
Soil The results confirm the drainage of the North and South Bofedales, due to the DIREMAR
differences in depth and the water table mainly, \\here the South Bofedal is 2017
shallower and has a deeper \¥ater table.
Multi- It contains the analysis of high and medium resolution satellite images. DIREMAR,
temporal Through unsupervised classification and application of the Normalized 2017
landscape Vegetation Difference Index (NOVI), the area of the bofedal was estimated at
analysis different times and years.
A map of susceptibility and vulnerability ofbofedales was generated,
indicating that the most vulnerable sites are at the margins of the bofedal.
16
2. THEORETICAL FRAMEWORK
The bofedales are a type of plant formation dependent on the constant contribution
of water and characterized by a high concentration of organic matter
(Squeo 2006, Ruthsatz 2012). The bofedales differ from other plant formations,
such as meadows, because they are at higher elevations throughout the Andes
(Ruthsatz 2012). They are distributed along the Andean Mountain Range, from
Peru and Bolivia to northern Argentina and Chile. In Bolivia, they are found
along the Altiplano, between 3,800 and 5,000 meters above sea level. The Puno
bofedales are distributed between 3,650 and 4,100 meters and the bofedales
from the Andean highlands between 4,100 and 5,200 meters (Garcia & Beck
2006, Meneses 2012); generally covering small areas scattered on slopes and
plains permanently saturated with water.
The landscape of the bofedales is characterized by a mosaic of puffed and
plaque-shaped cushions, interspersed with water springs and a network of
streams or permanent courses of surface water. These ecosystems receive rainwater,
water contribution from nearby bodies of water (for example, lagoons
and rivers), groundwater and the melting of glaciers (Ostria 1987, Contreras
2007, Zavala & Cepeda 2006).
Specifically, in the High Andean bofedales the dominant and structuring species
are of the Juncaceae family: Distichia muscoides, D. filamentosa, Oxychloe
andina and Patosia clandestina, which can reach coverage of up to 90
to 95%, depending on the state of conservation of the bofedal and its location
(Figure 1). Because of their type of growth and the environmental conditions in
which they are found, these species have a high capacity to form peat; in fact,
the roots of these species can be alive up to more than 40 cm deep (Figure 2).
Figure 1. Bofedales well preserved. Right. Bofedal of Oxychloe andina in
Aychuta, Sajama, we can see the minimum coverage of low-bearing gramineae
and the dominance of cushions (November 2014, photo Oscar Plata). Left.
Bofedal dominated by Distichia muscoides, in Tuni Condoriri, Real Mountain
Range. The almost null presence of gramineae and the high coverage of water
and cushions is seen (March 2013, BIOTHAW project photo).
At the ecosystem level, bofedales are key habitats for the conservation of bio-
10
17
diversity in the puna and the high Andean zone. They are water reservoirs and a
source of food for many species, especially during the dry season (Squeo et al.,
2006). Due to the high content of nutrients in their leaves (e.g. Distichia muscoides
and D. filamentosa; Loza-Herrera et al., 2015), plants of the bofedales
offer fodder very much desired by domestic camels (llamas, alpacas) and wild
camels (vicuñas); as well as for sheep, cattle and horses. In addition, the flora
of the bofedales contrasts with other formations of the puna because it has a
greater diversity of species typical of these habitats, both at the level of specific
wealth and plant endemism (Meneses 2012, Anthelme et al., 2014). In general,
wetlands of small extension, such as bofedales, are of great ecological value
(Biggs et al., 2017) and the Silala is particularly important, as it is located in a
semi-desert region.
3. GENERAL OBJECTIVE
To carry out the Environmental Impact Assessment study, in order to determine
the relationship between the artificial canalization of upwelling waters in the
Bolivian springs and their effect on the ecosystem of Silala and evaluate if these
impacts have put at risk the survival of the bofedales and their interrelation
with the species.
4. STUDY AREA
The Silala area is between 4,200–5,400 meters above sea level, in the canton of
Quetena, Municipality of South Lipez of Potosi. The area is located at 26 km
from Colorada Lagoon (Laguna Colorada), via secondary dirt roads. The
11
Pl!Jllouirpm duerticola Z an1eiosrirpm fllac<1111en.ris O-',)·thloe ,111di11fl
Figure 2. Three characteristic species of the Boli,-ian bofedales. Note the length of the live roots.
18
area constitutes a RAMSAR site and is part of the “Eduardo Abaroa Andean
Fauna National Reserve.”
5. METHODOLOGY
The field work was carried out between March and April 2018. For a better understanding
and description of the bofedales fed by the Silala waters, the zone
was divided into three areas. The South Bofedal (S) that corresponds to the
most fragmented site, the North Bofedal (N) and the Confluence Area (CONF),
where the waters coming from the South and North Bofedales converge. The
study area covers an area of approximately 120,671 m2, 20,373 m2 in the north,
90,503 m2 in the south and 9,795 m2 in the Confluence Area.
12
19
13 Tipos de vegetaci6n: Bofedal Sur
Et=._ .,.
• ~
i I,
Leyenda
cJ Red de Drenaje I ~ ~!
Tipo de vegetaci6n
Suelo desnudo I afloramiento sal/no
Ctsped N
Pajonal M Vegetaci6n acuati:ca I A
E 1,
Pradera
1111. Bofedal tragmentado
1:5,000
M Bofedal pajooal 0 12$ 2$0 ...37$ soo ~i M Bofedal
Metros
... ,.,. • ·02tW -~- ......
Vegetation type: South bofedal
20
14
!
-,.,,,__
0 40
••fll:l'W
Tipos de vegetaci6n: Bofedal Norte
Leyenda
cJ Red de ()enaje
Tipo de vegetaci6n
" ''-~
)' • <,
-~·.'
{./
'l
I,
SUelo desnudo/ aftotamiento salino
Cesped
Pajonal
M Vegetacion acuatica
1:2,000 I I Pradera
80
Metros
120 160
9' Bofedal ~agmentado
M Bofedal pajonal
M Bofedal
.-fh
Vegetation types: North bofedal
,-·. -:z1-i
21
15
N
A'"'----.
' ·-
E
,_,_
~
-,._,
~
-.,:._, ...
' -...
)
i
Tipos de vegetaci6n: Bofedal Confluencia
f~
t!
/;
.,_ '
, 2,000
. ,-.---.
. .u·~ · 80 ¥._' 1 , Metros
~·
' .........
(
.. ,.;l '- . - "'· f
.-•1.. . ,,~. , ."l'\. .- '
'\, • la.
_,,?
't--
«' Ii ,, \ , .. ,, '
r
120
I
160
'J
~~
~l ~ '
\,
~ .. ,.
·~·,:.c
)Ci. 1,;.
1
Leyenda
cJ Red de Orenaje
Tipo de vegetaci6n
·"" ''- ·i
;
SUelo desnudo/ afto,amiento :salino
Cesped
Pajonal
M Vegetacioo acuatica
Pradera
M Bofedal ~agmentado
M Bofedal pajonal
M Bofedal
...,,.,..
Vegetation types: Confluence bofedal
I
22
5.1 Diagnosis of abiotic and biotic factors in the Silala area
For the diagnosis of abiotic factors, a compilation of bibliographic information
was carried out. The biotic data consider bibliographic review, field data on flora
and vegetation. For fauna, information on vertebrates and macro-invertebrates
is included.
5.2 Determination of the actual area of the bofedales
The bofedales area was determined from the classification results of the
high resolution satellite images (DIREMAR 2016), and with botanical
information (indicated in this document), using geo-referenced coverage of
springs belonging to DIREMAR. Initially the bofedal identification criteria
were defined and later these characteristic elements were identified and georeferenced
during field trips, to then supplement said information with the
Normalized Difference Vegetation Index (NDVI) values from satellite images
of March 2016 (DIREMAR 2017) (Figure 4).
For the correct delimitation of bofedales, the presence of Oxychloe andina was
used as the most important bofedal indicator species in this region (Squeo et al.,
2006, Beck 2010, Meneses et al., 2015). Other indicator species of permanent
bofedal, and bofedal margins were also identified. The permanent bofedal is
one that is always green all year round and besides Oxychloe andina presents
species associated with this, such as Phylloscirpus deserticola or Zameioscirpus
atacamensis. In the bofedal margins there are other species that resist aridity
better, and they are only green seasonally. The most representative grassland
indicator species and other margin formations are Carex cf. maritime and
Deyeuxia spicigera. These characteristics were used to delimit the area of
the bofedal with satellite images and the NDVI that allows recognizing the
vegetation with high photosynthetic activity from other types of dry vegetation
or bare soil (Jensen 2016). The NDVI is calculated with a mathematical formula
that helps to discriminate objects in the landscape according to their spectral
reflectance characteristics. The index varies from -1 to +1, values close to +1
indicate that the vegetation is vigorous and with high photosynthetic activity,
and values close to 0 indicate presence of dry, degraded vegetation or bare
soil or, bodies of clear water or any other body with high absorbance of the
infrared band of the electromagnetic spectrum (Jensen 2016). In this study,
Pleiades multi-spectral satellite images were used in March 2016, provided
by DIREMAR 2017 (Figure 4). This image corresponds to the end of the wet
season, and is the most recent, which is why it is completely comparable with
the field data of this study (end of the wet season of 2018). The thresholds
were calculated at 0.6 for the bofedal, and 0.3, 0.4 and 0.5 for other formations
of drier vegetation such as scrublands, grass or meadows. Because in some
cases the reflectance between different species may be similar, the classification
of thresholds of vegetation types was carried out separately, sector by sector,
distinguishing the vegetation types according to their presence in the terrain.
16
23
17
Delimitaci6n de la superficie potencial de bofedal: Caso Bofedal Norte
·,
'{·
25 . · 100 200 --==--c::::z:i-lllJl••--=======------Metros 150
~
...
\. .
<.
Leyenda
~-
t'
G) lndividuos de Oxychloe
• Manantiales
Q Red de Drenaje
A _., Bofedal 2016
0 Extension maxi ma del
bofedal en el pasado
·. •N
A
Valores de NOVI -
Mnarzo d:,, e 2016 0.6: Bofedal
u -00 ., _,
Figure 4. Process of delimitation of the current bofedal. The yellow area corresponds to the classification made by DI REM AR (20 17). This coverage was then corroborated, corrected and complemented with data on the location of the springs and the presence of the
indicator species, such as 0. andina. The result of the delimitation is shown in green.
24
5.3 Vegetation map of the area and calculation of the bofedales area in
the past
In order to systematize the analysis process, a reclassification of the values
of the Normalized Difference Vegetation Index (NDVI) was carried out. The
NDVI is a mathematical formula that is applied to discriminate objects in the
landscape according to their spectral reflectance characteristics. The index that
varies from -1 to +1, it indicates vigorous vegetation with high photosynthetic
activity when the values are close to +1, and dry, diseased vegetation or bare
soil in the values close to 0 (Jensen 2016).
5.4 Current conditions of the bofedales: first line of analysis
This process consisted of two parts. Initially, different vegetation types were
identified in the field (March 2018) and thereafter, during the office work stage,
the coverage area was interpolated with the help of satellite images of 2016
and 2004, through a Geographic Information System (GIS).
The 2004 image was chosen because it is the oldest of the high resolution images
available. Using these two years it was possible to carry out a comparative
analysis with the images obtained in 2014. The values used to make the comparison
were those of the Normalized Difference Vegetation Index obtained by
DIREMAR (2017). Below are two scenes of images of the South Bofedal, in
2004 and in 2014 (Figure 5). At first glance it can be observed that notorious
changes occurred in the vegetation cover in said period.
Figure 5. Vegetation coverage of the soil in the South Bofedal. Above: before the presence of
the Bolivian State in the area (dry season, 16 June 2004). Below: after 8 years without maintenance
of the artificial canals (wet season, 14 March 2014, image corrected for changes in
humidity). The images are of high resolution (Quick Bird II) and are in true color. The
intense green color shows the vegetation in the bofedal areas and in white the areas of dry or
degraded bofedal. Source: DIREMAR (2017).
18
25
The identification of the vegetation types was carried out through the survey in
the field of indicator species. In addition, panoramic photographs of the study
site were taken, and these species were geo- referenced through a Garmin S60
GPS navigator. The position values were programmed to be captured using the
datum and ellipsoid WGS84 (World Geodetic System 1984) and the UTM19s
projection system (Universal Transverse Mercator Projection, South Zone 19).
The global position files were generated in GPX format as waypoints and tracks.
The waypoints were marked throughout the perimeter area in each location
where individual Oxychloe andina –a bofedal indicator species– were found.
In addition, according to the geo-morphological and physiognomic characteristics,
the tracks were marked on foot in order to delimit the sectors in which the
study area was subdivided.
Additionally, and only as a form of non-technical exploration, interviews were
carried out with local inhabitants, with whom the entire area, which, according
to them, covered the bofedal in 1970, was demarcated (with GPS); before the
availability of satellite images. The description of this tour is detailed in historical
and social aspects (Annex 1).
Through desk work, the spatial analysis was carried out in order to determine
the bofedal area. The information used consisted of spatial files in vector format,
satellite images, and raster images of the Normalized Difference Vegetation
Index (NDVI). The files obtained with the GPS navigator were converted
to SHP format, using the DNRGarmin software. Additionally, there was
spatial information in vector format with the location of springs and canals
(IGM 2016), and in raster format (image) of high resolution satellite images
and NDVI (DIREMAR 2017). The Auto-Sync tool of the ERDAS IMAGINE
2014 software was used for a geometrical correction of spatial co-registration
of the NDVI images. All images were co-registered using one of them (March
2016) as the referential image (Table 2). The Arc-Map 10.3 program was used
for spatial analysis. This analysis consisted of: 1) reclassification of the NDVI
image[s], 2) identification of the threshold that best fits the presence of bofedal
and other types of vegetation, and 3) selection and measurement of the area
corresponding to each type of vegetation.
In order to be consistent with the time of year in which the field trip was made,
the March 2016 image was used and the threshold of the Normalized Difference
Vegetation Index (NDVI) corresponding to bofedal type vegetation was
determined. Panoramic photographs were used to corroborate the result obtained
in Arc-Map. Based on this coverage, and assuming that the spatial displacement
of the bofedales is limited, the NDVI threshold of bofedales was
determined for a dry season, using the June 2004 image. This analysis allowed
us to identify that the threshold corresponding to the regions in which there is
important Oxychloe coverage is 0.3.
Table 2. Characteristics of the satellite images used for the analysis of the Normalized
Difference Vegetation Index (NDVI).
19
Date
16/06/2004
02/03/2016
Type
QB02
GE0l
Spatial NDVI threshold for bofedales
Resolution (m)
0,5 > 0,3
0,5 > 0,6
Source: Own elahoration hased on field control and satellite imar,es o{DJREMAR (2017)
26
Vegetation
An initial tour was carried out in order to verify the sites with canalization, the
size of the bofedales area and based on observations the design was adjusted in
the field. For each sector a physiognomic delimitation was carried out, in each
delimited sector two methods were used: transects and quadrants.
Transects: Transverse lines (not permanent) were installed along the bofedales,
according to the size of each sector (Figure 6). The longest lines reached 50
meters long in some sectors. In each transect, an attempt was made to accumulate
100 records (approximately one record every 50 cm), which includes both
species and other abiotic components (bare soil, organic matter, feces of herbivores),
and all types of anthropic interventions in the bofedal: type of canals
with and without stone bedding and its dry, drying or active state. This method
allows visualizing the change between the margin and the center of the bofedal.
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27
Figure 6. Transects along with the layout of quadrants evaluated in the North Bofedal of Silala.
Every 50 cm the dominant physiognomic unit was recorded (unit of relatively homogeneous
vegetation). A detailed description was made in quadrants of 1 m2, separated on average between
6-8 meters apart.
Quadrants of 1x1 meters were placed on each transect. The quadrants were
arranged as shown in Figure 6.
Physical measures of the bofedales: Compaction (kpA) was measured in the
quadrants with vegetation representative of bofedal, with a compactometer
(Agratronix, Streetsboro Model OH 44241, USA). Between 2 to 5 measurements
were performed, distributed uniformly in each quadrant (Meneses et al., 2014).
The depth of the organic sediment was measured with a steel penetration rod at
different points located on the transects.
With the same quadrant data, a map of the status of the bofedal was prepared,
according to the categorizations of the plants registered in Silala. The
categorization was based on the natural history of the plants, differentiating
particularly if these were typical of bofedal or of dry sites. Subsequently,
“weighted weights” were assigned to each species in each quadrant evaluated,
multiplying the value assigned by the relative area that each species covered
in the quadrant, in order to evaluate the conditions of the bofedales spatially.
Values close to 1 indicate good status and values close to 4 indicate degraded
bofedales. In order to reflect this information better, different colors were
assigned. The “degraded” sites were colored in red, the “dried” ones in orange,
the “regular” ones in yellow, the “good” ones in light green and the “very good”
ones in dark green.
21
tF', .. ·
D -----Q ----- □------0-------0 ------· □
Cuadrantes □ l•m
~
Transecto
( leclur:9 de planta.s cada 50 cm)
28
Ichthyofauna
In order to determine the presence of fish, surveys were conducted with hand
nets in different habitats and micro-habitats in the area. So as to determine the
populations of trout (Oncorhynchus mykiss), visual censuses were carried out
in different reaches of canals, including natural canals and zones of canalized
areas. Additionally, measurements were made of the main physical-chemical
parameters: pH, conductivity, dissolved solids and temperature. The measurements
were made at noon in different micro-habitats.
Herpetofauna
The collection was made with the free capture method, which consists of an intensive
search in habitats and micro-habitats with high probability of presence
of individuals (Heyer et al., 1994), through day and night walks to different
areas of the bofedales and the surrounding slopes. The margins and potholes
around the bofedales were surveyed. For the data collection, different techniques
were used, ranging from the use of sieves to capture amphibians within
the bodies of water, to the manual trapping of lizards and amphibians (Scrocchi
& Kretzshmatr, 1996).
The relative abundance of the species was estimated according to the following
criteria:
• Common (c), > 2 individuals registered every day.
• Frequent (F), registered at least twice a day.
• Rare (R), no more than 3 individuals throughout the study period.
• Exceptional (E), registered only once during the survey.
Photographic records were also taken and in all cases the greatest possible biological
and ecological information of the specimen collected or observed was
recorded.
The collected specimens were prepared and transported using standardized
techniques (Pisani & Villa 1974, Gaviño et al., 1979). The identification was
made using taxonomic keys, bibliographic descriptions and comparisons with
specimens deposited in the previously determined Bolivian Collection of Fauna.
Avifauna
For the assessment of birds, the transect count method was used. A single transect
was established that traversed the different habitats of each of the Bofedales
(South and North) and the area where the waters converge (Confluence Area).
The transect was traveled once a day, adding three repetitions. All birds detected
were recorded while walking at a constant speed (approximately 1 km/
hour). For each observation, time, species, number of individuals and type of
habitat were recorded. Identification at the species level was made by direct
observation using 10 x 35 binoculars and field guides (Fjeldså & Krabbe 1990,
Herzog et al., 2017). The assessments were mainly conducted between 8:00
and 17:00, except for one hour at noon. The nomenclature of the South American
Classification Committee was used (Remsen et al., 2018).
Mastofauna
First, a tour of the entire work area was carried out in order to establish the sampling sites
for micro- mammals, in relation to the canalization sites and the bofedales area. In this
22
29
way, we worked in the South Bofedal, the Central Canal (CC) and the North
Bofedal. The presence of medium to large mammals was established through
signals (feces, tracks and dens), during the entire stay in the field, after the
setting of traps for micro-mammals. The sampling of micro-mammals was
carried out with 100 snap traps (museum special and Victor), in each of the
sectors.
In the South Bofedal, the traps were placed in four lines that ran along the
canals, separated by about 10 meters, from the water springs (nascent) in a
northwest direction. In each line, 25 traps were placed, separated from each
other by about 10 meters, making a total of 100 traps, covering an approximate
area of 1.4 hectares.
In the Central Canal, 52 traps were placed, separated approximately 10 meters
from each other, along 600 meters; in two parallel lines on each side of the
course of this canal, covering an approximate area of 1.6 hectares.
Sampling in the North Bofedal was done in a single line, which ran from the
center of the bofedal towards the canal near the border with Chile; in a length of
approximately 1 km. 109 traps were placed, separated from each other by about
10 meters, covering an area of approximately 1.5 hectares.
All traps used as bait a mixture of oatmeal with tuna and drops of vanilla essence.
The traps were activated around 5 pm and checked and deactivated early the
next morning. The traps of the South and North Bofedales were activated for
two nights; while the Central Canal traps, for three nights. In total a catch effort
of 681 traps per night was completed.
All the specimens that fell into the traps were collected and taken to the camp
for further analysis and preparation. The standard measurements were taken:
length of the body, length of the tail, length of the hind leg and the ear, in
addition to the weight. Sex and reproductive status were also determined.
DATA ANALYSIS
Vegetation
The field work and the vegetation analyzes took into account only vascular
plants. This level of life organization is one of the most complexes to analyze
and its importance lies in the fact that it allows us to infer the natural and
human-induced impacts, because we know the type of ecosystem that different
species usually inhabit with preference.
For the case of the Silala wetlands, abundance range curves or Whittaker curves
were developed (Feinsinger 2004), that give us a visual idea of the composition,
richness and equitability of elements in a given area. In our case we graphed
the composition and abundance of both species (in black in all the figures), as
abiotic components (bare ground, stone, canals, etc. all in red in the figures).
The water is highlighted in light blue and the dead species, burned or organic
matter in yellowish green.
If the slope of the graph is pronounced it indicates low equitability, with
some species very abundant and other species that are not abundant or rare
(Feinsinger 2004). If, on the contrary, the slope is almost zero, a high level of
equitability is inferred, since all species register similar abundances. In that
sense, equitability is the degree to which the abundance of different species
differs (Feinsinger 2004). Additionally, the length of the curve will give us an
idea of the richness of the elements that make it up; the longer a curve, the greater
23
30
the number of elements that make up the community. Finally, the order in which
the components appear shows us that the species located in the upper part are
the most abundant and the species of the tail or lower part are those of lower
abundance. An additional advantage of abundance range curves is that they
clearly show the identity of the species, which helps distinguishing the relative
abundance of typical bofedal species, from others whose presence indicates
that the wetland would be drying up.
In order to explore the existence of general patterns in the composition of
plants in the South and North and the Confluence Area, a Principal Component
Analysis (PCA) was applied. This analysis gives us a global panorama of
the vegetation and helps to visualize patterns of organization of the species. It
uses calculations on the differentiation of sites based on an index (in this case
the Euclidean distance). In order to correct for the presence of double zeros
between pairs of sites, the data matrix with the species and their coverage were
transformed with the Hellinger formula (Legendre & De Caceres 2013).
Subsequently, in order to understand which environmental variables measured
in the field explain the patterns of plant communities, a Coronary Canonical
Analysis (CCA) was used, which performs calculations using both groups of
data and determines which environmental variables significantly affect plant
communities. Two CCA analyzes were run separately: the first with the average
and the standard deviation of the compaction and the second with variables
associated with the type of substrate (Annex 2), as independent variables. The
second CCA was run with the option “Forward selection”, with α = 0.05, to
see the types of substrate that contributed to better explain the composition and
abundance of plant communities (Leps & Smilauer 2003).
5.5 Environmental impacts to the bofedal caused by the artificial canal
system
Vegetation
In order to assess the impacts, quadrant data were used and multivariate analyzes
were applied. While with the data of transects, the different physiognomic
vegetation units were coded first. These units are composed of one, two or
even five species or abiotic elements, among of which are bare soil, sandy soil
and organic matter. For example, the unit composed of Oxychloe andina and
Festuca rigescens was coded as: oand_frig. In this way, the frequency of units
was quantified. Subsequently, the frequency of these units was calculated and
an Analysis of Correspondence with data on the composition and abundance of
the most frequent units was applied, thus avoiding methodological errors in the
analysis. These analyzes were carried out separately for the South and North
Bofedal. In the South Bofedal, only the first 15 units were considered more
frequently and in the North Bofedal only the first 12 units were considered.
24
31
Subsequently, with the help of the values proposed by Meneses et al. (2015),
the ecological quality of the different areas of the Silala bofedal was evaluated
qualitatively. This analysis was supported by revisions of the collections of the
National Herbarium of Bolivia.
Aquatic macro-invertebrates
The aquatic macro-invertebrates (Annex 5) are invertebrates, larvae, nymphs,
naiads or adults that live in the substrate, the column or the surface of bodies
of water, and that can be seen with the naked eye or with simple magnifying
glasses (Figure 7). Since they are in the water they can provide information
about the health of the ecosystems and the ecological quality of the water, in its
physical-chemical and morphological-structural components.
In order to evaluate the effect of the canalization on aquatic communities of
macro-invertebrates, the bodies of water of the North and South Bofedales and
the canal were categorized into three types of canals: canalized with stone (CP),
canalized without stone (SP) and natural or naturalized sections (N) (Figure 8).
The latter corresponds to sections of canals that are more similar to the natural
environments of a bofedal not intervened, which we assume are like this for the
time elapsed without canal maintenance.
25
Figure 7. Aquatic macro-invertebrates ofSilala. Photograph taken with 6X stereo-microscope.
32
26
Canalizado con piedra Canalizado sin piedra Naturalizado
Figure 8. Categorization of the types of canals in the Silala bofedal.
33
27
~
~
684 1.J0"\\'
oa•1·3o•v,
Mapa de Muestreo Limnol6gico
66"11YW 68·0'30-W
aa•1·0-w 68•0'30"\,','
68"0'0'W
GS•o·IT'/lr
i;:,,(,,
··- "-;,i
I~.-~~~i. ~W."'F \ .
./
PO~
Figure 9 : Sampling design in the sections of the modified canals from left to right: canals with stones, canals without s tones and naturalized canals.
34
Collection and metrics of macro-invertebrates
The fauna of macro-invertebrates was collected with a Surber net (15 x 15
cm, 0.02 cm2, with mesh size 250 μm). In each of the 20 sampling stations,
three subsamples were taken distributed in the different micro-habitats of the
section of the canals and ravines (Figure 9). The samples were fixed with
4% formaldehyde and transported to the Limnology Unit of the Institute of
Ecology of the Higher University of San Andres, where they were evaluated.
The samples were separated and identified at the highest possible taxonomic
resolution, with the help of specialized bibliography (Dominguez et al., 2006,
Dominguez & Fernandez 2009, Stark et al., 2009 and Prat et al., 2011). The
taxonomic richness, Shannon-Weiner diversity index, was calculated. In order
to see the difference between the three categories (canalized with stone (CP),
canalized without stone (SP) and naturalized sections (N)) the Kruskal-Wallis
statistic was used.
Physical-chemical and morphological-structural parameters
The physical-chemical parameters considered for this study were: pH,
Electrical Conductivity (EC), Total Dissolved Solids (TDS), Salinity (PSU),
Oxide Potential Reduction (OPR), Dissolved Oxygen (DO) Dissolved Oxygen
Percentage (DO%) and temperature (Multi 3630 IDS SET G, Germany). Among
the morphological-structural parameters were measured: the width of the river
(measuring tape, m), depth (graduated rod, m), velocity (Global Water FP111,
m/s). The type of substrate was evaluated in three transects of 10 meters with
granulometer: Block (B), Large Stone (LS), Fine Stone (FS), Coarse Debris
(CD), Fine Debris (FD), Coarse Gravel (CG), Fine Gravel (FG), Coarse Sand
(CS), Fine Sand (FS), Silt (S), Clay (C). A Substrate Diversity Index (SUDI,
using Simpson’s inverse index) was also calculated.
5.6 Fishes
The only exotic species detected in the Silala area is rainbow trout. In that
sense, this section refers to this species only. Rainbow trout (Oncorhynchus
mykiss) is an exotic species, which was widely introduced into aquatic systems
of the Bolivian Altiplano since the 1940s (Loubens 1989). Currently there is a
small “wild” population in canals and aquatic systems.
According to the results of the counts made during the fieldwork, the current
density of “wild” trout is very low, varying between 20 and 54 trout per
kilometer. The observed sizes vary between 9 and 25 cm in standard length,
approximately.
The same species of trout was introduced into aquatic systems of the Chilean
Altiplano (Vila et al., 2007). The trout found in rivers feed mainly on aquatic
insects and, probably, when they exist, on small native fish.
Trout is usually found in cold water river systems (streams, large and small
rivers) and also in lakes. The preferred temperature of this species varies
between 13 – 18 ºC (Garside & Tait 1958, Loubens 1991). Reproduction
can occur at temperatures below 13 ºC, up to 5 ºC (Luna & Valdestamon
2018). Consequently, the physical conditions of the biotope in Silala are
favorable for the development of the species. On the other hand, considering
the current density of trout, there are still abundant populations of some
invertebrates (such as amphipods) and, probably, some vertebrates such as
amphibian larvae, which can be used as a food source (Lippolt et al., 2011,
Buria et al., 2009). On the other hand, the species usually reproduces in
sandy bottom fluvial systems (Luna & Valdestamon 2018); consequently,
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35
it can also be considered that there are areas that could be used for reproduction.
In addition, there are some areas, for example near the military post, where
there are some lateral water overflows that the fingerlings can use in order to
protect themselves from predation by adults and also use as a growing area.
In other places, such as the Pampalarama Lagoon in the La Paz Valley, trout
fingerlings were observed in this type of habitats, where they remain protected
from adults. Although during this campaign –as mentioned in the report– it was
not possible to verify the presence of trout fingerlings in Silala.
Life cycle of rainbow trout
Males reach sexual maturity at 2 years and females at 3 years. The maximum
age recorded is 11 years in anadromous individuals and six years in non-anadromous
individuals (Luna & Valdestamon 2018, Lippolt et al., 2011). In Andean
systems, a period of reproduction is reported between April and July until September,
with a period of migration, from the lake to the rivers where they breed,
between November and March (Liberoff et al., 2014, Riva-Rossi et al. 2003,
Loubens 1992). There are other references of reproduction at the end of the dry
season, between August and November, in the southern hemisphere (Luna &
Valdestamon 2018).
The trout reproduction occurs in sandy bottom fluvial systems (Riva-Rossi et
al., 2003). When they reach sexual maturity, the adults migrate to the rivers;
the female digs a nest where she deposits the eggs that are fertilized by the
male. Subsequently, the eggs are covered again. When the hatching occurs, the
fingerlings migrate downstream (Luna & Valdestamon 2018). In the region of
Pampalarama in the La Paz Valley, it was observed that the fingerlings penetrate,
at least temporarily, in bofedales and flood areas bordering rivers, probably
as protection from predation by adults.
Cultivation and maintenance of “wild” trout populations in Silala
Fish populations and fishing in mountainous systems (rivers, lakes and reservoirs),
depend on uncontaminated water; expedited migratory routes and
sustainable fishing pressure (Vila 2007). The development of extensive fish
farming depends on an abundant and healthy stock, of physical factors such as
temperature (between 13 and 18 ºC to cultivate trout), adequate availability of
food and conditions for natural reproduction. It is necessary to have a stock of
reproducers for the production of fingerlings or the periodic breeding of juveniles,
for a process of growth in ponds.
The trout in the Silala area comes from a fish farming program that was
launched in 2013 (ERBOL 2016), with the inauguration of a pond system for
trout farming. Currently, the presence of trout in the area is limited to a small
wild population in the canals of anthropic origin built in the area of bofedales
and a very small population (< 50 individuals) that is maintained in an artisanal
pond. Although the physical conditions (temperature of 17 ºC at noon)
are within the appropriate range for extensive or intensive trout farming, the
observed specimens do not exceed 25 cm in standard length; although different
size classes are found.
Unfortunately, an official report on the number of trout
introduced in the area could not be found. According to press
reports, in March 2013, 50 individuals were introduced, without
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36
specific origin (La Razon newspaper 2013). The same reference mentions the
transfer of another 60 specimens from Lake Toro in Potosi, although there are
no references on the concretion of this fact. Although it was not possible to
confirm the presence of fingerlings, which could indicate the occurrence of
reproduction processes in the area, the current density of 20 to 54 trout per
linear kilometer and approximately 50 trout in ponds, could represent that the
trout was successfully established in the area and that there is reproduction,
which would have allowed the population to grow. This aspect seems to be
confirmed by the presence of individuals of different size classes, both in ponds
and in the canals of the area.
The impact of trout on the environment and aquatic biota
The activity of trout on canal margins could accelerate the erosion processes
and, consequently, the runoff of water from the canals. Taking into account the
refuge behavior of trout in cavities and their digging capacity (for example, for
the construction of nests for spawning), the physical influence of the species on
the canal infrastructure is likely. However, the current density of the population
does not seem significant for the production of a physical impact on the canals.
Consequently, it can be considered that the current erosion processes are mainly
due to a process of water erosion.
On the other hand, the likely impact of trout on other elements of the aquatic
biota should be considered. Numerous works in different regions where
Oncorhynchus mykiss and other trout species demonstrated the impact on
amphibian populations, due to four main factors: 1) direct depredation of
eggs and larvae, 2) alteration of reproductive behavior, 3) the effect on the
morphology of the larvae and 4) introduction of pathogenic organisms, such
as Saprolegnia diclina, which can produce a high mortality in eggs (Martin-
Torrijos et al., 2016, Bosch et al., 2006). Consequently, the likely impact of
introducing trout on amphibian populations in the area should be assessed in
greater detail.
Additionally, considering the evolution of the aquatic systems in the area,
in the absence of trout predators, the possible impact on some invertebrate
species should be considered, mainly a species of Trichoptera (Neotrichia sp.),
naturally rare in Silala.
On the other hand, taking into account the characteristics of the marsh systems
in the Southern Altiplano of Bolivia, the past presence of populations of Orestias
sp. (gr. agassii) in the Silala is likely. The study of ancient environmental DNA
is an alternative for the study of past biota. Ancient environmental DNA can be
found in sedimentary environments and its analysis can potentially reveal the
presence of fractions of biological communities (Haile et al., 2009, Willerslev
et al., 2014, Zobel et al., 2018). Consequently, the application of these
methodologies could represent an opportunity to confirm the past presence of
fish, particularly Orestias, as well as other species of fauna such as aquatic
snails.
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37
6. RESULTS
6.1 Historical occupation in the territory of Silala
The Silala bofedales and its surroundings present evidences of human settlements
and seasonal occupation, possibly for grazing and/or hunting activities.
This background gives the region a high historical-archaeological and cultural
value. The Silala bofedales suffered several human interventions over time,
among which we can mention:
The canalization of the Silala waters, which undoubtedly had the greatest impact
on the Silala bofedales. This canalization was authorized by Bolivia in
1908, with the sole objective that the Chilean Company “The Antofagasta and
Bolivia Railway Company Limited” to use the Silala waters for the filling of
steam locomotive cauldrons (Orellana et al., 2013). The artificial canalization
of water sources covers almost the entire surface of the Silala bofedal (Figure
10).
Figure 10 Canalization of Silala bofedales. A) South Bofedal, B) Canals near the Silala Military
Outpost, C) North Bofedal and D) Canal in the Cajon Ravine. (Photo: A. C. Simon Pfanzelt and
B. D. Loly Vargas Callisaya).
According to the perception of the local people interviewed (Joaquin Estelo and
Primo Berna, community members of Quetena Chico), the size of the bofedal
diminished from 1970 to 1978, and the typical vegetation of these bofedales
was in the process of drying out.
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38
During the fieldwork and thanks to the community members, it was possible to
highlight and geo- reference the remains of six landmarks (cement structures
1.5 meters high), which according to the testimonies of the community members
were 15 landmarks that surrounded the South Bofedal and were built by
the Chileans.
Another relevant historical antecedent that occurred in Silala was the extraction
of yareta, in the years before 1945. The interviewees indicated that the
extractions were made by people from Chile and, as evidence, they pointed out
the roads that lead to Chile, from the Silala hill.
It was also possible to identify settlements and temporary shelters in Silala
of people who made trips and tours as part of their livestock activities. The
transfer of livestock allowed them access to agricultural resources produced
in other eco-zones. The traditional destinations of the Quetena llama breeders
were: Toconao, San Pedro de Atacama and populations of the Loa River in the
west (today Chile), and Pirquitas, Rinconada and San Antonio de Los Cobres
(Argentina) to the south. More rarely, they also traveled to the valleys of the
eastern Andean slope, such as Tupiza or Tarija (Nielsen et al., 1981).
According to the interviewees, the people of Quetena Chico also used the Silala
bofedales as a stay and grazing site for their cattle. In the field we managed
to find traces of the small shelters (five caves or houses); which are no longer
used by the community members. Between the people of Quetena who lived
or traveled in different periods of time by the Silala bofedales, the following
were mentioned: Felix Berna, Hilarion Bern, Ladislao Bern Alvares, Remigio
Bern Ezquibel and Primo Bern. The latter inhabits his stay in Silala, between
April and September.
32
Figure 11. Water springs abstracted and canalized towards a main canal (Photo: Loly Vargas Callisaya).
39
6.2 Diagnosis of biotic and abiotic factors
6.2.1 Abiotic factors
Climatic Conditions
According to data from the Laguna Colorada station (Urquidi 2004), the average
annual temperature ranges between -15 °C and 14 °C, the average annual
rainfall is 59.1 mm and the average annual evaporation is 914 mm. Based on
climatic data, the size of the drainage basin and the expected infiltration, Urquidi
(2004) estimated that a drainage area of at least 4.7 times the current size
of the drainage area would be needed to maintain the flow of water measured in
the region (164 l/s). This means that the existence of the bofedal in the Silala is
due to the existence of a fossil aquifer and that the contribution of the current
rainfall is minimal.
Physical-chemical parameters
Below are the average physical-chemical parameters, taken from the work of
Urquidi (2004) and the work carried out in the field; the data correspond to
three stations in the North Bofedal (N), eight in the South Bofedal (S) and three
below the confluence. Additionally, the same parameters were taken at the fishing
sites in potholes (aquatic habitats with low velocity), rapids (deep aquatic
habitat and with greater velocity) and bofedales.
Canals
The Silala hydraulic system on the Bolivian side consists of three open canals
covered with ignimbrite stones: Main Canal, North Canal and South Canal.
33
Table 3. Physical-chemical parameters of the Silala bofedales. Data for 2004 (Urquidi 2004) and 2018 are
shown.
Parameters Urquidi NBofedal SBofedal Confluence Pothole Rapid
(2004) (2018) (2018) (2018) (2018) (2018)
Average pH 7,7 7,6 ±_l 8,47 ±_0,4 8,7 ±.0,1 8,3 8,3
Average
16 13,5 ±_4,4 15,3 ±_0,9 14,5 ±_3,4 16 16
temperature
(OC)
Conductivity Between80
187 ±_30 301 ±_28 262 ±_44 257 260
(μSiem) and350
Total
Dissolved
37 and 122 ±_18 122 ±_18 127 ±_11 139 129
Solids (TDS,
150
mg/I)
Bofedal
(2018)
8,4
17
255
128
40
The Main Canal is built along the main ravine from the confluence of the North
and South Canals to the borderline between Bolivia and Chile. It has a length
of 690 meters, an average width of 0.80 meters and an average depth of 0.50
meters. The side walls and the floor of the canal are made of ignimbrite stone
of different sizes that, in some places, are joined with mortar.
On the Main Canal, 31 meters from the confluence of the North and South
Channels, there is a disused desiltation chamber. The desiltation chamber is
made of stone covered with cement, with four cells. The internal walls of the
desiltation chamber are stained with copper sulphate, which was used as flocculator
and disinfectant of the desiltation chamber. Overlying the stone canal,
two iron pipes of 8 and 10 inches in diameter emerge, that are cut and partially
buried in many stretches of the ravine (Urquidi 2004).
Currently the Main Canal has a great deterioration and growth of grasses on
its margins, but the stone soles are in good condition. The interior of the canal
has aquatic plants that reduce the flow of water (Urquidi 2004). Parallel to the
Main Canal there is a dirt road that continues to be passable and continues to
the Inacaliri Post, in Chilean territory.
The North Canal is built of ignimbrite stone (walls and sole) and has an average
width of 0.57 meters, with an average depth of 0.36 meters. It has a length of
650 meters and collects water with water conveyance canals from 25 springs
that emerge in the North Bofedal. In this bofedal there are 4 piezometric wells
10 meters deep, with 2.5-inch iron pipe. The measurements in these wells indicate
piezometric levels between 0.40 and 0.67 meters above the surface. These
wells were installed by the Antofagasta-Bolivia Railway Company (FCAB)
(Urquidi 2004). The North Canal is in the same conditions as the Main Canal.
Already 14 years ago, Urquidi (2004) reports that the South Canal was completely
deteriorated and its soles had almost completely disappeared. In this
section of the ravine, of the walls or cliffs of ignimbrites, there were 18 springs
or water springs, all with water conveyance canals or stone collectors connected
to the conveyor canal. The density of springs in this section was extremely
high, having been inventoried up to 3 springs per linear meter (Urquidi 2004).
Soil
The following table summarizes the main characteristics of the Silala soils,
both of the North Bofedal and the South Bofedal, according to the report by
DIREMAR (2017), from whose report we summarize the following, which we
consider pertinent to our own work.
34
41
35
Table 4. Main soil characteristics in the North and South Bofedales of Silala. LCA: Environmental Quality
Laboratory of the Institute of Ecology of the Higher University of San Andres (UMSA), CIAT: Center for
Tropical Agricultural Research of the Autonomous Government of Santa Cruz.
Characteristics Silala North Bofedal Silala South Bofedal
Depth (m) Ave. =0,88 Ave.=0,64
n=15 n=15
Values of 0,55 to 1,4 m Values of 0,2 to 1,2 m
Water table (m) Ave.=0,29 Ave.=4,14
n=15 n=15
Values of0,1 to 0,4 m Values of 0,15 to 50 m
Organic matter (%) Ave.=11,23 Ave.=1,78
n=12 n=12
Values of0,17 to 71 Values of 0,1 to 11
pH(LCA) From 5,6 to 8,9 From 6,2 to 8,4
pH (CIAT) From 5,2 to 8,5 From 7,4 to 7,6
Electric Ave. =266,25 Ave.=129,67
conductivity
(μSiem)
n=12 n=15
Values of 26 to 785 Values of 61 to 290
Permeability Average = 2,656E-07 Average = 1, 146E-07
(cm/s)
Hydraulic Average = 4,99E-05 Average= 2,24E-04
conductivity n=3 n=3
(cm/s)
Apparent density Ave.=l,28 Ave.=1,47
(gr/cm 3
) n=7 n=ll
Values of 0,87 to 1,5 Values of 1,09 to 1,8
Porosity (%) Ave.=51 ,85 Ave.=44,6
n=7 n=ll
Values of 43,27 to 67,28 Values of 32,07 to 58,82
Capillarity Ave.=0,625 Ave.=0,26
(per velocity cm/min) n=2 n=4
Values of 0,42 to 0,83 Values of 0,04 to 0,5
Source: Data from the DIREMAR Report, 2017.
42
The texture is predominantly sandy, with values between 70%, and 95%, and
a layer of organic matter that reaches 100% for several areas sampled in the
North Bofedal and one point in the South Bofedal (DIREMAR, 2017).
The pH and electrical conductivity vary directly in relation to the depth of the
soil. The pH is more acidic in deeper horizons. The neutral and acid values
have been measured in the sand layer, inferring that these are influenced by the
washing of the bases, due to the movement of sub-surface waters (DIREMAR,
2017).
The hydraulic properties are typical of sandy soils, with infiltration velocities
above 30 mm/h, due to the type of soil that predominates in the bofedales. The
Field Capacity (FC) and Permanent Wilting Point (PWP) were also determined,
in order to determine the water available for plants in the bofedales.
The greater impact to the soil is translated in the removal or de-structuring of
the surface layer of the soil, which becomes more vulnerable to the erosion
by the strong winds, and a simultaneous phenomenon of compaction of the
deepest layers of the soil. Likewise, the deterioration of bofedales due to wrong
practices causes the salinization of bofedales by accumulation of sodium and
potassium salts, as well as other minerals.
Finally, due to extreme climatic conditions and poorly structured soils, there
are no agricultural practices in the area (SERNAP 2006). And soil formation
is characterized by intense abiotic weathering, but with very slow biotic
processes (humification).
6.2.2 Biotic factors
Flora
Until 2016, only a preliminary survey of the flora and fauna present in the
Silala in a report presented to the Foreign Ministry (Palabral-Aguilera et al.,
2016) would have been carried out. These authors registered a total of 36 plant
species (Palabral-Aguilera et al., 2016), which included species specific to the
bofedal (where the greatest sampling effort was made) and some species from
surrounding areas. With this work that figure increases to a total of 86 species
of plants (vascular and non-vascular), reported for the Silala area (Table 5).
The increase is explained by a greater sampling effort. It is important to note
that many of the reported species have some degree of threat (Table 5).
In the Silala, 86 species have been registered, in 65 genera of 35 families
(Figure 12). The most diverse family is Poaceae, with 23 species; followed by
Asteraceae with 15 species, and then Cyperaceae (with 6 species) (Table 5).
At the level of genera, the most diverse is Deyeuxia, with 11 species, followed
by Festuca and Senecio with 4 species each, and Werneria, Pycnophyllum
and Parastrephia with two species each, the rest of genera have only one
representative (Table 5).
36
43
37
Table 5. Species of plants registered in Silala until May 2018. The categorization of species corresponds to: 1
= typical ofbofedal; 2 = transition zone between the bofedal and the dry zone; 3 = dry zone; 4 = salinized areas;
and 5 = only in water courses and springs. The column "Code" indicates the abbreviation used in the abundance
range graphs and the column "Threat category" indicates whether the species has any degree of threat, according
to the red book of plants of Bolivia (Ministry of Environment and Water, 2012).
Family Species
Apiaceae Azore/la compacta
Lilaeopsis macloviana
Mulinum ulicinum
Araceae Lemna minuta
Asteraceae Baccharis to/a var. viscosissima
Comp.
Leucheria daucifolia
Oriastrum revolutum
Parastrephia lucida
Parastrephia quadrangular is
P erezia purpurata
Senecio
Senecio adenophyllus
Senecio chrysolepis
Senecio puchii
Werneria apiculata
Werneria glaberrima
Werneria pygmaea
Xenophyllum incisum var. incisum
Brassicaceae Descurainia myriophylla
Menonvillea virens
Mostacillastrum dianthoides
Petroraveniafriesii
Bryaceae Bryum
Cactaceae Cumulopuntia boliviana
Calyceraceae Calycera pulvinata
Campanulaceae Lobelia oligophylla
Caryophyllaceae Arenaria digyna
Colobanthus quitensis
Pycnophyllumbryoides
Pycnophyllum macropetalum
Cyperaceae Carex cf maritima
Eleocharis atacamensis
Phylloscirpus deserticola
Schoenoplectus californicus
Zameioscirpus atacamensis
Zameioscirpus muticus
Code
Acom
Lmac
Muli
Lmin
Btol
Ldau
Orev
Plue
Pqua
Ppur
Sade
Sehr
Spuc
Wapi
Wgla
Wpyg
Xinc
Dmyr
Mvir
Mdia
Pfri
Cbol
Cpul
Loli
Adig
Cqui
Pbry
Pmac
Cmar
Eata
Pdes
Seal
Zata
Zmut
Categorization
3
1
3
5
3
3
3
3
3
3
3
3
3
3
1, 2 and 3
3
1 and2
2
3
3
3
1 and2
1
3
3
1
1 and2
1 and2
3
3
1 and2
1
1
5
1
1
Threatened
Species
ENDANGERED
VULNERABLE
ENDANGERED
ENDANGERED
44
38
Family Species
Ephedraceae Ephedra breana
Fabaceae Adesmiaspinosissima
Gentianaceae Gentiana gayi
Haloragaceae Myriophyllum quitense
Hydrophyllaceae Phacelia nana
Indet. Indet.
Juncaceae Juncus stipulatus
Luzula vulcanica
Oxychloe andina
Loasaceae Caiophora coronata
Malvaceae Nototriche auricoma
Montiaceae Calandrinia acaulis
Nostocaceae Nostoc
Onagraceae Epilobiumdenticulatum
Orobanchaceae Castilleja pumila
Oxalidaceae Oxalis pycnophylla
Phrymaceae Mimulus glabratus
Plantaginaceae Plantago tubulosa
Poaceae Aciachnepulvinata
Anatherostipa bomanii
Deyeuxia
Deyeuxia breviaristata
Deyeuxia chrysantha
Deyeuxia chrysophylla
Deyeuxia crispa
Deyeuxia curvula
Deyeuxia eminens
Deyeuxia eminens var. eminens
Deyeuxia filifolia var. festucoides
Deyeuxia nitidula
Deyeuxia spicigera var.
cephalotes
Dielsiochloafloribunda
F estuca chrysophylla
F estuca orthophylla
F estuca potosiana
Festuca rigescens
Gram.
Nassella a.ff. rupestris
Pappostipafrigida
Poa lepidula
Puccinelliafrigida
Code
Ebre
Aspi
Ggay
Mqui
Pnan
Jsti
Lvul
Oand
Ccor
Naur
Caca
Eden
Cpum
Opyc
Mgla
Ptub
Apul
Abom
Dbre
Dchr
Dchr
Dcri
Deur
Demi
Demi
Dfil
Dnit
Dspi
Dflo
Fehr
Fort
Fpot
Frig
Pfri
Plep
Pfri
Categorization
3
3
1 and2
3
3
1
1 and2
1
3
3
3
5
3
1 and2
3
3
1 and2
3
3
3
1
3
3
3
5
5
3
3
1 y2
3
3
3
3
1
3
1 and2
3
4
Threatened
Species
ENDANGERED
VULNERABLE
IN DANGER
VULNERABLE
45
Regarding the diversity of plants for the South Lipez Province, based on a
bibliographic review and the database of the National Herbarium of Bolivia,
a total of 41 families, 93 genera and 196 species have been registered (Figure
12). In this context, the flora of Silala comprises 85% of the families, 70% of
the genera and 44% of the species of the entire South Lipez region.
Of the total species registered in Silala, and after comparing the species with
the data from the catalog of vascular plants of Bolivia (Jørgensen et al., 2014),
17 species are new records for the Department of Potosi (Table 6) and two of
these are new records for Bolivia (Menonvillea virens and Mostacillastrum
dianthoides), both of the Brassicaceae family. These species were confirmed by
the Brassicaceae family specialist, Diego Salariato.
39
Family Species
Potamogetonaceae Stuckeniapectinata
Pteridaceae Argy roe hos ma nivea
Ranunculaceae Ranunculus un iflo rus
Rosaceae Polylepis tarapacana
Salviniaceae Azollafiliculoides
Solanaceae Jaborosa squarrosa
Valerianaceae Valeriana petersenii
Verbenaceae Junellia pappigera
Code
Spec
Aniv
Runi
Ptar
A:fil
Jsqu
Vpet
Jpap
Categorization
5
1 and2
5
2
5
3
3
3
Threatened
Species
VULNERABLE
Source: Own elaboration based on field data and the records of Palabral et al., (2016).
250
196
200
150
100
93 86
65
so 35 41
0
Family Genus Species
Silala Sud Lipez
46
By categorizing the species registered in the bofedales, according to the place
where they can generally develop, we find that there are more species typical
of dry places (18), than typical species of bofedal (13). Eight generalist species
were recorded, which can be found in bofedales as well as in transition zones,
which have lower humidity and could become dominant species in meadows.
Seven other species are only found in water courses and springs, a species
found only in transitional zones and a species that develops only in saline areas
(Table 5).
Eight species present in the Silala region are in some category of danger: four
in the category IN DANGER and four as VULNERABLE (Figure 13). In
relation to South Lipez there are eleven species IN DANGER and seven in
VULNERABLE.
40
Table 6. New species records for the Department of Potosi. The species that are also new record for
Bolivia are highlighted with an asterisk.
Pctroravenia friesii
A renaria digy11a
Drycuxia Jilifoia
var. Jest11coidcs
Familia
Brassicaceae
Campanulaceae
Cmyophyllaceae
Cyperaceae
Gentianaceae
Juncaceae
Plantaginaceae
Poaceae
Potamogetonaceae
Rannnculaceae
Salviniaceae
Solanaceae
Especie
Me11om·illea 1'ire11s *
lvfostacillasrm111 dim,rhoiiles *
Petrornvenia ji-iesii
Lobelia oligophylla
Are11aria digyna IJJbclia o!Jgopl?Jlla
Ph_1-llosci1p11s desenicola
Ge11timw ga_,-;
J1111c11s s ripularus
Lu=ula ndcm,ica
Plantago r11b11losa
Deyeuxia filifolia var. fes rucoides L,11z1tla 1111/canica
Dev euxia 11itid11/a
Deye11xia spicigera var. cephalores
Str1cke11ia pecti11ara
Ra111111cu/11s 1111iflorus
.4-=olla filiculoides
Jaborosa sq1,arrosa
Drymxia lfitidula
47
Fauna
Macro-invertebrates
A total of 13,765 individuals were collected and 26 taxa could be identified.
60% correspond to the Insect Class, of which five taxa correspond to Ephemeroptera,
Plecoptera and Trichoptera (EPT). The remaining 40% corresponds to
other invertebrates: Amphipoda, Oligochaeta, Hirudinea, Nematoda and Trematoda
(Table 7). All the taxa mentioned in the table are new records for the area.
41
12 --1-l
10
8 7
6
4 4
4
?
0
No. of species, Sud Lipez \lo. species, Silala
ENDANGERED VULNERABLE
Figure 13. Number oftlJreatened species in South Lipez and Silala.
Order/Group Famih.· Sub-family. Ccnrc
Plecoptera Gripopterygidae Claudiopalo
F.vliemeroptera Raeti<bie A11desiop~
Tric/wptera Hydroptilidae ;l,fetridiia
Neottichia
Hvdrobiosidae Cail/mm,
Hemipti~·c, Corixi<la~ Ectemno.viel{ll
Coleop1era Flmidae Austrelmis
Diptem Chironomidae Diamc;illac Pamhevtaf!fia
Ta11ypodi11ae
Orthocladiinae Co1:i,:nrmeura
Onhodadiinae
C'hirnnmninae T!111vtars1i,
Simuliidae Simufillm
Limoniidae Jlexa1uma
Dolichopodidae
Tabanidae
Fmpididae
FDhydricme
Amphipod,1 I Hyallclidac Jlyalhda
Oligochaeu, Naididae Dem
Naididae Homochae/11
Fn~h vlraeidae
Hirudiea Glossiphonidae
48
Ichthyofauna
The aquatic systems of Silala are characterized by a basic pH, which varies
between 8.31 and 8.41; relatively low temperatures (16 to 17 ºC measured at
noon); low conductivity (255 - 267 μS) and presence of dissolved solids (128
- 139 ppm) (see Table 3).
Only one species of fish was recorded in the area, the trout (Oncorhynchus
mykiss), a species widely used in fish farming activities in the high Andean
area of Bolivia.
Although in systems of the southern Altiplano in Bolivia and in the north of
Chile, records of Orestias and Trichomycterus species, native to the Andean
region, are known. During the current campaign, no native species were
recorded in Silala. We do not have an explanation for the absence of native
fish in Silala, since these have been recorded in several sites not far from the
Silala bofedal (Figures 21 and 22). The nearest towns in which populations of
Orestias are found are between 65 km (Ascotan salt flat, in Chile) and the towns
of Alota and Quetena in South Lipez (approximately 71 km). In closer systems
such as Pastos Grandes or Laguna Colorada, there are no records of fish.
Considering the characteristics of the aquatic systems of the Silala area (mainly
the presence of highly degraded bofedales) and the water quality, it is presumed
that there were favorable conditions for the presence of Orestias species in that
area. Currently, however, most systems have been modified by the presence
of canals. The velocity of water in this type of systems, despite the presence
of vegetation, is a strongly limiting factor for the current presence of Orestias
species, which are mainly associated with lentic systems (bofedales). When
this native species is found in running water systems, it is associated with
areas of stagnated water (pothole), with presence of vegetation and low current
speed. One of the important problems to evaluate is the introduction of species
(such as trout), usually associated with the introduction of parasites such as
the white spot disease or Ich (Ichthyophthirius multifiliis) or the saprophyte
Saprolegnia difilis, which can have effects on populations of native species of
fish and amphibians (Wurtsbaugh & Alfaro 1988).
Populations of Trichomycterus species were recorded in aquatic systems of the
southern Altiplano of Bolivia and northern Chile and Argentina (Figure 14).
The closest towns to the Silala in which populations of Trichomycterus were
registered are approximately 71 km away, in the area of Alota and Quetena
in southern Bolivia. Considering the current characteristics of the Silala’s
aquatic systems (mainly the presence of canal systems with running water)
and the water quality, currently there are favorable conditions for the presence
of species of the Trichomycterus genre in the area. In general, species of this
genre are considered indicators of running water systems (rivers and streams).
The absence of Trichomycterus species allows us to speculate that the zone
included mainly lotic systems (bofedales), in which the presence of said genre
is less likely.
42
Nematoda Do1ylaimidae Dorylaimus
Trematoda Dugesiidae Dugesia
Hydracarina
49
43
Silala y puntos cercanos de muestreo de Orestias
1o·o·o·w 68°D'0'W 66°D'0'W 64°o·o·w
~ ~
pb -H--J-------,~ .-=-------ba,--------a--;------,,=---P-~--~,--------t---+-+ pb
w w
~ ·ro ~
b u b
b -tt-- ---m- ---=-=------i----------t---r~~-----t---i-T b o a. o
N ~ N
~ Powsi
•
Antofagasta
~ ~
b b o ------------~------..,_--------+-+--~o
~ ~
N N
1o·o·o·w
Leyenda
• Orestias
• Silala
D Bolivia
LJChile
D Argentina
68°o·o·w 66°0'0'W 64°o·o·w
0 37,5 75 150 225 300
Kilometers
1 :4.000.000
Figure 14. Distribution map of Orestias species in the southern Altiplano of Bolivia and northern Chile. Map
prepared by A. Mariscal with data from the collections of the National Museum of Natural History.
50
Herpetofauna
In the four days of sampling, it was possible to register only one species of
amphibian (Rhinellaspinulosa), which was observed frequently along the
bofedales (n = 33 observations, Fig. 42), and two species of reptiles: Liolaemus
puna, distributed mainly in the areas of rocky slopes of the northeast slope (n =
9), and Liolaemus schmidti (n = 1) that was observed in an area of scrublands
(Fig.42). None of the registered species is found in the Red Book of Vertebrates
of Bolivia, nor is it an endemic species, but all three are listed in the category
“Deficient Data (LC)” of the IUCN (Table 8).
In the last decades, the local disappearance of the Rhinella spinulosa toad in
other areas of the Bolivian Altiplano has been seen with concern. Reason why
we consider very important for its conservation the registration of a population
of this species in the Silala area and it would be important to generate actions
in order to guarantee its conservation in this area.
44
Silala y puntos cercanos de muestreo de Trycomicterus
70°0'0'W 68°0'0'W 66°0'0'W 64°0'0'W
<J) <J)
b b
p ++--+----'"--'c----+----.'-,-=--+"------r-t--+p
~ ~
<J)
b ·ro
(.)
<J)
b
b ++-- -----~- -+-------+---l-'-'--"---1--1-+o
0 a.
N I!!
0
N
~
Q
<J)
b p
<J)
b
-j-j---------11---- -;;as;------t----t-'c--:~',----t,--t-p
N
N
Antofagasta
N
N
<J) <J)
b b
o ++-------+--+----=-r--+---!'---r--------+-t--+o
~ ~
70°0'0'W
Leyenda
• Silala
T rychomicterus
LJBolivia
LJChile
LJArgentina
68°0'0'W 66°0'0'W 64°0'0'W
150 225 300
1 :4.000.000
Figure 15. Distribution map of Trichomycterus species in the southern Altiplano of Bolivia and northern Chile.
Map prepared by A. Mariscal with data from the collections of the National Museum of Natural History.
51
45
Figure 16. The Rhine/la spinulosa toad, with an abundant population in the area. a) Female, b) Male (Photos L.
Zegada).
Table 8. List of amphibian and reptile species captured in the Silala locality.
RELATIVE UICN
ABUNDANCE CATEGORY
ORDER/FAMILY GENRE SPECIES HABITAT
ANURA
Rhine/la Rhine/la spinulosa Bofedal F LC
Bu onidae
SAURIA
Liolaemidae
Liolaemus Liolaemus puna Roquedal F LC
Liolaemus schmidti Scrubland C LC
Relative abundance: Common (C); Frequent (F); Rare (R); Exceptional (E). Deficient Data (LC)
52
Through a review of the published and relevant information, it has further been
possible to observe the presence of the Liolaemus pachecoi in rocky hillsides
(Palabral-Aguilera et al. 2016) of the Silala area. Similarly, considering the
possible distribution according to the environmental conditions and the types
of habitats present in the area, the species that are likely to be found in this area,
with additional work efforts, are: Telmatobius huayra, an amphibian endemic
to Bolivia and found in the Vulnerable category in the Red Book of Vertebrates
of Bolivia; the Tachymenis peruviana snake of wide distribution and presence
in these regions of the Altiplano, and the Liolaemus hajeki lizard, registered
on the other side of the border, in the Silala basin itself. Likewise, the presence
of some other species of the Liolaemus genre cannot be ruled out, which is the
most representative within the herpetofauna of the region.
Avifauna
According to the rarefaction curve and the Chao index (30.5 ± 3.5),
in the 2018 sampling > 70% of the avifauna in the Silala area was
recorded. During this study 389 individuals were observed, of 26
46
a) b)
c) d)
Figure 17. a) Liolaemus schmidti (Photo Ariel Liully); b) L. schmidti, which is abundant in the scrublands
of the area (Photo L. Zegada); c) Liolaemus punafound on rocky hillsides (Photo L. Zegada); d) Liolaemus
pachecoi present in in the rocky areas, which are used as refuge (Photo: Tamara Perez).
53
bird species. The greatest abundance of birds was observed in the bofedales,
with 180 individuals (101 records), followed by the rocky places with 122
individuals (74 records) and pastures with 79 individuals (41 records) (Table
9). Nine of the 26 species were recorded only in one type of habitat, with two
or more records and could be considered as habitat specialists. Six of these nine
species were observed
only in bofedales: including two species of ducks (Anas flavirostris, Lophonetta
specularioides) (Figure 17A), species that depend on bodies of water, such as
the White Wing Remolinera (Cinclodes atacamensis), species that use cushions
and other vegetation in the bofedales, such as the Ochre-Naped Ground
Tyrant (Muscisaxicola flavinucha), the Andean Negrito (Lessonia oreas), and
the Rufous- bellied seedsnipe (Attagis gayi) (Figure 17). Three other species
were observed only in rocky outcrops: two species of raptors (Falco femoralis,
Geranoaetus polyosoma) and the Gray-faced Goldfinch (Sicalis uropygialis).
Five species were recorded in three habitats and can be considered as habitat
generalists: cordilleran canastero (Asthenes modesta) (Figure 17 E), and Finches
(Phrygilus atriceps, Phrygilus dorsalis, Phrygilus plebejus and Phrygilus
unicolor) (Figure 17 F-H), which were observed in large numbers feeding on
seeds in different habitats.
More than 80% of the individuals observed in the Cream-winged Cinclodes
(Cinclodes albiventris) (Figure 18) and the Grey-breasted Seedsnipe (Thinocorus
orbignyianus) (Figure 17 B) were recorded only in the bofedales, while the
Rufous-naped Ground Tyrant (Muscisaxicola rufivertex) was only observed
in the rocks, capturing insects; thus, these three species could be considered
as almost habitat specialists (Table 9). It is highlighted the abundance of the
different species of Finches (Phrygilus atriceps, Phrygilus dorsalis, Phrygilus
plebejus and Phrygilus unicolor), that were observed feeding on the seeds of
grasses in the bofedal. The presence of these grasses between the cushions of
the bofedal indicates some degradation of the habitat. Both Phrygilus atriceps
and Phrygilus dorsalis are found in different habitats, including pastures and
bofedales; on the other hand, Phrygilus plebejus and Phrygilus unicolor are not
typical species of bofedales and are observed in pastures and bushes (Herzog
et al., 2017).
Together with the observations made during 2016 (Palabral-Aguilera et al.), a
total of 35 species of birds have been recorded in Silala. Four families are the
dominant ones (with the largest number of species): Thraupidae (5 species),
Furnariidae (5 species), Tyrannidae (5 species) and Anatidae (4 species) (Table
9). Two species registered in the Silala are under threat categories, the Darwin’s
rhea (Rhea pennata) (considered In Danger in the Red Book of Vertebrates
of Bolivia) and the Diademed Plover (Phegornis mitchellii) (considered Near
Threatened in both the Red Book of Vertebrates of Bolivia, and the Red List of
IUCN) (Figure 17 C). Six species are considered endemic to the Central Andes
zoogeographic region (CAN). Seven species have migratory movements, the
Baird’s sandpiper (Calidris bairdii) (Figure 17 D) and the Solitary Sandpiper
(Tringa solitaria) are boreal migrants, the Rufous-naped Ground Tyrants
(Muscisaxicola flavinucha, Muscisaxicola cinereus and Muscisaxicola
rufivertex) are southern migrants and the Andean Negrito (Lessonia oreas) has
altitudinal movements (Table 9).
47
54
48
Table 9. List of birds registered in the Silala.
FAMILY SPECIES
BOFEDAL
Rheidae Rhea pennata
Tinamidae Tinamotis pentlandii
Anatidae Oressochen melanopterus X
Lophonetta X
svecularioides*
Anas jlavirostris* X
Anas georgica
Columbidae Metriopelia aymara
--
Trochilidae Oreotrochilus estella X
Charadriida Phegornis mitchellii
e
Scolopacida Calidris bairdii
e Tringa solitaria
--
Thinocorida Attagis gayi* X
e Thinocorus orbignyianus X
Laridae Chroicocephalus
serranus
Ardeidae Egretta thula
--
Accipitridae Geranoaetus polyosoma *
Falconidae Phalcoboenus
me~alopterus
Fa/co femoral is*
Psittacidae Psilopsiagon aurifrons
--
Fumariidae Geos itta punens is
HABITAT
UICN
PASTURE ROCKY (2018)
OUTCROPS
X
-- --- -
-- --- -
X
-- -
NT
-- -
X
-
-- --- -
X
X
X
-- --- -
X
CONSERVATION CONDITION
Red Book
of Bolivia
(2009)
EN
---
---
---
NT
---
---
---
---
Endemic
CAN
X
X
--
--
--
--
--
--
X
MIGRATORY
Boreal Migration
Boreal Migration
SOURCE
2
1
1, 2
1, 2
1, 2
2
1
1
2
2
2
1, 2
1, 2
1, 2
2
1, 2
1, 2
1
1
1
55
49 HABITAT
UICN
FAMILY SPECIES
BOFEDAL PASTURE ROCKY (2018)
OUTCROPS
Ochetorhynchus X
ruficaudus
Cinclodes albiventris X X
Cinclodes atacamensis* X
-- -- -
Asthenes modesta X X X
Tyrannidae Lessonia areas* X
Muscisa:xicola cinereus
Muscisa:xicola X
flavinucha *
Muscisa:xicola rufivertex X X
Agriornis montanus X
Thraupidae Sicalis uropygialis * X
Phrygilus atriceps X X X
-
Phrygilus dorsalis X X X
Phrygilus unicolor X X X
-
Phrygilus plebejus X X X
Fringillidae Spinus atratus X X
---
Legend:
* Habitat specialists (species registered only in one type of habitat with two or more records).
Threat Category: EN (Endangered), NT (Near Threatened)
Endemic CAN: Endemic of Central Andes zoogeographic region (CAN) (Stotz et al., 1996)
Source of Information: 1. Registration during 2018 assessment; 2. Report (Palabral-Aguilera et
al., 2016)
--
CONSERVATION CONDITION
Red Book
of Bolivia
(2009)
---
---
---
Endemic
CAN
--
X
X
X
--
MIGRATORY
Attitudinal
migration
Partial
austral
Migration
Austral Migration
Partial
austral
Migration
Attitudinal
migration
SOURCE
1
1, 2
1, 2
1, 2
1, 2
2
1, 2
1
1
1
1, 2
1, 2
1, 2
1
1, 2
56
50
B)
D
E)
Figure 17. Birds observed in the Silala bofedales. A) Lophonetta specularioides B) Thinocorus orbignyianus; C)
Phegornis mitchellii; D) Calidris bairdii; E) Asthenes modesta; F) Phrygilus unicolor; G) Phrygilus atriceps; H)
Phrygilus dorsalis (Photos: Omar Rocha).
57
Mastofauna
In relation to medium and large mammals, the presence of southern viscacha
(Lagidium viscacia) was visually evident in the area, mainly in the cliff of the
North Bofedal and vicuñas (Vicugna vicugna) in the South Bofedal. In addition,
viscacha feces were found in the Central Canal and in the South Bofedal, near
the rocky outcrops. In the Central Canal, bone remains of tuco-tuco (Ctenomys
sp.) were found, but the species cannot be identified. In this canal there were
a large number of dens, possibly associated with these rodents. We also found
feces and bone remains of Andean fox (Lycalopex culpaeus) in the North
Bofedal and Central Canal, as well as bone remains of vicuñas, which could
indicate the presence of pumas in the area.
Until this study, there was no report of the micro-mammal species for the area.
With a total effort of 681 traps per night, 94 individuals were captured, giving a
capture success of almost 14%; which is quite high, considering that the average
capture success is 10%. (http://www.openepi.com/v37/SampleSize/SSPropor.
htm). However, most of the individuals collected correspond to two species.
The North Bofedal is the site with the largest number of individuals captured (67
individuals and a capture success > 30%), belonging to four genera (Phyllotis,
Tapecomys, Calomys, Abrothrix, all Cricetidae). In the Central Canal, 23
individuals were captured (capture success > 9%), belonging to the same four
genera of the North Bofedal. The South Bofedal was the site with the least
capture success (2%), with only four individuals captured belonging to two
genera (Calomys, Abrothrix). The genus with the highest number of captures
was Phyllotis and Calomys had the least number of individuals captured (Figure
19).
51
A)
Figure 18. Birds observed in the Silala bofedales. A) Cinclodes albiventris; B) Oressochen melanopterus (Photos: M.
Isabel Gomez).
58
Within the Phyllotis genre two species were identified (P. xanthophygus ->
85% of the captured individuals and P. cf. xanthophygus), which are typically
high Andean, common near sites with rocky outcrops (Anderson, 1997) (Figure
20). The species P. xanthophygus (Figure 21a) is generally associated with
scrublands and tola formations, in addition to stony areas, which could explain
its great relative abundance in the North Bofedal.
The presence of Abrothrix andinus is registered for the area of Los Lipez (Anderson,
1997), for which we suppose that the two specimens collected in the
North Bofedal belong to said species (Figure 21b). In addition to this species,
19 individuals of the Abrothrix genre were captured, but their taxonomy is
not clear, although it is clear that they do not correspond to Abrothrix jelskii,
a species that would be expected to be found in the area (Figure 20; D’Elia et
al., 2015). For Bolivia, only these two species of Abrothrix are registered (Anderson,
1997), so it would be very important to fully determine the identity of
the other 16 specimens, which morphologically seem to represent four species
(Figure 21c, d, e, f).
The presence of Tapecomys wolffsohni (Figure 21g) extends its range of distribution
(described for this species by Anderson, 1997), since their previous
records reached only 2,800 meters above sea level. Despite being the second
most abundant species in the area (Figure 20), very little is known about its
biology and ecological aspects.
Regarding individuals of the Calomys genre, five individuals were identified as
Calomys musculinus (Figure 21h), whose presence had already been registered
southeast of the Department of Potosi; even at more than 4,000 meters above
sea level (Anderson, 1997). It is possible that Calomys Lepidus is also found
in the area, since this is a species that can be found at more than 4,000 meters
above sea level (Anderson, 1997).
Andean mouse (Andinomys edax) is a monotypic species that could be found
in Silala, since it inhabits mountainous areas of Potosi and Chuquisaca, at more
than 3,700 meters above sea level; although there are no records in the drier
part of Potosi (Anderson, 1997). Another species that could be found in the
Silala area is the Andean big-eared mouse (Auliscomys sublimis), 52
Abundance of the four genera of
rodents of Silala
24
■ Phyllotis Tapecomys ■ Calomys ■ Abrothrix
Figure 19. Pie chart showing the abundance of the four genera found in Silala.
59
which is common over 3,800 meters above sea level. It lives near bofedales,
associated with rocks and vegetation of low bearing and scrublands; and can
get to use the tuco-tuco (Ctenomys) tunnels.
53
Phyllotis xanthophygus
Phyllotis cf. xanthophygus - Tapecomys wolffsohni
Calomys musculinus - Abrothrix and in us - Abrothrix spl = Abrothrix sp2
Abrothrix sp3
Abrothrix sp4 -0 5 10 15 20 25 30 35 40
Figure 20. Species of micro-mammals found in Silala. The bars represent the relative abundance (captures) of each of
the species.
60
54
Figure 21. Species of micro-mammals found in Silala. a) Phyllotis xanthophygus, b) Abrothrix andinus, c) Abrothrix
spl, d) Abrothrix sp2, e) Abrothrix sp3, t) Abrothrix sp4, g) Tapecomys woljfsohni, h) Calomys musculinus.
61
In summary, the wealth of species (flora and fauna) currently present in the Silala area
is as follows:
* Considering the four morph-types of Abrothrix as distinct species.
6.3 Determination of the actual area of the bofedales
In the study area, individuals of Oxychloe andina were found, which is a kind of
bofedal plant sensu strict (i.e., plants strongly adapted to water saturation, which
form peat-like soils, and which are rich in organic matter); and also species of
margin plants, referred to a more general type of wetland, that includes vegetation
from less organic soils and that does not form peat. In this sense, the current total
area of the bofedal is very limited and its spatial distribution is highly fragmented
in several sectors. The rest of the surface is covered by the other generalist species,
which indicates that the bofedal has undergone a process of drainage and regression.
In sum, the following types of vegetation were found: bofedal, mixed bofedal,
scrubland bofedal, wet scrubland, dry scrubland, meadow, grass, areas with saline
outcrops. In addition, portions without vegetal cover were found, with sandy soils
of volcanic origin, bare rock and organic matter without vegetation (Table 11).
Adding all types of soil cover, the total area of study in Silala covers 114,817 m2
(11.48 hectares) (Table 11). Most of the wetland corresponds to the South Bofedal
(87,892 m2), while the North Bofedales and Confluence Area are smaller (20,290
m2 and 6,635 m2, respectively). Of this total, only 7,680 m2 (0.76 hectares) correspond
to actual bofedal at present. In conclusion, it can be affirmed that 107,137
m2 (10.7 hectares) of bofedal have been lost due to canalization.
55
Table 10. Summary of the biodiversity recorded in Silala.
Taxonomic Group No of N°of N° of
total endemic endangered
species species species
for
Bolivia
Flora 86 1 9
Macro-in vertebrates ¥ 26 0 1
Fish 1 - -
Amphibians 2 1 1
Reptiles 4 - 2
Birds 35 - 2
Mammals 13* 1 1
New
records
for Potosi
17
15
-
-
-
-
#
New
records
for
Bolivia
2
1
-
-
-
-
#
N°of
typical
bofedal
species
13
6
-
-
-
19
0
. .
¥ In the case of macro-mvertebrates, the determmatlon 1s at the level of genera or farmhes, due to the the
difficulty of obtaining codes for Bolivia.
62
Although the largest bofedal is the South Bofedal, it is the one that is most affected,
followed by the Confluence Area. Both bofedales have a dominant presence
of generalist species, which form scrublands or meadows.
In conclusion, taking into account that: 1) a bofedal has peat-like soils, which
have plant material that is not completely decomposed, and 2) only certain
plant species, such as Oxychloe andina and, to a lesser extent, Zameioscirpus
atacamensis, form this type of soils. It can be concluded that the bofedal area
identified in the study area is highly degraded and fragmented because it is surrounded
by scrublands and other types of vegetation, which indicate draining
processes.
6.4 Calculation of the bofedal area in the present and recent past
Throughout the study area there are artificial canals built during the last century.
These canals continuously diverted the water that naturally irrigated from
the bofedal, modifying the natural hydrological conditions of the region, causing
the drainage of the soils and changes in the vegetation. The process of
invasion of scrubland and meadow species is a result of this draining process.
According to the floristic and spatial analyzes of the study area, the three areas of
the Silala were at one time large and continuous peatlands that covered practically
the entire area of the three plains analyzed (North, South and Confluence).
This is supported by the fact that, in all the margin of the study area, there are
isolated individuals of bofedal plants (Oxychloe andina) (Figure 23). These
individuals grow by rhizomes, that is to say that they reproduce mainly in a
vegetative way through the prolongation of subterranean stems. For this reason,
it can be affirmed that these isolated groups could not appear individually, but
they had to have conformed at some time in the past a continuous structure or
much less fragmented than what is observed in the present. For this reason,
it can be affirmed that the true bofedal area was much wider in the past. The
56
Table 11. Surface area (m2
) of the different Silala bofedal fragments.
Type of vegetation South A South B South C South D SouthE SouthF North Confluence Total
Bofedal 2.512 2.310 1.779 6.601
Scrub land Bofedal 151 584 735
Fragmented Bofedal 68 177 99 344
Scrubland 53 6.149 3.864 5.134 14.750 13.522 6.214 49.686
Meadow 2.447 12.802 3.820 19.069
Mixed Meadow 6.073 781 3.957 10.811
Grass 7.811 2.222 10.033
Saltpeter bed 2.878 2.878
Bare soil 12.463 22 65 239 558 408 322 14.078
Aquatic Vegetation 582 582
Sector Total 23.205 6.246 9.153 10.398 10.130 28.760 20.290 6.635 114.817
Source: Own elaboration based on field data and satellite images.
63
satellite images analyzed by DIREMAR indicate that this sector is dry at least
since 1975 (the year in which the Landsat satellite began capturing images of
the Earth) (DIREMAR 2017).
The absence of images or photographs makes it impossible to know the exact
date when was the last time the dead plants in this sector were wet and vigorous.
However, a comparison of aerial-photogrammetric flight images of 1967 and
2001 suggest that the bofedal was dry since 1970 (Figure 22). This shows that
the bofedal was almost completely dry since the 60s. It can be seen in the same
figure that the canals were clearly defined, and they were the cause for the
degradation of the bofedal.
Figure 22. Detail of images of the South Bofedal during 1967, 2001, 2004 and 2016. Note that
the images correspond to different seasons of the year (1967, 2001, 2016 wet season) and 2004
(dry season). The images of 1967 and 2001 correspond to aero-photogrammetric flights and
have a spatial resolution of 1 meter. The images of 2004 and 2016 correspond to Quick Bird
II satellite images of 0.5 meters of spatial resolution and true color combination. The recovery
of vegetation in 2016 is evident, though minimal. Source: Satellite Images: DIREMAR 2017.
Aerial photographs: Photographic Archive of the Military Geographical Institute (MGI) –
Bolivia.
57
Tahle 12. Values of the potential areas of the hotedal (m2
) in 21Xl4, in 2016, and the maximum extension that could
have been reached before 1975.
Bofedal South A South B South C South Il South E South F North Confluence
Maximum po~~ihle
23.205 6.246 9.153 10.398 10.130 28 759 20.291 9.752
extension•
2004** 0 63 0 1.247 1174 0 2.012 107
2016*** 0 151 0 2.5 12 2.3 IO 68 2.540 99
• According to flora and landscape indicators, it is estimated that the area of the hotedal covered this area.
•• Year wilh lhe oldesl high resolulion image.
• •• Y car with the high rcsolulion image in the most rcccnl wcl season.
Sm,,.,.,,_. Own e/nhomfio11 hnied m, high rl'solutio11 imagl'i /TJTR F.MA R 1()/ 7), a11d field dnta co/lec1im1.
Total
117.934
4.60J
7.679
64
58
Ano 2004
Cambio de cobertura del Bofedal Silala
is '\so _ Joo 450 600
· - Mettos
'~, _
/
Cobertura Bofedal
Bofedal 2004
- Bofedal 2016
N ~
~~<~
~
1\1 ,.~
'~ ·1· -,----1-1
Figure 23. Potential area of the bofcdal in the past {black contour). In 2004 (yellow fill) and in 2016 {blue fill). Source: Own elaboration based on high resolution images (DIREMAR 2017).
65
In conclusion, the presence of isolated individuals of Oxychloe throughout the
entire margin of the study area is a landscape indicator that the bofedal could
occupy the entire surface that today occupies the scrublands, meadows and
grasses. If we consider that Oxychloe only grows in conditions of permanent or
semi-permanent water saturation, it can be affirmed that, the bofedal regression
process allowed the invasion of other species, which survive better in drier
conditions, due to a significant decrease in water supply. This decrease is
clearly related to the construction of the canals, because elements that altered
the natural drainage of the bofedal can be recognized. The result was a degraded
area, with artificial drainage in the form of a fishbone.
6.5 Current conditions of the Silala bofedales.
For its altitudinal range (between 4100-4300 meters) and for the species present,
the Silala bofedales are considered high Andean.
Botanical description of the Silala bofedales
In Silala, fragments were delimited according to the physiognomy and the
dominant plants (see methodology). The following describes the flora of each
fragment of the South Bofedal, North Bofedal and Confluence Area, which are
related to the vegetation map (Figure 24).
59
66
60
Sectores
_ S_AO
_ S_A1
_ S_A1b
S_A2
S_A3
S_B
s_c
S_D
_ S_E
_ S_F
-- NConfluenc ia
N
A
--==16-5-==~3•0-----■8c60::=====9=90-------1 ,3~euos
Figure 24. Differentiation of the fragments in the North Bofedal, South Bofedal and Confluence Area. The characteristics of the fragments are detailed in table
67
61
Table 13. Coverage of species and abiotic elements found in the different fragments of the Silala bofedal. These fragments were differentiated at the landscape level on basis of their
physiognomy.
Surface Percentage
Area Altitude Gradient Organic Percentage of
of coverage Percentage
Fragment Species m2 m % matter coverage of
of other
species, as abiotic
cm common to elements
bofedals
an
degradation
Deserted areas (before Xenophyllum incissum var. Unavailable 3
the road) (S AO) incissum Deyeuxia curvula 2
Junellia
1444 4410 <1%
I
pappigera >I
Nototriche >l
auricoma 95
Nase/la aff.
rupestris
Bare soil
Open meadow in which Sandy soil 45.5
the Deyeuxia curvula
species predominates Saline outcrop 3
(following the road) Stone I
(S_Al) Camelid feces 6208 4409 <1% Unavailable 0.5
Deyeuxia curvula 45
Xenophyllum incissum var. incissum 2
Eleocharis atacamensis 3
Festuca potosiana >I
Salinized grass in which Bare soil 42
the Carex species and
Stone >I
isolated Oxychloe
cushions predominate Carex c£ maritima 5438 4409 <1% Unavailable 50
S_A2 Oxychloe andina 5
Deyeuxia curvula 2
F estuca potosiana I
Salinized grass in which Bare soil 7
the Carex species
Carex c£ 89
predominates S_A3 Unavailable
maritima 3761 4409 <1% 2
Deyeuxia 2
curvula >I
68
62
Meadow with isolated
cushions of Oxychloe
S B (below the fenced
water spring)
Low salinized grass
dominated by Carex cf.
maritima s_c species
(following SENAMHI's
gauging site)
Bofedal
S_D
Bofedal
S_E
Artificial canals
Oxychloe andina
Festuca
potosiana Carex
cfmaritima
Xenophyllum incissum var. incissum
Bare soil
Carex cf
maritima
Deyeuxia
chrysantha
Plantago tubulosa
Puccinellia frigida
Stuckenia pectinata
Xenophyllum incissum var. incissum
'Zameioscirpus muticus
Dry canals
Active canals
Bare soil
Organic matter, dead Oxychloe
cushions
Carex cf. maritima
Deyeuxia chrysantha
Festuca potosiana
Festuca rigescens
Oxychloe andina
Plantago tubulosa
Puccinellia frigida
Ranunculus
Xenophyllum incissum var. incissum
'Zameioscirpus muticus
I
Active canals
Festuca rigescens
Oxychloe andina
6268 4407 <1%
Average:49.1
maximum: 74
minimum: 19
9170 4405 <1%
Average: 61.6
maximum: 86
minimum: 30
Average: 44.5
maximum: 64
10421 4403 <1% minimum: 25
I
89
67
>l
5
>l
>l
>l
30
40
55
20
IO
>I
>I
25
I
>I
2
2
4
IO
2
5
I
I
>I
>I
>I
>I
>I
69
63 Lemna minuta
I Unavailable
5
Stuckenia 10236 4394 2%
Lobelia oligophylla
Plantago tubulosa
Phylloscirpus deserticola
Xenophyllum incissum var. incissum I 2
Degraded bofedals Active Canals 49
- watercourse margins Organic matter 7
S_F
Stone 5 Unavailable
Submerged algae 28890 4382 1% 15
Ranunculus uniflorus 20
Deyeuxia chrysantha 4
Oxychloe andina >l
North Bofedal Active canals 2
(N) Water springs 2.5
Peat 0.5
Festuca potosiana 20
Deyeuxia eminens 10
Festuca chrysophylla Average: 111.1 20
Festuca ortophylla maximum: 268 20
Carex cf maritima 20373 4355 5% minimum: 20 >I
Festuca rigescens 5
Lobelia oligophylla >I
Aciachne >I
Oxychloe andina 15
Phylloscirpus deserticola I 3
'Zameioscirpus atacamensis 2
Confluence between the Canals 5
South and North Bofedal Organic matter I
(CONF) Sandy soil 0.5
Deyeuxia eminens 70
Deyeuxia spicigera 6678 4320 7% Unavailable 3
Festuca potosiana 10
70
64
Gramineas quemadas
Lobelia oligophylla
Phylloscirpus deserticola
5
3
3
71
South Bofedal fragments
Six fragments distinguishable at the landscape level have been delimited in this
area on basis of the physiognomic units of the vegetation (Table 13). The first
four fragments can be recognized in Figure 25.
Figure 25. Panoramic view of the first four fragments that can be distinguished at the landscape level
in the South Bofedal. The different color contours mark the different fragments. Red—Prairie with
isolated cushion plants of Oxychloe; blue—salinized Carex grass with isolated cushion plants of
Oxychloe; brown—salinized low grass of Carex cf. maritima; green—bare soil/saline outcropping]
65
72
This sector is physiognomically characterized by open areas, with 95 % of
bare and sandy soils 5% of vegetation cover, 3% of the Xenophyllum incissum
var. incissum—a species characteristic of lagoon margins and bofedals of the
southern region of Bolivia—and 2% of Deyeuxia curvula— species commonly
dominant at bofedal margins under drying out processes of the Xerophytic
puna. This sector also comprises species with a vegetation cover smaller than
the 1 %, such as Junellia pappigera, Nototriche auricoma, Nasella aff. rupestris.
These species are commonly found in dry and sandy plains and hillsides of Sur
Lipez.
Deserted areas (following the road)
Three different physiognomic units have been differentiated. These reflect a
visual gradient of desiccation, that range from very dry (S_A1), in the central
part, with fragmented cushions of the O. andina (S_A2) species surrounded
by species of Carex cf. maritima (S_A3). Each of these units is described below:
66
Deserted area S AO
Figure 26. Fragment of the deserted bofedal, before the road.
73
This fragment is physiognomically characterized by presenting 45,5% of Sandy
and bare soil, 3% of saline outcrops, 1% of stones, 0,5% camelid feces, a n d
50% of vegetation cover. The predominant species is the Deyeuxia curvula
(porke), covering 45 % of the area, followed by the Xenophyllum incissum var.
Incissum with 2%, Eleocharis atacamensis 3%, and the Festuca potosiana, with
a cover of less than 1%.
67
Open meadow with a predominance of the Deyeuxia curvula S_Al species
Figure 27. Deserted bofedals (following the road).
74
This fragment is physiognomically characterized by 58 % of total vegetation
cover, 42% of bare soil, and 0.1% of stone. The predominant species is the C.
cf. maritima, covering 50% of the area. This species can generally be found
in high Andean bofedals, covering less than 1% of the area. This sector also
comprises fragmented cushions of the O. andina species, reaching as much
as 5% of the total vegetal cover, Gramineae, such as the D. curvula, with a
coverage ratio of 2%, and F. potosiana,1%.
68
Salinized grass, where the Carex species and isolated Oxychloe cushions (S_A2) predominates
Figw·e 28. ViewoftheS_A2 fragment.
Figure 29. View of the S_A3 fragment.
75
This sector comprises dry Stone Canals. It is physiognomically characterized
by presenting 7% of bare soil and 93% of vegetation cover. The predominant
species is the Carex cf. marítima with a coverage ratio of 90%, followed by the
Deyeuxia curvula, 2%, the Xenophyllum incissum var. Incissum, 1%, and the
Puccinellia frigida less than 1% of coverage ratio.
Following a detailed examination of these species’ composition , the rankabundance
curves for the South Bofedal fragments (S) A1, A2 and A3 show
a similar species composition and abiotic elements (Figure 30). All of these
species have few elements and a high ratio of sandy soils (sare) and saline
outcrops (asal). The predominant species of sites S_A2 and S_A3 is the Carex
cf. marítima, though it takes a secondary predominance at the A1 transect,
following the Deyeuxia curvula. The three transects comprise Xenophyllum
incissum var. incissum (Xinc) species and Werneria pygmaea (Wpyg), to a
lesser extent. The presence of Oxychloe andina is an indication of the presence
of a bofedal and is found in the A2 fragment, with a low abundance ratio.
Figure 31 shows the different components, such as, soils, plants, and saline outcrops present
in a longitudinal profile that extends from A0 t o A3, which depicts a desiccation gradient that
ranges from very high to intermediate dryness.
69
0,0
S_A1 S_A2 S_A3
,
--0,5 ' <
-5
'
-1 ,0 a.
0
~
0)
..Q
-1 ,5
Figw-e 30- Rank-abundance curves for the flora found in the trnnsects of fragments Al, A2 and A3, within
the South Silala Bofedal.
76
Meadow comprising isolated cushions of the Oxychloe - S_B species (below
the fenced water spring)
This bofedal is surrounded by Festuca potosiana and Deyeuxia curvula, and
comprises canalized springs and dispersed cushions of Oxychloe andina, of a
diameter of 1 x 1 m and 0,5 x 0,5 m. This fragment comprises 10% of manmade
canals and 90% of vegetation, where the Carex cf. maritima predominates with
89 % of coverage ratio, followed by the Oxychloe andina (1%) and the Festuca
potosiana and Xenophyllum incissum var. incissum (less than 1%). Note that
water springs are absent in this sector.
70
0 J,.,,,,,., P.,ft/'IX""
@ n,_wttrm l'IIP'lwl,,
@ x,,,opJnH,.,n ,,,,,.,,.,,,
@ Ajlo,u,..,,nto ~,/,,,.
© c,, ,.,.,.q.,.,,,,,,,..,11
@o.,;_i,Jrl<>r;,,,,1,,,.,
(!) l-}$/'lt.,p,.,10,,,,,.,,
@ £i'«J,..,r11, .,,..,...,_,,,,,,
Sector desertico (A)
l
Figure 31. Longitudinal profile of the A sector. Schematics of the main vegetation components and abiotic
elements.
Figure 32. View of the meadow that comprises isolated cushions of Oxychloe.
77
Low salinized grasses dominated by the Carex cf. maritima species
Physiognomically, this fragment comprises 25% of open, salinized soils and
75% of total vegetation cover. The predominant species is the Carex cf. maritima
( 67%), Deyeuxia curvula (5%), Xenophyllum incissum var. incissum
(2%), Festuca potosiana ( 1%), and Plantago tubulosa, Puccinellia frigida,
Stuckenia pectinata, Zameioscirpus muticus, Deyeuxia chrysantha (less than
1%). The area also comprises camelid feces (less than 1%).
71
0
r 0 [k-_\~11.r1aro1V11I" @ PltmloKf"' l11bwlos-.1
@ Ca1'<'.ref.m.1r11im1,1 © Pll_,·llo.,rirp1,s ,t,f,r/lrol,l
@ lAIHl111 ohb"Of'h.\•ll;1 0 PuNIR<'llt,·1Jr1gula
© J A?nffu m1n11/11 © Slurl.·,111,, p,.rtuwt"
Pradera con cojines aislados (B)
Figure 33. Cross profile of the B fragment (meadow with isolated cushions). Note the presence of different
semi-naturalized canals that penetrate the bofedals, some of which are d1y while some that present varying
amounts of water.
Figme 34. View of the S_C fragment.
78
This bofedal comprises 2 % of dry canals and 4 % of active canals, open areas
with 10% of bare soil, 2 % of organic matter, 5% of dead Oxychloe andina
cushions, and 77% of total vegetation cover. The predominant species are O.
andina (40%) and Festuca potosiana (30%), followed by Carex cf. maritima
(5%), Deyeuxia chrysantha (1%), Festuca rigescens (1%), and Ranunculus,
Xenophyllum incissum var. incissum, Puccinella frigida, Plantago tubulosa and
Zameioscirpus muticus (less than 1%).
72
© C,1w;ef.m,1r1111,111
@ l..n,,.111..;,.,,11,,,
@ SYrlO ,,,,1111(((,
© ✓lj1t>l'llllrt"1IIO$tt{J,KJ
© X,11U'f'l,~l/ll1" tttlHi,tnr
@ J.>11ra,wJ/111fr1xul11
(!) Slwl,,111,1 f'HIINaf,1
@ l >,,-w11J1;,..,,n,Hla
Cesped salino con Carex (C)
Figure 3 5. Cross profile of the C fragment ( saline grasses, with a predominance of the Carex cf. maritima
species). Note the open areas, Canals, and saline outcrops.
Bofedal {S_D)
Figure 36. View of the S D fragment.
79
This bofedal comprises 8 % of active canals and 92 % of total vegetation cover.
The predominant species are Festuca rigescens (55 %) and fragmented O.
andina cushions (20 %). The water in the active canals is covered by Lemna
minuta (5 %) and Stuckenia pectinata (7%)—a submerged species. The area also
comprises species as the Lobelia oligophylla, Plantago tubulosa, Phylloscirpus
deserticola (1% of coverage ration each), and Xenophyllum incissum var.
incissum.
73
0
[
Ci) foluca po10,iana
@ C111-u: if. maritima
@ P fa11tago lubulosa
© F f'$//lrtl ,·igf'.f("l'I/S
® o .• ,-r1,1-, .... ,,.,,. l @ D eye1u:ia c10-t111la
0 De_w•11.cia dt1J'Sa 11//,a
@ O.ryddoe 1111urta
Bofedal (D)
Figure 37. Cross profile of the D fragment. Note the presence of Oxychloe andina cushions and peat (dead
Oxychloe), canals and the predominance of Gramineae in the bofedal margins and Gramineae common of
bofedals in-between the cushions.
Scrub land Bofedal S _ E
Figure 38. View of the S_E fragment.
80
This watercourse comprises 25 % of open canals, 7% of organic matter, 5 % of
rocks, 15% of submerged algae, 20 % of Ranunculus uniflorus—floating at the
canal margins—and 4% of Deyeuxia chrysantha, at the watercourse margins,
with small cushions of O. andina (less than 1%).
The rank-abundance curves show that the B to F fragments of the SE bofedal
comprise 12 and 24 species, respectively. Abundant Carex cf. maritima species
are present in all fragments, followed by Gramineae as Deyeuxia curvula (B),
Festuca potosiana (D and F), F. rigescens (E) or Pucinellia frigida (C). These
Gramineae generally grow in meadows and their presence is an indication that
the bofedal is under a desiccation process.
In the D and E fragments, the O. andina is the most abundant species, while
it only takes the fifth place among other dominant species in the B fragment,
is almost absent in fragment C and is completely inexistent in the F fragment
(Figure 40).
The C fragment (S_C) comprises 12 species, five of which are reduced in
proportions (Arenaria spp., Ranunculus uniflorus, Calandrinia acaulis,
Lilaeopsis macloviana and Oxychloe andina). This fragment also comprises
a great extent of bare soil, organic matter, saline outcrops and stones. The
presence of Oxychloe andina is significantly reduced and presents indications
of having endured recent burning by burnt Gramineae (qgram).
The S_B fragment presents a heterogeneity of species, which are, in some
cases, associated to the water springs and saline outcrops, in other. In the S_B
and S_C, the Lilaeopsis macloviana and Ranunculus uniflorus species—which
develop in water springs or courses—are the least abundant ones (Figure 40).
74
Degraded bofedals - watercourse margins S F
Figure 39. View of the S_F fragment.
81
General remarks on the South Bofedals
Most of the Canals constructed in the South Bofedal do not comprise ignimbrite
structures, as opposed to the North Bofedal. Several areas with saline
outcrops can be found in the lower area of the south bofedal.
75
0
-1
-2
·c..
0 -3 ~
-4
-5
'\''•
-6 ~-------------------------'lo~, ,~·'~,----------
Figure 40. Rank-abundance curves for the SouthBofedal fragments: S_B, S_C, S_D, S_E and S_F.
82
The decision was made to denominate the S_B fragment as a meadow, owing
to its reduced coverage ratio of cushions and the predominance of Gramineae.
Salt outcrops can also be found in-between the bofedal fragments and the
surrounding area.
The S_D fragment is the only one that can be denominated as a bofedal. This
fragment is not, however, in good conditions, due to the presence of Gramineae
in its crest.
76
Figw·e 41. Details of the two sectors found in the South bofedal: a) Area comp,ising cushion fragments of
Oxychloe andina and b) fragmented cushions developed in a canalized patch of the South Bofedal.
Figw·e 42. Desiccated section of the S C fragment The desiccation was provoked by a diversion made to
measure the flowrate of the area.
83
This bofedal comprises 75% of Gramineae, 20% of cushions (O. andina, P. desertícola
y Z. atacamensis), 2% of canals, 2.5% of water springs, and 1% of peat. The
cushions are found in the south central portion and are surrounded by Festuca
potosiana in areas of mild humidity. A canal is found on the margins of these
cushions. Close to the Canals, the dominant species is the Deyeuxia eminens.
Tussoks of Festuca chrysophylla and F. orthophylla can be found throughout
bofedal margins. Carex cf. maritima, Festuca rigescens, D. eminens, and Lobellia
oligophylla can be found in flooded areas, and Aciachne (though in a
reduced amount) in areas that are enduring a desiccation process.
This is currently the largest fragment of the Silala bofedals. Thirty-four elements
have been observed in this area, including abiotic species and characteristics.
A high density of springs (up to three per lineal meter according to
Urquidi 2004) has also been recorded
77
North Bofedal (N)
Figw·e 43. View of the No1th fragment.
84
This fragment presents the greatest amount of species typical of bofedals, such
as: Oxychloe andina, Zameioscirpus muticus, Eleocharis atacamensis, and
Phylloscirpus desertícola, although the predominant species is the Gramineae
Festuca potosiana, followed by the Oxychloe, and the Deyeuxia eminens var.
Eminens Gramineae, both common of bofedals. Despite this predominance
mentioned, equitability is high in this fragment. The presence of organic matter,
bare soils, stones, canals, and sandy soils is noted (Figure 44).
Physiognomically, three vegetation units are distinguished (Figure 60): a) two
bofedal patches in good conditions and dominated by O. andina cushions; b)
a unit comprising the greatest amount of canals, where Gramineae associated
with flowing water bodies (D. eminens) can be found; and c) a unit of dryportion
Gramineae (F. potosiana).
78
Figw·e 44. Rank-abundance ctuve for the N01th bofedal (N) and the confluence of both canals (CONF).
85
South and North Bofedal Confluence (CONF)
This fragment is found in the area in which the waters of the South Bofedal
enter a naturally- formed ravine and merge with the North canal, converging to
flow in direction to Chilean territory. Although smaller fragments of 2 m2, approximately,
can be observed, the partial absence of O. andina is notiecable in
this area. The most abundant species is the D. eminens, followed by the Carex
cf. maritima and F. potosiana.
79
[Map legend, from top to bottom: Blue-Scrubland associated \\~th a high water current (Deyeuxia eminens); redscrubland,
bofedal (F estuca potcsiana); grecn-Bofedal (Oxychloe andina)]
Figure 45. North Bofedal, Silala. The contours in different colors represent the patches that can be
distinguished at the landscape level.
0 r n,-,, /"M''",. ..
@ Drn~w ,,,.,.,nu
@ tn 1w11nft"!I"'" '
© <>,,.ltlu, ... ,,,,. ..
@ .,,,_. ...., .• ···"•-··.. l @ OJ_'Mltlw •-,u (.110)
(D f>t1-T1<1 r,,nwl.J
@ ( ,1tY.r,J'.•,u1t,m,1
Botedal (N)
Figm-e 46. Cross profile of the North bofedal. Schematics of the main vegetation and abiotic element
components. Note the presence of Oxychloe andina and Zameioscirpus spp. cushions, d.ty areas and
canals lined with stones.
86
Current state of the bofedals
The composition of species in the Silala varies in each bofedal. Many smaller
proportion species can be found throughout the North, South and Confluence
quadrants. Nevertheless, 41% of C. cf. maritima, particularly, and O. andina
and F. potosiana, to a lesser degree, determine the bofedals composition (Figure
48).
The multivariate Principal Component Analysis provides general insights on
the composition and abundance of plants in the Silala. Four major groups
of plant communities can be distinguished. The First Axis (24% of the total
variance) is dominated by the Carex cf. maritima, Festuca potosiana, and—to a
lesser degree—by Oxychloe andina. On the right side of this axis, the main set
of areas affected the most by the different canalization works stands out with a
quadrant dominion of C. cf. maritima (8). These areas are scattered throughout
different sectors of the South Bofedal. This species is associated with more
open areas, namely, with exposed organic matter and saline outcrops. The
second set, with a high abundance of Puccinellia frigida, is found close to this
C. cf. maritima dominated quadrant.
The third group is characterized by a predominance of D. eminens, the most
abundant in northern quadrants, close to the stone-lined Canals, which are in
turn characterized by a greater water flow (see results with macroinvertebrates).
80
Figure 4 7. View of the confluence area.
87
Figure 48. Articulation of the plant species examined as a function of the dominant species of
the North (N) and South (S) bofedals and the Silala Confluence (Biplot). To carry out the analysis,
126 quadrants were employed. The circles depict the different plant groups. This analysis
allows depicting the differential impacts of the canalization works on the plant species of the
South and North bofedals. The direction and length of the arrows show the correlation between
the variables and the principal components. The codes are presented in Annex 2. Color Green
depicts the quadrants of the North (N) fragment; Pink represents the S_A quadrants; Black the
S_B quadrants; Red the S_C quadrants; Brown the S_D quadrants; cherry the S_E quadrants;
Blue the S_F quadrants; and purple the confluence sites (CONF).
The 2nd component of the analysis of principal components (17% of the
total variance) is dominated by O. andina and F. potosiana. The North
(N) bofedal quadrants are mainly found in the lower left side of the biplot,
which corresponds to areas with a reduced presence of C. cf. maritima
and/or areas where F. potosiana predominates. These areas are enduring
a desiccation process and are generally to be found in bofedal margins.
Their presence is also of importance in the confluence. The last group
comprises a predominance of O. andina, which is mainly found in the
81
-,'2...f.t_.
-..- C\I
ci.
E
0 u
.1...0
0
1.0
0
0
1.0
0
9
.1..0.
9
-2
N 7_CA
ff_7 C6 S_Et_C3
S 01 C5
S 01 Cl
H 10 CG
-0.15
-1 0
S_82_C5
N S_C2
-0.05
2 3
0.15
......
0
N
I
88
North and S. D. fragments. The spatial distribution of bofedal species is not
uniform throughout its areas.
The analysis demonstrates that the composition of species in the North and
South Bofedals and Confluence areas is mainly determined by C. cf. maritima,
and O. andina and F. potosiana to a lesser degree, as clearly evidenced by
their proportion of data variation (41%). Nevertheless, there are many smaller
proportion species scattered throughout the North and South bofedals, and
the Confluence area. The spatial distribution of bofedal species is not uniform
throughout its areas, There are areas where species are mixed and others where
some of the species highlighted in the biplot arrows predominate (C. cf. maritima,
F. potosiana and, to a lesser degree, O. andina).Thus, the multivariate Principal
Component Analysis evidences the high degree of fragmentation of the
Silala bofedals and allows visualizing the differential effects of the canalization
works between the South and North bofedals, demonstrating that the South
bofedal is the one that has been affected the most, owing to the abundance of C.
cf. maritima, which is also reported as a species typical of dryer areas that only
have semi-permanent humidity.
The above explains the compaction into different fragments determined at the
global level (49). The North and S_D bofedals present the least compaction
(233,1 ± 273,3; 104,4 ± 179,7) kPa, respectively. While the most compacted
fragments are the S_F (216,1±191,3), S_C (915,6±374,9), S_A and S_B
(625±107; 561,3±455) kPa, respectively.
Consistently with our results, Coronel (2010) reports that the C. cf. maritima
species is one of the most abundant ones in driest areas as evidence of
the effects of the Mauri river diversion. Likewise, Buttolph (1998) found
in Cosapa (Potosi) that the C. cf. maritima and D. curvula species are
abundant in the driest areas. In the case of the Silala, the surveys were
completed long after the canalization works were installed, which is why
it is likely that species as the W. pygmaea and P. tubulosa (which
82
1000 I -~
800 .. Q.
"' I C -0 600 ·;:;
~ a
E 400
0
V 200 I I
I 0
NO SE...A SE_B SE_C SEJ) SE....F
Lugar
Figure 49. Compaction in vegetation quadrants measured in different fragments of the North (N) and South
(S) bofedals of Silala. Only the areas where it was possible to use a compaction meter are included. The
codes are presented in Annex 4.
89
recorded a low abundance rates in our examinations) were more abundant, inasmuch
as they are indicative of reductions in the water table. Our examinations
in the Silala bofedals have resulted in concerns regarding the total absence of
Distichia muscoides, a cushion plant that is more susceptible to reductions in
water availability and climate change (Loza Herrera et al. 2015) and is displaced
first after water availability is reduced.
The canonical correspondence analysis (CCA), which accounts for the variations
in abundance and species compositions as a function of environmental
variables measured, demonstrates that the species are organized on basis of a
compaction gradient. The presence of Carex cf. maritima, Puccinellia frigida,
Plantago tubulosa and Gentiana gayi species is to be noted in the most compacted
areas, while that of the O. andina, muticus, E. atacamensis and W. pygmaea
species is most manifest in the least compacted one (Figure 50).
These results are evidence of the effects that the canalization works have had
on the vegetation, inasmuch as there is a positive feedback between reduced
water supply and changes in the vegetation. The greater degree of compaction
entails an additional problem, as it reduces the soil porosity necessary for
the free circulation of water and air, and restricts the growth of plant roots in
compacted surfaces. Thus, in areas where the amount of water has depleted,
plants that require less water develop in the Silala (Carex cf. maritima, Puccinellia
frigida, Plantago tubulosa). The least compacted areas, on the contrary,
are dominated by species that require higher amounts of water that are common
of bofedals—the O. andina, Z. muticus, and E. atacamensis species in the case
of Silala. These are found precisely where the presence of stone-lined canals
is reduced (central part of the North bofedal), and in some areas of the S-D
wetland. However, although these areas were the least compacted one in the
Silala bofedals, the compaction degree is high compared to referential areas of
the Cordillera Real, where compaction in Oxychloe andina cushions is 117.5
± 122.4 kPa. In addition, loose cushions of this species, which are common in
the Cordillera Real due to their high water content (Loza Herrera et al., 2015),
have been found in the Silala.
Supporting these results, a second canonical correspondence analysis generated
with all the abiotic variables related to the substrate has led to the observation
that the species characteristic of more compacted areas, such as. P. frigida,
C. maritima, W. pygmaea, and X. incisum, are also the species associated with
saline outcrops. Organic matter is mainly associated with Deyeuxia sp. 1 and
2, P. deserticola, Z. atacamensis (Figure 51) where the degree of compaction is
inferior.
It should further be noted that, out of the purely aquatic plant species, S. pectinata,
Myriophyllum sp. L. minuta, Ranunculus and M. glabratus were observed
in the area; mosses species were nevertheless absent in our evaluations, though
they are usually present in bofedal watercourses (Gonzales 2014) and are very
common in pooling waters (Loza Herrera 2012). From the literature read, according
to Rambaud et. al. (2009), this group of organisms is among those that
are affected the most by canalization works in wetlands, constituting another
piece of evidence of the negative effect of canalization works.
83
90
Figure 50. Analysis performed to explain the abundance and composition variations on basis
of the main substrate types found in the Silala bofedals. Biplot of the canonical correspondence
analysis, presenting the environmental variables ([based on the Spanish acronyms] morg:
organic matter; hcam: camelid feces; asal: saline outcrops). To the left, species and environmental
variables biplot (morg and hcam). To the right, quadrants present in the bofedals and
environmental variables. By applying the “forward selection” option, it was found that only
the saline outcrop and the organic matter are significantly associated with the vegetation cover,
Annex 3 (Trace=0.43, F=2.09, P<0.05). The environmental variables are indicated with arrows
(hcam y morg). The abbreviated name of each of the species is detailed in Annex 2.
Figure 51 . Analysis performed to explain the abundance and composition variations on basis
of the main substrate types found in the Silala bofedals. Biplot of the canonical correspondence
analysis, presenting the environmental variables ([based on the Spanish acronyms]
morg: organic matter; hcam: camelid feces; asal: saline outcrops). To the left, species and
environmental variables biplot (morg and hcam). To the right, quadrants present in the bofedals
and environmental variables. By applying the “forward selection” option, it was found that
only the saline outcrop and the organic matter are significantly associated with the vegetation
cover, Annex 3 (Trace=0.43, F=2.09, P<0.05). The environmental variables are indicated with
arrows (hcam y morg). The abbreviated name of each of the species is detailed in Annex 2.
84
I \fT.ir, S
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;; 1
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linu1 Coca
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t.O
91
Map of the bofedal state
The map generated on basis of the vegetation cover and the categorization
performed completely supports the findings of the multi-variate analysis and
compaction data. The areas that have been degraded the most are found in the
A fragment of the South Bofedal. Evidence of this assertion is the presence of
small O. andina cushions (< 1 m2) and the traces of canals that stretched from
this fragment to the South Bofedal. It has been observed that the latter was almost
dry (orange squares) and that O. Andina cushions, in a regular state, were
completely absent (yellow squares, Figure 52). Site C presented a degraded to
dry state with a complete absence of plant cushions. Site D, the one with the
best state of preservation within the South bofedal, owing to a greater coverage
ratio of O. Andina cushions, but with a high risk of fragmentation due to the
fact that degraded bofedal patches were found in the adjacent quadrants, presented
a dry to regular state. Site F, close to the military post, presented a dry
to regular state. Due to its reduced width, it is likely that this area might suffer
more negative effects at the margins, as O. andina cushions were not found at
its core, only some P. deserticola and Z. atacamensis, which do not compose a
high amount of organic matter, as the Juncaceae (see section 6.2.2).
85
92
86
6a" l '30•w
"~
i:
(i&•1·30--,•1
Estado del bofedal seg(m cobertura de vegetaci6n
68'1'0V: 6!''0'30"W
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• l"iydegtadldo
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( Ji t;. ,::i;
POTOS/
Figure 52. State of the Bofedal: Quadrant-based anal ysis of the vegetat ion cover. The category values are low if the bofedal is dry, or degraded, and high if the bofedal is in a good state (Degraded = 0 - I 00, Dry = IO I -200, Regular = 20 I - 300, Good =
30 1-400, Very good = 401 -500). The values of O to 500 are the result of the sum of the vegetal species product in percentages multiplied by assigned weights (the weights are: O=bare soil; I =dry vegetation; 2=margin vegetation; 3= bofcdal vegetation;
5= 0. andina) en each quadrant
e"'
i:!
93
6.6 Environmental impacts on the bofedals derived from the presence of
artificial canals
6.6.1 Ecological quality of the bofedals
The current state of the Silala bofedals presents a high degree of fragmentation
and desiccation. Of the 10 fragments examined, five are highly degraded; one
is in a degraded state; three are in a regular state, and only one fragment is in
good conditions (Figure 53)—though its quality is too low in comparison to the
Sajama bofedals (see Meneses et al. 2014), which is the most comparable area
where systematic appraisals have been completed.
Figure 53. Mean ecological quality of the three different fragments of the Silala on basis of
the transects examined. The scores were averaged to obtain a single value for each fragment.
CONF: confluence, N: north, S: south. The fragments were coded in alphabetical order according
to their order of appearance from the starting point to the endpoint of each bofedal.
Supporting these data, we found that in the South bofedal, the most frequent
units are the Carex.cf maritima (6.5%) and Deyeuxia curvula (5%) species.
However, in this bofedal, the cushions have less than 2% of frequency ratio
(Figure 54). The disruption only allowed the Carex cf. maritima and D. curvula
to persist in the area, despite the high number of dry canal systems and saline
outcrops.
In the North Bofedal, the trend is similar, and the coverage ratio of the Carex.
cf maritima species— in the system of dry canals—is very high (15%), just
like the Deyeuxia curvula—sandy soil— (10%) and Festuca potosiana (8%).
All of these are not typically found in preserved bofedales. In addition, the
cushions frequency is so low that it is not among the first 20 units of higher
87
Unidad de
vegetaci6n C6digo Puntaje
Bofedal pajonal CO F
Bofedal pajonal N
Bofedal NA
Bofedal pajonal N_B
Cesped salinizado Carex
y Oxychloe (a islado) S_A2
Pradera c/Oxych1oe S (aislado) 8
Cesped bajo S_C
salinizado Carex
0 4 8
Bofedal S_D,__-'--------'
Bofedal S E t---+---4---- +i
Bofedal degradado S_F
borde de canal
12 16 20
94
frequency, which is why it is not seen in Figure 54. The less degraded areas are
found in the central part of the bofedal. The high frequency of Carex cf. maritima
(cmar) is an indication of the high frequency of dry and salinized areas
(Coronel 2010, Buttolph 1998, Meneses et al., 2014).
From the appraisal made in the Silala bofedals, the total absence of Distichia
muscoides, a cushion plant that is more susceptible to water depletion, climate
change (Loza Herrera et al., 2015) and salinization (Ruthsatz 2012) and that is
the first to be displaced following a depletion of water availability, has arisen
concern. Although low in abundance, DIREMAR (2017), Lliully (2018) and
Ortuño T. (2018) back up the presence of this cushion in the Villamar (Silala
region), Canchilla, Villamar (Laguna Colorada influence area) and Quetena
Grande bofedals, respectively.
The desiccation effects that take place in the Silala bofedals have also affected
their forage quality, which was considered of a very high quality (Alzerreca et
al 2001, Meneses et al 2012, Beck et al 2010, Villarroel 1997, Mamani s/a).
Fragmentation and desiccation of the bofedals reduce the ecosystem’s capacity
to retain water (Squeo et al., 2006, Meneses et al., 2014), which constitutes
one of the most severe impacts on ecosystems such as bofedales, with highly
significant effects for human beings and activities, particularly in arid regions.
88
<C:....-d nwt~t~,,. _•_~,o:.,r..~a ...-., ~=~ c...-.ct,..,.. .... tl,._...,..,....~.,--
·~'"C-
d -~I--t!l-o-o.,-...-..~...WM 0.W-...,ltll-\M .....
~d~~""""'........,
a,..,(l, 'l'Wl!l!lr,\I ~~ --· C«tlll d -,111,p,
0
f""°""".l,o•"•'"""'
~,.-c,flr,wwh.f_""-'do.
r~pgeq,;i,,,,.,
~WM!lf,wlo..-c-
d.-.....~ sw-<MVi., -
Bo~&I sur
Bofedal n0t1e
Fte<ucncla de unidades (%)
Figure 54. Global frequency of the units found in the South and North Silala bofedals. This graph presents
only the 20 first most frequent units for each bofedaL The units typical of preserved bofedals are presented
in green.
95
6.6.1 Macroinvertebrates
The taxonomic richness (H = 12.8, p <0.05) and diversity (H = 13.8, p <0.05)
both differ among the three canal types. It is clear that these two indicators of
biodiversity present higher ratios “naturalized” canals, which are more similar
to a natural bofedal (Fig. 67). This is not the case for the abundance of individuals,
which does not differ between the three types of canal (H = 3.1, p = 0.2;
Figure 55). This final finding suggests that stone-lined canal (CP) environments
are not so heterogeneous, but have a similar productivity.
Using an NMDS, with the Bray-curtis linkage, it was possible to demonstrate
that the composition and relative abundances of taxa assemble similar sets of
species among the samples taken from stone- lined canalization (CP), canalization
without stone-lining (SP), and naturalized sections (N). This assembling
was corroborated with an ANOVA of similarity (ANOSIM-Bray-Curtis,
999 permutations) (Table 14). The macroinvertebrate group that characterizes
the naturalized canalization
(N) section is composed of: Austrelmis, Hyallela and Simulium. It is very
similar to the community of macroinvertebrates of the bofedal pools (EBNL),
which are characterized by: Hyallela, Dero and Glossiphonidae. The canals
without stone-lining (SP) are characterized by: Hyallela, Austrelmis and Metrichia
species. The stone-lined canals (CP) are characterized by: Hyallela, Andesiops
and Austrelmis species; however, the canalized section further south
are characterized by: Paraheptagyia, Claudioperla and Hydrobiosidae
89
".,1
,.
·•1
.,
•.\
., ..
" "' t
('r <r er
Figure 55. Graphs that present the richness, diversity, and abundance (mean and ranges), compared among
the sites: naturalized canals (N), canalization without stone-lining (SP) stone-lined canalization (CP)
Table 14. Significance of theANOSIM among proposed groups.
A."\'OS™
R2= 0,5
N
SP
SP CP
0,033 0.0033
0.0011
96
Environmental parameters
Within the environmental parameters, the physical-chemical parameters (Annex
2) and the morpho-structural parameters (Annex 3) were both separated,
followed by a Principal Component Analysis (PCA) with seven environmental
parameters and 20 sampling stations. During the analysis, it was observed that
the electrical conductivity (EC) is closely related to the altitude; i.e. the areas
with low altitudes present the lowest EC values. This may be due to the fact that
the EC is related to the presence of ions (sulphate and nitrates, for example)
in water. The vegetation absorbs these nutrients from groundwater sources,
which decreases at the lowest points. The low values of Fluvial Habitat Index
are due to the medium’s homogenization with the percentage of blocks and
stones. Finally, as expected, the highest flow is found in the lowest sections.
90
(J :io
0 30
0 2~
(l i fl
~
""ii: (l i )
C -a
0
0
u 0 00
0 00
O.C>-J
0.12
-ll 11(
-l:- f :f
,.
~-:] -,·' J ~ •J.
_iti;:L►i
(.,,,.i
I
. -ff\ e fl-11.
I
·.1;; -L E6'i,
• F3f
.(J 7-1 -u ·o -U UH (J Cl) urn u 10
\ . ~
- Arde~ iups ~ Cl.:iud ioper J ,..., .... ~
'\, A~istrclmis far<i he~lJ~yi ;;
/ Glc-~si pl iuniJ.ie
Figure 56. NMDS completed using the Bray-Curtis linkage; sections with stone-lined Canals (CP),
sections where stone-lining is absent (SP) and naturalized sections (N).
97
Figure 57. Analysis of the principal components for the environmental parameters of the Silala
bofedals. Note that the naturalized and stoned-lined canalization sites (in green) present the
highest fluvial habitat values, percentage of vegetation (Veg. %), and electrical conductivity
(EC), and a reduced percentage of large stone blocks. The stoned-lined canalized sites, on the
other hand, are characterized for presenting a high percentage of blocks and large stones and
low values of habitat stability (FHI) [sic, there seems to be a contradiction].
Relation of macroinvertebrates with environmental parameters
In order to examine the relation that macroinvertebrates have with environmental
parameters, an analysis of canonic correspondence (CCA) was completed between the
most representative PCA variables and the macroinvertebrate fauna. The Cailloma,
Claudioperla, and Paraheptagyia genuses present a positive relation with the flowrate
(Flow (Velocity)) and a negative relation with the altitude and electrical conductivity.
The Ectemnostega, Empididae, Hydracarina and Neotrichia taxa present a positive
relation with the fluvial habitat stability (FHI) and a negative relation with the amount
of blocks and large stones. These taxa are found in naturalized sites. (Figure 58).
91
2-4
I
-3,1. -2,4
\n.i. I
--,,•E~"ll>------ - -- --- - J•
'i::7L
Co1nponent l
98
Figure 58. Principal Component Analysis completed to relate the taxa with the environmental
variables of the Silala bofedals. Note the positive relation of Cailloma, Claudioperla and
Paraheptagyia with the flow and velocity (beige color circle) and a negative relation with
altitude. The Ectemnnostegam Neotrichia, Hydracarina and Empididae have a positive relation
with the high fluvial habitat values (FHI) and a negative one with the percentage of blocks and
stones.
Birds
A comparison between the bird species found in three bofedals comparable to
the Silala (Silala, Eduardo Avaroa Natural Andean Fauna Reserve (Hennessey
et al 2003) and the northern region of Chile (Innova Chile, 2010), it has been
found that 19 bird species inhabit the Silala, 29 the Eduardo Avaroa reserve and
18 the northern region of Chile (Table 15). Fifteen common species were found
in the three bofedals surveyed.
92
1,
%of blocks an
large stone
•oer
Ortho
h---,------,- _aba□ida_ I •
Glossiph ,
Altitu
Axis
Flow(Vel.)
99
Ten of the bird species recorded in the Eduardo Avaroa Reserve were not found
in the Silala bofedals (Table 15). It should be noted that the Muscisaxicola
juninensis and Gallinago andina species, which are all characteristic of bofedals,
are completely absent in the Silala bofedals. This could be to the degraded
state and/or reduced extent of the bofedals. The other four species that were not
observed in the Silala are migratory birds, so they might arrive to the site in a
different season (the Vanellus resplendens and Pygochelidon cyanoleuca cyanoleuca
(altitudinal migratory birds), Muscisaxicola frontalis (austral migratory
species that might be observed in the site between June and September), and
Hirundo rustica (boreal migratory species, rare to abundant from September to
March (Herzog et al. 2017)). It should be noted that the difference between bird
species groups could be due to different variables, such as: (1) disturbance or
degradation state of the habitat, which could affect the vegetation and resource
availability for the birds, (2) differences in sampling efforts (the Eduardo Avaroa
Reserve bofedals have been visited for many years, during different times
of the year and by different researchers), (3) the surface area of the bofedals and
species- area relation suggest that larger bofedal areas, as those of the Eduardo
Avaroa Reserve, have a greater diversity of bird species, and (4) the closeness
among bofedal areas (the closest they are, the easier the movement and arrival
of bird species).
93
Table 15. Bird species that use bofedals as habitats (AIO), according to Stotz et al. (1996), in the Silala;
the table includes the birds of the Eduardo Avaroa Reserve and Northern region of Chile only by way of
comparison.
Family Scientific name Silala EA Reserve North of Chile Migratory birds
Anatidae Oressochen melanopterus X X
Anas jlavirostris X X
Columbidae Metriopelia aymara X X
Charadriidae Vanellus resplendens X M. altitudinal
Phegornis mitchellii X X
Scolopacidae Gallinago jamesoni X
Gallinago andina X M. altitudinal
Thinocoridae Attagis gayi X X X
Thinocorus orbignyianus X X X
Thinocorus rumicivorus X
Acci itridae Geranoaetus polyosoma X X
Strigidae Athene cunicularia X
Picidae Colaptes rupicola X
Falconidae Phalcoboenus
X X
mef!alovterus
Fumariidae Geositta punensis X X X
Cine/odes albiventris X X X
Cine/odes atacamensis X X X
Asthenes modesta X X X
Tyrannidae Lessonia areas X X X M. austral
Muscisaxicola juninensis X
Muscisaxicola cinereus X X M. austral
Muscisaxicola jlavinucha X X X M. austral
Muscisaxicola rujivertex X X X M. austral
Muscisaxicola frontal is X X M. austral
Agriornis montanus
I
X X X
Hirundinidae Pygochelidon cyanoleuca X X M. austral
Hirundo rustica H X X M. boreal
Thraupidae Phrygilus atriceps X X
Phrygilus unicolor X I X X
N° of species 19 29 18
100
Mammals
The Silala region is remarkable for its abundance and diversity of rodents
(Table 16), though the North and South bofedal mammal species need to be
contrasted and compared. The differences between both these bofedals allows
suggesting that the South Bofedal (where only two genuses and a maximum of
four species can be observed) could be a reflection of what might happen to the
rodent diversity of the area if the North Bofedal dried out. It should be recalled
that the North Bofedal comprises the greatest vegetation diversity, which is
reflected in a more significant productivity, and rodent abundance and diversity.
94
35
30
25
20
15
10
5
0
13
Familia
21
15 14 I Genero
■ Silala ■ REA
29
19 18
Especie
N Chile
Figure 59. Number offamilies, genuses, and species observed in the Silala bofedals, the EA Reserve, and
the Northern region of Chile. Source: Prepared by the authors.
T able 16 . Mammals of the Silala bofeda:s.
Ordor/Fawily <kuu, Specie, Loglype Loi.:at.iou
C2rn.h·orous RN c:~ RS
Cauidae Fawily l'seudalopex Pseudaiopexculpaeu.s Fee.es, b<ine reml!ins X X
Artiodactyla
Camelidae Vicugna Vicugnavicugna Direct observ11tion, X X
bone remains
Rodentia
Chinchillidae Lagidium Lagidiurn viscacia Vrrect observ11t10n, X
feces
Criwlidae l'hylloti.s Phylhtisxi:.mthophygu.s Capture 29 9 - Ph; lloti: cf. Capture 6
zanthophJ,-gi,s
Crioetidae Tapecomys Tapecomys»·olffsoh•ti Capture 16 & - Crioetidae Calomys Calo mys musculir.us Capture 3 I 1
Cricetidae A':,rothrix A broihrix andiMu.s Capture 2
sp l Capture l I
<p l. c~pn.-.. 'i 1 1
sp 3 Capture 2 4 1
sp4 Capture 2
101
It is likely that the Silala bofedal rodents migrated progressively from Chile,
long before the Chilean bofedals dried out, or that the mammal diversity of the
Silala constitutes a lateral relict from the retrogression of the Ballivian lake.
These hypotheses could be determined through DNA samples, in order to find
evidence of either bottlenecks (first hypothesis), or genetic erosion (second
hypothesis). Regardless of the actual cause, the Silala bofedals constitute a type
of productive desert oases, that are home to and sustain a great amount of life
forms, some of which have been found to be new to the diversity of the State
and must thus be preserved and protected.
6.7 Preparation of restoration measures that should be implemented to ensure
the survival of the bofedal ecosystems
In order to address the preparation of restoration measures, a definition of
preparation and restoration is first herewith presented. Below, following said
definition, a series of actions are proposed on basis of the problems observed
in the Silala area (Table 17) and some necessary considerations to implement a
restoration plan successfully are suggested.
Preparation: Determination of objectives, and what should be done, how and
when to do it, and following which order (Bernal, 2012).
Restoration: Process to contribute to the restoration of a certain
degraded, harmed or destroyed area, ecosystem, or landscape
for the purpose of helping the system retake its ecological
95
102
pathway, maintain its resilience, preserve the biological diversity, and reestablish
their functionality (SEMARNAT, 2013).
Bearing the above definitions in mind, and based on our field observations, the
authors hereby propose the following two restoration components: A) abiotic
restoration of the area and b) biotic restoration (Table 17).
Table 17. Preparation of restoration measures based on the problems observed in the Silala and
including recommendable terms for their implementation.
96
Objectives Problem
Specific
Actions Term objectives
The presence of To eliminate and/or To properly remove the Short-term
water abstraction reduce the presence current ignimbrite lining of
canals . of artificial canals the canals and fill them
The North Bofedal and reestablish the with organic matter to
To
comprises 25 canalized natural water flows. allow water to naturally
implement
springs. irrigate the area.
The South Bofedal
actions that
comprises 18 canalized
promote the
abiotic
springs.
restoration Alteration of the hydric To return the To extend the current Mid-term
of the regime of the springs springs' natural irrigation area of the canals,
bofedals flow to its allO\,~ng the springs to
natural naturally irrigate the bofedals.
conditions
103
97
The high evaporation rate To protect the Protecting coconut or jute Mid-term
and desertification bofedal eroded sheets can be used on bare
processes that will only areas surfaces to control water losses
intensify the deterioration to evaporation (Aguirre et al.
of the bofedals. 2018). The North bofedal
comprises areas with a high
amount of organic matter and
remains ofbofedal vegetation
which could be selected to
cover them with jute sheets
(Figure 60).
To excavate The water can be conveyed to Mid-term
infiltration cover the entire potential
ditches surface area of the bofedal.
To slow down the Permeable embankments Mid-term
water flow (made of stone or wood with
small holes) could be installed
to collect sediments,
regenerate the soil at the canal
base, and allow the latter to be
re-colonized by vegetation
(Figure 61). It is, however,
recommended to perform pilot
tests, inasmuch as excess use
of this embankments could
destroy these habitats.
Bofedal compaction as a Delimitation of To create a signaled path for Short-term
result of stamping pathways to human transit, preventing the
prevent bofedals and
dispersed their
transit. surroundings from being ~- _,_ ~
To The presence of species To reduce the To eliminate species that Mid-term
implement characteristic ofbofedal interference of compete with the plants typical
biotic margins at the heart of the species ofbofedals by, for instance,
restoration bofedals (the North uncommon to cutting the invasive grasses.
actions and Bofedal, particularly, has bofedals. This action must be
improve the been invaded by Gramineae implemented with the
vegetation characteristic ofbofedal supervision of an expert in
quality of margins, e.g. F potosiana, Grarnineae and vegetation
the bofedals which compete for water uncommon to bofedals.
and resources against
species characteristic of
the bofedal nuclei.
Bofedal To promote the Seeds of species typical Mid-long
fragmentation. reproduction of ( Oxychloe andina, term
dominant species Zameioscirpus spp.
of the bofedals and Phylloscirpus deserticola) of
bush species of the bofedals should planted in
margins (seed areas where organic matter is
planting in situ). present
The presence of
seeds in the soil Plant nurseries of typical
favors natural bush species should formed
regeneration on the margins
(Parastrephia lucida,P.
quadrangularis ,Junellia
104
98
species success10n.
Bofedal To promote To increase the density of Mid-lo
fragmentation. vegetation typical vegetation species term
reproduction. An (Oxychloe andina,
increase vegetation Zameioscirpus muticos, Z.
cover prevents atacamensis, Phylloscirpus
water losses and deserticola). Patches of
soil erosion, and cushion plants could be
promotes water removed from altered areas
retention. (presenting evidence of
desiccation and destruction by
stomping) of the Silala bofedal
and relocated in areas where
they are more likely to
survive.
Proper criteria To compete surveys on the Midmust
be applied to vegetal reproduction of the long
select species to be species that predominate the term
used for bofedals, in plant nurseries
restoration and in situ.
To study the To conduct germination Long-t
viability of seeds viability and seed production
typical of margins rate tests, in parcels, in situ, and
and bofedals. in laboratories to make the
work and experiments
effective.
Proper criteria To define criteria for the Mid-te
must be applied selection of species, which
to select species should have the following
to be used for characteristics: high survival
restoration ration, extended root systems,
fast biomasses production, and a
high flower and fruit generation
rates at early ages.
To avoid using invasive species
(Trifolium, Phalaris, etc .).
The presence of trout To gradually Intensive fishing of sub-adults Short-t
( Oncorhynchus sp ), an reduce this fish and alevins with sieves.
exotic species that might species from the
alter the native aquatic natural flows and
fauna of the area. pools of the
Silala hofr,bl
105
Some remarks:
The restoration process described herewith encompasses several disciplines, as
a result the preparation and implementation of the Project must be carried out
with the help of a multidisciplinary team (Montes et al. 2007). More specific
remarks are detailed below:
• The restoration costs (budget) necessary for the short, mid and long-term
implementation and monitoring must be duly considered, looking forward to
reaching the goals set.
• The feasibility of reaching each of the objectives and goals set for the
Project must also be borne in mind.
• It is necessary to count on the views of all those who are directly concerned
(local communities, the regional and national government).
• The expectations and willingness of those concerned to monitor and reach
the goals set must be duly considered.
6.8 Preparation of an environmental monitoring programme for the Silala
Monitoring is essential to assess the efficacy and efficiency of restoration efforts,
as well as to systematically follow through the state of the bofedals, the region’s
biodiversity response to climate change (bearing in mind that this is one of the
regions that presents the most water deficit in Bolivia), and future surveys that
might help find ways to mitigate the harm and help the environment adapt to
the restoration efforts. It must, nevertheless, be noted that, in order to have a
proper monitoring plan, it is necessary
99
Figure 60. Protection of eroded areas with
coconut fiber sheets (Photograph: Aguirre
eta!. 2018).
Figure 6 1. Permeable embankments used
to slow down flowing water (Photograph:
Aguirre et al. 2018)
106
to know the budget, time and work force available. The authors hereby proposed,
based on their research, some potential variables for a monitoring programme.
-Monitoring the phreatic level related with the bofedal productivity: The phreatic level
is an indicator of the availability of water for vegetation throughout the year. This indicator
can help attain knowledge on: the amount of water available yearly for certain
predominant and/or key bofedal species and the vegetation’s response to these changes
(in terms of biomass and reproduction).
The authors propose that thirty 1-m2 quadrants were Oxychloe andina is present be
selected. These quadrants should be located randomly in the North and South bofedals.
Each of the quadrants must be related to a piezometer to measure to phreatic level.
The response variables shall encompass biomass, reproduction and phenology. This
will help assess what the minimal water conditions for a certain species to develop and
reproduce.
-Desertification advance monitoring. 25 x 25 m parcels must be established, in four
different environment types: hillsides, bofedals, plains, saline areas, each with their
respective replicas (at least three for each environment type). These parcels must be
used to assess the vegetation cover (its richness and abundance) and the humidity and
temperature variables at different soil depths. The measurements must be performed at
least twice a year (during wet and dry seasons). This monitoring programme will allow
appraising the variations of desertification in different micro-habitats of the Silala. It
will further help attain knowledge of the most vulnerable areas and serve as a monitoring
point to follow through the restoration measures proposed.
Simultaneously with the parcel-based measurements, it is necessary to set up a weather
station in the region in order to count on systematic measurements of the environmental
variables throughout the year (temperature, wind, precipitation). These variables
are of importance to analyze their influence in the region’s vegetation and fauna.
-Quantification of degraded peat: Bofedals that accumulate peat present a low organic
matter decomposition rate. The degree of disturbance can be quantified by calculating
the percentage of exposed peat (see results, below), which is actually completely
degraded (soft substrate, lacking a particular structure; this peat transudes when
squeezed). Throughout the Silala region, there is a significant cover of dry organic
matter, which is more susceptible to eolian erosion. Some of these sites where peat
is present (areas where there once were bofedals, and that now comprise either no
bofedal at all or degraded bofedals) could be selected to carry out this quantification,
by measuring the bofedals actual extent and delimitating it. Yearly measurements must
be completed to verify if changes have occurred in their extent.
- Key bird species monitoring in the Silala bofedals. The abundance of bird species
should be estimated employing the transect method in three areas of the Silala and
quantifying the number of individuals for the following species: Oressochen melanopterus,
Cinclodes albiventris, Lessonia oreas, (Muscisaxicola flavinucha), (Muscisaxicola
juninensis), Phrygilus atriceps, Phrygilus plebejus, and Phrygilus
unicolor. This estimation should be performed every two years during the
100
107
same months and applying the same sampling efforts.
The sampling route should cover the ravine, starting at the South bofedal, in
direction to the area where the waters merge (confluence area) and ending in
the North bofedal (Figure 62); the quantification should be repeated for three
consecutive days. This route should cover 3,7 km and must be completed at a
constant pace (1 km per hour, approximately) between 8:00 and 12:00, keeping
a record of each observed bird as follows: time, species amount of individuals
and habitat. The objective of monitoring these key species is to count on an
additional measure of the state of the bofedals. If the amount of birds characteristic
of bofedals (Oressochen melanopterus, Cinclodes albiventris, Lessonia
oreas, Muscisaxicola flavinucha and Muscisaxicola juninensis) increases, it
could be inferred that the bofedals are improving. If the amount of granivorous
species increases (Phrygilus atriceps, Phrygilus plebejus and Phrygilus
unicolor) within the bofedals, it would mean that the Gramineae species have
also increased and that the bofedals continue degrading. The data contained in
this report could serve as a baseline.
Monitoring of the bofedal extent (in situ) and contrasting the data obtained
with satellite images, particularly during dry and humid seasons
In case restoration measurements are implemented, the following are hereby
proposed:
-The development of seedlings (initial number, mortality, etc.) should be
monitored in the hillsides and the reproduction of vegetation (clods) in the
bofedals should also be supervised.
-Intensive trout farming requires a monitoring programme and properly prepared
management plans should the idea to implement it stand.
101
Figure 62. Monitoring route to quantify the bird species of the Silala bofedals
108
7. CONCLUSIONS
■ The Silala bofedals have been fragmented and degraded, and are highly vulnerable;
actions are required to restore them, their biodiversity, their general physiognomic appearance,
and the functions of their ecosystems.
■ The evidence suggests that the bofedals once covered a larger extent before the canalization
works were introduced. It is estimated that the bofedals once covered a potential
Surface area of 11,48 hectares and that only 0,76 hectares of bofedal extent remains at
present, which, nevertheless, is not in proper preservation conditions. It can thus be
claimed that more than 10 hectares of bofedals have been lost due to the canaliza-
6.9 Mitigation and control of the impacts on the Silala bofedals
The following environmental problems have been identified in the area, and
some actions and plans are proposed to address them:
102
Problem Plan
Waste
Bofedal areas (particularly the South management
bofedal) where solid waste is accumulated
The natural aquatic vegetation cover has
been eliminated. The current cleansing of
aquatic plants within the canals destroys
the habitats necessary for the aquatic fauna
and prevents them from retaining
sediments.
The main water source of the South
Bofedal has been restricted throughout its
perimeter to ensure water availability [ for
the canals]. Such action is not advisable to
preserve the water quality in its source,
inasmuch as this artificial restriction [ made
of concrete] could alter the physicalchemical
characteristics of the water and
contaminate it.
Cleansing of aquatic
plants that grow in the
canals must be stopped.
The water quality must
be evaluated
The enhancement of the flowrate disturbs The natural flows must
amphibian species reproduction (Rhinella be restored to reduce the
spinulosa). flowrate pace.
Action
Creation of reuse, management and
recycling deposits. The bofedals must
be cleaned and the inorganic waste
should be collected.
Actions in the bofedals must be
implemented so as to avoid
eliminating the plants from the canals.
Implementation of signaling that
explains what should be done and not
in each area.
The works must be implemented after
the water source is abstracted and the
impact these works have on the water
quality must be evaluated.
The materials and stone lining must be
removed from the water courses in
order to restore them to their natural
state and allow the growth of aquatic
plants.
109
tion works.
■ The apparent, though minimal, regeneration of the bofedal[s] in the past 15 years
reinforces the recommendation that restoration measures be implemented to ensure the
bofedals’ preservation.
■ The Silala bofedals constitute a desert-area productive “oasis” species, are home
to and ensure the sustainability of a significant amount of life forms—some of which
have been proved to be new to the State’s diversity records. If canalization continues,
the bofedal vegetation and fauna will remain threatened.
Biotic and abiotic factors
■ The species found to inhabit the Silala include 86 flora species and 81 fauna species,
making a total of 167.
■ Thirteen species of plants common of bofedals and 18 bofedal margin species
have been registered. Four of these are categorized as Threatened species, i.e. Azorella
compacta, P. deserticola, Z. atacamensis and O. andina), while other four are categorized
as Vulnerable (P. quadrangularis, N. auricoma, F. potosiana and P. tarapacana).
■ Seventeen plant species have been recorded for the first time within the Potosi
department (Table 7); two of these constitute new recorded species for the Bolivian
State (Menonvillea virens and Mostacillastrum dianthoides).
■ An abundant population of the Rhinella spinulosa amphibian has been registered
reproducing in the Silala water bodies.
■ Three lizard species of the Liolaemus genus have been found, together with a
fourth species (Liolaemus hajeki), making the Silala one of the areas of greater diversity
of species of this genus in the south Altiplano region of Bolivia.
■ The Silala bofedals, and their vicinities, provide resources for 35 bird species.
Two of these are categorized a s Threatened species, i.e. Rhea pennata (Threatened)
and (Phegornis mitchellii) (Near-threatened). Six are considered endemic species of
the Central Andes zoogeographic region. Seven of these are boreal, austral and altitudinal
migratory species. The presence of Oressochen melanopterus, Cinclodes
albiventris, Lessonia oreas and Muscisaxicola flavinucha and the absence of Muscisaxicola
juninensis and Gallinago andina both call for attention, as they would be an
indication of the degraded state and/or reduced extent of the Silala bofedals.
■ The rodent species found in the Silala are those characteristic of the Andean
region (Potosi and Oruro, under similar conditions); however, unidentified
species of the Abrothrix genus might constitute new observed species for
the area, or State.
■ Species of Heleobia (Caenosgastropoda; Cochliopidae) and mollusks
commonly linked with bofedals have not been observed.
■ The waters of the Silala bofedals are of a basic type; with a pH between 8
to 9 in the South bofedal and between 7 to 8 in the North bofedal. The alkalinity
ratio is high, making the bofedal ecosystem susceptible to saline outcrops.
■ The general conductivity is low, i.e. 160-300 μs/cm; these waters have a
reduced content of nutrients, which tend to diminish downstream of the canal.
Current state
103
110
■ Three different bofedal areas have been distinguished, the North, South
and Confluence areas.
The vegetation of these bofedals is generally fragmented.
Environmental harm derived from the effect of the hydraulic infrastructure
■ The scientific evidence demonstrates that the bofedals have fragmented as
a result of the hydraulic infrastructure. This can be further ascertained based
on the following evidence: 1) the absence of species characteristic of these
environments, e.g. Distichia muscoides (Juncaceae), Werneria spathulata, Cuatrecasasiella
argentina (Asteraceae); the large presence of Carex cf. maritima
and gramineae as Festuca potosiana (an endemic specie, though common of
bofedal margins), which are not characteristic of bofedal environments and
are indications of the degradation of the Silala derived from the hydraulic infrastructure.
This in turn caused a reduction of the potential extent for species
common of bofedals and an increased soil compaction, reducing its water retention
capacity.
■ The hydraulic infrastructure drastically homogenized the aquatic environment,
giving place to fewer macroinvertebrate groups characteristic of bofedals.
Of the groups associated with bofedal waterbodies, it was possible to find
only: Austrelmis, Hyallela and Simulium. In the stone canals, on the other
hand, the following species were mainly found: Paraheptagyia, Claudioperla
and Hydrobiosidae, which are groups associated with the enhanced water flow
provoked by the hydraulic infrastructure.
■ The canalization works introduced in the upwelling waters increased the
flowrate downstream, affecting the availability of water for the cushions of
plants common of bofedals
(e.g. at the South _ C fragment), reducing aquatic diversity (E11L), and potentially
disturbing the reproduction and larval development (metamorphosis) of
the Rhinella spinulosa amphibian—threatening its survival at the C fragment.
■ The only ictic species found in the area is the Oncorhynchus mykiss trout,
which originates from an intensive and extensive trout farming programme
promoted by the Potosi Departmental Government. Wild trout populations can
currently be found in the artificial canals of the area.
■ The introduction of this trout farm seems to have had an impact on the Silala
ecosystem, which is hard to measure in concrete terms due to the absence
of past data on aquatic biodiversity (invertebrates, and the possible presence of
Orestias in the area) preceding the instalment of the trout farm. It is highly recommendable
that the trout population and invertebrate communities be monitored
in order to obtain more evidence on the possible impacts.
104
111
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Wurtsbaugh W. A. & Alfaro T. R., 1988. Mass mortality of fishes in Lake Titicaca (Peru–Bolivia) associated with the
protozoan parasite Ichthyophthirius multifiliis. Transactions of the American Fisheries Society 117: 213-217.
Zobel M., Davidson J., Edwards M. E. et al., 2018. Ancient environmental DNA reveals shifts in dominant
mutualisms during the Late Quaternary. Nature Communications |DOI: 10.1038/s41467-017- 02421-3
108
115
ANNEXES
Annex 1
1. Historical and social considerations
In order to obtain information on the historical aspects and possible past impacts
on the Silala, primary and secondary information was collected. The
formed was obtained from interviews to the people of the area during two field
visits, 25 March–4 April and 19–23 April 2018, and the latter included data on
the socioeconomic activities of either the existing communities, or those that
interfered the area surveyed. Data on the possible threats and impacts derived
from the different socioeconomic activities and historical information was also
collected.
The field works comprised different stages: the first consisted performing interviews
and polls at the military post, Laguna Colorada and Quetena Chico community.
The second consisted in the coordination and actual field trip to the Silala
bofedals, accompanied by inhabitants of the Quetena Chico community to
get information on the historical aspects and preservation state of the bofedals.
Contacts with people from Laguna Colorada were also made to complete interviews
to Mr. Jacobo Berna (51 years old) and his family, who provided the
authors with historical information of the Silala based on their wide knowledge
of the area. From 1 to 4 April, semi-structured interviews were completed with
the people of the Quetena Chico community. Telephone contact was first made
with Mr. Aurelio Berna to inform him of the projected interviews, particularly
concerning a Quetena individual that visits the Silala bofedals more frequently.
During the authors’’ stay at the community, the latter’s authorities were first
contacted, and the objective of the work to be completed was communicated
and socialized with the people.
The people of the community were then interviewed and a meeting was scheduled
with Mr. Primo Berna (63) and his family to complete the semi-structured
interview referred to above at his home in Quetena Chico (Figure 1). Several
people of the Quetena community were interviewed, separating them into: 1)
people who did not know the Silala bofedals; 2) people who had been to the
Silala bofedals in one opportunity; and 3) people who had been to the bofedals
on different opportunities.
109
116
Perception of the community people on the Silala Bofedals: In order to obtain
this information, semi-structured interviews were completed with people who
had been to the Silala bofedals on several opportunities. These interviews were
made to obtain information on the activities performed in the Silala bofedals
area, the local historical aspects of the area surveyed, the people’s perception
on the state of preservation of the region, and the changes perceived throughout
the years.
It was also possible to contact another people group that had been to the bofedals
since 1948, and whose family had temporally lived in the Silala area since
1970. A field visit to the Silala bofedals was then scheduled with these community
people (Figure 2). The observations made during the different field visits
to the bofedals and their vicinities, accompanied by Joaquin Estelo ( 83) and
Primo Berna (63) are detailed below:
• The characteristics of the bofedals since 1948.
• The surface area covered by the bofedals in 1970-1978.
• The historical and sociocultural aspects of the Silala.
• The historical aspects and specifics of the canalization works and the exploitation
of the waters of Silala by Chile.
• The traditional management and preservation of the bofedals.
Clearly, this information is not technical in nature, but it might be useful to correlate
the findings of this report with the events recalled by the people of the
area.
2. RESULTS
2.1. Historical settlements in the Silala region (social field)
The Silala bofedals and their vicinities have a historical-archeological value
inasmuch as evidence of human settlements and seasonal habitation has been
found, likely connected with cattle raising and/or hunting near the water course
and bofedal areas. These findings bear a relation with the following periods: the
late formative, the late regional development and the Inca periods (SERNAP,
2006). 110
F igure 1. Interview to Primo Berna and his \\~fe in
Quetena Chico (Photograph: Loly Vargas Call:isaya)_
F igure 2_ Field visit to the Silala bofedals
"'ith Primo Berna, inhabitant of Quetena
Chico (Photograph: Loly Vargas Callisaya)_
117
The Silala bofedals area has received different human interventions throughout
the time, among which the following can be mentioned: a) Chile’s introduction
of canalization works in 1908 (Orellana et al. 2013), b) “yareta” (Azorella
compacta) exploitation before 1945 by the Chuquicamata mining company
(Gutierrez-Viñuales 2008), and c) sporadic human settlement by llama cattle
raisers (Nielsen et al. 1981).
2.2. Canalization of the Silala waters
The introduction of canalization works in the bofedal area that was authorized
in 1908 by Bolivia was intended to allow The Antofagasta and Bolivia Railway
Company Limited to build canals to exploit the waters for their steam engines
(Orellana et al 2013).
According to Messrs. Joaquin Estelo and Primo Berna, the canals built by Chile
in the Silala bofedals cover almost the entirety of their Surface area. During
the field work completed for this study, it was possible to corroborate the existence
of artificial canals in the South and North bofedals, in the vicinities of the
military post and Silala waterfall, and throughout the Cajon ravine (Figure 3).
The spring waters were abstracted from their main upwelling pools at the South
bofedal as far as the border between Bolivia and Chile.
Figure 3. Artificial canals built in the South and North bofedals. Note that the canals of the
North bofedal form a clear fishbone shape to abstract all the water course and take the water to
the main canal. (Photograph: Simon Pfanzelt).
During the interviews, settler Joaquin Estelo (83) said that he had been to the
Silala springs in 1945, when the bofedals were still guarded by the Chilean police
forces and maintenance works for the artificial canals were still performed
by Chilean people.
111
118
The canalization of these water sources was made with stones. Most of the
pooling waters were canalized and driven top the main canal (Figure 4). The
cleaning and maintenance of the canals was made with a brush, and the Chilean
stuff also extracted the aquatic vegetation and everything that could obstruct
the flow of water in the canals (fact noted by Joaquin Estelo).
The people interview noted that the canals were intended to abstract as much
water as possible and drive it to a main canal. They also said that, in some
areas of the bofedals, the water was also collected by means of pipes that were
buried underground. During the field visit completed, it was possible to observe
remains of pipes in the North bofedal, in Cajon ravine (Figure 5), which,
together with artificial canals conveyed the water to a desilting chamber.
According to Bazoberry (2003), once in Chilean territory, the water was
collected in a storage reservoir and distributed by means of pipelines to the
Chuquicamata mining fields, by a drinking water aqueduct to Antofagasta; and
to Inacaliri dam.
112
Figure 4. Abstracted and canalized pooling waters driven to the main canal. A). South bofedal; B). North
bofedal (Photograph: Loly Vargas Callisaya).
119
2.3. Surface area of the bofedals between 1970-1978
In order to obtain information of the state of the bofedals during the 1970-1978
period, interviews and site visits were completed with Primo Berna, employing
a GPS system and marking the [original] bofedal limits based on his perception
and memory. The results have been mapped on Figure 8. According to the
mapping completed, back in 1970, the bofedals were more reduced in extent
in comparison to what was observed in the field—an interesting account that
could be contrasted with technical data. The community inhabitants stated that
the bofedal vegetation was enduring a desiccation process and said that dry
peat could be observed in the bofedals. They further stated that the vegetation
was already reduced in extent at one meter of distance from the main canals.
2.4. Traditional management and preservation of the bofedals.
The people interviewed stated that they perform a traditional management of
the bofedals to preserve them; these activities include: opening irrigation channels,
irrigating the bofedals and planting seeds in them. Each of the families
makes use of a specific bofedal section to graze their cattle and are in charge of
that particular section.
Since 1997, following the denouncement put forward by the national press regarding
the use of the Silala waters by Chile, the Quetena Chico community
had Primo Berna stay in the Silala region to exert sovereignty.
2.5. Boundary stones set up by Chile
The people interviewed mentioned the presence of boundary stones surrounding
the South bofedal. These boundary milestones (15, approximately) were
1.5 m-high concrete structures built by the Chileans to guard the bofedals.
They further noted that the Chilean policemen once patrolled the vicinities of
the bofedals. During the field visit, and with the help of the people from community,
it was possible to corroborate and obtain geographical references (Table
1) of the remains of six of these stone structures (Figure 9) in the South
bofedal.
113
Figure 5. Artificial canals installed to abstract the water. A) water abstraction pipeline. B) "desilting
chamber" built in the Cajon ravine (Photograph: Loly Vargas Callisaya).
120
114
Table I. Geographical coordinates of the remains ofboundary stones found in the south bofedal.
Boundary Area Coordinate X Coordinate Y Altitude
stone MASL
1 19K 0603358 7566074 4415
2 19K 0603357 7566067 4414
3 19K 0603345 7566053 4414
4 19K 0603320 7566023 4425
Silala Hill 19K 0602817 7665963 4444
Vicinities of 19K 0602837 7565689 4421
the road
121
2.6. Yareta extraction
Another relevant historical antecedent that occurred in the Silala was the extraction
of yareta, in the years before 1945. The interviewees indicated that the
extraction of yareta (Azorella compacta) was done using carts and as evidence,
there are currently cart roads called the “yaretales”, located on the Silala hill
(Figure 10). These cart roads are the silent witnesses of the intensive extraction
of Azorella compacta and, according to Jacobo Berna, Joaquin Estelo and
Primo Berna these plants were used by the Chuquicamata copper mining company.
2.7. Temporal settlements and shelters in the Silala
The community of Quetena Chico made long trips to Chile, transporting their
animals, charque [dry meat] and saltpeter to trade them for Chilean products:
apples, pears, wheat, corn. These last two were milled in Chile to make flour
and gather bread for their communities. These trips made by the people of
Quetena Chico
115
Figure 6. Evident remains of boundary stones of the South Bofedal. A) stone marker in the hill found
close to the South bofedal. B) stone marker close to the road to the milita1y post (photograph: Loly
Vargas Callisaya).
Figure 7. Silala hill; note the roads to transpo1t yareta in carts (Photograph: Loly Vargas Callisaya).
122
in the past, were based on livestock activity and were traditionally complemented
by seasonal caravans, which allowed access to agricultural resources
produced in other eco-zones.
According to Joaquin Estelo, he would travel to Chile to buy basic foods, which
took him four days from Quetena Chico to Silala (Figure 26); during these trips
made with the animals, would he always head to the Silala waters in order for
the animals and people to be able to drink water. After reaching the Silala, they
would more to the Chilean towns of Toconao and Caspana.
According to Nielsen et al. 1981, the traditional destinations of the Quetena
llama cattle raisers were: Toconao, San Pedro de Atacama, communities of Rio
Loa, in the west (currently Chile), and Pirquitas, Rinconada and San Antonio
de Los Cobres (Argentina) to the south. They also made less frequent trips to
the valleys of the eastern Andean slope, such as Tupiza or Tarija. This information
is consistent with the testimonies of the people interviewed.
Ribera & Liberman 2006, highlight that this activity had a high cultural heritage
value that was lost and that was part of the survival strategies of highland
and dry valleys carried out through exchange routes.
Among the testimonies and stories told by the interviewees, the Quetena Chico
community people indicate that, before 1940, their grandparents already made
trips to the Silala, because that area was an important shelter due to its water
resources. This is consistent with the ruins or shelters (caves) found near the
Silala Bofedals (Figure 12). These “caves” comprised a dormitory (a cave) of 3
x 3 meters, approximately, and a kitchen where people prepared foods (according
to Primo Berna). Five shelters were registered and georeferenced around
the Silala; these are no longer used by the community members. According
to interviewees Primo Berna, Joaquin Estelo and archaeologist Angela Lanza,
these visits to the Silala had different reasons:
116
Figure 8. On the right side, Joaquin Estelo, inhabitant of Quetena Chico, who told the authors about the trips
he would make to Chile when transportation was yet not available in the area (Photograph: Loly Vargas
Callisaya).
123
- Some people used “caves” as a temporary shelters, when they brought
their products to trade them for basic foods in Chile (Joaquín Estelo).
- Some community members of Quetena Chico used the bofedales of Silala,
as a temporal shelter and grazing site for their livestock.
Among the people of Quetena who lived or traveled in different periods of time
by the bofedals of Silala since 1940, mention can be made to: Felix Berna,
Hilarion Berna, Ladislao Berna Alvares, Remigio Berna Ezquibel and Primo
Berna. The latter currently lives in the Silala from April to September, since
1997.
Another trace of human settlements found in Quebrada Cajon, about 200 meters
from the border between Bolivia and Chile, corresponds to household ruins
(Figure 13). This ruin is found in Bolivian territory and the testimonies indicate
that a Chilean person inhabited it (Jacobo Berna, Joaquin Estelo, Primo Berna
and second lieutenant Victor Astete).
117
Figure 9. Temporal shelters used by the people of the Quetena Chico community in the Silala (Photograph: Loly
Vargas Callisaya).
124
3. References
Bazoberry, Q. A. 2003, The myth of Silala. Plural Editorial. La Paz, Bolivia.
Nielsen, A. E., Vazquez M. M., Avalas J. C. and Angiorama C. I., 1999. Archaeological
Surveys in the “Eduardo Abaroa” Reserve (South Lipez, Department
of Potosi, Bolivia). In: Relations of the Argentine Society of Anthropology
XXIV, Buenos Aires.
Orellana, R. Yañez N., Montero Y., Weisner R., Hantke M., Del Castillo L., Rovere
& M., 2013. Conflicts and Agreements on Transboundary Waters. Regulatory
Frameworks and International Regulatory Practices. Cordillera University
– Sustainable Water, La Paz, Bolivia.
Ribera M. O. and Liberman M., 2006. The use of land and biodiversity resources
in the protected areas of Bolivia. A critical analysis with proposals for its
conservation and sustainable management. SERNAP-GEF II. La Paz, Bolivia.
SERNAP, 2006. Updated Management Plan for the Eduardo Abaroa National
Andean Fauna Reserve. Bolivia Gutierrez-Viñuales A. 2008. Chuquicamata:
industrial heritage of copper mining in Chile. In: APUNTES
(NOTES) Vol. 21, N° 1 (2008): 74-91.
118
Figure IO. Traces of human settlement in Cajon Ravine ( ancient house that was once inhabited by a Chilean national)
(Photograph: Loly Vargas Callisaya).
125
119
Annex2:Codes and meaning soffragment sand abbreviated species
Species
Algae
Arenaria sp.
Astragalus sp.
Calandrinia acaulis
Carex cf maritima
Deyeuxia chrysantha
Deyeuxia curvula
Deyeuxia 1 sp.
Deyeuxia 2 sp.
Eleocharis atacamensis
Festuca potosiana
Festuca rigescens
Gentiana gayi
Gentiana sedifolia
Juncus stipulatus
Lemna sp.
Lilaeopsis macloviana
Lobelia oligophylla
Mimulus cf glabratus
Moss
Nostoc
Oxychloe andina
Gramineae sp.
Phylloscirpus deserticola
Plantago tubulosa
Pucinellia frigida
Deyeuxia eminens var. eminens
Ranunculus sp.
Stukenia sp.
Werneria pygmaea
Xenophyllum incissum var.
incissum
Zameioscirpus atacamensis
Zameioscirpus muticus
Acronym
Alga
Aresp
Astsp
Caca
Cmar
Dchr
Deur
Deyspl
Deysp2
Eata
Fpot
Frig
Ggay
Gsed
Jsti
Lemsp
Lmac
Loli
Mgla
Mussp
Nossp
Oand
Gram
Pdes
Ptub
Pfri
Demi
Ransp
Stusp
Wpyg
Xinc
Zata
Zmut
abiutic
Saline outcrop
Water
Canal
Bird feces
Camelid feces
Viscacha feces
Organic matter
Dead gramineae
Dead Oxychloe
Stone
Burned gramineae
Sandy soil
Bare soil
Acronym Site Acrunym
asal South A SA
agua South B S B
can South C S C
haves South D SD
hcam South E S E
hvisc South F S F
morg North N
mgram Confluence CONF
moxy
pie
qgram
sare
sdes
126
120
Annex 3: Forward selection of PCA analysis with environmental variables that
significantly affect plant communities.
Variable Var.N Lambda A p F
Camelid feces (hcam) 5 0.19 0.071 2.78
Saline outcrop ( asal) 0.13 0.091 1.78
Organic matter (morg) 7 0.11 0.050 1.67
Dead gramineae (mgram) 8 0.09 0.159 1.34
Dead Oxychloe (moxy) 9 0.09 0.222 1.27
Stone (pie) 10 0.07 0.322 1.05
Viscacha feces (hvisc) 6 0.07 0.228 0.99
Water 2 0.06 0.449 0.84
Burned gramineae ( qgram) 11 0.04 0.446 0.67
Canal (can) 3 0.04 0.677 0.53
Sandy soil (sare) 12 0.03 0.771 0.39
127
121
Annex 4: Photographic guide of the taxa found in the Silala wetlands.
Claudioperla (Gripopterygidae-Plecoptera) Andesiops (Baetidae-Ephemeroptera)
Metrichia (Hydroptilidae-Trichoptera) Neotrichia (Hydroptilidae-Trichoptera)
Cailloma (Hydrobios idae-Trichoptera) Ectemnostega (Corixidae-Hemiptera)
Paraheptagyia (Diamesinae, Chironomidae- Diptera)
Austrelmis (Elmidae- Coleoptera)
128
122
Tanypodinae (Chironomidae- Diptera) Orthocladiinae (Chironomidae- Diptera)
Tanytarsus Chironominae, Chironomidae- Diptera) Simulium (Simuliidae- Diptera)
Hexatoma (Limoniidae-Diptera) Dolichopodidae (Diptera)
Tabanidae (Diptera)
Empididae (Diptera)
Ephydridae (Diptera) Hyallela (Hyallelidae-Amphipoda)
129
123
Dero (Naididae-Oligochaeta) Homochaeta (Naididae-Oligochaeta)
Enchytraeidae (Oligochaeta) Gloss iphonidae (Hirudinea)
Dorylaimus (Nematoda-Dorylaimidae) Dugesia (Dugesiidae-Trematoda)
Hydracarina (Acari)
130
124
Annex 5: Physical-chemical parameters of the sampling stations in the Silala wetlands.
Parameter CANAL
NORTH SOUTH
BOFEDAL BOFEDAL
pH 9 8 9
OD 7 6 7
CE 264 188 293
TDS 174 123 188
Annex 6: Habitat and morphological-structural parameters of the Silala wetlands.
Parameter CANAL
NORTH SOUTH
BOFEDAL BOFEDAL
Average vel. 0 0 0
Flow 0 0 0
%BAloc 5 33 11
%PG Aloe 9 33 14
P%F Aloe 6 0
%CG 8 0 4
%CF 14 0 3
%GG 10 0 12
%GF 8 7 16
%A 0 13 6
%Silt 0 7 0
%Veg 27 7 32
IHF 51 39 45
Annex 23.4
FUNDECO, “Study of Evaluation of Environmental Impacts
in the Silala, Palynology”, 2018
(English Translation)

133
SURVEY OF ENVIRONMENTAL IMPACT
ASSESSMENT IN THE SILALA
Palynology
Luis Pacheco D.Cs.
Coordinator
MNHN Mus Naoanal
de HilllDrts Natw'al
134
Authors:
Luis F. Pacheco, D.Cs.
Coordinator
Lie. Mariela Escobar Torrez
Botanist - Specialist in
Palynology
Univ. Diego Martinez
Geologist Specialist
MSc. Teresa Ortufio Specialist in
high Andean ecosystems and
wetlands and in Palynology
Lie. Katerine Escobar Torrez
Ecologist - Specialist in
Palynology
Univ. Jeanette Pacajes
Biologist - Palinologist
135
Authors:
Luis F. Pacheco, D.Cs.
Teresa Ortuno, MSc.
Coordinator. Director of the Institute of Ecology of the Higher
University of San Andres (UMSA).
Botanical biologist specialized in Palynology (current and past)
and Systematics of vascular plants ( Gomphrena,
Amaranthaceae ),
Lie. Katerine Escobar Torrez Biologist specializing in Palynology (current and past) in High
Andean eco-regions, Puna (bofedals) and the Amazon.
Researcher associated with the National Herbarium of Bolivia.
Lie. Mariela Escobar Torrez Ecologist biologist specializing in animal-plant relationship
(pollination) and palynological (current pollen) studies.
Researcher associated with the National Herbarium of Bolivia.
Univ. Diego Martinez Geologist - graduated formation directed to studies of
Univ. Jeanette Pacajes
External Collaborators
Marie-Pierre Ledru, PhD.
Stephane Guedron, PhD.
paleontology and geology of the Quaternary. Investigations and
independent consultancies.
Biologist - graduated. Training aimed at palynology and
dendrochronology. Laboratory assistant. Thesis student at the
Palynology Unit of the National Herbarium of Bolivia.
Paleontologist specializing in studies of ecosystem dynamics and
global changes. Director of Investigation in the Institute of Research
for Development (IRD). Researcher at the Institute of Evolutionary
Sciences of Montpellier (ISE-M)
Geochemist specialized in metals and metalloids in the current
environment and past eras. Investigator at the University of
Grenoble Alps and Research Institute for Development (IRD)
136
FINAL REPORT
SURVEY OF ENVIRONMENTAL IMPACT ASSESSMENT IN THE SILALA
INDEX
EXECUTIVE SUMMARY
Palynology
1. Background
2. Theoretical framework
3. General objective
4. Area surveyed
4.1. Description of the area surveyed
5. Methods
6. Sampling Points
7. Results and interpretation
7.1. Interpretation/stratigraphic description of the soil in the South bofedal
(profiles BSP2 and BSP14) 7.2. Interpretation of the relationship of the stratigraphic
profiles – extent of the South Bofedal
7.3. Paleoecological interpretations and age-depth models for the South Bofedal
(profiles BSP2 and BSP14)
7.3.a. Age-depth model based on 14C dating in the South Bofedal
7.3.b. Geochemical analysis (XRD) for the South bofedal (profiles BSP2 and
BSP14)
7.3.b.1 Geochemical analysis in soil profile BSP2
7.3.b.2 Geochemical analysis in soil profile BSP14
7.3.c. Zoning of palynological samples from the South Bofedal (profiles BSP2
and BSP14)
7.3. c.1. Zoning of soil profile BSP2
7.3. c.2. Zoning of soil profile BSP14
7.3.d. Changes observed in the vegetation of the South Bofedal (profiles BSP2
and BSP14)
7.3. d.1. Vegetation changes observed in soil profile BSP2
7.3. d.2. Vegetation changes observed in soil profile BSP14
7.4 Effects of canalization on the South Bofedal
7.4.a. Effects of canalization on soil profile BSP2
7.4.b. Effects of the canalization on soil profile BSP14
7.5. General conclusions on the changes recorded in the South Bofedal
7.6. Stratigraphic interpretation of the soil in the North Bofedal (BNP7)
7.7 Interpretation of stratigraphic profile relationship – extent of the North
Bofedal
7.8 Paleoecological interpretations and age-depth model for the North Bofedal
137
7.8.a. Age-depth model based on 14C dating in the North Bofedal (profile
BNP7)
7.8.b. Geochemical analysis of the North bofedal (profile BNP7)
7.8.c. Zoning of palynological samples from the North Bofedal (profile BNP7)
7.8.d. Vegetation changes observed in the North Bofedal (profile BNP7)
7.9 Effects of the canalization on the North Bofedal (profile BNP7)
7.10. General conclusions on the changes occurred in the North Bofedal
8. Determination of the historical environmental impacts caused by the presence
of the artificial canals system
8.1. Environmental impacts recorded in the South Bofedal 8.1.1. Impacts detected
in BSP2 profile
8.1.2. Impacts detected in BSP14 profile
8.2. Environmental impacts recorded in the North bofedal 8.2.1. Impacts detected
in BNP7 profile
9. General conclusions of the survey
10. Technical summary: Result Interpretation 11. Bibliography
Annex 1
Annex 2
Annex 3
Annex 4
138
TABLE AND FIGURE CONTENTS
Table 1. Profiles and trial pits selected for the South Bofedal
Table 2. Comparative summary of the composition and abundance of palynomorph
pollen taxa found in each profile studied in the different periods of time
Table 3. Summary of interpretations and reconstruction of past vegetation
through pollen analysis. Vegetation profile BSP2
Table 4. Summary of interpretations and reconstruction of past vegetation
through pollen analysis. Vegetation profile BSP14
Table 5. Summary of interpretations and reconstruction of past vegetation
through pollen analysis. Vegetation profile BNP7
Table 6. Summary of interpretations and reconstruction of XRD geochemical
analysis
Figure 1. Schematic summary of the methodological protocol used in the stratigraphic
geochemistry palynological section
Figure 2. Area surveyed with the sampling points in the South Silala Bofedal.
Longitudinal transect sampling for the South Bofedal. B) Transverse and longitudinal
transect of samples for the North Bofedal. The points correspond to the
sampling of stratigraphic profiles (Table 1)
Figure 3. Graphical representation of the stratigraphic description of BSP2
profile in relation to the profile depth (cm) A. Lithological relationship of the
profile with the age model from 1880; B. equivalent to the last 17 cm of the
stratigraphic profile
Figure 4. Graphical representation of the stratigraphic description of BSP14
profile in relation to the profile depth (cm), where the 14C dating points are
punctually highlighted
Figure 5. Image taken from the IEIA Silala 2 report, from figure 24, showing
the differentiation of the fragments in the North, South and confluence Bofedals
Figure 6. Stratigraphy of profiles of the South Bofedal and their location in the
areas defined in the vegetation survey from the Silala environmental impact
report, where A) shows the profile BSP8, B) profile BSP6, C) profile BSP2,
meticulously studied, and D) BSP4 profile
Figure 7. Age-Depth model of the sediment profile of the South Bofedal BSP2
139
Figure 8. Trace elements found in the geochemical analysis of BSP2 profile, in
concentration per second (cps)
Figure 9. Mn/Fe ratio in a soil profile from the South Bofedal (BSP2) of the
Silala region – Bolivia. In the x-axis, the age scale is observed in years AD and
in the y-axis and the values of the Mn/Fe ratios
Figure 10. Concentration in cps of trace elements found in the geochemical
analysis of BSP14 profile
Figure 11. Percentage of representative pollen taxa found in sediment profile
BSP2. On the left, it is possible to observe the AD time scale accompanied by
the lithology of the profile studied, and to the right the zonation that defines the
changes in vegetation, extended in the diagram with red lines
Figure 12. Pollen diagram of the concentrations of pollen, spore, algae and
ameba taxa (palynomorphs) counted in the profile and related to Lycopodium
spore counting to calculate the amount of palynomorphs that exist in a cm3
of sediments treated in the BSP2 laboratory. To the left, the time scale in AD
years, and to the right, the zoning that defines the vegetation changes extended
in the diagram with red lines
Figure 13. Percentage of representative pollen taxa found in sediment profile
BSP14. To the left, the depth in cm accompanied by the lithology of the profile
studied and the points at which dating was completed
Figure 14. Stratigraphy of profiles of the North Bofedal and their location in the
areas defined in the vegetation study of the Silala environmental impact report,
where A) shows BNP1 profile, B) BNP3 profile, C) BNP4 profile and D) BNP7
Figure 15. Age-Depth model of the sediment profile of North Bofedal BNP7
Figure 16. Trace elements found in the geochemical analysis of BNP7 profile,
in concentrations per second (cps)
Figure 17. Percentage of representative pollen taxa found in sediment profile
BNP7. To the left, the time scale in AD accompanied by the lithology of the
profile studied and, transversally, the zonation that defines the changes in the
vegetation, extended in the diagram with red lines
Figure 18. Wealth analysis based on the Chao index in the three profiles evaluated
by means of palynological analysis
140
EXECUTIVE SUMMARY
We present the final results, corresponding to the third report of consultancy
entitled “Survey of Environmental Impact Assessment in the Silala.” This
report focuses on the analysis of the historical changes recorded in the
bofedal[s] during the last 100 years and is based on a palynological analysis
of sediment profiles sampled in the South and North Bofedals, complemented
with stratigraphic and geochemical analyzes focused mainly on soil profiles: in
the South Bofedal, profile 2 (BSP2), South Bofedal, profile 14 (BSP14) and, in
the North Bofedal, profile 7 (BNP7).
The collection of soil profile samples and the soil stratigraphic description was
performed in March 2018, after which the chosen profiles were selected and
divided in two equal parts. One sample was sent to the EDYTEM laboratory in
Savoie (France) for its geochemical analysis, and another was left in Bolivia as
a “witness” for the palynological survey and to refer the samples for their 14C
dating. With these analyzes, it has been possible to infer the changes that took
place in past vegetation and the effects caused by the canalization on the South
and North bofedals.
Seven profiles were sampled in the South Bofedal and four in the North Bofedal,
using a “RUSSIAN perforator”; plus, two additional profiles from trial pits in
the South Bofedal. The sampling strategy included following a longitudinal
transect with a desiccation gradient through the South and North Bofedals.
From all the samples, four profiles were selected for the South Bofedal (BSP8,
BSP6, BSP2 and BSP14) and four additional ones for the North Bofedal (BNP3,
BNP4 and BNP7 [sic]), on basis of the organic matter proportions of the soil
profiles’ superficial layers.
In the South Bofedal profiles, carried out in places where the degree of desiccation
was very high, it was possible to observe an unexpected presence of organic
matter. In these sites, it has not been possible to find bofedal-characteristic
vegetation, which is an indication that the bofedal might have been larger
before canalization. The presence of organic matter in these profiles is clear
evidence that the area of the bofedal was wider and that it probably decreased
as a consequence of canalization; thus, the presence of organic matter served
to support the calculation of the estimated area that the South Bofedal covered
originally, which was carried out as part of this survey’s vegetation study.
141
Four profiles were sampled in the North bofedal, showing stratification processes
with variations in organic matter thickness; this can be attributed to changes in
water availability in earlier times. The upper stratum of the four profiles presents
a high proportion of organic matter, which is an indication of the fact that the
desiccation process had a smaller impact on the North Bofedal—as opposed
to the South Bofedal. This can be attributed to factors such as the gradient and
the geomorphology (a more closed valley), where most of the canalized water
sources converged in a main canal that passed through the North Bofedal. These
factors must have influenced water availability positively, for the preservation
of the North bofedal in certain areas near the main canal.
The samples for the 14C analysis were sent to the Beta Analityc Laboratory,
in Florida (United States). The profiles selected for dating were profiles BSP2
and BSP14, for the South Bofedal, and BNP7, for the North bofedal; 2 samples
were taken from each profile to complete the dating and calibration (see Table 1
in Annex 3). The results of the calibration of 14C dating were analyzed with the
Clam program (Blaauw, 2010) and age-depth models were developed for soil
profiles BSP2 and BPN7. The age model for BSP2 soil profile, based on 14C
dating, was compared with the variation of atmospheric lead (Pb) concentrations
found in the geochemical analysis in this same profile. Atmospheric Pb was
deposited between 1930 and 1980, due to its presence in the atmosphere derived
from Pb use as an enhancer in gasoline during those years. Subsequently, the
use of Pb in gasoline was banned in many countries, due to its negative effects
on the environment and the proliferation of disease—fact that resulted in a
gradual decrease in Pb deposition.
The age model for the BNP7 profile was collated by means of a geochemical
analysis, where an increase in the Iron/Titanium (Fe/Ti) ratio was detected.
This finding is explained by the occurrence of greater aerobic oxidation
in the medium, which is an indication of water scarcity. This interpretation
is supported by a comparison with other works carried out in high mountain
bofedals of Peru and Argentina, as well as on the experience of the experts who
contributed to this work. This indication of water reduction concurs in time
with the event known as the Little Ice Age (LIA), which had a dry phase from
1750 to 1850. This event occurred regionally and has also been detected by
other authors who have completed works on Andean bofedals.
The collection of samples for the geochemical analysis (XRD) was performed
every 0.5 cm, from the surface to the deepest profile base, providing high
resolution to our interpretations.
142
Through this analysis, changes in the environment can be detected by the
concentration of the different elements (metals) in the soil profiles, which are
in turn related with [radiocarbon] dating. This allows inferring what happened
in the environment in the past, with a main focus on the last 100 years.
The geochemical survey results show a clear process of gradual desiccation,
which is more evident in the South Bofedal. This period of desiccation began
around 1908, which is a clear sign of the effects that canalization had on the Silala
springs. The concentrations of terrigenous metals indicate that desiccation was
more severe during the 50s and 60s and that it continued until the 1990s, which
can clearly be observed in iron fluctuations (Fe). This period is considered
as the critical stage of the impacts of canalization. The bofedal desiccation
process is also reflected in the increase in bromine and nickel concentrations,
which respond to an accelerated process of humification, caused by dryness
in the environment. Similarly, the Fe/Ti ratio shows high values, due to the
oxidation caused by the reduction of water levels; and, conversely, a reduction
in the ratio of Mn/Ti and Mn/Fe, which is an indication of a decrease in water
inflows to the bofedal.
In order to compare vegetation composition before and after the canalization
works were installed, a palynological analysis was carried out, with pollen
readings every 0.5 cm, for the first 17 cm of the BSP2 profile, the first 20 cm
for the BSP14 profile and the first 16 cm for the BNP7 profile; this was done
for the purpose of studying, in greater detail, the history of the South and North
bofedals in the last 100 years. Overall, the results of the three profiles provide
evidence of a period with higher regional humidity before canalization was
introduced in 1908. This interpretation is based on the presence of thola plants
in greater quantity, verified by pollen from plants of the Asteraceae families
(Parastrephia) and Solanaceae (Fabiana dense), and a reduction of species of
the Poaceae and Cyperaceae families, which are known as plants that colonize
fragmented bofedals. This also concurs with an increase in the presence of
algae, which develop in humid environments, which correspond to the
bofedals before 1908. From 1908 onwards, a gradual desiccation process took
place and is evidenced by the change in palynomorph composition, reflected
in the increase of Palaeoarcella sp, which is a protozoan indicator of water
stagnation. This desiccation process reached its climax around 1950, when the
eutrophication processes of these stagnant waters, together with desiccation,
allowed the colonization and predominance of plants of the Cyperaceae
family in both the South and North bofedals. The Cyperaceae species are
143
opportunistic plants that thrive in humid soils, but with lower water levels than
those existing in the bofedals.
In conclusion, the results of the stratigraphic, metal and palynological analyzes
indicate that, compared to previous periods of natural dryness—as the Little
Ice Age dry phase—the effects of canalization had a greater impact on the
availability of water and the state of preservation of the Silala bofedals. In turn,
this decrease in water availability is likely to have affected the microclimate
and vegetation within the bofedal and in the surrounding areas.
Our results clearly show that the canalization process had a greater impact on
the South Bofedal, which cannot be attributed to climatic, or any other, changes.
Finally, Figure a) summarizes the results of this study, which are shown
separately for each of the three profiles studied in detail (BSP2, BSP14 and
BNP7), to show the coincidences. The red color indicates drier stages and the
dark blue color indicates periods with higher humidity. The critical desiccation
period is clearly distinguished in the three profiles. Said period occurred
between 1950 and 1990 and can clearly be attributed to the canalization of the
Silala Befalls water springs and not to climatic effects.
Figure a. Summary in time scale in years AD of the historical reconstruction
of profiles BSP2 and BSP14 of the south bofedal and profile BNP7
of the north bofedal compared with regional climatic events detected
in the last 500 years. LIA [PEH] = Little Ice Age; S = dry; H = humid.
Liu et al., 2005 PEH
Sajama
PIA ratio (log)
2
-
1 1500 1600 1700
H
~
o.
0
-0
-0.8
-1.2
Apaestegui et al., 2018
1800 1900 2000
S - BSP2
• BSP14
L---------1 ___ _ BN P7
1500 1600 1700 1800 1900 2000 Anos (AD)
seco __ ...._._ humedo
144
1. Background.
The present document constitutes the final report and corresponds to the third
product of the environmental impact study carried out in the Silala, which is
focused on the palynological study of the South and North Bofedals. This work
was completed in coordination with the vegetation team. It describes the results
of the stratification, palynology and geochemistry studies (X-ray diffraction),
which were applied to detect the effects that the canalization introduced in the
Silala area had since 1908.
In the present report, the results are arranged following a rationale that is
consistent with the methodological scheme and are divided into two parts i) the
South Bofedal and ii) the North Bofedal, which respond to the terms of reference
(hereinafter, TOR) listed below (1 to 5). In order to facilitate following up their
respective responses, the subtitles that cover each of the TOR are presented
below:
1. Estimation of plant diversity in the region in the last 100 years, comparing
the surface areas of the current bofedals, scrublands and degraded bofedals of
the Silala, through a pollen and fossil spores (palynology) survey. This survey
is compared with results from other bofedals in the area: 7.3.c and 7.8.c (see
index).
2. Paleoecological interpretations of the bofedal and Age/Depth model
corresponding to the bofedal: 7.3, 7.8.
3. Reconstruction of past vegetation and interpretation of possible anthropic or
climatic changes: 7.3.d and 7.8.d.
4. Analysis of the metal composition by X-ray diffraction (XRD); supplementary
analysis for the pollen analysis, which will allow to better understand the
changes in the vegetation, determining if they are due to natural or anthropic
causes: 7.3.b, 7.4, 7.8.b., 7.9.
5. Determination of the historical environmental impacts caused by the presence
of the system of artificial canals on the vegetation: 8.1 and 8.2.
Additionally, subtitle 10 includes a summary of the results, following the order
presented in the TOR.
2. Theoretical framework
According to DIREMAR (2017), currently, the predominant species
found in the South and North bofedals are Distichia muscoides,
Oxyclhoeandina and/or Plantago tubulosa in bofedal areas in
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145
associations such as a) Distichia muscoides – Oxychloe andina, in saturated
hydromorphic soils and phreatic levels with surface runoff; b) Plantago
tubulosa – Gentiana sp, on hydrothermal soils that do not present submergence
and superficial phreatic level.
The studies completed by Diremar (2017) provide information on the soils’
characteristics and their depth. These data were used as baseline information to
locate the drilling tests of the soil profiles for the palynological study. According
to this study, the North Bofedal presents a greater soil depth, where most of the
sampled points were deeper than 0.80 m, reaching the deepest place at 1.40
m, while the South Bofedal presented lower soil depth—the shallowest depth
was of 0.40 m and the greatest depth surpassed the 1.20 meters. The sediment
profiles present coincidences; a depth of 1.50 m was obtained in the North
Bofedal, while, in the South Bofedal, it was possible to obtain profile drillings
no deeper than 0.50 m due to the soil compositions, with the highest percentage
of sand and stones, confirming the previous study on the depth in the North and
South Silala bofedals. On the other hand, the organic matter (OM) vs. depth
values show that the soil in the North Bofedal is more homogeneous, with soils
with higher OM, near the 0.70 cm, while the South Bofedal presents greater sand
with depth and a presence of Maximum OM at 0.24 cm. Sediment deposition
varies a lot from bofedal to bofedal and it is therefore important to perform
tests to obtain a good soil profile to be studied and complete dating surveys for
each profile studied, given the heterogeneity in the sediment deposition found
in Andean bofedals, including the Silala.
At this point, it should be noted that geochemical studies the variations of the
elements are quite subtle to detect concentration changes in detail [sic], allowing
to perform a more detailed reconstruction. On the other hand, it can be observed
that the water table levels in the Silala bofedals are more heterogeneous than
those of other bofedals with different characteristics, as the Villamar bofedal
for instance, which displays more homogeneous levels. Thus, the Silala
bofedals have been reported as bofedals that are undergoing a degradation
process as a result of the canalization works, which have caused a reduction
in the groundwater levels and, particularly, a reduction in the characteristic
vegetation layer. Despite this, these bofedals currently have sufficient water
storage capacity.
The study of the “Environmental Impact Assessment in
the Silala” (Silala EEIA 2) shows more specific vegetation
data with the detailed identification of species that can be
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146
considered as indicators of degradation in the bofedals, e.g. species that colonize
the bofedal when a drying process is recorded, i.e. Cyperaceas (Carex cf.
maritima), Poaceae, as the Deyeuxia curvula, Deyeuxia eminens var. eminens,
Festuca potosiana, as well as those which, on the contrary, are considered
typical and bofedal-forming, where the Juncaceae and Xenophyllum incisum
are found, which are a humidity indicator.
Palynology is a discipline that studies pollen from a Paleoecological point
of view, and can be used in studies of paleoclimate and past vegetation
reconstructions, due to the close relationship between the flora and the processes
of the terrestrial system, and mainly because the structure of pollen and spores
allows them to be preserved and fossilized. This fact allows, through pollen
analysis, inferring the vegetation composition in a system under study over time
(Seppa, 2007, Brewer et al., 2007, Twidle, 2012). The investigations carried out
in the reconstruction of past environments are carried out in places where a
stratification of soil can be distinguished, allowing to obtain sediment profiles
with a continuous, stable and low oxidation sedimentation process (less oxygen
and greater preservation), as is the case of the vegetation of high Andean bofedals.
Given the importance of data on the type of sedimentation that took place, it is
advisable to make precise stratigraphic descriptions in the areas studied, which
can give indications of the mechanisms that gave rise to sedimentation on basis
of a textural analysis of the clastic components (composition of the rocks found
in the sedimentation of the superficial layers represented in soil profiles). Soil
profiles have different shapes (rounded, angled, etc.), and they also vary in the
percentage distribution of their components and color.
Sediment profiles are dated through different methods, the best known being
Radiocarbon dating (14C), which is an isotope present in sediment samples that
contain organic matter. This method was used to date samples with a maximum
of 40,000 years of age (Cook & van der Plitch, 2007, Hattle & Jull, 2007),
but currently 14C dating can be used for more recent times with low error
margins, facilitating the reconstruction of more modern vegetation. To this end,
calibration programs are used, where the age-depth model results are obtained
by precise statistical means (https://www.radiocarbon.com). These models give
an age equivalence for the different depths of soil profiles as a function of the
sediment deposition time. However, to have more certainty on the sample ages,
it is desirable to complete the dating with other dating methods, such as the
210Pb (Espi 1997).
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147
Modern palynological studies also use other complementary methods to give
greater precision to the interpretations of environment reconstruction, one of
which is the analysis of the composition of metals by X-ray diffraction (XRD).
This analysis can detect the concentrations of metals in sediments, to allow
the possibility of determining whether their presence is due, for example, to
plant bioaccumulation, metal accumulation from the atmosphere, or whether
the accumulation derives from other anthropogenic disturbances (mining,
industrial waste, among others).
Complementary studies, of pollen with metal analysis, conducted in the
bofedals of the Peruvian, Chilean and Argentine Andes (Schittek et al., 2015,
Schittek et al., 2016) demonstrate the effectiveness of the combination of these
methods to infer climate changes or the effects recorded in vegetation due to
changes in hydrological regimes, especially in a type of azonal vegetation, such
as bofedals. However, few of these surveys comprise recent reconstructions in
time—as is done in the present survey.
This study has been designed to study the soil profiles of the Silala region
bofedals in order to assess whether the canalization works, introduced in the
area surveyed at the outset of the twentieth century, had the impacts that can be
detected in the changes recorded in the pollen deposited in the vegetation and
the accumulation of metals in the soil.
3. General objective
The objective of the present work was to carry out a palynological and
geochemical study (XRD) in the Silala bofedals in order to reconstruct the
history of the vegetation and see if it is possible to detect some of the effects
caused by the canalization of the springs—which has been in place in the area
surveyed since 1908.
In order to achieve said objective, and with the help of earlier geographical
information system surveys and the characterization of the current vegetation
of the area, the questions that are sought to be answered are:
Does the stratigraphic description of soil profiles in a longitudinal transect in
the South and North bofedals support the presence of wetlands (bofedals) in
the area studied?
Does the interpretation of the geochemical analysis of metals give any
indications of anthropic disturbance focused on the fluctuation in the wetlands’
water levels?
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148
Do the changes in the composition of palynomorphs in the sediment profiles,
of the South and North bofedals, provide any signs of anthropic disturbance
derived from the canalization of water sources during the last 100 years?
4. Area surveyed
4.1. Description of the area surveyed
The area surveyed is part of the southern block of the Western Maintain Range,
and corresponds to a Volcanic Zone of the Central part of the Andes, with
exposed rocks (ignimbrite, andesite and dacite) that belong to the Miocene (23
to 5 ma) (Baker Y Francis 1978). The geomorphology of the region is the result
of different—particularly volcanic—processes (predominance of volcanic
craters, lava flows and pyroclastic deposits). Other important processes are the
successive glaciations that took place between the Pliocene and Holocene that
defined the wide and U-shaped valleys, as well as the formation of deposits of
lateral moraines and the superposition of fluvioglacial, alluvial, colluvial and
eolian materials. The deposits in the bofedales are constituted by sand, silt and
clay (D., Martinez Obs. Pers.).
The few palynological studies in the area allow recognizing different Holocene
periods (the last 10,000 years before the present) in the highland region. Lake
Titicaca is a reference of these regional changes that are also reflected in the
south of Bolivia and north of Chile. The progressive increase of aridity in the
environment, from the beginning of the early Holocene, continued during the
period of extreme aridity in the Middle Holocene (8000 to 3500 years BP) [sic,
the sentence is incomplete] (Mouguiart et al., 1997; 1998; Abbot et al., 2000;
2003 Saez et al., 2007; Moreno et al., 2007; Pueyo et al., 2011).
During the mid and early Holocene, an increase in the activity of the Parinacota
volcano was detected (Moreno et al., 2007). Subsequently, during the late
Holocene, an increase in rainfall was recorded, coinciding with the settlement
of human populations in Chile’s northern region, and the occurrence of brief
arid intervals (Messerli et al., 1993). However, the data obtained from the late
Holocene has very low resolution and the increase in the settlement of human
population is not quite clear, particularly for the last 300 years.
5
149
19
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
5. Methods
The methodological sequence is presented in Figure 1. Annex 2 presents the methodology employed
in extenso.
Figure 1: Schematic summary of the methodological protocol used in the palynological study, including the
stratigraphic and geochemical sections.
1. Stratigraphic analysis: Although stratigraphic analyzes are not contemplated in the terms
of reference, it is essential to have this information, as it is necessary to describe the
characteristics of the soil more accurately and perform an effective interpretation of the
historical reconstruction of palynology and geochemistry.
Several soil profiles were made, as indicated in section 6 (surveyed area, Figure 2). Each of
the soil profiles was described on basis of the soil characteristics and stratigraphy. The
information was used as a basis to select the most consistent soil profiles in order to perform
a paleo-ecological reconstruction. In some occasions, the soil profiles used in pollen studies
can come from areas where the soil may have been affected by landslides or other forms of
soil removal, either by natural or anthropic events. These events generate “hiatus” within the
profile and can result in inconsistencies in the age-depth models. Therefore, in order to reduce
the possibility of making this mistake, it is necessary to consider the completion of a
5. Methods
The methodological sequence is presented in Figure 1. Annex 2 presents the
methodology employed in extenso.
Figure 1: Schematic summary of the methodological protocol used in the palynological study,
including the stratigraphic and geochemical sections.
1. Stratigraphic analysis: Although stratigraphic analyzes are not contemplated
in the terms of reference, it is essential to have this information, as it is
necessary to describe the characteristics of the soil more accurately and perform
an effective interpretation of the historical reconstruction of palynology and
geochemistry.
Several soil profiles were made, as indicated in section 6 (surveyed area, Figure
2). Each of the soil profiles was described on basis of the soil characteristics and
stratigraphy. The information was used as a basis to select the most consistent
soil profiles in order to perform a paleo-ecological reconstruction. In some
occasions, the soil profiles used in pollen studies can come from areas where
the soil may have been affected by landslides or other forms of soil removal,
either by natural or anthropic events. These events generate “hiatus” within the
profile and can result in inconsistencies in the age-depth models. Therefore, in
order to reduce
6
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150
the possibility of making this mistake, it is necessary to consider the completion
of a stratigraphic study that allows having greater certainty of using the appropriate
profiles. It is also important to verify the presence of organic matter,
which is necessary to carry out 14C dating. Organic matter can ensure efficient
preservation of fossil palynomorphs, which improves the accuracy of studies.
In the case of this project, the identification of the strata with greater presence
of organic matter was especially useful for the vegetation team to perform an
approximate calculation of the area that the bofedal might have had before the
canalization works were introduced in the Silala area (see subtitle 7.2 of this
report).
2. 14C dating: With the data from the dating completed (Annex 4) and the
stratigraphy, the age- depth model was constructed by means of the Clam program
(Blaauw, 2010), for the South bofedal BSP2 profile and the North bofedal
BNP7 profile. The BSP14 profile does not have an age model, due to a slow
sedimentation process (see section 7.3.a). The calculations of age models were
completed on basis of the dating available per profile, before making the pollen
diagrams. Therefore, the age model is first performed in order to be able to
relate [it] to the profile depth. Finally, this relationship is used to interpret and
compare the palynological and geochemical data (XRD).
3. Geochemical analysis: The profiles selected for the geochemical analysis
are: BSP14, located in the South bofedal area, with current vegetation in good
condition; the BSP2 profile, located in a degraded area of the South Bofedal,
with saline outcrops; and the BNP7 profile, located in a currently stable vegetation
area, in the North bofedal.
The XRD geochemical analysis is a method that measures the concentration of
chemical elements and their changes over time. The presence of the different
elements constitutes indicators of impacts or effects that occurred in the environment.
To visualize the information, the data are presented in a chemical element
diagram that allows relating the concentrations with the age models (see
figures 7, 12). In the case of the Silala, the results of the records obtained for the
period following 1900 are the ones used to interpret the effects of canalization
(BSP2, BSP14 and BNP7). Additionally, the BNP7 profile recorded a climatic
event related to the dry phase of the Little Ice Age.
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151
4. Palynological analysis: The percentages of relative abundance of the palynomorphs
found during pollen counts are plotted in the polynomial diagrams.
These values represent the relative abundance of the different taxa represented
by pollen, spores, algae and amoebas generally denominated palynomorphs.
In the case of algae and amoebas, these are not pollen elements, but rather
palynomorphs that are useful for interpretations, since they are indicators of
the environmental conditions of interest, such as water availability and others.
The pollen count was performed with a high resolution level, determining approximately
300 grains of pollen every 0.5 centimeters; in addition, markers of
Lycopodium spores, added to the samples, were also counted during the chemical
treatment of the sediment in the laboratory; this marker is counted within
the samples to obtain pollen concentration (see Annex 2). To carry out a proper
vegetation reconstruction, the age calibration model and the soil stratification
profile are added to the right side of the pollen diagram.
Additionally, a figure of the pollen count diagram was added as a function of
the total pollen concentration for each taxon for the BSP2 profile. In this case,
the relationship between the pollen count values and the Lycopodium count
values is used; the value provides the amount of pollen that is found in 1 cm-3
of the sample.
In the pollen diagram, a zoning was carried out, which defined several “zones”,
which were used as a basis to describe the results and reconstruct the vegetation.
These zones were defined as a function of the changes recorded in the
composition of taxa identified in the pollen count and their relation in a determined
period of time. Four pollen zones were identified in the BSP2 and BNP7
profiles, and three in the BSP14 profile, which correspond to periods of time
with evident changes in the composition of pollen taxa. Annex 3 presents some
of the pollens determined in the study, as well as some photos of the pollen
obtained from reference plates of plants collected in the Silala, during the field
work.
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6. Sampling points
For the sampling of the profiles in the South Bofedal, an approximately longitudinal
transect was followed from the first water springs to the border, along
which seven profiles were obtained and two trial pits were dug and sampled.
The criterion used to carry out the transect was based on the assumption that
the southeastern part of the Silala suffered a strong drying effect, which is currently
observed in the vegetation map and corresponds to the bare soil area (see
Figure 2).
The South bofedal presents an irregular and reduced depth, reaching a maximum
of 1m in the deepest parts (DIREMAR 2017). The depth of the soil profiles
that were drilled reached 60 cm. On the other hand, the physiognomy of the
vegetation shows a visible degree of impairment, due to the severe desiccation
of the bofedal, as a result of the water canalization and diversion. Of the seven
profiles made in the South Bofedal, four were identified and were thoroughly
studied from the stratigraphic point of view of the soil (BSP2, BSP6, BSP8,
BSP10, BSP14) (Figure 2A), in addition to the trial test pits BSP7, BSP9 (see
Table 1 and Fig.2). Profiles BSP2 and BSP14 were studied with palynological
methods, dating and heavy metal studies.
22
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
hand, the physiognomy of the vegetation shows a visible degree of impairment, due to the severe
desiccation of the bofedal, as a result of the water canalization and diversion. Of the seven profiles
made in the South Bofedal, four were identified and were thoroughly studied from the stratigraphic
point of view of the soil (BSP2, BSP6, BSP8, BSP10, BSP14) (Figure 2A), in addition to the trial test
pits BSP7, BSP9 (see Table 1 and Fig.2). Profiles BSP2 and BSP14 were studied with palynological
methods, dating and heavy metal studies.
Table 1: Profiles and trial pits selected for the South Bofedal (analyzed in depth for this report). The dated
profile (analyzed in depth for the present report) is shown in italics and the trial pits are presented in bold letters.
Geographical reference
Code
(UTM)
E
19K
N
Altitude
(m)
Depth
(cm)
BSP2 602984 7565848 4412 42, 0
BSP6 603110 7565799 4416 58, 0
BSP8 603331 7565708 4413 24, 0
BSP10 602901 7565841 4415 41,6
BSP14 602846 7565820 4412 43,5
BSP7 603331 7565713 4413 63, 0
BSP9 603382 7565700 4416 44, 0
BNP7 600842 7566289 4364 73,5
BNP1 600931 7566328 4367 48, 0
BNP3 600758 7566262 4352 22,2
BNP4 600846 7566295 4354 150,9
9
23 153
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Figure 2. Area surveyed with the sampling points in the South Silala Bofedal. A) Longitudinal transect sampling
for the South Bofedal. B) Transverse and longitudinal transect of samples for the North Bofedal. The points
correspond to the sampling of stratigraphic profiles (Table 1). The orange line indicates the transect direction.
10
154
Four profiles were carried out in the North Bofedal, bearing the codes BNP1,
BNP3, BNP4, BNP7 (Table 1, Fig. 2B); the sampling was carried out in such
a way that the profiles are located longitudinally in the bofedal, except for the
BNP6 profile made close to the edge (Figure 2B). Of these profiles, BNP7 was
dated and studied with palynological methods and with a heavy metal survey.
The physiognomy of the vegetation shows a greater drying effect on the far
ends of the North bofedal main canal, while the cushions bordering the main
artificial canal remain in good condition (Figure 2B).
The depth of the soil in the North Bofedal is irregular, like the South bofedal;
however, the profiles reached greater depth, reaching 151 cm in the BNP4
profile. According to the vegetation and soil report records (DIREMAR 2017),
the average depth in the North Bofedal is 111 cm.
7. Results and interpretations
7.1. Interpretation/stratigraphic description of the soils in the South
Bofedal (profile BSP2 and BSP14)
The BSP2 profile has a depth of approximately 40 cm, dominated mainly
by fine sand, from the profile base to a depth of 8 cm, when the substrate is
dominated by organic matter towards the profile surface (Figure 3A) (Annex
1). This variation in the deposition of sedimentary material shows a change
in the water flows, which reduced with the settlement of organic matter. In
addition, with the help of the age model, it is possible to demonstrate that the
last 20 cm of the profile represent the last 120 years of the bofedal (Figure 3B).
11
155
On the other hand, the BSP14 profile shows two layers of organic matter, one
between 1-10 cm of depth and another between 16-22 cm (see Figure 4) (Annex
1). These layers indicate the development of a bofedal in these areas, which
might have been interrupted during some periods of time.
The first change of soil stratum happened near the point with dating that
corresponds to an age of 680 – 862 years ago, and therefore in a period prior
to the canalization process; the first change of stratum in the soil can be
evidenced. The change that occurred was from a high percentage of organic
matter to a soil with a higher percentage of fine sand particles, in a clay-silty
matrix. The beginning of this process indicates that the bofedal-characteristic
vegetation is likely to have stopped developing, due to the presence of more
water, derived from the reactivation of water flows at this point. This type of
stratum continued until the next change, which occurred between 1960 – 1980
years (Figure 6). This period corresponds to the critical period, due to a lack of
water, that occurred approximately 50 years after the canalization works were
installed—which remain in operation until the present time.
The increase in organic matter at this stage suggests a new reduction in water
availability, which caused a desiccation at the site and led to the re-establishment
and/or re-colonization of typical bofedal species. This process was accompanied
by a change in the soil structure, with an increase in organic matter. In this
period, a process of eutrophication seems to have occurred, which occurs when
a waterbody dries up and puddles of stagnant water are produced.
25
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
A) B)
Figure 3. Graphical representation of the stratigraphic description of BSP2 profile in relation to the profile depth
(cm) A). Lithological relationship of the profile with the age model from 1880. B) The same as A, but for the
last 17 cm of the stratigraphic profile.
On the other hand, the BSP14 profile shows two layers of organic matter, one between 1-10 cm of
depth and another between 16-22 cm (see Figure 4) (Annex 1). These layers indicate the development
of a bofedal in these areas, which might have been interrupted during some periods of time.
The first change of soil stratum happened near the point with dating that corresponds to an age of 680
– 862 years ago, and therefore in a period prior to the canalization process; the first change of stratum
in the soil can be evidenced. The change that occurred was from a high percentage of organic matter
to a soil with a higher percentage of fine sand particles, in a clay-silty matrix. The beginning of this
process indicates that the bofedal-characteristic vegetation is likely to have stopped developing, due
to the presence of more water, derived from the reactivation of water flows at this point. This type of
stratum continued until the next change, which occurred between 1960 – 1980 years (Figure 6). This
period corresponds to the critical period, due to a lack of water, that occurred approximately 50 years
after the canalization works were installed—which remain in operation until the present time.
The increase in organic matter at this stage suggests a new reduction in water availability, which
caused a desiccation at the site and led to the re-establishment and/or re-colonization of typical bofedal
species. This process was accompanied by a change in the soil structure, with an increase in organic
matter. In this period, a process of eutrophication seems to have occurred, which occurs when a
waterbody dries up and puddles of stagnant water are produced.
12
Calizas
g i ~ g
~ ~ ~ ~
Barro Arena Grava
Aflos
AD /BC
2000
1990
1980
1970
1960
1950
1940
1930
1920
1910
1900
1890
1880
156
26
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Figure 4. Graphical representation of the stratigraphic description of BSP14 profile in relation to the profile
depth (cm), where the 14C dating points are punctually highlighted
7.2. Interpretation of the stratigraphic profile relation – extent of the South Bofedal
Figure 5. Image taken from the IEIA Silala 2 report (figure 24), showing the differentiation of the fragments in
the North, South and confluence Bofedals. The characteristics of the fragments are detailed in table 13 of the
final report: “Survey of Environmental Assessment in the Silala” (IEIA Silala).
13
Prof.
1980-• 1 0
1960 AD
680-•
862AD 20
30
S.Clor1t1
_ S_AO
_ S_AI
_ S_Alb
S_A2
S_AJ
·s-_·c
s_o
• s_e
_S_F
• connuenc:11 -·
LIMO
BSP14 ~
0
E
Calizas
ARENA GRAVA
C .0 .0 :5
~ .0 .0
CD 0 0
Cl a. (.) .0
Sectores del bofedal Solala
A
s_a
s_o
- ="-'="-' -----===="'----''l!-
157
27
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Figure 6. Stratigraphy of profiles of the South Bofedal and their location in the areas defined in the vegetation
survey from the Silala environmental impact report, where profiles BSP8 (A), BSP6 (B), BSP2 (C) and D)
BSP4 (D) are shown.
In the second environmental impact report of the Silala study (IEIA Silala 2, section 6.5), different
patches of plant communities were differentiated in the South Bofedal (Figure 5). The longitudinal
transect of the collection of profile samples for the present study follows a gradient of reduction of
humid conditions, which are reflected in the physiognomy of the vegetation towards the southeast of
the area surveyed.
In the last point, area S_A0 (Figure 5), it was difficult to obtain a compact soil profile, because the
substrate of that site had a high percentage of sand, supported by a silty matrix; thus, a trial pit had to
be made at that point (profile BSC9). This type of soil is usually found in sites with water
accumulation. On the surface of the S_A0 area (Figure 5) substrates of reduced vegetation were found
in areas of bare soil, represented mainly by Deyeuxia curvula. The tillers of this species are shown
inclined towards the direction of the wind, because they are exposed to wind currents. Wind erosion
is a very strong environmental pressure in the study area; it promotes a slow formation of soils, which
occurs almost only in sites with vegetation.
Soil profile BSP8 (Figure 6A) is found in vegetation type S_A1b (Figure 5), which has a
predominance of Deyeuxia curvula and the presence of Xenophyllum incisum var. incissum, which is
In the second environmental impact report of the Silala study (IEIA Silala
2, section 6.5), different patches of plant communities were differentiated in
the South Bofedal (Figure 5). The longitudinal transect of the collection of
profile samples for the present study follows a gradient of reduction of humid
conditions, which are reflected in the physiognomy of the vegetation towards
the southeast of the area surveyed.
In the last point, area S_A0 (Figure 5), it was difficult to obtain a compact
soil profile, because the substrate of that site had a high percentage of sand,
supported by a silty matrix; thus, a trial pit had to be made at that point (profile
BSC9). This type of soil is usually found in sites with water accumulation. On
the surface of the S_A0 area (Figure 5) substrates of reduced vegetation were
found in areas of bare soil, represented mainly by Deyeuxia curvula. The tillers
of this species are shown inclined towards the direction of the wind, because
they are exposed to wind currents. Wind erosion is a very strong environmental
pressure in the study area; it promotes a slow formation of soils, which occurs
almost only in sites with vegetation.
Soil profile BSP8 (Figure 6A) is found in vegetation type S_A1b
(Figure 5), which has a predominance of Deyeuxia curvula and
the presence of Xenophyllum incisum var. incissum, which is
14
N
A A)
P:,:.1 BSPS
UIOlogl11
10
L:t"!: .. J<•oc-• Tlpo :.:-::-...:~:taQ....,..,.-., 20
C "'-~o.er .. .,.
0 s..:, ....
-, B)
~ =
BSP6
C) Hi! ii
";::: Lilologla
10
":::I 8SP2
LIIOIO(Jla 20
10 30
20 40
30
50
40
158
a species that is an indicator of high humidity in the soil inasmuch as it grows
on edges of waterbodies and/or bofedals (IEIA Silala 2).
Coincidentally, the first 5 cm of the BSP8 profile presented organic matter,
which was not found in the BSC9 profile. This suggests that the establishment
of bofedal species occurred in the S_A1b patch, capable of contributing to the
formation of soil rich in organic matter. This hypothesis is based on the fact
that the study area is in an arid environment, where there is strong soil erosion
and slow humification processes, which reduce the likelihood of soil formation
with a high amount of organic matter. Therefore, in the absence of bofedal
vegetation, which contributes to the formation of organic matter, the soil would
present a high percentage of sand, as observed during field work on the slopes
(rocky and scrub) that surround the bofedals. These interpretations indicate that
vegetation patch S_A1b was part of the extent of the south bofedal, as indicated
in the vegetation report (IEIA Silala 2).
Unlike profiles BSC9 and BSP8, profiles BSP2 (Figures 6C) and BSP6 (Figure
6B) are found in areas with remnants of cushions of Oxychloe andina (a species
characteristic of bofedals). At present, these areas are found in bare soils
with saline outcrops (see Figure 5 and 6) and were classified as open pastures of
sectors enduring a desiccation process (IEIA Silala 2). However, the thickness
of the layers of superficial organic matter found in these profiles (8 and 7 cm,
respectively) indicate that these areas comprised bofedals in the past.
7.3.Paleoecological interpretations and age-depth model for the South
Bofedal (profiles BSP2 and BSP14)
With the information of the dating and stratigraphy, the age-depth model was
built for the BSP2 profiles of the South Bofedal. The BSP14 profile does not
have an age model, due to a slow sedimentation process (see section 7.1). The
calculations of the age models were based on the dating available per profile
before making the pollen diagrams. Therefore, the age model was first performed
in order to relate it to the profile depth. Finally, this relationship is used
to confirm with the palynological and geochemical data (XRD).
7.3.a. Age depth model based on 14C dating in the South Bofedal
The BSP2 and BSP14 soil profiles were dated in the South bofedal.
The results of the calibration of 14C dating were analyzed in the
Clam program (Blaauw, 2010), on basis of two dating surveys
15
159
completed at different depths for each profile. For the BSP2 profile, the first
dating was performed at 7 cm depth and corresponds to the year 1958 AD. The
second dating was 38 cm deep and corresponds to 1711 AD. The age-depth
model shows a linear relationship with constant sedimentation, where it can be
inferred that every 5 mm of depth in the profile there is sediment accumulation
that corresponds to a period of 8 years (Figure 7).
The model is supported by the concentration of atmospheric lead (Pb) obtained
from the geochemical analyzes (Figure 9), which shows a high coincidence
with the atmospheric accumulation of Pb, which increased between 1930 and
1970-80, due to the use of Pb to improve gasoline (Espi et al., 1997). This
atmospheric accumulation of Pb was reduced from 1980 onwards, when the
use of Pb was banned, due to its negative effects on the environment. In profile
BSP2, the atmospheric deposition of Pb increases from approximately 1935 to
1980 to then decrease. These results concur with other scientific investigations
(Espi et al., 1997), which corroborates the high reliability of the model used in
this study.
For the BSP14 profile, the calibration results based on 14C dating show a large
difference in ages between the two dating points (> 1000 years between each
point, Figure 4). The most superficial dating point (9.5 cm depth) corresponds
to the period between 1980-1960, with a reliability of 84.6%. The second
dating (at 17.5 cm depth) corresponds to an age between 680-862 years, with a
reliability 95.4%.
Due to the short difference in depth between the two points submitted
to dating, it is not advisable to develop an age-depth model, as in
the case of the BSP2 profile, since in this case it would be necessary
29
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
7.3.a. Age depth model based on 14C dating in the South Bofedal
The BSP2 and BSP14 soil profiles were dated in the South bofedal. The results of the calibration of
14C dating were analyzed in the Clam program (Blaauw, 2010), on basis of two dating surveys
completed at different depths for profile. For the BSP2 profile, the first dating was performed at
7 cm depth and corresponds to the year 1958 AD. The second dating was 38 cm deep and corresponds
to 1711 AD. The age-depth model shows a linear relationship with constant sedimentation, where it
can be inferred that every 5 mm of depth in the profile there is sediment accumulation that
corresponds to a period of 8 years (Figure 7).
The model is supported by the concentration of atmospheric lead (Pb) obtained from the geochemical
analyzes (Figure 9), which shows a high coincidence with the atmospheric accumulation of Pb, which
increased between 1930 and 1970-80, due to the use of Pb to improve gasoline (Espi et al., 1997).
This atmospheric accumulation of Pb was reduced from 1980 onwards, when the use of Pb was
banned, due to its negative effects on the environment. In profile BSP2, the atmospheric deposition
of Pb increases from approximately 1935 to 1980 to then decrease. These results concur with other
scientific investigations (Espi et al., 1997), which corroborates the high reliability of the model used
in this study.
Figure 7. Age-Depth model of the BSP2 sediment profile of the South bofedal.
16
.;.:,
?1d :r 1ii:ix ) r j
3-! rr,
€1?11 .... i,:,
160
to have a greater number of dating surveys. For this reason, the interpretation
of the historical reconstruction in this profile will be carried out on basis of the
relation of variations obtained from the other (stratigraphic, geochemical and
palynological) analyzes and the intervals that are observed before and after the
points where the dating surveys were completed The interpretations are made
in a depth scale of centimeters.
7.3.b. Geochemical analysis (XRD) of the South bofedal (profile BSP2 and
BSP14)
7.3.b.1. Geochemical analysis in the BSP2 soil profile
The age-depth model indicates that a depth of approximately 17 cm corresponds
to 1880 AD (AD = anno dominia = after Christ = current calendar, all ages
mentioned below correspond to AD). According to the same model, a depth
of 8 cm would correspond to 1950. For the following interpretations, we take
these points as a reference (Figure 7).
Figure 8a shows that the concentrations of lead (Pb) present fluctuating values
between 1880 and 1975, approximately; with peaks in 1935 and 1953. From
1975 onwards, the values of lead begin to drop, coinciding with a decrease in
the use of lead in gasoline globally.
Iron (Fe) values remain high from 1880 to 1906, with a peak towards the end of
that period. Subsequently, the concentration of Fe declined steeply until 1925
to then rise again to reach another peak in 1938. This high iron value was
remained the same until 1953 and then fell continuously until 1990, when a
slight increase can be observed, lasting until the present (Figure 8b).
The concentration of bromine (Br) shows stable values between 1906 and
1948; it then presents slight oscillations in its concentrations until 1940, when
it began to increase, reaching a peak in 1958. These values of Br remain high,
with slight changes, until 1982, and then drop up to the present time (Figure
8c).
The concentration of nickel (Ni) remained stable from 1878 to 1906. Subsequently,
the nickel values dropped markedly until 1925. From that date on, the values began to
17
161
increase following the same pattern of bromine, reaching high values from
1968 to 1990, with more marked fluctuations than Br (Figures 8c and d).
The ratio between silicon and titanium (Si/Ti) remains constant from 1880
to 1916. From 1916 onwards, a slight increase began and remained the same
until 1950. From 1950 onwards, the Si/Ti ratio increased drastically until 1985.
Subsequently, the Si/Ti values decreased until 2004, to slightly increase again,
up to the present (Figure 9e).
The ratio between iron and titanium (Fe/Ti) remains constant from 1880 to
1916. As of that date, the Fe/Ti values increase slightly until 1925, with a peak
in 1935. A decrease is then observed until 1978, prolonging up to the present
(Figure 8f).
The ratio of manganese and titanium (Mn/Ti) remains stable in the same period
as Fe/Ti. As of approximately 1916, a slight increase in the Mn/Ti ratio has
been recorded, reaching its maximum point in 1980. It subsequently decreased
until 2004, when a new increase started and remained up to the present (Figure
8f and g).
The Mn/Fe ratio shows a pattern similar to of the Mn/Ti ratio, but it is not as
marked as the former (Figure 9).
Figure 8. Trace elements found in the geochemical analysis of BSP2 profile, in concentration per second (cps)
Figure 9. Mn/Fe ratio in a soil profile from the South Bofedal (BSP2) of the Silala region – Bolivia. In the xaxis,
the age scale is observed in years AD and in the y-axis and the values of the Mn/Fe ratios
18
Mos
!~ AO,SC
2000
1990
1980
1970
1960
1950 r 1940
1930
1920
1910
1900
1890
1880
i • ••l•'l" 11 ·•*••-*
«ihl.•10.l; •J F• \ • 10.lJ
162
32
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Figure 8. Trace elements found in the geochemical analysis of BSP2 profile, in concentration per second (cps)
Figure 9. Mn/Fe ratio in a soil profile from the South Bofedal (BSP2) of the Silala region – Bolivia. In the xaxis,
the age scale is observed in years AD and in the y-axis and the values of the Mn/Fe ratios
7.3.b.2. Geochemical analysis of soil profile BSP14
The silicon/titanium (Si/Ti) ratio presents a peak prior to the 680 – 862 period. The Si/Ti ratio then
presents a reduction and a subsequent stabilization between 1960 and 1980. From this point onwards,
the values increase gradually (Figure 10a).
7.3.b.2. Geochemical analysis of soil profile BSP14
The silicon/titanium (Si/Ti) ratio presents a peak prior to the 680 – 862 period.
The Si/Ti ratio then presents a reduction and a subsequent stabilization between
1960 and 1980. From this point onwards, the values increase gradually (Figure
10a).
The iron/titanium (Fe/Ti) ratio remains stable until the period between 1960 –
1980, when a gradual increase is observed, reaching a maximum peak at 4 cm
depth (after 1960-1980), to then decrease towards the present profile (Figure
10b).
The variations in the manganese/titanium (Mn/Ti) and manganese/iron (Mn/
Fe) ratios show similar stable values up to the 1960-1980 calibrated years,
with a subsequent increase in both ratios’ fluctuations (Figures 10 c and d,
respectively).
The lead concentration (Pb) presents fluctuating values from the lowest profile
levels, with a high peak in the period of stratification profile change, which
took place before the 680 and 862 period. Subsequently, an interval of decrease
in the deposition of Pb is registered until the 1960-1980 period, when the Pb
concentration increased abruptly, with another peak at 8 cm depth (after 1960-
1980), to then decrease and fluctuate towards the present time (Figure 10 e).
19
0.08
0.06
~
~ 0 .04
descenso leve
0 .02
\ ioccemeota 11 1111
11111111111111111u1111m~ 11111,,,,,,11,,,1111l1i.llli 0.00
~ib-~i~~~~~~~~~~~~i~~~ii~~~~~ii~~iiii'\,~
Anos (cal. BC/AD)
163
The iron (Fe) concentration presents low values in the profile base, increasing
abruptly in the 680 and 1980 period, although with strong fluctuations.
Subsequently, the concentration of Fe is reduced towards the upper levels of
the profile, corresponding to more recent times (Figure 10 f).
The concentration values of Br and Ni follow the same pattern, with fluctuating
values until a period before the 680-862 interval. Since then, a reduction in the
concentration of Br and Ni is registered, coinciding with the change of soil from
organic material to sand and prolonging up to 1960 to 1980. Subsequently, the
concentrations of Br and Ni increase and remain stable up to the surface of the
profile (Figures 10 g and h respectively).
7.3.c. Zoning of palynological samples from the South Bofedal (profiles
BSP2 and BSP14)
7.3.c.1. Zoning of soil profile BSP2
The results of the counting of palynomorphic counts, described according to
the zonation (zones) that indicate taxon changes in certain time spaces (Figures
12 and 13) are presented below.
34
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Figure 10. Concentration in cps of trace elements found in the geochemical analysis of BSP14 profile
7.3.c. Zoning of palynological samples from the South Bofedal (profiles BSP2 and
BSP14)
7.3.c.1. Zoning of soil profile BSP2
The results of the counting of palynomorphic counts, described according to the zonation (zones) that
indicate taxon changes in certain time spaces (Figures 12 and 13) are presented below.
20
Profundidad
(OTl)
0
1980· •
1960AO 10 -
15
680-862 -
AO
20
I 51015202H0350 20 ,o 60 I0100120 0 20,060 80100120 O 1 1 l , SO 204DIOIOIOOl101,oo St •l1 1•?1••12••Zlt•Zlt•Jle•llia •JS•o•sso55i065T07!1 I 2 3 4 5 I 1 I
a)Sill(110t·1) b)Fem c)Mnrn(110e•21 d~n/Fe(x 10e•2) e)Pll(110e2) 0Fe (xl0e3) g)Ni(l10e2) h)Br(i !Oe3)
164
35
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Figure 11. Percentage of representative pollen taxa found in sediment profile BSP2. On the left, it is possible
to observe the AD time scale accompanied by the lithology of the profile studied, and to the right the zonation
that defines the changes in vegetation, extended in the diagram with red lines.
Figure 12. Pollen diagram of the concentrations of pollen, spore, algae and ameba taxa (palynomorphs) counted
in the profile and related to Lycopodium spore counting to calculate the amount of palynomorphs that exist in
Figure 12. Pollen diagram of the concentrations of pollen, spore, algae and ameba taxa
(palynomorphs) counted in the profile and related to Lycopodium spore counting to calculate
the amount of palynomorphs that exist in a cm3 of sediments treated in the BSP2 laboratory.
To the left, the time scale in AD years, and to the right, the zoning that defines the vegetation
changes extended in the diagram with red lines
21
... ... ... ... ... ... ... ... ... N > )> (X) (X) (0 (0 (0 (0 (0 (0 (0 (0 (0 (0 0 0 ::ll (X) (0 0 ... N w :,. u, Ol ..., (X) (0 O ci 0 0 0 0 0 0 0 0 0 0 0 0 0 0 () (/)
I
!
X I ' Poaceae 1
_. I t - Dsyeuxia '2. 1 i Festuca co
Parastrephia al
5· Senecio (/)
0 i Gomphrena
3c!.ol l --, Brassicacae
r -j MenonviDa macrocarpa
Cactaceae 1 i- - Pycnophyllum
-:- _ Ceras~um
Arenana
Saticomia
Ephedra breana
Gentiana
Nototriche
Aa
7 Ca/andrinia acaulis
1· - ' ~ Ranunculaceae
"' 0 Cyperaceae
h Juncaceae ..,,
i 0
So/anum
Chenopodium
----r - ' Alga
! restos insectos
j -1- , •. ~ Palaeoarcel/a
0
... tv (;) i ~
~
is
~
g
,.I
0
or
r
f
isl
I r
' ~r r
I
r
r
t -
~-
" 0
"' 0
~
0)0)cocowcocococo(Ococo~e~
~~go~~~~~~~~g~~
~ Litologia
: : -------1-
,...,_. Poaceae 1 ... L 1 -- , l w • w Oeyeuxia
... ... i : · -----~ Festuca
,.. ! S ◄ ~, 7 W ♦ Paraslrephia ·, ,, • 1--Senedo
ty . ,-.. .. .._ 1- - i ·
Gomphrena
MenonviBa macrocarpa
. Cactaceae 1
- ~ f"/alophyffum
- ~ Cerastium
: - - Arenaria
, ; SaliC-Om1a ·._.-1 - - -:---; - - Ephed111 breana J ! Genliana
...
----+
+- .._.l
-; ---f- _ 1~tolriche
· · Calandrinla acaulls
· , , Ranunculaoeae
~ Cyperaoeae
I"' ~ 0 ♦ i • • r-~ Juncaoeae
I- Solanum i ~ Chenopodium
_ .......... -1 ~1- Alga
restos insectos __ ;.-- "r" _. ~,.. - Pafaeoan:elfa
_. I\) w ~
165
Zone 1 (1878-1906 AD): predominance of terrestrial species of Asteraceae
(Senecio), and also percentages > 20% of algae, but in low concentrations that
correspond to less than 1000 grains of palynomorphs per cm3 of soil sample
treated in the laboratory.
Zone 2 (1906-1948 AD): the percentages of algae decrease (<10%), fluctuating
until almost, from 1935 to approximately 1950 [sic]. While, the values
of terrestrial plants increase, Gomphrena (Amaranthaceae), Parastrephia
(Asteraceae) and Senecio (Asteraceae) as of 1935, where the pollen concentration
of Asteraceae increases, together with Cyperaceae and Palaeoarcella amoeba; it
is worth noting that the amoeba is not pollen, but a palynomorph, which in this
case constitutes a protozoan that has a carapace or teak, and that is preserved in
a similar way as pollen (Silva Do Santos et al., 2011). In this zone, the pollen
concentration increases, mainly for terrestrial pollen (> 5000 grains per cm3).
Zone 3 (1948-1976 AD): in this age range, there is a considerable increase in
the presence of Cyperaceae (which reaches a percentage greater than 60%).
At the same time, it reduces the presence of terrestrial pollen and increases
the presence of Palaeoarcella ameba carapaces. Pollen concentrations increase
progressively, showing a concentration of > 5000 grains per cm3 of soil to >
25,000 grains per cm3 towards the end of the zone.
Zone 4 (1976 AD - present): an abrupt reduction of Cyperaceae (<20%) and
of Palaeoarcella, coinciding with an increase in the presence of terrestrial taxa
(Parastrephia, Senecio, Brassicaceae, Pycnophyllum and Cerastium), as well as
Poaceae, in addition to an increase of Juncaceae from 1997 to the present; the
concentrations drop again until the end of the zone that they increase, mainly
due to the presence of Juncaceae, accompanied by Cyperaceae and Brassicaceae
(> 30,000 grains per cm3).
7.3.c.2. Zoning of soil profile BSP14
The percentages obtained from the pollen counting are outlined in the pollen
diagram as a function of their depth (Fig. 13). To The lithology and dating
values obtained in the chosen depths – performed through the 14C method –
are presented on the left side of Figure 16.
The zonings were performed as a function of a change in the composition
of taxa identified at different depths. The pollen diagram for the South
Bofedal (BSP 14) corresponds to a depth of 20 cm, allowing to focus
on a period of time of 100 years—although from the dating results,
22
166
the profile is older than 1000. Annex 3 presents some palynomorph records
found in the countings. The palynological interpretations were performed in
the same way as for the XRD analysis, taking into account three phases with
evident changes in the pollen taxa composition.
The description of the counting of palynomorph counts, described as a function
of the zonings (zones) and indicating taxa changes in determined time spaces,
is presented below.
Zone 1 (20 - 18 cm deep, stage prior to the 680 – 862 period): in this temporal
zone, the dominant pollen is Eleocharis (Cyperaceae) (~ 80%), accompanied,
in smaller proportion, by Paleoarcella (~ 10 – 40%) and Juncaceae (<10%). In
addition, the presence of Senecio and Cerastium (<10%) is verified.
Zone 2 (18 – 10 cm deep, between 680-862 to 1980-1960): predominance
of taxa of Cerastium (~ 60%), Brassicaceae (20%), Senecio (~ 50%) and
other Asteraceae (~ 80%). Eleocharis is very reduced (<5%), along with the
Paleoarcella amoeba, which disappears in this period. In contrast, Juncaceae
increases with a high peak (~ 60%) and an increase in the presence of algae is
observed (~ 40%).
37
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
The zonings were performed as a function of a change in the composition of taxa identified at different
depths. The pollen diagram for the South Bofedal (BSP 14) corresponds to a depth of 20 cm, allowing
to focus on a period of time of 100 years—although from the dating results, the profile is older than
1000. Annex 3 presents some palynomorph records found in the countings. The palynological
interpretations were performed in the same way as for the XRD analysis, taking into account three
phases with evident changes in the pollen taxa composition.
Figure 13. Percentage of representative pollen taxa found in sediment profile BSP14. To the left, the depth (in
cm) accompanied by the lithology of the profile studied and the points at which dating was completed
The description of the counting of palynomorph counts, described as a function of the zonings (zones)
and indicating taxa changes in determined time spaces, is presented below.
Zone 1 (20 - 18 cm deep, stage prior to the 680 – 862 period): in this temporal zone, the dominant
pollen is Eleocharis (Cyperaceae) (~ 80%), accompanied, in smaller proportion, by Paleoarcella (~
10 – 40%) and Juncaceae (<10%). In addition, the presence of Senecio and Cerastium (<10%) is
verified.
Zone 2 (18 – 10 cm deep, between 680-862 to 1980-1960): predominance of taxa of Cerastium (~
60%), Brassicaceae (20%), Senecio (~ 50%) and other Asteraceae (~ 80%). Eleocharis is very
23
1980- -
1960AD
680-862 -
AD
~ o 20 40 so so 100 204060 2020406080
167
Zone 3 (10 – 0 cm of depth, second period, subsequent to the 1960 – 1980
calibrated years): The decrease or disappearance of taxa of Asteraceae,
Gomphrena, Brassicaceae and Cerastium (with values <5%) is verified. On the
other hand, there is an increase of Eleocharis (~ 20 – 80%), Juncaceae (~ 20%),
Poaceae (> 20%) and Paleoarcella amoeba (~ 20 - 40%). In addition, there is
a progressive reduction in the presence of algae (<40%) and aquatic insects
(<20%).
7.3.d. Changes observed in the vegetation of the South Bofedal (profiles
BSP2 and BSP14)
7.3.d.1. Vegetation changes observed in soil profile BSP2
In general, low concentrations of pollen and palynomorphs were found during
the period prior to the canalization (between 1878 and 1906), this is due to
the fact that the geochemical analysis indicates a deposition of terrigenous
elements, which are small rock and mineral fragments, among others that
are dragged from a terrain by erosion and that are constantly deposited in the
sediment; this deposition in the stratification is interpreted as the circulation of
water with more stable levels in this period.
The results as a whole show that part of the pollen determined belongs to a
local vegetation that is currently found in areas near this point of the BSP2
profile and is represented mainly by shrubs of Asteraceae, such as Senecio,
Parastrephia lepidophyla and P. quadrandularis, and some Poaceae (Festuca
and Deyeuxia)—species that have a high ecological value for presenting
adaptations that allow them to develop in arid ecosystems (IEIA silala2); the
presence of the pollens of these species indicate that the site surveyed had a
larger cover of this type of vegetation and, consequently, higher humidity than
that observed in stages subsequent to the canalization, 1906 approximately.
The presence of these thola-forming species before the introduction of
canalization works seems to indicate that, at this stage, their development was
favored mainly by a scarce anthropic use that intensified thereafter, following the
canalization, for its use as firewood, markedly reducing the pollen percentages
of these species. Asteraceae pollen has higher percentages between 1880 and
1930, remaining the same until the 1950s, when its abrupt reduction began,
which is the most critical stage of the canalization effects.
24
168
Between 1910 and 1930, an increase of Gomphrena pollen is observed.
Due to the location of these sites, it is likely that this corresponds to the
Gomphrena umbellata species, which is an annual species that sprouts in large
quantities when there is abundant precipitation. This observation supports the
interpretation of the existence of higher humidity conditions in the environment
before the 1950s. In addition, in the pollen counts, it is also possible to observe
the presence of algae (non-pollinic palynomorphs), between 1880 and 1906,
which it reduces from approximately 1908, to then almost disappear towards
1935.
In the palynological survey, it is possible to distinguish four stages of humidity
changes in the environment, which have occurred gradually: i) The first one
lasted from 1880 to 1930, showing higher levels of water at the site, identified
by the high percentages of algae. ii) The second occurred between 1930 to 1950,
where a gradual reduction of water flows is detected, producing stagnant waters
(puddles), identified by the presence of Palaeoarcella, an amoeba that grows in
this type of water [and] is used as an indicator of these aquatic environments
(Traverse 2007), in addition to the presence of macroinvertebrate remains, (the
dipterous larvae of the Chironomidae family), typical of these environments,
all these palonimorphs decrease in percentage from 1950 onwards [sic]. iii)
The third stage coincides with a critical dry environment, from 1950 onwards,
when a reduction of pollen and palynomorphs, indicating wet environments, is
observed. iv) The fourth stage occurred between 1990 to present, approximately,
identified by the reduction of Cyperaceae pollen and which is almost replaced
Juncaceae since 1997, accompanied by the increase of taxa of terrestrial
shrubs (Parastrephia, Senecio, Brassicaceae, Pycnophyllum) and graminoids
(Deyeuxia, Festuca), in minor concentration; this stage coincides with the
canalization dismantling process in the bofedals.
The third stage, identified in the palynological analysis, coincides with the
increase in the concentrations of nickel (Ni), bromine (Br) and manganese (Mn)
after 1950, attributed to the accelerated humification. On the other hand, in this
stage, it is possible to observe an abrupt increase in the percentages of Cyperaceae
in the pollen diagram, a family whose species found in the Silala have been
classified as opportunistic since they invade areas rich in organic matter and
moisture, easily invading bofedals that are undergoing a fragmentation process.
Another indicator of disturbance and fragmentation in the bofedals, after 1950,
is the progressive increase of graminoids, which is related to an increase in the
values of the Silicon/Titanium (Si/Ti) ratio attributed here as the deposition of
phytoliths coming from the graminoids.
25
169
With these results we propose a hypothesis, based on the interpretation of the
BSP2 profile, which indicates that the area flooded from the beginning of the
20th century to the 50s, which then gradually decreased. After the 50s, a drier
environment is observed, favoring the increase of plants of the Cyperaceae
family, soil salinization and a greater oxidation in the environment.
7.3.d.2. Vegetation changes observed in the BSP14 soil profile
In the first period (prior to the calibrated age of 680-862), it is possible to observe
a predominance of Eleocharis (Cyperaceae), a plant that colonizes disturbed
bofedals (IEIA Silala 2). On the other hand, the presence of Paleoarcella is
also verified, which is related to stagnant waters and is an indication of a
desiccation process in the middle. The intermediate period is related to a wet
phase, suggested by the reduction in pollen of bofedal species (Eleocharis and
Juncaceae) and the increase in the presence of algae.
The wet phase of this intermediate period (between the calibrated ages of 680-
862 to 1962-1980) is supported by an increase in the presence of pollen of
Parastrephia, Senecio, other Asteraceae and Cerastium [sic]. These groups
decrease in subsequent stages, suggesting that, before canalization, thola
shrubs and other composite and herbaceous shrubs were more abundant in the
surrounding areas. The reduction of these palynomorphs is more marked after
the 1960-1980 period and is attributed to the anthropic use of these resources,
which is likely to have caused a reduction in the plant cover of these species.
In the third period (following the calibrated age of 1980-1962), and towards
the present, it is possible to observe a gradual process of desiccation in the
environment and the surrounding areas, with a reduction of shrub vegetation
(thola shrubs). In addition, there is a predominance of Eleocharis and Poaceae,
associated to a process of bofedal fragmentation, which was probably
exploited by graminoids that colonized those bofedal areas. Another identified
palynomorph that reaches high percentages in this period is the Palaeoarcella
amoeba, which is also an indication of water stagnation and desiccation at the
site.
26
170
7.4. Effects of canalization on the South Bofedal
7.4.a. Effects of canalization on soil profile BSP2
The geochemical study of the BSP2 profile evidences the effects of canalization
(Figure 9). Changes are observed in the concentrations of terrigenous elements
such as iron, bromine and nickel, which are indicators of the processes that
occurred due to the canalization of the Silala springs. The mineral elements
that were deposited by erosion, such as titanium, aluminum, zirconium and
rubidium (not graphed), follow the same pattern as iron concentrations (Figure
10b), found along the entire BSP2 profile. These patterns give evidence of three
changes, the first two are abrupt reductions in the deposition of these minerals:
i) the first between 1908 to 1925, as a first effect of the canalization process, ii)
the second coincides with the photo of the image satellite data taken in 1960,
where it can be observed that the South bofedal was very dry (IEIA Silala2)
and that the artificial canals were clearly defined. In this context, our results
strongly suggest that the construction of canals led to bofedal desiccation and
degradation, and influenced the increase in aridity in the surrounding areas.
The third change iii) occurs from 1993 onwards, when a slight increase in the
concentrations of terrigenous elements is observed, coinciding with the period
of bofedal recovery, which occurred after 1995, according to historical data.
In nature, Bromine is found in the form of salts or organic substances. These
substances are produced by various organisms. Bromine is mainly found in
water soluble salts and is obtained from the oxidation of saline waters; in
addition, it has been observed that humification processes promote the formation
of bromine, by forming humic acids (Zaccone et al., 2008). The processes of
humification occur due to a rapid decomposition of the organic matter for the
formation of peat. The increase in bromine (Figure 9c), recorded between 1940
and 1982, must be related to the bofedal desiccation process and, consequently,
to the accelerated humification, which occurred as a result of the canalization
of the bofedals and/or springs and that promoted – in the area where the profile
was made – the deposition of bromine as a result of the process of formation of
humic acids and oxidation of salty waters.
Nickel accumulates in the sediments from the high flow of particles highly
related to the presence of organic carbon and the chlorophyll fluxes,
which occur due to the decomposition of diatoms and/or plants in saline
waters: for this reason, nickel is considered a good paleo-indicator of
organic carbon production; although due to elements such as Cu and Zn,
27
171
it tends to be masked with anthropic uses, creating confusion in the interpretation
of the origin of its deposition (Böning, et al., 2015). In the profile studied, the
age interval (1940 to 1982), in which an increase in nickel is observed (Figure
9d), coincides with the one that has the highest concentration of bromine,
caused by the decomposition of plant matter. The changes in the concentrations
of both elements, Br and Ni, indicate that there was a eutrophication process
in the wetlands, which perhaps was accelerated by the humification process,
increasing the total organic carbon.
Silicon is common in environments of volcanic origin (quartz sandstone), but
it can also be of organic origin, as it is an abundant component of graminoid
species (in phytoliths, Schittek et al., 2014). In dry environments, as in the
Silala, silicon is found in the plants of the graminoid group, which are part of
the characteristic vegetation (tillers) that grasslands form on slopes and plains.
These graminoids colonize the bofedals that are undergoing a fragmentation
process due to lack of water. In this sense, the presence of graminoids within
the Juncaceae cushions is considered as an indicator of bofedal degradation
as said family predominates in well preserved bofedales (IEIA Silala 2). The
increase in the values of the Si/Ti ratio in the profile coincides with periods
in which the environment underwent a desiccation process. This fact allows
deducing that this increase was associated with the phytolith deposition that
occurred gradually since the beginning of the 20th century, but with greater
intensity from 1950 to 1985 (Figure 9e), when the effects of canalization were
critical. The Si/Ti ratio then decreases towards the present time. This signal
given by the Si/Ti relationship fully concurs with the other aspects that are
indications of bofedal fragmentation following the introduction of canalization
works.
According to Schittek et al. (2015, 2016), well-preserved bofedals generally
have stable water levels and anoxic conditions. In these bofedals, the values of
the iron and titanium (Fe/Ti) ratio are reduced, unlike the values of manganese/
titanium (Mn/Ti) and manganese/iron (Mn/Fe), which are high. Based on the
results obtained by Schittek et al. (2015, 2016), it is possible to interpret that
the increase in the Fe/Ti ratio (Figure 9f) indicates greater Fe oxidation on
the surface derived from water level changes, which are in turn the result of
canalization. These alterations in water availability began in stages subsequent
to 1925 and lasted until the 1980s, showing some consistency with the values
of Mn/Ti and Mn/Fe (Figures 9j and 10), whose values are visibly reduced
from 1960 onwards.
28
172
7.4.b. Effects of the canalization on soil profile BSP14
The interpretation for this profile was made in three parts, i) the period preceding
the canalization, corresponding to 680 – 862; ii) an intermediate period between
680 – 862 and the most recent period of 1960 – 1980, where it was possible to
observe, as has already been noted, a change in the stratigraphic composition,
with an increase in sand and silt particles; and iii) a third period following 1960
and 1980.
In the first period, the dominance of organic matter is observed. However, the
values of the ratio of Fe/Ti, Mn/Ti, and Mn/Fe remain stable, accompanied
by the Si/Ti ratio. All these indicators suggest that the bofedal was firmly
established at that time; this is confirmed by a reduced input of terrigenous
elements at the site: low concentrations of iron and moderate concentrations of
nickel and bromine.
The intermediate period shows a change in the sediment deposition, with an
increase in the concentrations of the typically terrigenous element, iron and
reductions of other elements (Br and Ni) and the ratio of Mn/Ti and Mn/Fe,
which are characteristic of the presence of bofedals. Additionally, stability was
observed in the Fe/Ti ratio, which, as a whole, strongly suggests a change in
sediment deposition and reflects the inflow and stability of the water flow at
this site.
The third period, the most recent one, is related to the effects that followed the
canalization. To demonstrate these effects, two aspects are initially considered:
1) Our interpretation was made from the most recent dating time, which is
found at 9 cm of depth and corresponds to a period calibrated between 1960
and 1980, which is related to the “second desiccation period” caused by the
canalization and is observed in the BSP2 profile. This period was interpreted as
a stage of bofedal degradation, which is also likely to have caused desiccation
in surrounding areas.
2) Profile sampling location. In the case of the BSP2 profile, it was a point
found far from the channel, while the BSP14 profile was performed at a site
with vegetation in a good state of preservation, in the South bofedal.
Taking these two aspects into account, it can be concluded that most of the
values of the geochemical survey support the assumption of a change that took
place in the landscape derived from canalization.
29
173
On the one hand, an increase in the Si/Ti ratio following the 1960-1980 period,
related to the greater deposition of phytoliths by graminoid species, which have
become predominant in degraded bofedales. On the other hand, an increase in
the concentrations of Br and Ni is also observed, above what was found for
the first period. This is clearly related to the formation process of humic acids
by the decomposition of vegetal matter, which is an indication of a process of
eutrophication in the wetlands. Additionally, the change in water availability,
which results in desiccation in areas far from the main canal, is detected by
an increase in the Fe/Ti ratio and the fluctuations of the Mn/Ti and Mn/Fe
ratio (Schittek et al., 2015; 2016). Finally, the decrease in the deposition of
terrigenous elements, such as Fe and other geochemical elements, clearly
marks a stage of greater aridity, related to the critical period of dryness already
reported in the BSP2 profile.
7.5. General conclusions on the changes recorded in the South Bofedal
The south bofedal shows a clear desiccation process observed in the vegetation
changes and in the variation of water levels derived from the effects of the
canalization works.
In both profiles (BSP2 and BSP14), a subsequent critical phase is recorded
around 1950, which persisted until the 90s, a decade in which interventions to
recover the watercourses of the bofedal are took place.
Evidently, in past times, it is also possible to observe variations in the water
level (groundwater table), which may be due to other climatic events (profile
BSP14); however, our results indicate that the effect of these events did not
have a major impact on the vegetation, as a re-establishment of the latter is
observed in subsequent stages. And that the critical stage is definitely the one
in which the most significant impact for vegetation change at the local level, in
and around the South bofedal, is recorded [sic].
30
174
45
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
7.6. Stratigraphic interpretation of the soil in the North bofedal (BNP7).
Figure 14. Stratigraphy of the North Bofedal profiles and their location in the areas defined in the vegetation
survey of the Silala environmental impact report, where A) shows BNP1 profile, B) BNP3 profile, C) BNP4
profile and D) BNP7, which was carefully studied.
Figure 14 presents a map of the North Bofedal, in which vegetation surveys are identified with green
bars and the codes of the profiles are presented in red. The schemes of the profiles performed are also
shown, with the different strata found at different depths. A more specific characterization of each of
these profiles is found in Annex 1, which presents the descriptions of the textural characteristics for
each level or stratum of all the profiles studied. At the end of each description, an interpretation of
the sedimentary mechanism that might have allowed its development is included.
The BNP7 soil profile, with a depth of 70 cm, has a greater depth of organic matter near the surface;
therefore, it was selected as the most suitable for the study. In this profile, it is to be expected that the
palynomorphs are likely to have remained in good conditions, as there was less oxidation.
Currently, in the area where the BNP7 profile was sampled, the current vegetation shows the
development of cushions of Oxychloe andina and Zameoscirpus muticus on the margins—which are
both species characteristic of wetlands in good condition. However, it is also possible to observe
Figure 14 presents a map of the North Bofedal, in which vegetation surveys
are identified with green bars and the codes of the profiles are presented in red.
The schemes of the profiles performed are also shown, with the different strata
found at different depths. A more specific characterization of each of these
profiles is found in Annex 1, which presents the descriptions of the textural
characteristics for each level or stratum of all the profiles studied. At the end
of each description, an interpretation of the sedimentary mechanism that might
have allowed its development is included.
The BNP7 soil profile, with a depth of 70 cm, has a greater depth of organic
matter near the surface; therefore, it was selected as the most suitable for the
study.
31
B C
'::
10 10
20 20
30 30
40 40
50
60
70
80
90
20
30
50
60
70
175
In this profile, it is to be expected that the palynomorphs are likely to have
remained in good conditions, as there was less oxidation.
Currently, in the area where the BNP7 profile was sampled, the current
vegetation shows the development of cushions of Oxychloe andina and
Zameoscirpus muticus on the margins—which are both species characteristic
of wetlands in good condition. However, it is also possible to observe patches
of Poaceae, such as Festuca potosiana, F. rigecens and Cyperaceae, such as
Eleocharis, Carex, Phylloscirpus. These species are considered indicators of
bofedal degradation.
7.7. Interpretation of stratigraphic profile relations – extent of the North
Bofedal
In the North bofedal, four profiles were sampled, showing stratification processes
with variations in the thickness of organic matter; this can be attributed to
changes in water availability in earlier times. In the upper stratum of the four
profiles, it has a high proportion of organic matter, which indicates that the drying
process had less impact on the north bofedal, compared to the south bofedal.
This can be attributed to factors such as slope and geomorphology (more closed
valley), where most canalized water sources converged on a main canal that
crossed the north bofedal. These factors must have positively influenced the
availability of water, for the maintenance of the North bofedal in certain areas
near the main canal. All together we would indicate that the extension of this
bofedal was not affected, however some change in the watercourse promoted
the strata variability (exchange between sandy material and organic matter) in
some areas of the bofedal (BNP1 and BNP4).
7.8. Paleo-ecological interpretations and age-depth model for the North
Bofedal
7.8.a. Age-depth model based on 14C dating in the North Bofedal (profile
BNP7)
With the dating obtained for the BNP7 soil profile, an age model has been
developed, which allows us to reconstruct the changes that have taken place
in the environment of the North bofedal for the last 100 years. Two dates were
made, the first at 4.5 cm and the second at 44.5 cm in depth, with ages calibrated
to 1943 and 1193, respectively (Figure 15). Based on these two dating, the agedepth
model was elaborated, which allows us to infer a sedimentation rate of 5
mm every 19 years.
32
176
47
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Figure 15. Age-Depth model of the sediment profile of North Bofedal BNP7
In addition, based on our geochemical study, the proposed age model is supported by elevated values
of iron concentration (Fe) and the increase in the iron/titanium ratio (Fe/Ti) between the years 1750
to 1850 (Figure 16). This increase in the Fe/Ti ratio indicates a greater oxidation of these elements on
the surface and corresponds to a dry phase already known in the Andean region, called the Little Ice
Age (LIA; Abbot et al., 1997; Liu et al., 2005).
7.8.b. Geochemical analysis of the North Bofedal (BNP7 Profile)
The results of the geochemical analysis of the BNP7 profile are interpreted from the year 1720 to the
present.
The Si/Ti relation presents two intervals of increase and stability (Figure 17a). In 1750 a very low
value is recorded which rises and fluctuates until ca. 1847. Subsequently, stable values were observed
with slight fluctuations until ca. 1950. In more recent times, the maximum Si/Ti ratio is observed,
which is maintained until 1990, then drastically reduced until the present. We have already mentioned
that the increases in the Si/Ti relation indicate a greater abundance of gramineous plants, which would
have dominated the bofedal, due to their degradation when the water supply and decrease of
juncaceous species was reduced.
In addition, based on our geochemical study, the proposed age model is
supported by elevated values of iron concentration (Fe) and the increase in the
iron/titanium ratio (Fe/Ti) between years 1750 to 1850 (Figure 16). This
increase in the Fe/Ti ratio indicates a greater oxidation of these elements on the
surface and corresponds to a dry phase already known in the Andean region,
called the Little Ice Age (LIA; Abbot et al., 1997; Liu et al., 2005).
7.8.b. Geochemical analysis of the North Bofedal (BNP7 Profile)
The results of the geochemical analysis of the BNP7 profile are interpreted
from the year 1720 to the present.
The Si/Ti relation presents two intervals of increase and stability (Figure
17a). In 1750 a very low value is recorded which rises and fluctuates until
ca. 1847. Subsequently, stable values were observed with slight fluctuations
until ca. 1950. In more recent times, the maximum Si/Ti ratio is observed,
which is maintained until 1990, then drastically reduced until the present. We
have already mentioned that the increases in the Si/Ti relation indicate a greater
abundance of gramineous plants, which would have dominated the bofedal,
due to their degradation when the water supply and decrease of juncaceous
species was reduced.
33
0
:=
0
N
0
E "'
~
£a .o ~"
0
"'
0 "'
.0. ..
500 1000 1500 2000
cal BC/AD
177
The Fe/Ti ratio (Figure 17b) shows low and stable values up to ~1775, increasing
suddenly thereafter, with a peak in 1847. Subsequently, the Fe/Ti ratio drops
towards 1860 and remains stable to the present. Similarly, the Fe concentration
values show similar behavior (Figure 17f).
The ratio patterns of Mn/Ti (Figure 17c) and Mn/Fe (Figure 17d) are similar,
remaining stable until 1850, then increasing until 1900. Subsequently an abrupt
reduction is observed in both relations, which lasts until 1950. These values
increase slightly between the 70s and 80s and decrease towards the present.
The Br and Ni deposition patterns show a similar pattern, with little variation
in the sample (Figure 17g and h respectively). Finally, Pb (Figure 17e) presents
a weak deposition signal compared to the profile of the south bofedal BSP2.
Considering that, the origin of Pb deposition is purely atmospheric and the low
concentrations of Pb could be explained by the fact that this is an area with
dense vegetation cover, which prevents Pb from being deposited directly in the
sediment. This would not have happened in the BSP2 profile. This interpretation
is supported by the stratigraphic description, which shows that the presence of
a good layer of organic matter was permanent during the period studied.
34
2000
1950
c ,,oo
~
(.)
!!
I ....
1100
,, ..
1 LIi 2 2.6 l lS 2 4 6 I 10t2l .. 16 0 1 2 J 4 0 6 10 16 2'0 0 lil20:S04060GO O 5e•l 1&•22e•22~•23-P2Je•2 ~ 6 1 15 & 2 4 6 610121416
•) svn b} rem (x10) Cl Mnnl d) Mn/Pl (x10-2) •) Pb (.1110e3} f) ,. (x10t3) g) NI (x l0t3) h) Br (1C10t3)
Figure 16. Trace elements found in the geochemical analysis of BNP7 profile, in concentrations [Per second
(cps)
178
7.8.c. Zoning of palynological samples from the North Bofedal (profile
BNP7)
The percentages obtained from the pollen count are plotted in the pollen
diagram (Figure 18). Annex 2 shows some records of the palynomorphs found
in the counts.
The zoning was done in a similar way as for BSP2, based on a period of time in
which we interpreted a change in the composition of identified taxa. The North
Bofedal pollen diagram corresponds to a period of 300 years before the present,
but we focus mainly on the last 100 years.
Zone 1 (1750-1850 AD) - The pollen with the greatest relative abundance corresponds
to Poaceae and Eleocharis (Cyperaceae), both taxa with 80%. The
presence of Chenopodiaceae (Amaranthaceous), Senecio (Asteraceae), and algae
and Paleoarcella in smaller percentage (10%) is also observed. Algae were
abundant near the end of the most recent zoning boundary and contrary to the
reduction in the percentage of Paleoarcella.
49
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
7.8.c. Zoning of palynological samples from the North Bofedal (profile BNP7)
The percentages obtained from the pollen count are plotted in the pollen diagram (Figure 18). Annex
2 shows some records of the palynomorphs found in the counts.
The zoning was done in a similar way as for BSP2, based on a period of time in which we interpreted
a change in the composition of identified taxa. The North Bofedal pollen diagram corresponds to a
period of 300 years before the present, but we focus mainly on the last 100 years.
Figure 17: Percentage of representative pollen taxa found in sediment profile BNP7. To the left, the time scale
in AD accompanied by the lithology of the profile studied and, transversally, the zonation that defines the
changes in the vegetation, extended in the diagram with red lines
Zone 1 (1750-1850 AD) - The pollen with the greatest relative abundance corresponds to Poaceae and
Eleocharis (Cyperaceae), both taxa with 80%. The presence of Chenopodiaceae (Amaranthaceous),
Senecio (Asteraceae), and algae and Paleoarcella in smaller percentage (10%) is also observed. Algae
were abundant near the end of the most recent zoning boundary and contrary to the reduction in the
percentage of Paleoarcella.
35
Litologia
....................................................... ................................................... l'\Jl'\Jl'\J )> )>
1.0©CDOOO O :JI
!]
8r
T ~I T T
~ -
T
!]
~f'dffi~m~ ~ g
Poaceae
r Asteraceae
-----, Parasthrephia r Senecio/Wermeria
T Brassicaceae
----- Gentianaceae -----r-----T Chenopodiaceae
Caiophora
Ranunculaceae
Eleochaeris
't' l:: >= ....-=1 Cyperaceae
Juncaceae
~ ;I °T ----1----'----+--+-----j- So/anum
iJY i .::-----, ..+- w w ', '.I Pa/eoarcel/a
~T 1----,w--.-1 lnsecto
179
Zone 2 (1850-1909 AD) - In this period Asteraceae and Juncaceae are observed,
both with ca. 40%; and a slight decrease of Eleocharis from 80 to 40%. Towards
the upper limit of the temporal zone, from 1875, the presence of Poaceae and
Caiophora (Loasaceae) is verified. During this period, the presence of algae
decreases gradually, until the end of the upper limit of the zoning.
Zone 3 (1909-1950 AD) - In this period the pollen of Juncaceae dominates (40
%) and the presence of Asteraceae is observed, which shows two small peaks
(5%); in addition to the presence of the genus Senecio. In this temporal range,
there is a marked reduction in the presence of algae from 25 to 10%, together
with a reduction in the presence of Palaeoarcella from 40 to 10%. Additionally,
there is a progressive increase of Poaceae from 5 to 70%.
Zone 4 (1950 AD - present) - Dominance of Poaceae (approx. 80%) is verified,
which increases gradually until the present. Cyperaceae species present a
higher percentage at the beginning of the temporal zone, with 40% and then
decreasing towards 1990 by 20%. Simultaneously, the percentage of Juncaceae
increases by 20%. The presence of typical hillside elements (external to the
bofedal) such as Brassicaceae, Chenopodiaceae, Senecio and Parastrephia is
also observed; represented with percentages less than 5%. Additionally, there
is a reduction in the presence of algae (˂ 10%) and a gradual increase in the
amoeba Paleoarcella (30%).
7.8.d. Vegetation changes observed in the North Bofedal (BNP7 Profile)
In the period between 1750 and 1850 a dry environment is evident, identified by
the values described in the geochemical study (Fe, Fe/Ti, Si/Ti), which coincides
with the Little Ice Age (LIA). Pollen indicators of dry climate are observed in
the dominance of Eleocharis and Poaceae, species that have been identified as
colonizers of degraded bofedales. Also noteworthy is the high percentage of
Paleoarcella amebas that show a drying process in a period coinciding with
the HSP, between 1783 and 1812. Conversely, around 1830, the percentages of
algae increase, indicating a reestablishment of humidity in the medium.
Between 1850 and 1909, wet conditions continued to be restored, favorable for
the development of the bofedal, as evidenced by the presence of Juncaceae in
a greater percentage than Cyperaceae; in addition, there was an increase in the
coverage of shrub vegetation in surrounding areas, represented by the presence
of Asteraceae. Additionally, the presence of algae and the disappearance
36
180
of the amoeba Paleoarcella coincide with the same pattern of a re-establishment
of favorable conditions for the development of the bofedal.
From 1908 (beginning of the canalization) and until 1950, it is observed
that the presence of Poaceae pollen, initially reduced, increases gradually,
indicating the colonization of grasses in the bofedal. This coincides again with
the decrease of algae, and an increase in the presence of amoebas. However,
in this stage a transition process of a high percentage of Juncaceae and the
simultaneous deposition of Asteraceae pollen from nearby areas is observed.
The latter decreased significantly in the next temporal range, between 1950 and
the present.
We want to emphasize the reduction of Asteraceae, as it shows us the reduction
of shrubs on the slopes. In the last phase, between 1950 and 1990, the most
critical effect of the canalization is observed, when the percentage of Juncaceae
is considerably reduced and replaced by Cyperaceae, which coincides with
an increase in Poaceae, reflecting this drastic change in bofedal vegetation. In
addition, the presence of the Paleoarcella amoebas indicates a stagnation of
water, probably occurring in areas farther from the main canal, which in this
zone had a constant supply of water from the canalized waterways; therefore,
it is logical that the bofedal have remained on the banks of this canal. Finally,
in the last stage, starting in 1998, the presence of Chenopodiaceae is observed,
which tends to grow in places that are more saline or may come from cultivated
areas.
7.9 Effects of the canalization on the North Bofedal (BNP7 Profile)
The interpretation of the results of the geochemical analysis of the BNP7 profile
is divided into two stages. The first, older, indicates a climatic effect and the
second after the canalization that reflects the anthropic effect.
The first stage occurs approximately from 1775 to 1850, coinciding with a
change in the regional climate historically known as the Little Ice Age (LIA).
This was divided into two phases: a wet phase followed by a dry phase (Abbot
et al., 1997; Liu et al., 2005; Apaestegui et al., 2018). During the dry phase a
change in iron (Fe) concentrations and the Fe/Ti relation can be seen (Figure
17 b and f), suggesting fluctuations in the surface water level that lasted for
approximately 75 years. In addition, an increase in the Si/Ti ratio is also
observed during this period (Figure 17a), which indicates greater deposition of
graminoids phytoliths (Cyperaceae and Poaceae), which give greater support to
the occurrence of a dry stage during this period.
37
181
In the post LIA stage, between 1850 and 1900, the Mn/Ti and Mn/Fe ratio
indicate that an increase in water levels occurred, which is reflected in a period
of bofedal stability (Schittek et al., 2016). From the year ca.1900 a decrease
in both relations is observed, which indicates a decrease in the levels of water
contribution to the bofedal (Schittek et al., 2016). Towards 1950, it is observed
that the values of the ratios Mn/Ti and Mn/Fe increase, which coincides with
a period of increase in the exploitation of the bofedales in the Silala, also
observed in the south bofedal (BSP2 Profile). During this period, the area’s
shrub resource was exploited, in addition to maintaining the canals.
The anthropic effect detected by the ratio Si/Ti shows us period was critical
of aridity between 1950 and 1990, which can be attributed to the effects of the
canalization, detected already in the South Bofedal (BSP2 Profile). Again, this
indicates an increase in the number of gramineae that colonized the degraded
bofedal.
7.10. General conclusions on the changes occurred in the North Bofedal
The paleo-ecological analysis of the north bofedal records two important
historical stages in and around the bofedal. The first related to an event recorded
as the Little Ice Age, which between the years 1750 - 1850 is recorded as the
dry phase of this event, is reflected in the bofedal with a decrease in the entry
of terrestrial elements in response to a decrease in the water table, resulting in a
change in the composition of the vegetation of the bofedal and its surroundings,
with a decrease in shrubs (thola formations).
The second stage began in the 1950s, and in the South Bofedal is recognized as
a critical stage of the canalization effect. It is observed that in the north bofedal
this stage also had consequences on the availability of water and the vegetation
of the bofedal and surrounding areas, which in comparison with the climatic
event (LIA) had a greater impact.
8. Determination of the historical environmental impacts caused by the
presence of the artificial canals system
8.1. Environmental impacts recorded in the South Bofedal
38
182
8.1.1. Impacts detected in BSP2 Profile
Stratification analyses suggest that the southern bofedal was larger, covering
area S_A1b (Figure 3). The results of this report support the estimate of the surface
area of the south bofedal before the canalization, which was made in the
second report of the project; that is, before the canalization, the south bofedal
must have covered about 23,205 m2 (IEIA Silala 2).
XRD analyses indicate that, approximately since 1908 and during the following
20 years, there was a decrease in the deposition of terrestrial elements, such
as iron (Fe), titanium (Ti), aluminum (Al), zirconium (Zr) and rubidium (Rb);
and that, starting in 1925, a gradual process of soil drying occurred, which
became critical around 1950 and remained until about 1997. Since then, there
has been a slight increase in water levels that have influenced the deposition of
these terrestrial elements.
The values of nickel (Ni), bromine (Br), manganese (Mn) indicate that a humification
process occurred from 1945 until the 90s, which coincides with the
increase of organic matter in the stratigraphic description of the profile. This
process is very possibly the result of the canalization, due to the drying of this
zone, which caused the stagnation of waters and the establishment of opportunistic
plants.
In summary, large areas of the bofedal were progressively drained since 1908
and had a maximum of draining by 1950. This would have promoted the eutrophication
of some springs, through which water probably still flowed from
springs, which facilitated the entry of grass (Graminoids) to this site.
Conditions that are slightly more humid have been observed since the 1990s,
which coincides with the dismantling of canals, which would have favored the
growth of typical bofedal plants, such as Juncaceae, as well as the growth of
shrubs in nearby areas.
The changes in vegetation recorded in the palynological analysis suggest, as
did the XRD analysis, that there was a drying process due to canalization. Four
stages are distinguished: i) the first was a wet stage, between 1880 and 1930, ii)
the second occurred between 1930 and 1950, during which there was a gradual
reduction in water availability and iii) after 1950, which coincides with the dry
stage, with a marked reduction in water availability and finally,
39
183
iv) after 1990, when water levels at the site increase, possibly due to the absence
of maintenance of the canals.
8.1.2. Impacts detected in BSP14 Profile
Three marked periods are observed that are evidenced in soil, metal and
palynological stratigraphy analyses: a period before 680 - 862, an intermediate
between 680 - 862 and 1960-1980, and a third from 1960-1980 to the present.
These periods are characterized by changes in water availability in the bofedals.
In the first period, it is determined that the bofedal was already established in
the area, but suffered a period of drought due to natural climatic events. This
is based on the greater presence of phytoliths, evidenced by the increase in the
Si/Ti ratio and the higher concentration of Br and Ni, and the decrease in Fe.
Subsequently, in the intermediate period, a re-establishment of wet conditions
is observed, verified by the stable values of the Si/Ti, Fe/Ti, Mn/Ti ratio and the
decrease of Br and Ni.
In the third period, there is an evident drying process due to the effect of the
canalization due to the increase in the Si/Ti ratio, Fe/Ti, and higher concentration
of Br and Ni.
Palynological analyses of the BSP14 Profile show that the composition of the
bofedal changed in each of the defined periods. The first one was a dry period,
followed by a wet period, in the intermediate period related to a higher water
intake, which helped the development of typical bofedal plants (Juncaceae).
It is evident that there is a greater effect of the canalization in the third period
(1960-1980 to present), observed in the increase of Cyperaceae, Poaceae and
the presence of the amoeba Paleoarcella, in addition to the reduction of shrub
forms coming from the neighboring vegetation.
8.2. Environmental impacts recorded in the North bofedal
8.2.1. Impacts detected in BNP7 Profile
40
184
The analysis of XRD records the effects of HSP between 1775 and 1850,
evidenced by changes in the Fe/Ti ratio and the concentration of Fe that
suggest changes in water levels caused by the dry phase of LIA, which
would imply lower water availability in this period and which coincides with
other paleoclimatic surveys in the Andes (Liu et al., 2005). In addition, the
interpretation is reaffirmed with the increase in the Si/Ti ratio, associated with
the increase in graminoids in the medium, which is an indicator of fragmented
and degraded bofedals.
The palynological survey coincides with the geochemical analysis, detecting
a dry phase in the period between 1750 and 1850, due to the dominance of
Eleocharis and Poaceae, and the presence of the Paleoarcella ameba between
1783 and 1812. Thus, the available information suggests the existence of a
drying process in an interval coinciding with the LIA.
The effect of the canalization is reflected in two stages marked by the analysis
of XRD and the palynological survey: a transition stage between 1909 and
1950, when the bofedal and surrounding areas show an environment with
persistent humidity, evidenced in the ratio of Mn/Ti and Mn/Fe and the increase
of Juncaceae and presence of Asteraceae (shrubs); and a second critical stage,
from 1950 to 1990, which suggests a reduction in the nearby vegetation
cover, and a decrease in Juncaceae, accompanied by the increase of Poaceae
and Cyperaceae that colonized the bofedal and Cyperaceae that colonized the
bofedal, and the increase of Poaceae and Cyperaceae that colonized the bofedal.
This critical period is also observed in the increase in the Si/Ti ratio interpreted
as the increase in phytoliths indicating fragmented bofedals.
The geochemical and palynological analyses show a coincidence in the
reconstruction interpreted for these periods, clearly evidencing that the effect
of the canalization had a greater impact on the wetlands and the surrounding
vegetation than the regional climatic changes that occurred during the LIA
9. General conclusions of the survey.
The three profiles analyzed show us a different evolution at the level of deposition
of sediments, different ages and geochemical and pollen composition. This was
expected, since it is a palynological survey carried out in high altitude bofedals
in the Andes, where in each profile there is a different story. Therefore, it is
not possible to compare aspects such as the type of sedimentation that directly
influences the dating, which is why it was necessary to carry out dating for each
profile.
41
185
In three soil profiles, it was possible to reconstruct the environment based on
pollen indicators of current bofedal species in good condition (current minimum
areas), scrublands, thola formations, and degraded bofedals. The reconstruction
mainly focused on the last 118 years (from the year 1900). The calculation of
the ages was carried out based on 14C dating. With these dating, the age-depth
models for the profiles were elaborated. The calibrated ages proposed in the
age models were supported by the geochemical results of the concentrations of
elements such as lead, iron and the iron/titanium ratio, which are coincidentally
related to historical periods registered regionally in other surveys, ensuring
high reliability in our data.
The stratification analyzes provide solid evidence that the South Bofedal was
more extensive before the canalization, covering the S_A1b area (Figure 3). The
results of this report support the estimated calculation of the area of the South
Bofedal before the canalization, which was made in the second report of the
survey. That is, before the canalization, the South Bofedal must have covered
about 23,205 m2 (IEIA Silala 2). This shows a high coincidence between the
stratigraphic analyzes carried out on the soil profiles, with the results obtained
on the current vegetation.
The three surveyed profiles, despite being located in different areas of the
bofedals and showing different stratification, register a high coincidence in
the responses to climate changes and the effects caused in the bofedals. This
was due to the changes in the water contributions that occurred during the
canalization process, which began in 1908.
The results are summarized in two stages from the beginning of the canalization.
The first stage, from 1908 to 1950, shows a slow decrease of humidity in the
environment in relation to the next stage. Two of the profiles analyzed, BSP2
and BNP7, show this gradual and progressive change of desiccation in relation
to the BSP14 profile, this due to the location of the profiles in the bofedal.
The BSP14 profile located near the main canal has been able to influence the
desiccation process in order to make it slower.
The second stage covers a period from approximately 1950 to the year
1990. The geochemical and palynological analyzes for that period
show high coincidence in the three surveyed profiles: a critical period
of desiccation in the environment and reduction of water input levels.
These changes were more evident in the profiles of the South Bofedal than
in the profiles of the North Bofedal. This period is considered critical,
because the climatic effects historically registered as the small ice age had
42
186
effects and repercussions of smaller scale, in comparison to those registered
after the canalization. The canalization modified the landscape on a larger scale
and affected plant diversity in the bofedal and surrounding areas.
In the three surveyed profiles, it can be observed that the pollen belonging to
vegetation of areas near the bofedals, such as the taxa of the families Asteraceae
(Senecio, Parastrephia), Caryophyllaceae (Cerastium, Arenaria), Gomphrena,
present in previous periods and in the first stage of the canalization, it is greatly
reduced after the critical stage (1950 to 1990). This suggests that, since the
beginning of the canalization, the vegetal cover found around the bofedals was
affected by the anthropic use.
In the palynological and geochemical survey of the Silala, indicators have
been recorded that allow us reaching solid conclusions regarding the effects
caused by the canalization of the Silala springs. These indicators are based
on the current analogues, based in turn on the current vegetation descriptions
(IEIA Silala 2), reference samples obtained in the survey, and references of
geochemical surveys in other Andean bofedals. The most important indicators
of the geochemical survey recorded in this survey are the concentration values of
iron, nickel, bromine, lead and the ratios of iron/titanium, manganese/titanium,
manganese/iron and silicon/titanium. From the palynological analysis, it was
important to record the percentages of Poaceae and Cyperaceae as indicators
of fragmented bofedals, Juncaceae as indicators of bofedals in good condition,
Asteraceae and vegetation pollen from areas near the bofedals, which indicate
the state of the local terrestrial vegetation, humidity indicator algae, and
protozoa such as amoebae (Paleoarcella) and insect remains indicating water
stagnation. In general, the results of all these indicators, described in detail in
the preceding pages, are congruent and support the general conclusions of this
survey and those of the vegetation team.
10. Technical summary: Interpretation of results
1. The estimation of the diversity of plants in the region in the last 100 years,
comparing the areas of current bofedals, scrublands and degraded bofedals
in Silala, through the survey of pollen and fossil spores (palynology). Survey
compared with results from other bofedals in the area.
43
187
The profiles of the South and North Bofedals evaluated in the palynological
survey show different stages of the composition (Table 2) and wealth (Figure
18) of pollen taxa, and therefore in the diversity of the bofedals. The results
vary according to the location of the profiles in the bofedals, as expected.
Let us recall that the BNP7 and BSP14 profiles were closer to current water
sources and the BSP2 profile was in an area of the bofedal that is currently
degraded. However, the three profiles coincide with the change in composition
and decrease in wealth, from the beginning of the canalization in 1908, and that
the changes have become critical since 1950.
Table 2: Comparative summary of the composition and abundance of palynomorph pollen taxa
found in each surveyed profile in the different periods.
Figure 18: Wealth analysis based on the Chao index in the three profiles evaluated by means of palynological
analysis
BSP2 Profile BPS14 Profile BNP7 Profile
Time
Zone
Pollen and
palynomorphic
diversity
Time
zone
Pollen and palynomorphic
diversity
Time
zone
Pollen and payinomorphic
diversity
Zone 4
(1976 AD
- present)
Reduction of Cyperaceae
(<20%) and
Palaeoarcella (<20%).
Increase in terrestrial
taxa (Parastrephia,
Senecio, Brassicaceae,
Pycnophyllum and
Cerastium) and Poaceae
(~ 10%), in addition to
the increase in Juncaceae
from 1997 to the present
(> 40%).
Zone 3
(10 - 0
cm deep,
second
period,
after
1960 -
1980
calibrated
years)
The decrease and disappearance
of pollen taxa of Asteraceae,
Gomphrena, Brassicaceae and
Cerastium (values < 5%),
contrary to the increase of
Eleocharis (~20–80%),
Juncaceae (~20%), Poaceae (>
20%) and the amoeba
Paleoarcella (~20–40%). In
addition, a progressive
reduction in the presence of
Algae (< 40%) and aquatic
insects (< 20%).
Zone 4
(1950 AD
–
present)
Poaceae (approx. 80%)
dominates, Cyperaceae with
the highest percentage at the
beginning of the zoning (40%)
decreasing in 1990 (20%),
Juncaceae increases by 20%.
The presence of Senecio,
Parastrephia, Brassicaceae
and Chenopodiaceae is
observed in percentages less
than 5%. Additionally, the
reduction of algae (˂10%) and
the gradual increase of
Paleoarcella (30%) is
observed.
Zone 3
(1948 –
1976 AD)
Increase in the presence
of Cyperaceae (> 60%).
Reduction of terrestrial
pollen (< 10%) and the
presence of
Palaeoarcella (> 20%) is
increased.
Zone 2
(18 - 10
cm deep,
intermedi
ate
period)
Cerastium (~60%),
Brassicaceae (20%), Senecio
(~50%) and other Asteraceae
(~80%) dominate. Eleocharis is
reduced (< 5%), and conversely
Juncaceae increases up to
~60%. An increase in the
Zone 3
(1909 –
1950 AD)
The pollen of Juncaceae
(40%) dominates and the
presence of Asteraceae with
two small peaks (5%). The
presence of algae (25-10%)
and Palaeoarcella (40-10%)
is reduced, and there is a5 8
Figure 18: Wealth analysis based on the Chao index in the three profiles evaluated by means of palynological
analysis
BSP2 Profile BPS14 Profile BNP7 Profile
Time
Zone
Pollen and
palynomorphic
diversity
Time
zone
Pollen and palynomorphic
diversity
Time
zone
Pollen and payinomorphic
diversity
Zone 4
(1976 AD
- present)
Reduction of Cyperaceae
(<20%) and
Palaeoarcella (<20%).
Increase in terrestrial
taxa (Parastrephia,
Senecio, Brassicaceae,
Pycnophyllum and
Cerastium) and Poaceae
(~ 10%), in addition to
the increase in Juncaceae
from 1997 to the present
(> 40%).
Zone 3
(10 - 0
cm deep,
second
period,
after
1960 -
1980
calibrated
years)
The decrease and disappearance
of pollen taxa of Asteraceae,
Gomphrena, Brassicaceae and
Cerastium (values < 5%),
contrary to the increase of
Eleocharis (~20–80%),
Juncaceae (~20%), Poaceae (>
20%) and the amoeba
Paleoarcella (~20–40%). In
addition, a progressive
reduction in the presence of
Algae (< 40%) and aquatic
insects (< 20%).
Zone 4
(1950 AD
–
present)
Poaceae (approx. 80%)
dominates, Cyperaceae with
the highest percentage at the
beginning of the zoning (40%)
decreasing in 1990 (20%),
Juncaceae increases by 20%.
The presence of Senecio,
Parastrephia, Brassicaceae
and Chenopodiaceae is
observed in percentages less
than 5%. Additionally, the
reduction of algae (˂10%) and
the gradual increase of
Paleoarcella (30%) is
observed.
Zone 3
(1948 –
1976 AD)
Increase in the presence
of Cyperaceae (> 60%).
Reduction of terrestrial
pollen (< 10%) and the
presence of
Palaeoarcella (> 20%) is
increased.
Zone 2
(18 - 10
cm deep,
intermedi
ate
period)
Cerastium (~60%),
Brassicaceae (20%), Senecio
(~50%) and other Asteraceae
(~80%) dominate. Eleocharis is
reduced (< 5%), and conversely
Juncaceae increases up to
~60%. An increase in the
Zone 3
(1909 –
1950 AD)
The pollen of Juncaceae
(40%) dominates and the
presence of Asteraceae with
two small peaks (5%). The
presence of algae (25-10%)
and Palaeoarcella (40-10%)
is reduced, and there is a
44
BSP14 BSP2 BNP?
Anos (AD) Anos (AD)
2000
2000
Prof.
crn
2 1980
1950
4
6 1960
1900
8
1980-- 1940
1960 AO,o
1850
12
1920
14
1800
16
1900
680-862-
AD 18
1750
20 1880
20 40 60 30 40 so ' 60 20 30 40
Riqueza (Chao)
188
58
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Zone 4
(1976 AD
- present)
Pycnophyllum and
Cerastium) and Poaceae
(~ 10%), in addition to
the increase in Juncaceae
from 1997 to the present
(> 40%).
(10 - 0
cm deep,
second
period,
after
1960 -
1980
calibrated
years)
contrary to the increase of
Eleocharis (~20–80%),
Juncaceae (~20%), Poaceae (>
20%) and the amoeba
Paleoarcella (~20–40%). In
addition, a progressive
reduction in the presence of
Algae (< 40%) and aquatic
insects (< 20%).
(1950 AD
–
present)
The presence of Senecio,
Parastrephia, Brassicaceae
and Chenopodiaceae is
observed in percentages less
than 5%. Additionally, the
reduction of algae (˂10%) and
the gradual increase of
Paleoarcella (30%) is
observed.
Zone 3
(1948 –
1976 AD)
Increase in the presence
of Cyperaceae (> 60%).
Reduction of terrestrial
pollen (< 10%) and the
presence of
Palaeoarcella (> 20%) is
increased.
Zone 2
(18 - 10
cm deep,
intermedi
ate
period)
Cerastium (~60%),
Brassicaceae (20%), Senecio
(~50%) and other Asteraceae
(~80%) dominate. Eleocharis is
reduced (< 5%), and conversely
Juncaceae increases up to
~60%. An increase in the
Zone 3
(1909 –
1950 AD)
The pollen of Juncaceae
(40%) dominates and the
presence of Asteraceae with
two small peaks (5%). The
presence of algae (25-10%)
and Palaeoarcella (40-10%)
is reduced, and there is a
59
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
presence of algae is observed
(~40%).
progressive increase in
Poaceae (5-70%).
Zone 2
(1906 –
1948 AD)
Reduction of algae (<
10%), which fluctuates
from approximately 1935
to 1950. Terrestrial
plants increase,
Gomphrena
(Amaranthaceous)
(60%), Parastrephia
(Asteraceae) (20%) and
Senecio (Asteraceae) (>
50%), from the year
1935 Cyperaceae (>
10%) and the
Palaeoarcella amoeba (>
20%) increase.
Zone 1
(20 – 18
cm deep,
first
period,
previous
to 680 –
862
calibrated
years)
Eleocharis (Cyperaceae)
dominates this area (~80%),
Paleoarcella (~10–40%) in
smaller proportion and
Juncaceae (< 10%). In addition,
there is a continuous presence
of Senecio, Brassicaceae and
Cerastium (< 10%).
Zone 2
(1850 –
1909
AD)
Presence of Asteraceae and
Juncaceae both approximately
40%, and a slight decrease of
Eleocharis (80–40%). As of
the year 1875, Poaceae and
Caiophora (Loasaceae) (> 20
and 40%, respectively). The
presence of algae decreases
gradually (50–10%).
Zone 1
(1878 –
1906 AD)
Dominance of terrestrial
taxa, Asteraceae (mainly
Senecio) (> 60%) and
algae (> 20%).
Zone 1
(1750 –
1850
AD)
Dominance of Poaceae and
Eleocharis (Cyperaceae)
(80%). In addition, there is the
presence of Chenopodiaceae
(Amaranthaceous), Senecio
(Asteraceae) in lower
percentage (10%). The
presence of Algae (~80%) and
Paleoarcella (~40%), the first
abundant near the end of the
upper limit of zoning contrary
to the reduction of the
percentage of Palaeoarcella.
Table 2: Comparative summary of the composition and abundance of palynomorph pollen taxa found in each
surveyed profile in the different periods.
2. Paleo-ecological interpretations of the bofedal related to the Age/Depth model corresponding to
each bofedal, and 3. The reconstruction of past vegetation and interpretation of possible anthropic
or climate changes.
Results 2 and 3 are summarized in Tables 3, 4 and 5, which show high coincidence in the
interpretations for the three surveyed profiles. A gradual desiccation throughout the Silala region
culminates with a critical stage of desiccation from the 1950s. This stage is coincident in all the
indicators (stratigraphy of soils, metals and pollen).
Evidence suggests that the impact was greater in the South Bofedal due to its geo-morphological
characteristics. Another recurring result is that, in periods before the canalization, vegetation on the
slopes showed higher pollen taxa wealth, as evidenced by the three surveyed profiles. Finally, it is
important to record the regional climate event, the Little Ice Age (LIA), in the reconstruction of the
BNP7 profile. As pointed out, the LIA did not have such a strong effect on the vegetation, nor the
bofedal, as the canalization of the springs carried out at the beginning of the 20th century.
2. Paleo-ecological interpretations of the bofedal related to the Age/Depth
model corresponding to each bofedal, and 3. The reconstruction of past vegetation
and interpretation of possible anthropic or climate changes.
45
189
Table 3: Summary of interpretations and reconstruction of past vegetation through pollen analysis.
Vegetation Profile BSP2.
Results 2 and 3 are summarized in Tables 3, 4 and 5, which show high coincidence
in the interpretations for the three surveyed profiles. A gradual desiccation
throughout the Silala region culminates with a critical stage of desiccation
from the 1950s. This stage is coincident in all the indicators (stratigraphy of
soils, metals and pollen).
Evidence suggests that the impact was greater in the South Bofedal due to its
geo-morphological characteristics. Another recurring result is that, in periods
before the canalization, vegetation on the slopes showed higher pollen taxa
wealth, as evidenced by the three surveyed profiles. Finally, it is important to
record the regional climate event, the Little Ice Age (LIA), in the reconstruction
of the BNP7 profile. As pointed out, the LIA did not have such a strong effect
on the vegetation, nor the bofedal, as the canalization of the springs carried out
at the beginning of the 20th century.
61
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Table 3: Summary of interpretations and reconstruction of past vegetation through pollen analysis. Vegetation
Profile BSP2
Age Ranges
SOIL PROFILE – SOUTH BOFEDAL – PROFILE 2 (BSP2)
Time Range 4 (1976
AD – present)
Reduction of pollen of Cyperaceae that is almost replaced by Juncaceae approximately from 1997, accompanied by
the increase of taxa of shrubs: Parastrephia, Senecio, Brassicaceae and Pycnophyllum. The Poaceae (Deyeuxia,
Festuca) are present in smaller percentage. This stage coincides with the process of dismantling the canals.
Time Range 3 (1948
– 1976 AD)
It presents a critical dry environment due to the canalization effect since 1950. There is a reduction of pollen and
palynomorphs, indicators of humid environments. There is a reduction of Asteraceae, associated with the presence
of tola formations; there is an increase of the Cyperaceae species, which are opportunistic plants that colonize
bofedals in process of fragmentation and degradation, by reduction of water supplies.
It is interpreted that there was waterlogging at the beginning of the 20th century, but water supplies were gradually
reduced, reaching a critical stage towards the 1950s. The environment was definitely drier after the 1950s, which
favored the abrupt increase of Cyperaceae.
Time Range 2 (1906
– 1948 AD)
The pollen of Asteraceae presents higher percentages between 1880 and 1930, maintaining until the 1950s. Between
the years 1910 and 1930 an increase of pollen of G. umbellata is observed, which is an annual species that sprouts
in large quantities when there is high rainfall or water contributions. This observation supports the existence of
greater humidity in the environment before the 1950s.
Between the years 1930 and 1950, a gradual reduction of the water contributions and appearance of stagnant waters
(puddles) is detected, which is verified by the presence of Palaeoarcella, an amoeba that is considered an indicator
of this type of environment (Traverse 2007). This observation is supported by the presence of macro-invertebrate
remains, (i.e., dipterous larvae of the Chironomidae family) typical of stagnant water. All these palynomorphs
decrease in percentage from the year 1950.
Time Range 1 (1878
– 1906 AD)
The period between 1880 and 1930 shows higher levels of water, which is verified by the high percentages of algae
between 1880 and 1906. Subsequently the presence of algae is reduced, almost disappearing around 1935.
The presence of pollen of species that form tola formations (mainly Asteraceae) presents higher percentages between
1880 and 1930, which is maintained until the 1950s. Subsequently, the pollen of Asteraceae is reduced, indicating
less humidity and possible anthropic use.
46
190
To conclude, it is important to take into account that there is a different sedimentation
process in the surveyed soil in the bofedals, in terms of stratification
and calibrated ages at depth; therefore, great care must be taken in the comparison
between the soil profiles of the same bofedal and, therefore, with other
bofedals in the area. However, we can find a coincidence with respect to the
indicators (pollen, metals).
Table 4: Summary of interpretations and reconstruction of past vegetation through pollen
analysis. Vegetation Profile BSP14
62
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Table 4: Summary of interpretations and reconstruction of past vegetation through pollen analysis. Vegetation
Profile BSP14
Age Ranges
SOIL PROFILE – SOUTH BOFEDAL – PROFILE 14 (BSP14)
Time Range 3 (10 -
0 cm deep, third
period, after the
interval 1960 -
1980)
A critical drying stage is detected after 1950 to the present. A gradual process of desiccation is observed in the
bofedal and in the surrounding areas, with shrub vegetation reduction of the tola formations. The vegetation of the
bofedal presents dominance of Cyperaceae and Poaceae, which indicates a process of fragmentation and degradation
of the bofedal.
Palaeoarcella reaches high percentages in this period. This amoeba is indicative of stagnant water and drying at
the site.
Time Range 2 (18 –
10 cm deep,
intermediate period
after dating,
previous to 680 –
862)
This period is related to a wet phase due to the increase in the presence of algae, which indicates an increase in
water levels at the site.
It is a wet stage, which is verified by the increase in the presence of the pollens of Parastrephia, Senecio (Asteraceae)
and Cerastium (Caryophyllaceae). All this period prior to the canalization shows that the tola formations and other
compounds and herbaceous shrubs had greater coverage on the slopes of the areas surrounding the bofedal.
Time Range 1 (20 –
18 cm deep, first
period, before the
interval 680 – 862)
The dominance of Cyperaceae is observed, associated with the colonization of fragmented bofedals. There is the
presence of Paleoarcella, which is related to the stagnation of waters, indicating a drying process.
47
191
Table 5: Summary of interpretations and reconstruction of past vegetation
through pollen analysis. Vegetation Profile BNP7
4. The analysis of the composition of metals by X-ray diffraction (XFR) is
a complementary analysis to the analysis of pollen, which will allow better
understanding the changes in the vegetation, determining if they are due to
natural or anthropic causes.
The results of the XRD analysis in the three profiles (Table 6), give us evidence
of drying processes, by changes in the water supply, in the Silala North and
South Bofedals. These processes are of different origins. The first drying
period corresponds to a process of natural origin, in a previous time (between
1775 and 1850), which is registered in the North Bofedal (BNP7 Profile). This
period of desiccation coincides with the already surveyed Little Ice Age, which
determined a change in the regional climate recorded in previous surveys in
the region (Liu et al., 2005; Apaéstegui et al., 2018). The second period of
desiccation is after the canalization that began in 1908. This period is gradual
and shows its most critical stage from the year 1950, continuing until the year
1990. This critical period is observed in the three profiles, with change in the
concentrations of trace elements.
63
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Table 5: Summary of interpretations and reconstruction of past vegetation through pollen analysis. Vegetation
Profile BNP7
Age Ranges
SOIL PROFILE – SOUTH BOFEDAL – PROFILE 7 (BSP7)
Time Range 4
(approx. 1997 –
present)
Approximately, as of 1997, the presence of Chenopodiaceae is observed, which grows in places that are more saline
or that come from areas of cultivation (quinoa).
Time Range 4 (1950
AD – present)
A reduction of Juncaceae is observed, which is replaced by Cyperaceae, and there is an increase in pollen of
Poaceae, with a drastic decrease in Asteraceae, which is vegetation from nearby areas. The presence of Paleoarcella
indicates stagnant waters and a drying process in the area.
Time Range 3 (1909
– 1950 AD)
It includes the beginning of the canalization in the area. There is a low presence of Poaceae pollen at the beginning
of the period and a gradual increase after the canalization. At the same time, the algae decrease, indicating a reduction
in humidity. On the other hand, the presence of amoeba increases, indicating the presence of stagnant water. In this
stage of gradual transition, there is a high percentage of Juncaceae and Asteraceae from nearby areas.
Time Range 2 (1850
– 1909 AD)
Between 1850 and 1909, the reestablishment of humid conditions is observed, after the dry phase of the Little Ice
Age (LIA). There is a higher percentage of Juncaceae than of Cyperaceae and the presence of Asteraceae, related
to nearby tola formations.
In 1830, the percentages of algae increase, and the Paleoarcella amoeba disappears, which would indicate a
reestablishment of humidity in the environment.
Time Range 1 (1750
– 1850 AD)
High percentages of Eleocharis and Poaceae, which are indicators of dry climate. High percentage of Paleoarcella
amoeba between the years 1783 and 1812.
This period of desiccation coincides with the climatic event of the Little Ice Age.
4. The analysis of the composition of metals by X-ray diffraction (XFR) is a complementary analysis to
the analysis of pollen, which will allow better understanding the changes in the vegetation,
determining if they are due to natural or anthropic causes.
The results of the XRD analysis in the three profiles (Table 6), give us evidence of drying processes,
by changes in the water supply, in the Silala North and South Bofedals. These processes are of
different origins. The first drying period corresponds to a process of natural origin, in a previous time
(between 1775 and 1850), which is registered in the North Bofedal (BNP7 Profile). This period of
desiccation coincides with the already surveyed Little Ice Age, which determined a change in the
regional climate recorded in previous surveys in the region (Liu et al., 2005; Apaéstegui et al., 2018).
The second period of desiccation is after the canalization that began in 1908. This period is gradual
48
192
5. The determination of the historical environmental impacts caused by the
presence of the system of artificial canals on the vegetation.
Impacts detected in the South Bofedal
The results indicate that the impacts of the canalization are more evident
in the South Bofedal. The BSP2 and BSP14 Profiles indicate that, before
the canalization, the species from the surrounding areas deposited a greater
quantity of pollen from tola formations or nearby zones, than in periods after
the canalization. Likewise, in figure 18 of this technical summary, it is observed
that the profiles of the South Bofedal show lower pollen wealth in relation to
the profile of the North Bofedal. This decrease can be interpreted as a reduction
effect on the vegetation cover of areas around the bofedal.
On the other hand, XRD analyzes show consistently that, since 1908 and for the
next 20 years, there was a decrease in the deposition of terrigenous elements
such as iron (Fe), titanium (Ti), aluminum (Al), zirconium (Zr) and rubidium
(Rb); and that from 1925 a gradual process of soil drying occurred, which
increased in 1950 until about 1997. Since then, there has been a slight increase
in water levels, which have influenced the deposition of iron, aluminum,
zirconium and rubidium.
Table 6: Summary of interpretations and reconstruction of the XRD geochemical
analysis
64
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
and shows its most critical stage from the year 1950, continuing until the year 1990. This critical
period is observed in the three profiles, with change in the concentrations of trace elements.
5. The determination of the historical environmental impacts caused by the presence of the system of
artificial canals on the vegetation.
Impacts detected in the South Bofedal
The results indicate that the impacts of the canalization are more evident in the South Bofedal. The
BSP2 and BSP14 Profiles indicate that, before the canalization, the species from the surrounding
areas deposited a greater quantity of pollen from tola formations or nearby zones, than in periods after
the canalization. Likewise, in figure 18 of this technical summary, it is observed that the profiles of
the South Bofedal show lower pollen wealth in relation to the profile of the North Bofedal. This
decrease can be interpreted as a reduction effect on the vegetation cover of areas around the bofedal.
On the other hand, XRD analyzes show consistently that, since 1908 and for the next 20 years, there
was a decrease in the deposition of terrigenous elements such as iron (Fe), titanium (Ti), aluminum
(Al), zirconium (Zr) and rubidium (Rb); and that from 1925 a gradual process of soil drying occurred,
which increased in 1950 until about 1997. Since then, there has been a slight increase in water levels,
which have influenced the deposition of iron, aluminum, zirconium and rubidium.
Table 6: Summary of interpretations and reconstruction of the XRD geochemical analysis
Profile Geochemical Interpretations (XRD)
BSP2 The terrigenous elements (Ti, Al, Zr, Rb and Fe) follow the same pattern of variation in
their concentrations, evidencing three changes: i) a reduction between 1908 and 1925, as
a first effect of the canalization process, ii) an even greater reduction, from 1938 to 1993,
where the dryness in the environment increases; these changes show the effect of
canalization in the bofedal and the increase in dryness in surrounding areas. The third
change iii) occurs from 1993, with a slight increase in the concentrations of the
terrigenous elements, coinciding with the recovery period of bofedals, which occurred
according to historical data after 1995.
Accompanying these variations in the concentration of terrigenous elements, elements
such as Br and Ni are observed. An increase of these elements translates as acceleration
of humification processes and organic matter. In addition, the greatest increase of these
elements is observed between the years 1940 and 1983, considered the critical period of
desiccation of the bofedal.
On the other hand, the increase in Silicon between the years 1950 and 1985, verified in a
comparative way in the Si/Ti ratio, indicates a process of colonization of graminoids in
areas of the bofedal, which gives clear evidence of degradation of the bofedal.
Finally, the Fe/Ti ratio, which indicates fluctuations in water levels, coincides in
indicating a drying period from 1925 to 1980. Conversely, the values of the Mn/Ti and
Mn/Fe ratios, indicators of bofedals stability, show a marked reduction starting in 1960.
BSP14 The geochemical analysis of this profile shows three periods: i) The first period is focused
on a period prior to channeling (calibrated years 680 – 862). ii) An intermediate period
between the calibrated ages of 680 – 862 and 1960 – 1980, where a change in the
stratigraphic composition is observed, with the increase in sand and silt particles. iii) And
a third period after the time of the channeling (1960 – 1980).
In the first period, the dominance of organic matter supports the stable values of the Fe/Ti,
Mn/Ti and Mn/Fe ratios. The slight increase in the Si/Ti ratio, the moderate concentration
of Ni and Br and the decrease in the entry of terrigenous elements (Fe), suggests that at
this time the bofedal was already established in the area. We consider that the Silala
bofedal is more than 1,000 years old.
193
indicating a drying period from 1925 to 1980. Conversely, the values of the Mn/Ti and
Mn/Fe ratios, indicators of bofedals stability, show a marked reduction starting in 1960.
BSP14 The geochemical analysis of this profile shows three periods: i) The first period is focused
on a period prior to channeling (calibrated years 680 – 862). ii) An intermediate period
between the calibrated ages of 680 – 862 and 1960 – 1980, where a change in the
stratigraphic composition is observed, with the increase in sand and silt particles. iii) And
a third period after the time of the channeling (1960 – 1980).
In the first period, the dominance of organic matter supports the stable values of the Fe/Ti,
Mn/Ti and Mn/Fe ratios. The slight increase in the Si/Ti ratio, the moderate concentration
of Ni and Br and the decrease in the entry of terrigenous elements (Fe), suggests that at
this time the bofedal was already established in the area. We consider that the Silala
bofedal is more than 1,000 years old.
The intermediate period suggests a change in deposition of sediments, with the increase
of iron concentrations, a terrigenous element, and in the decrease of other elements
characteristic of the presence of bofedals, verified by the Mn/Ti, Mn/Fe ratios and the
presence of Br and Ni; in addition to the stability in the Fe/Ti ratio, which reflects the
intake and stability of the water supply in this site.
In the third period, the increase in the Si/Ti ratio (after the 1960 – 1980 interval) is
observed, accompanied by a greater increase in the concentrations of Br and Ni, high
values in the Fe/Ti ratio and an increase in the fluctuations of the Mn/Ti and Mn/Fe ratios.
These data together indicate a dry stage, coinciding with the critical period of dryness
observed in the BSP2 Profile.
65
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
66
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
BSP7 Two stages are observed, the first –the oldest– that indicates a climatic effect (the Little
Ice Age - LIA) and the second, after the canalization, which reflects the anthropic effect.
In the first stage (climatic effect), approximately between the years 1775 and 1850, an
increase in the concentrations of Fe is verified, and in the Fe/Ti and Si/Ti ratios; that
together indicate a stage of desiccation of the bofedal. This stage clearly coincides with
a change in the regional climate historically recorded as the Little Ice Age (LIA). In turn,
the Little Ice Age was divided into two phases: a wet phase, followed by a dry phase
(Abbot et al., 1997, Liu et al., 2005, Apaestegui et al., 2018), the dry phase being the one
registered in this survey.
Subsequently, the values of the Mn/Ti and Mn/Fe ratios show a period of bofedal stability
between 1850 and 1900. As of this year, there is a decrease in these ratios, which reflects
a decrease in water levels.
From 1950 to 1990 (second stage), the Mn/Ti, Mn/Fe and Si/Ti ratios increase
simultaneously; which indicates desiccation and colonization by graminoids species in
the bofedal. All this coincides with the critical period detected in the South Bofedal.
The values of nickel (Ni), bromine (Br), manganese (Mn) indicate that there was a process of
humification, from 1945 to the 1990s, which coincides with the increase of organic matter in the
stratigraphic description of the soil. This process is possibly the result of the canalization, due to the
drying up of this area that caused the stagnation of waters and the settlement of opportunistic plants,
in addition to soil salinization.
It should be clear that large areas of the Silala bofedal have progressively dried out since 1908 and
had a maximum level of drying by 1950. This would have promoted the eutrophication of some spring
waters, through which waters of the springs probably still flowed, which facilitated the entry of
opportunistic plants to the bofedals (Poaceae) resulting in its fragmentation and degradation.
The changes in vegetation recorded in the palynological analysis suggest –as in the XRD analysis–
that there was a drying process due to the canalization. We have managed to distinguish four stages:
i) the first stage was humid, between 1880 and 1930; ii) in the second stage, between 1930 and 1950,
there was a gradual reduction of water supply; iii) after 1950, which is the driest stage; and iv)
The values of nickel (Ni), bromine (Br), manganese (Mn) indicate that there was a
process of humification, from 1945 to the 1990s, which coincides with the increase of
organic matter in the stratigraphic description of the soil. This process is possibly the
result of the canalization, due to the drying up of this area that caused the stagnation
of waters and the settlement of opportunistic plants, in addition to soil salinization.
It should be clear that large areas of the Silala bofedal have progressively dried out
since 1908 and had a maximum level of drying by 1950. This would have promoted the
eutrophication of some spring waters, through which waters of the springs probably
still flowed, which facilitated the entry of opportunistic plants to the bofedals (Poaceae)
resulting in its fragmentation and degradation.
The changes in vegetation recorded in the palynological analysis suggest –as in the
XRD analysis– that there was a drying process due to the canalization. We have
managed to distinguish four stages: i) the first stage was humid, between 1880 and
1930; ii) in the second stage, between 1930 and 1950, there was a gradual reduction
of water supply; iii) after 1950, which is the driest stage; and iv) approximately from
the 1990s, when an increase in water contributions was detected, probably due to the
dismantling of the canals.
50
194
Impacts detected in the North Bofedal.
The XRD analysis records the effects of the dry phase of the Little Ice Age (LIA)
between the years 1775 AND 1850, evidenced by changes in the Fe/Ti ratio and Fe
concentration. The palynological survey also gives evidence of this dry stage, with
the presence of Eleocharis and species of the Poaceae family, and of the amoeba
Paleoarcella. This period coincides with other paleo-climate surveys in the Andes. In
addition, the interpretation is reaffirmed with the increase of the Si/Ti ratio, associated
with the increase of graminoids in the environment, which is a good indicator of
fragmented and degraded bofedals.
The effect of the canalization is reflected in two stages marked by the XRD analysis and
the palynological analysis. A transition stage between 1909 and 1950 is distinguished
first, when the bofedal and the surrounding areas showed an environment with persistent
humidity, evidenced in the Mn/Ti and Mn/Fe ratio and the increase of Juncaceae and
presence of Asteraceae (shrubs), but in process of gradual desiccation. In addition, there
was a second critical stage –from 1950 to 1990 AD– that suggests a decrease in the
nearby vegetation cover and a decrease in Juncaceae, accompanied with the increase
of Poaceae and Cyperaceae, which colonized the bofedal. This critical period is also
observed in the increase of the Si/Ti ratio, interpreted as the increase of phytoliths,
which indicate a state of fragmentation and degradation of bofedals.
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Annex 1
Stratigraphic Description of the South Bofedal profiles.
BSC9 Trial pit:
A. Depth: 0 – 12.5 cm; texture: fine sand, grain supported with planar and
specific contacts in a silty matrix. The lithic fragments represent around 30%.
Isolated clays composed of ignimbrite with diameters ranging between 7 to
12 millimeters, rounded with low sphericity. There is no evidence of organic
matter forming soil. It has a strong reaction to acid attack. Grayish-brown color
(Hue 7.5 YR 4/2). Deposits formed by material fall in sub-aquatic environment
contributed by wind currents with contributions of colluvial material.
B. Depth: 12.5 – 24.5 cm; texture: massive clay, with silty component and
isolated grains of different sizes of sand. Presence of isolated roots. Reddishbrown
matte color (Hue 2.5 YR 4/3). Sedimentation by decantation of material
contributed by wind developed in floodplains.
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C. Depth: 24.5 - 44 cm; texture: fine to very fine sand, supported grain, planar
and specific contacts in silty matrix. The lithic fragments are present in about
30%. Isolated clasts of up to 4 millimeters in diameter, sub-rounded with high
sphericity, composed of ignimbrite. Isolated presence of roots. Dark- reddish
color (Hue 2.5 YR 3/2). Deposits formed by the fall of material in the subaquatic
environment contributed by wind currents.
D. Depth: 44 - 52 cm; texture: level formed by large clasts (ranging in diameter
between 13 to 16.5 centimeters) of ignimbrite composition, clasts supported
with specific contacts on medium to coarse sand matrix, sub-rounded with low
sphericity, the major axis parallel to the horizon. Dark orange color (Hue 5
YR 6/3). Deposits formed by detritus flow in high energy systems. Reduced
transport.
BSP7 Trial pit:
A. Depth: 0 - 12 cm; texture: medium sand, supported grain, planar and specific
contacts in a silty matrix. Lithic fragments present in around 20%. Clasts of
up to 9 millimeters in diameter, very angular with low sphericity and quartz
compounds. There is no soil development and there is a moderate presence
of roots. There is a reaction to the attack with acid (10% HCl) throughout
the level. Grayish- brown color (Hue 5 YR 4/2). Sedimentation by traction
and decantation of materials product of turbulent flows. Sub-aerial exhibition
without soil development. The presence of carbonates indicates photosynthesis
and precipitation of carbonates by evaporation in the aquatic system.
B. Depth: 12 - 31 cm; texture: sand from fine to very fine grains; grain supported
with planar and punctual contacts in a sandy silt matrix. Lithic fragments present
in around 40%. Clasts of up to 6 millimeters in diameter composed of low
sphericity sub-angular ignimbrite. Moderate presence of roots. Brown color
(Hue 7.5 YR 3⁄4). Deposits formed by the fall of material in the subaqueous
medium contributed by wind currents.
C. Depth: 31 - 45 cm; texture: very fine sand, grain supported with specific and
planar contacts in clay loam matrix. Lithic fragments representing about 40%.
Isolated roots. Dark brown-black color (Hue 10 YR 3/3). Deposits formed by
the fall of material in the subaqueous medium contributed by wind currents.
Minimal decrease in the energy of the medium.
D. Depth: 45 - 58 cm; texture: very fine sand, grain supported with specific and
planar contacts in silty clay matrix. The lithic components represent around
15%. Isolated clasts up to 7 millimeters in diameter, it is angular with low
sphericity and ignimbrite compounds. Isolated roots. Dark brown- black color
(Hue 10 YR 3/3). Deposits formed by the fall of material in the sub-aquatic
environment contributed by wind currents.
E. Depth: 58 - 63 cm; texture: sediment composed of small
ridges (diameter between 7.5 to 12.5 centimeters), clasts
supported with specific contacts, without preferential orientation,
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on medium to coarse sand matrix, very angular sphericity clasts and ignimbrite
compounds. Opaque orange color (Hue 5 YR 6/3). Deposits formed by detritus
flow in high energy systems.
BSP8 Profile:
A. Depth: 0 - 5 cm; texture: organic matter, clastic fraction composed of
heterogeneous sands ranging from very fine to medium, matrix supported in silty
matrix. Lithic fragments with a presence of around 20%. Gray-yellowish brown
color (Hue 10 YR 5/2). Development of soil with periods of sedimentation.
B. Depth: 5 - 22 cm; texture: medium to very thick fine sand, matrix supported
on sandy silt matrix with specific contacts (isolated character). The lithic
fragments represent approximately 30%. Presence of roots. Gray-yellowish
brown color (Hue 10 YR 4/2). Material traction deposits of episodic turbulent
gravity flows and decantation when the system energy has been reduced.
C. Depth: 22 to 35 cm; texture; clay with isolated grains of coarse sand.
Light gray color (Hue 10 YR 7/1). Sedimentation by decantation of material
contributed by wind developed in floodplains.
BSP6 Profile:
A. Depth: 0 - 8 cm; texture: organic matter, lithic fraction composed of clay
and very fine sand. Lithic fragments up to 3 millimeters in diameter. Opaque
yellow-orange color (Hue 10 YR 7/3). Development of soil without total
sedimentation interruption.
B. Depth: 8 - 15 cm; texture: very fine to fine sand, supported grain, planar,
specific contacts in clay matrix with around 20% lithic components. Isolated
clasts of 3 to 5 millimeters in diameter, sub- angular of high sphericity. Moderate
presence of organic matter. Reddish-gray color (Hue 2.5 YR 4/1). Decantation
of sub-aquatic grains contributed by wind, periods of stability with sub-aerial
exposure and soil formation.
C. Depth: 15 - 29 cm; texture: medium coarse sand, clasts supported with planar
and specific contacts on very thin silty sand matrix. The lithic components
represent around 20%. Isolated clasts of between 5 to 9 millimeters in
diameter, very angular to round with low sphericity, composed of ignimbrites
and Andesite in a smaller quantity. Presence of roots. Dark reddish-gray color
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(Hue 2.5 YR 3/1). Deposit by traction and decantation of materials product of
turbulent flows.
D. Depth: 29 - 57.5 cm; texture: fine to medium sand, grain supported with
planar and specific contacts on very thin silty sand matrix. It presents about
30% of lithic fragments. Frequent clasts with diameters between 5 to 11
millimeters, angular and sub-angular of high and low sphericity in the clasts
composed of ignimbrite and sub-angular high sphericity in clasts composed of
quartz. Isolated presence of roots. Dark reddish-gray color (Hue 2.5 YR 3/1).
Deposit by traction and decantation of materials product of turbulent flows.
BSP2 Profile:
A. Depth: 0 - 3 cm; texture: organic material with silty clastic-clay material.
Brown color (HUE 7.5 YR 4/3). Consolidation of soil development with
interruption in the sedimentation rate and sub-aerial exposure
B. Depth: 3 - 8.3 cm; texture: organic matter, clastic material composed of clay.
Homogeneous deposit. Reddish-black color (HUE 10R 2/1). Development of
soil with sedimentation present but decrease of the sedimentation rate.
C. Depth: 8.3 - 12 cm; texture: fine sand in silty clay matrix, grain supported
with high organic content, base of the irregular segment. Very dark blackreddish
color (HUE 2.5 YR 2/2). Deposit by traction and decantation of
materials product of turbulent flows.
D. Depth: 12.5 - 21.5 cm; texture: very fine sand on silty clay matrix, supported
matrix, lithic around 30%. Lithologically homogeneous segment with an
irregular base. Presence of roots. Dark reddish- gray color (HUE 7.5 R 4/1).
Decantation of sub-aquatic grains contributed by wind, intermittent flows with
local reworking and little transport.
E. Depth: 21.5 - 23 cm; texture: fine to medium sand, grain supported with
silty matrix, clasts isolated up to 7 mm with high sphericity and sub-rounded,
irregular base. Brownish-gray color (HUE 5YR 4/2). Deposit by traction and
decantation of materials product of turbulent flows, with erosion of the bed and
reworking without considerable transport.
F. Depth: 23 - 37 cm; texture: section of decreasing grain, described in three
parts: Base: Medium to fine sand, grain supported with planar contact, silty
matrix, with lithic fragments close to 35%. Clasts up to 1 cm in diameter whose
presence represent up to 15% of the total, it has an ignimbrite composition.
Medium: Fine grain sand, grain supported with silty matrix, lithic fragments
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around 30%. Very isolated clasts up to 3 mm in diameter, high sphericity and
sub-angled. Top: Fine to very fine sand in silty clay matrix, supported matrix,
with lithic fragments around 30%. Presence of isolated roots. Dark grayreddish
color (HUE 7.5 R 3/1). Deposit by traction and decantation of materials
product of turbulent long-term flows, with progressive decrease in the energy
of the medium giving way to a deposition by decantation.
G. Depth: 37 - 42 cm; texture: fine sand, supported grain, silty matrix, planar
and specific contacts, with lithic fragments around 20%. Irregular base. Dark
reddish color (HUE 2.5 YR 2/1). Decantation of sub-aquatic grains contributed
by wind, reworking of bed material.
H. Depth: 43 cm - profile base; texture: very coarse gravel, clasts up to 4 cm in
diameter of ignimbrite composition, low sphericity and angled. Medium to fine
sand matrix. Red-grayish color (HUE 2.5 YR 6/2). Detritus flow reservoirs in a
medium of high energy and low transport.
BSP10 Profile:
A. Depth: 0 - 4.5 cm; texture: organic matter with little sediment composed of
clay. Brown color (Hue 7.5 YR 6/3). Soil development and sub-aerial exposure.
B. Depth: 4.5 - 10.5 cm; texture: organic matter with higher sedimentation of
clays. Presence of roots. Dark brown color (Hue 7.5 YR 3/1). Development
of soil with occurrence, even sedimentation of very fine material as wind
contribution.
C. Depth: 10.5 - 19 cm; texture: fine sand, heterogeneous (grains of very coarse
sand), grain supported with planar contacts on a very fine silty sand matrix. The
lithic fragments represent up to
20%. Abundant roots. (Hue 7.5 YR 7/5). Sedimentation by traction and
decantation of materials product of turbulent flows.
D. Depth: 19 - 23 cm; texture: very fine sand, grain supported in chaotic
arrangement with planar contacts, specific and locally without contact. Clay
matrix and presence of lithic fragments of around 25%. Moderate presence of
roots. Gray-brown color (Hue 7.5 YR 4/2). Deposits formed by falling material
in sub-aquatic environment contributed by wind currents.
E. Depth: 23 - 33.5 cm; texture: coarse gravel (clasts from 15 to 32 mm); matrix
supported with floating clasts. The matrix is constituted by medium to fine sand
(lithic fragments around 30%). The clasts are composed of ignimbrite, very
angular and with high sphericity. Abundant presence of roots. Dark brown color
(Hue 7.5 YR 3/3). Deposits formed by detritus flow in high energy systems.
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F. Depth: 33.5 - 44 cm; texture: fine to very fine sand, grain supported with
specific contacts in clay loam matrix, lithic fragments present in around 30%.
Floating clasts of 9 to 14 millimeters in diameter, angled with high and low
sphericity. Moderate presence of roots. Dark brown color (Hue
7.5 YR 3/3). Deposits formed by material fall in sub-aquatic environment
contributed by wind currents with alluvial material contribution.
BSP-14 Profile:
A. Depth: 0 - 10 cm; texture: organic matter with little sediment composed
of clay. Dark brown color (Hue 10 YR 2/2). Soil development and sub-aerial
exposure.
B. Depth: 10 - 16 cm, texture, medium to fine sand, grain supported on silty
clay matrix, specific contacts; the lithic fragments make up about 30%. High
organic content. Yellow-grayish brown color (Hue 10 YR 5/3). Sedimentation
by traction and decantation of materials product of turbulent flows. Reactivation
of a gravity flow system.
C. Depth: 16 - 23 cm; texture: organic matter. Dark brown color (Hue 10 YR
2/2). Soil development and sub-aerial exposure.
D. Depth: 23 - 37 cm, texture, medium to coarse sand, heterogeneous, grain
supported with specific planar contacts, on a silty sand matrix. The lithic
fragments make up about 25%. Clasts of up to 11 mm composed of Andesite
and ignimbrite, very angular with high sphericity. Yellow-grayish brown color
(Hue 10 YR 4/2). Sedimentation by traction and decantation of materials
product of turbulent flows.
Stratigraphic Description of the North Bofedal profiles.
In the North Bofedal, soil profile samples distributed longitudinally were
obtained. The textural characteristics of each level or stratum of each profile
surveyed are summarized below.
BNP 1
A. Depth: 0 - 16cm; texture: organic matter with clastic-clayey material.
Brownish-black color. Interpretation, soil development with interruption in
sedimentation rate and sub-aerial exposure.
B. Depth: 16 - 22 cm, texture, medium to fine sand, in silty matrix, supported
grain, planar contacts, with lithic fragments around 40%. Isolated clasts up
to 7 mm of ignimbrite, angular and of low sphericity. Brownish-black color.
Interpretation, deposition by traction and decantation of materials product of
turbulent flows, with erosion of the bed and reworking without considerable
transport.
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C. Depth: 22 - 27 cm; texture: organic material with clay clastic material.
Brownish-black color. Interpretation, soil development with interruption in
sedimentation rate and sub-aerial exposure.
D. Depth: 27 - 33 cm; texture: fine sand in silty matrix, grain supported, lithic
around 35%. Isolated clasts of up to 10 mm of ignimbrite, very angular and
of low sphericity. Black-brownish color. Interpretation, decantation of subaquatic
grains contributed by wind, intermittent flows with local reworking
and little transport.
E. Depth: 33 - 40 cm; texture: organic material with clay clastic material.
Black-brownish color. Interpretation, soil development with interruption in the
sedimentation rate and sub-aerial exposure.
F. Depth: 40 - 51 cm; texture: fine to very fine sand, grain supported on silty matrix,
with lithic fragments present in 30%. Black-brownish color. Interpretation,
decantation of sub-aquatic grains contributed by wind, intermittent flows with
local reworking and little transport.
BNP 3
A. Depth: 0 - 16 cm; texture: organic material with clay-silty clastic material.
Isolated clasts up to 14 mm of ignimbrite, angular and with low sphericity.
Reddish-gray color. Interpretation, soil development with interruption in
sedimentation rate and sub-aerial exposure.
B. Depth: 16 - 44 cm; texture: very fine sand, grain supported on silty matrix,
lithic fragments present in 30%. Dark gray-reddish color. Interpretation, soil
development with sedimentation present but decrease in the sedimentation rate.
BNP 4
A. Depth: 0 - 9 cm; texture: organic material with clay clastic material.
Brown-reddish color. Interpretation, consolidation of soil development with
interruption in the sedimentation rate and sub- aerial exposure.
B. Depth: 9 - 25 cm; texture: organic matter, clastic material composed of
clay. Reddish-black color. Interpretation, soil development with sedimentation
present but decrease in the sedimentation rate.
C. Depth: 25 - 35.5 cm; texture: organic matter, clastic material composed of
clay. Reddish-black color. Interpretation, soil development with sedimentation
present but decrease in the sedimentation rate.
D. Depth: 35.5 - 40 cm; texture: fine to medium sand in clay matrix, supported
matrix, lithic fragments around 30%. Reddish-black color. Interpretation,
material traction deposits of episodic turbulent gravity flows and decantation
when the energy of the system has decreased.
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E. Depth: 40 - 48.5 cm; texture: fine to very fine sand, grain supported with silty clay
matrix, lithic fragments around 10%. Reddish-black color. Interpretation, deposits
formed by material fall in sub- aquatic environment contributed by wind currents.
F. Depth: 48.5 - 69 cm; texture: fine to very fine-grained sand, grain supported with
clay matrix, lithic fragments around 25%. Dark gray-reddish color. Interpretation,
deposit by traction and decantation of materials product of turbulent flows of long
duration, with progressive decrease of the energy of the environment giving way to a
deposition by decantation.
G. Depth: 69 - 87 cm; texture: medium grain sand, supported grain, silty matrix, planar
and specific contacts, lithic fragments around 30%. Reddish-black color. Interpretation,
deposition by traction and decantation of materials product of turbulent flows, with
erosion of the bed and reworking without considerable transport.
H. Depth: 87 - 106 cm; texture: medium sand, grain supported with silty clay matrix,
lithic fragments around 20%. Reddish-black color. Interpretation, detritus flow deposits
in an environment of high energy, of low transport.
I. Depth: 106 - 111 cm; texture: fine sand in silty clay matrix, supported grain, lithic
fragments around 30%. Dark gray-reddish color. Interpretation, deposits formed by
material fall in sub-aquatic environment contributed by wind currents.
J. Depth: 111 - 115 cm; texture: fine to medium grain sand in clay matrix, supported
matrix, lithic fragments around 10%. Reddish-black color. Interpretation, material
traction deposits of episodic turbulent gravity flows and decantation when the system
energy has decreased.
K. Depth: 115 - 139 cm; texture: fine sand, grain supported with clay matrix, lithic
fragments around 40%. Reddish-black color. Interpretation, deposits formed by
material fall in sub-aquatic environment contributed by wind currents.
BNP 7
A. Depth 0 - 25 cm; texture: organic material with clay-silty clastic material. Dark
reddish brown color. Interpretation, soil development with interruption in the
sedimentation rate and sub-aerial exposure.
B. Depth: 25 - 37.5 cm; texture, organic material with clay-silty clastic material.
Dark reddish brown color. Interpretation, soil development with interruption in the
sedimentation rate and sub-aerial exposure.
C. Depth: 37.5 - 40.5 cm, without data. Sample thickness removed.
D. Depth: 40.5 - 50.5cm; texture: fine sand matrix supported on clay-silt matrix.
Brownish-gray color. Interpretation, deposits formed by material fall in sub-aquatic
environment contributed by wind currents.
E. Depth: 50.5 - 57 cm; texture: fine sand, matrix supported on a clay matrix, specific
contacts and no contacts. Dark reddish brown color. Interpretation, deposits formed by
material fall in sub-aquatic environment contributed by wind currents.
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F. Depth: 57-76.5 cm; texture: fine grain sand, matrix supported with clay matrix,
lithic fragments around 10%. Dark reddish gray color. Interpretation, deposits formed
by material fall in sub-aquatic environment contributed by wind currents.
ANNEX 2
METHODOLOGY
1. FIELD VISIT
In March of this year, a visit was made to the study area for sampling, as well
as identifying and describing the ecological and geological characteristics of
the area, which allowed an interpretation of the results more appropriate to the
nature of the place.
In this way it was observed that in the study area the main course of the Silala
flows for around 50 kilometers where two main bofedals named South Bofedal
and North Bofedal have been identified.
1.1 SAMPLING
For the fulfillment of the proposed objectives, the sampling was mainly oriented
to the Palynology that includes floral samples for reference pollen, soil samples
to obtain surface pollen and sediment samples from bofedals for fossil pollen.
And as a complement, the stratigraphic description of sediments was made in
the profiles obtained and in two trial pits.
1.1.1 PALINOLOGY
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1.1.1.1 REFERENCE POLLEN
Species of greater presence and/or own of the zone were identified, from which
floral samples were taken; those mature but not open flowers in such a way that
intact stamens are conserved inside (containing the pollen grains). In this way
contamination of the samples is also avoided. The flowers were deposited in
properly coded paper envelopes. In some cases, a complete fertile plant sample
was taken.
1.1.1.2 SURFACE POLLEN
In each bofedal studied different plant communities were identified, according to
the predominance of a certain type of vegetation. Within each plant community
an approximate area of one hectare was established, where the vegetation is
physiognomically homogeneous. Within this area ten samples of surface soil
were randomly taken with a small spoon, an approximate quantity of 10 g,
introduced in Ziploc bags with their respective sampling codes.
1.1.1.3 FOSSIL POLLEN
For the sediment sampling of the bofedals, two Russian-type drills were used.
One of 50 cm and one of 100 cm in length. The dimensions of the profiles are 5
cm in diameter and variable length according to the consistency of the sediment
in each bofedal.
In both bofedals, the sampling transect was defined according to the criterion
of affectation by drying observed. Thus, in the South Bofedal, the sampled
transect is longitudinal, while in the North Bofedal this transect is transversal.
A total of 26 profiles of variable length (10- 139 cm) were taken, which were
deposited in longitudinal sections of 1.5-inch PVC pipes and covered with
plastic film to conserve their moisture and avoid contamination.
This number of samples includes the replicas of several profiles.
1.2 STRATIGRAPHICAL DESCRIPTION
The stratigraphic description of some profiles was carried out in the field with
the purpose of defining the viability of success in the subsequent required
analyzes.
Additionally, we made the description in two trial pits, both located in the South
Bofedal, this due to the marked drying of said bofedal.
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Both trial pits with a dimension of 50 x 40 cm, one of 52 cm and another 63 cm
deep. For the description of the color of sediment the Munssell Book (1976)
was used, for the size of the textural grain Chilingar was used (1956), this allows
to locate it in Wentworth’s scale (1922). The Compton manual (1962) was
used to describe the shape of the particles.
1.3 PHOTOGRAPHS TAKING
Photographs were taken in strategic places in order to obtain representative
views of our samplings.
The profiles obtained were also photographed in order to capture the coloration
at the time of extraction.
2. LABORATORY WORK
The profiles obtained and transported to the city of La Paz, were conserved in
facilities of the Institute of Geological Sciences and the Environment (IGEMA),
where we made the selection of those profiles suitable for the realization
of the proposed analyzes. In this way, for the detailed stratigraphic description,
5 profiles (BSP2, BSP6, BSP8, BSP10, BSP14) and the two trial pits (BSP7,
BSP9) were selected in the South Bofedal, while in the North Bofedal, 4 profiles
were selected (BNP1, BNP3, BNP4, BNP7).
The profiles BSP2, BSP14 (South Bofedal) and BNP7 (North Bofedal) in addition
to the detailed stratigraphic description were studied with palynological
methods, 14C dating and X-ray diffraction analysis of metals (XRD).
These profiles were divided into two equal halves, one half was sent to France
for the XRD analysis and the other half was left in Bolivia as a control copy for
the palynological study and the sending of samples for 14C dating.
2.1 POLLEN EXTRACTION
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In the cases of surface pollen and fossil pollen, Lycopodium tablets (allochthonous
pollen) were used in order to facilitate the calculation of the concentrations
of the different palynomorphs identified (Court, 1974).
2.1.1 REFERENCE POLLEN
Under a stereomicroscope, the anthers of the flowers that are soaked are separated.
The product obtained is introduced into properly coded test tubes where
it is crushed with the aid of a glass rod. Finally, we continue with the protocol
of Faegri & Iversen.
Laboratory protocol for sediment samples (modified by Erdtman in 1954 and
by Faegri & Iversen in 1989)
1. Take a small amount of sediment (1 cm3).
2. Place the sediment in test tubes.
3. Assign correlative codes to each sample.
4. Put the sediments in a 400 cm3 glass. Add 50 cm3 of 10% KOH.
5. Put the glasses in a hot stove for 5 to 10 minutes.
6. Filter with distilled water through a 180 μm metal mesh. Centrifuge the filtered
material and repeat as many times as necessary until a clear solution is
obtained.
7. Add 10% hydrochloric acid (HCl) to balance the tubes and centrifuge.
8. Add pure HCl and heat in a water bath for 10 minutes. This treatment eliminates
carbonates,
but is susceptible to the degradation of exine.
9. Wash with distilled water and centrifuge.
10. Carefully add a 70% HF solution and let it work overnight.
11. Wash twice with distilled water.
12. Acetolysis: First, prepare in a Pyrex glass of 600ml anhydrous acetic acid
and then carefully drip H2SO4 concentrate. For this action, glasses and protective
gloves should be used (9 ml of acetic acid anhydride and 1 ml of H2SO4
are required for each sample). After mixing with the rest of the sample, heat in a
pot for 5 minutes (in this way the organic material is destroyed with the exception
of pollen grains). Then it is centrifuged.
13. Add concentrated acetic acid and centrifuge.
14. Wash twice with distilled water.
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15. Add pure alcohol and centrifuge (in this way the sample is dried).
16. Put glycerin in the test tubes according to the amount obtained.
17. Assembly: wash the coverslips in 96% alcohol.
18. On the coverslip, place a small tube of glycerin gelatin and a drop of the
sample 55 μl.
19. Heat the coverslip in an oven at 80°C.
20. In order to seal the plate melted paraffin, glass glue or fine nail polish can
be used, which is
carefully placed on the edge of the coverslip.
21. Leave one hour in a horizontal position, with the coverslip facing up.
2.1.2 SURFACE POLLEN
In test tubes with distilled water 2 grams of soil were introduced together with
a Lycopodium tablet (allochthonous pollen), when the tablet is dissolved,
proceed with the complete protocol of Faegri & Iversen.
2.1.3 FOSSIL POLLEN
Longitudinally the profiles were divided into portions every 0.5 cm to the depth
of 10 cm and towards the base every 1 cm. These portions were stored in Ziploc
bags labeled with sample code and depth. 0.5 cm3 was taken from each portion
with evident organic content, 1 cm3 was taken from those portions with little
organic matter. In both cases, the sample was soaked in distilled water together
with a Lycopodium tablet and when this was dissolved, the Faegri & Iversen
protocol was followed. In case of enough organic matter, exposure to HF is
avoided, proceeding directly to acetolysis.
The protocol of Faegri & Iversen allows obtaining the aforementioned, where
the pollen grains without plasmatic content are conserved. This residue was
diluted with glycerin and reserved in appropriately coded Eppendorf tubes
until the plates were assembled, the identification and counting of the existing
palynomorphs.
2.2 STRATIGRAPHICAL DESCRIPTION
66
210
The detailed stratigraphic description of the selected profiles was based on the
description of the textural characteristics of the levels identified in the sections
according to the following parameters:
2.2.1 TEXTURE
2.2.1.1 GRAIN SIZE
size of the diameter of the grains, clasts or detritus is described.
Initially (determination in the field) the grain size is determined by making
a comparative observation with the graph in order to determine the size of
sedimentary particles established by Chilingar (1956). Once the particle size is
obtained, it is classified including the sample in a category of the Wentworth
Grade Scale (1922) (see Figure 1).
2.2.1.2 SHAPE OF THE COMPONENTS
The shape of the sediment components is described considering the roundness
or angularity and the sphericity of the grains, clasts or detritus by direct
observation and its comparison with the scheme of Sphericity, Roundness and
Degree of Selection instituted by Compton (1962) (see Figure 2).
83
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
2.2 STRATIGRAPHICAL DESCRIPTION
The detailed stratigraphic description of the selected profiles was based on the description of the
textural characteristics of the levels identified in the sections according to the following parameters:
2.2.1 TEXTURE
2.2.1.1 GRAIN SIZE
The size of the diameter of the grains, clasts or detritus is described.
Initially (determination in the field) the grain size is determined by making a comparative observation
with the graph in order to determine the size of sedimentary particles established by Chilingar (1956).
Once the particle size is obtained, it is classified including the sample in a category of the Wentworth
Scale (1922) (see Figure 1).
Figure 1: Wentworth Grain Scale (1922)
2.2.1.2 SHAPE OF THE COMPONENTS
shape of the sediment components is described considering the roundness or angularity and the
sphericity of the grains, clasts or detritus by direct observation and its comparison with the scheme
of Sphericity, Roundness and Degree of Selection instituted by Compton (1962) (see Figure 2).
67
Millimeten, (mm) Micrometers (μm) I Phi(,) Wentworth size class Rocktype
4096 ~ -----_ J:::_ -~ --- 2.56 - Ccbbla 1 Coogloma<ata/
64 - f--- --- - 1 -6.0------- Breccia
Pebble C,
4 ------ •2.0-------
Granule
2.00 ·1,0
Very coarse sand I
1.00 - ------ - 0.0
Coarse sand
1f.! 0.50 500 1.0 Medium sand "C Sandstone
1/4 0.25 250 - 2.0 cZ
1/8 0.125 125
Fmesand
3.0
1/16 63
Very fine sand I
0.0625 4.0 I Coarse sin
1/32 0.031 31 5.0 -
Me(fiumsitt
1/64 0.0156 - - - - 15.6 - - - 6.0 ------- i"ii' Siltslone
F,nesilt
1/128 0.0078 - - - 7.8 - - - 7.0 - - - - - -
11256 ---0.0039 -~ 3.9---; 8.0
Very fine sill
0.00006 0.06 1◄.0 Clay
..,,
::,
:Ii
Claystcne
211
84
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Figure 2: Shape diagram of the clasts.
2.2.1.3 PERCENT RATIO OF COMPONENTS
The sediments surveyed are mainly composed of quartz grains, lithic fragments (resulting from the
erosion and weathering of surrounding rocks that are ignimbrites and andesites), silt and clay. The
percentage estimate is made by observation and comparison with the Graph for the Estimation of
Percentages (see Figure 3).
Figure 3
Figure 3: Estimation of components by percentages
84
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Figure 2: Shape diagram of the clasts.
2.2.1.3 PERCENT RATIO OF COMPONENTS
The sediments surveyed are mainly composed of quartz grains, lithic fragments (resulting from the
erosion and weathering of surrounding rocks that are ignimbrites and andesites), silt and clay. The
percentage estimate is made by observation and comparison with the Graph for the Estimation of
Percentages (see Figure 3).
Figure 3
Figure 3: Estimation of components by percentages
2.2.1.3 PERCENT RATIO OF COMPONENTS
The sediments surveyed are mainly composed of quartz grains, lithic fragments
(resulting from the erosion and weathering of surrounding rocks that are ignimbrites
and andesites), silt and clay. The percentage estimate is made by
observation and comparison with the Graph for the Estimation of Percentages
(see Figure 3).
2.2.2 ESTIMATION OF SEDIMENT COLOR
The color of the different segments of the obtained profiles was determined by
direct visual comparison with the Munsell Color Chart and described with the
corresponding code.
68
212
2.3 14C DATING
For the 14C dating, 5 grams of sample were taken at the points where a marked
change in stratification was observed, and then these were dried in an oven at
25°C and later sent to the Beta Analytic Laboratory, Florida-United States.
In the BSP2 profile, two samples were taken, one at 7 cm and the second at
38 cm in depth. In the BNP7 profile, 2 samples were taken at 4 cm and 45 cm
depth and finally in the BSP14 profile, 2 dating were carried out at the depths
of 9 and 17.5 cm.
2.4 X-RAY DIFFRACTION ANALYSIS OF METALS (XRD)
A complete longitudinal section of the BSP2, BNP7 and BSP14 profiles were
reserved and sent for the XRD analyzes carried out every 0.5 cm in facilities of
the EDYTEM Laboratory in Savoie, France.
3. OFFICE WORK
3.1 PALINOLOGY
3.1.1 REFERENCE POLLEN
We proceeded to make the microscopic plates in order to observe the structural
characteristics of the pollen of each species sampled. Then we proceeded to
the description and obtaining of photographs. These remain as a record of the
identification of the diversity of pollens in the surveyed area.
3.1.2 SURFACE AND FOSSIL POLLEN
Microscopic plates were made using 25 μm of pollen extract and under different
light microscopy the different palynomorphs were identified. The identification
of pollen grains is based on the description of the exine’s own characteristics:
structure, ornamentation, grain position, openings, shape and size. For
identification, photographs of the obtained reference plates and the database
of other works carried out in similar environments were used. Identification
keys Heusser (1971), MarkGraf (1978), Roubik & Moreno (1981) and pollen
catalog Sandoval (2010).
The count of the different identified palynomorphs was done following the line
method, trying to count a minimum of 300 pollens per prepared sample (Court,
1974).
69
213
Once the palynomorph count is complete, this database is introduced to the
Psimpoll program for the calculation and layout of the percentages and the
concentration of each palynomorph.
For a better interpretation, the data of the stratigraphic description of each
profile and the estimated age according to the obtained age model were added
to the diagram.
3.2 STRATIGRAPHICAL DESCRIPTION
The descriptions allowed elaborating graphic schemes of the texture of the
ground in relation to the depth. In addition, in the case of BSP2, BSP14 and
BNP7 profiles, it can also be related to the age of the profile.
3.3 14C DATING
The results sent by the Beality Analytical Laboratory were calibrated and
analyzed in the Clam program (Blaauw, 2011) (Table 1), thus, the agedepth
model was obtained, which shows a linear relationship with constant
sedimentation, as a consequence of an insufficient number of points analyzed.
86
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Once the palynomorph count is complete, this database is introduced to the Psimpoll program for the
calculation and layout of the percentages and the concentration of each palynomorph.
For a better interpretation, the data of the stratigraphic description of each profile and the estimated
age according to the obtained age model were added to the diagram.
3.2 STRATIGRAPHICAL DESCRIPTION
The descriptions allowed elaborating graphic schemes of the texture of the ground in relation to the
depth. In addition, in the case of BSP2, BSP14 and BNP7 profiles, it can also be related to the age of
the profile.
3.3 14C DATING
The results sent by the Beality Analytical Laboratory were calibrated and analyzed in the Clam
program (Blaauw, 2011) (Table 1), thus, the age-depth model was obtained, which shows a linear
relationship with constant sedimentation, as a consequence of an insufficient number of points
analyzed.
Table 1: Results obtained for BSP2, BSP14 and BNP7 profiles, in the Beta Analytical Laboratory. Calibrated
ages were added for each dating in years AD, anno domini.
Bofedal Profile Depth 14C Age Calibrated Age
South BSP2 7-7.5 103.29 ± 0.39 pMC 1956-1957 AD
BSP2 38-38.5 240 ± 30 BP 1726 - 1806 AD
BSP14 9-9.5 124.50 ± 0.46 pMC 1980-1962 AD
BSP14 17.5-18 240 ± 30 BP 680-862 AD
North BNP7 4 - 4.5 133.28 ± 0.50 pMC 1976 - 1978 AD
BNP7 45-45.5 860 ± 30 BP 1176-1274 AD
3.4 X-RAY DIFFRACTION ANALYSIS OF METALS
The results sent by the EDYTEM Laboratory allowed elaborating graphs of the behavior of the metals
analyzed in relation to the time and to the lithological characteristics of the samples.
Due to the characteristics of the area, important events marked in the global history and recent studies
carried out in the continent were identified as relevant metals for our results; Pb, Fe, Br, Ni, Ti, Al,
Zr and Rb. Also Si/Ti, Fe/Ti and Mn/Ti ratios.
70
214
3.4 X-RAY DIFFRACTION ANALYSIS OF METALS
The results sent by the EDYTEM Laboratory allowed elaborating graphs of the
behavior of the metals analyzed in relation to the time and to the lithological
characteristics of the samples.
Due to the characteristics of the area, important events marked in the global
history and recent studies carried out in the continent were identified as relevant
metals for our results; Pb, Fe, Br, Ni, Ti, Al, Zr and Rb. Also Si/Ti, Fe/Ti and
Mn/Ti ratios.
C
Annex 3
Fossil pollen
Photos registered in this survey
A B
D E F
A. Amaranthaceae, Gomphrena. Monad grain, spherical shape with a diameter of 10-13 μm,
Spherical-hexagonal field, pantoporated and fenestrated exine.
B. Caryophyllaceae, Pycnophyllum. Monad grain, oblate-spheroidal shape, equatorial length 15um,
circular lobed field, tricolpate, prominent colpos, circular pores and reticulated-tilted exine with a
71
215
A. Amaranthaceae, Gomphrena. Monad grain, spherical shape with a diameter
of 10-13 μm, Spherical-hexagonal field, pantoporated and fenestrated exine.
B. Caryophyllaceae, Pycnophyllum. Monad grain, oblate-spheroidal shape,
equatorial length 15um, circular lobed field, tricolpate, prominent colpos,
circular pores and reticulated-tilted exine with a thickness of 1.5 μm.
C. Brassicaceae, monad grain, oblate-spheroidal shape, circular lobed area,
equatorial length 20 μm, tricolpate, narrow colpos, microreticulated-tilted
exine of <2 μm thickness.
D. Cyperaceae, Eleocharis, pseudo-monad grain, unperturbed, triangular field,
round edges, convex base, uneven and thin exine (Sandoval et al., 2010, Roubik
1991). Size: 55x40 μm.
E. Chenopodiaceae, spherical monad grain, pantoporated exine, circular pores
of 1-2 μm in diameter with thin annulus, a number of approx. 65 pores, exine
thickness of 2-2.5 μm.
F. Gentianaceae, monad grain, oblate-spheroidal shape, reticulated exine, subcircular
field, tricolpate, moderately long and broad colpos, circular pores, 2
μm exine thickness (Roubik 1991, Heusser 1981). Size: 33x35 μm.
G. Juncaceae, monad grain, aberrant shape, heteropolar, monoporated, nonannular
circular pore, psilate exine of <1 μm thickness (Sandoval et al., 2010).
Size: 37X35 μm.
F. Gentianaceae, monad grain, oblate-spheroidal shape, reticulated exine, sub-circular field,
tricolpate, moderately long and broad colpos, circular pores, 2 μm exine thickness (Roubik 1991,
Heusser 1981). Size: 33x35 μm.
G H I
J K L
G. Juncaceae, monad grain, aberrant shape, heteropolar, monoporated, non-annular circular pore,
psilate exine of <1 μm thickness (Sandoval et al., 2010). Size: 37X35 μm.
H. Asteraceae, Parastrephia quadrangularis, monad grain, sub-prolate to prolate-spheroidal, circular
field, tricolpate, pantoporated, equine exine, conical equids of obtuse apex, length of thorns of
approximately 3 μm (Collao-Alvarado et al. 2015, Sandoval et al., 2010). Size: 21x38 μm.
I. Poaceae, Festuca, monad grain, prolate-spheroidal shape, psilate exine of <1 μm thickness, circular
field, monoporated, circular pore, annulated and operculated (Heusser, 1981).
J. Asteraceae, Werneria, monad, radiosymmetric, spheroid field, tricolporate, easily distinguishable
colpos, equine ornamentation with spines of 4 μm and distance of 6 μm between thorns (Collao-
Alvarado et al., 2015, Sandoval et al., 2010). Size: 37x38 μm.
K. Asteraceae, Senecio, monad, radiosymmetric, spheroid field, tricolporate, equine ornamentation
72
216
H. Asteraceae, Parastrephia quadrangularis, monad grain, sub-prolate to prolatespheroidal,
circular field, tricolpate, pantoporated, equine exine, conical equids
of obtuse apex, length of thorns of approximately 3 μm (Collao-Alvarado et al.
2015, Sandoval et al., 2010). Size: 21x38 μm.
I. Poaceae, Festuca, monad grain, prolate-spheroidal shape, psilate exine of
<1 μm thickness, circular field, monoporated, circular pore, annulated and
operculated (Heusser, 1981).
J. Asteraceae, Werneria, monad, radiosymmetric, spheroid field, tricolporate,
easily distinguishable colpos, equine ornamentation with spines of 4 μm and
distance of 6 μm between thorns (Collao- Alvarado et al., 2015, Sandoval et al.,
2010). Size: 37x38 μm.
K. Asteraceae, Senecio, monad, radiosymmetric, spheroid field, tricolporate,
equine ornamentation with thorns of 3 μm and distance of 5 μm between the
thorns (Sandoval et al., 2010). Size: 43x42 μm.
L. Montiaceae, Calandrinia, monad, apolar, spheroid field, pantoporated, pores
of variable size, granulated surface, micro-equidated tectum exine (Heusser
1981). Size: 66 μm
L. Montiaceae, Calandrinia, monad, apolar, spheroid field, pantoporated, pores of variable size,
granulated surface, micro-equidated tectum exine (Heusser 1981). Size: 66 μm
Palynomorphs
Photos registered in this survey
M N O
P Q R
Zoopalinomorfo Zoopalinomorfo
73
217
90
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Reference Pollen
Photos registered in this survey
1 2
3
1. Orchidaceae, Myrosmodes paludosa, pollen in tetrads, kidney shape, each unperturbed unit with
triangular shape of obtuse angles. Reticulated structure, exine thickness of 2.5 μm. Size 54.26 ±
6 μm.
2. Caryophyllaceae, Cerastium peruvianum, monad pollen, spherical shape, pantoporated, annular
circular pores with a diameter of 5 μm. Reticulated homo-broached structure. Exine thickness of
3 μm. Size 33 ± 4 μm.
3. Brassicaceae, Menonvillea macrocarpa, monad pollen, prolate spheroidal shape, circular field,
tricolpate, wide colpos of narrow ends. Reticulated and tilted hetero-broached structure, staff
length of 1 μm. Exine thickness of <1 μm. Size 22.18 ± 2.33 μm.
11
74
10 μm
VE
218
1. Orchidaceae, Myrosmodes paludosa, pollen in tetrads, kidney shape, each
unperturbed unit with triangular shape of obtuse angles. Reticulated structure,
exine thickness of 2.5 μm. Size 54.26 ± 6 μm.
2. Caryophyllaceae, Cerastium peruvianum, monad pollen, spherical shape,
pantoporated, annular circular pores with a diameter of 5 μm. Reticulated homo-
broached structure. Exine thickness of 3 μm. Size 33 ± 4 μm.
3. Brassicaceae, Menonvillea macrocarpa, monad pollen, prolate spheroidal
shape, circular field, tricolpate, wide colpos of narrow ends. Reticulated and
tilted hetero-broached structure, staff length of 1 μm. Exine thickness of <1 μm.
Size 22.18 ± 2.33 μm.
91
4 5
6
VE VP
VP
VE
VE
4. Brassicaceae, Mostacillastrum dianthoides, monad grain, oblate-spheroidal shape, circular field,
tricolpate, wide colpos of round ends, reticulated and tilted homo-broached exine, staff length of
2 μm. Thickness of the exine of 1.5 μm. Size 14.48 ± 0.23 μm.
5. Poaceae, Festuca potosiana, monad, circular shape, circular area, monoporated, circular pore with
prominent annulus, psilate exine. Size 32.36 ± 1.18 μm.
6. Gentianaceae, monad, sub-prolate shape, sub-circular field, tricolporate, long and wide colpos,
circular pores of 7 μm in diameter. Micro-reticulated – tilted structure, staffs of 1.5 μm length.
Exine thickness of <1 μm. Size 32.2 ± 2.87 μm.
75
10 μm
f------------1
20 μm
219
4. Brassicaceae, Mostacillastrum dianthoides, monad grain, oblate-spheroidal
shape, circular field, tricolpate, wide colpos of round ends, reticulated and tilted
homo-broached exine, staff length of 2 μm. Thickness of the exine of 1.5 μm.
Size 14.48 ± 0.23 μm.
5. Poaceae, Festuca potosiana, monad, circular shape, circular area, monoporated,
circular pore with prominent annulus, psilate exine. Size 32.36 ± 1.18 μm.
6. Gentianaceae, monad, sub-prolate shape, sub-circular field, tricolporate,
long and wide colpos, circular pores of 7 μm in diameter. Micro-reticulated –
tilted structure, staffs of 1.5 μm length. Exine thickness of <1 μm. Size 32.2 ±
2.87 μm.
7 8 9
VP VP
VE
7. Malvaceae, Nototriche auricoma, monad pollen grain, spherical shape, spheroidal field,
pantoporated, circular pores 3 μm in diameter, thin annulus. Equine structure, conical equines 2.3
μm long. Exine thickness of <1 μm. Size 35.18 ± 5.47 μm.
8. Asteraceae, Parastrephia lepidophylla, monad grain, spherical oblate shape, circular field,
tricolporate, broad colpos as long as the pollen grain, elongated pores, equine exine, spines wider
than long. Size 17 ± 1.32 μm.
9. Ranunculaceae, Ranunculus praemotus, monad pollen grain, spherical shape, spheroidal field,
zono-colpate, six short colpos. Micro-equine structure, equines of obtuse apex. Exine thickness
of 1.5 μm. Size 45.05 ± 3.21 μm.
76
20 μm
220
7. Malvaceae, Nototriche auricoma, monad pollen grain, spherical shape,
spheroidal field, pantoporated, circular pores 3 μm in diameter, thin annulus.
Equine structure, conical equines 2.3 μm long. Exine thickness of <1 μm. Size
35.18 ± 5.47 μm.
8. Asteraceae, Parastrephia lepidophylla, monad grain, spherical oblate shape,
circular field, tricolporate, broad colpos as long as the pollen grain, elongated
pores, equine exine, spines wider than long. Size 17 ± 1.32 μm.
9. Ranunculaceae, Ranunculus praemotus, monad pollen grain, spherical
shape, spheroidal field, zono-colpate, six short colpos. Micro-equine structure,
equines of obtuse apex. Exine thickness of 1.5 μm. Size 45.05 ± 3.21 μm.
10 11 12 13
VP
10. Asteraceae, Senecio candollei, monad pollen grain, oblate spheroidal shape, circular field,
tricolporate, elongated pores, long and wide colpos. Equine structure, triangular equines, 2.5 μm
wide base, sharp apex, length of 3 μm, separation of 2 μm between equines. Exine thickness of 2
μm. Size 26.16 ± 0.61 μm.
11. Asteraceae, Senecio chrysolepis, monad grain, oblate spheroidal shape, circular field,
tricolporate, long and wide colpos, elongated pores. Equine structure, conical equines with acute
apex, base 2.5 μm, length 2.5 μm, separation between equines of 1.5 μm. Exine thickness of 1.5
um. Size 23.43 ± 1.6 μm.
12. Asteraceae, Senecio comoris, monad grain, oblate spheroidal shape, circular field, tricolporate,
long and relatively narrow colpos, elongated pores. Equine structure, conical equines with acute
apex, 2 μm base, length of 2.2 μm, separation between equines of 2.5 μm. Exine thickness of 2
μm. Size 25.6 ± 0.8 μm.
13. Asteraceae, Senecio rufescens, monad grain, oblate spheroidal shape, circular field, tricolporate,
77
10 μm
f--------,
10 μm
f----,
10 μm
f----------1
10 μm
1-----------i
221
10. Asteraceae, Senecio candollei, monad pollen grain, oblate spheroidal shape,
circular field, tricolporate, elongated pores, long and wide colpos. Equine
structure, triangular equines, 2.5 μm wide base, sharp apex, length of 3 μm,
separation of 2 μm between equines. Exine thickness of 2 μm. Size 26.16 ±
0.61 μm.
11.Asteraceae, Senecio chrysolepis, monad grain, oblate spheroidal shape,
circular field, tricolporate, long and wide colpos, elongated pores. Equine
structure, conical equines with acute apex, base 2.5 μm, length 2.5 μm,
separation between equines of 1.5 μm. Exine thickness of 1.5 um. Size 23.43
± 1.6 μm.
12. Asteraceae, Senecio comoris, monad grain, oblate spheroidal shape,
circular field, tricolporate, long and relatively narrow colpos, elongated pores.
Equine structure, conical equines with acute apex, 2 μm base, length of 2.2 μm,
separation between equines of 2.5 μm. Exine thickness of 2 μm. Size 25.6 ±
0.8 μm.
13. Asteraceae, Senecio rufescens, monad grain, oblate spheroidal shape,
circular field, tricolporate, long and wide colpos, elongated pores. Equine
structure, conical equines, 3.5 μm base, length of 3 μm, separation between
equines of 1.5 μm. Exine thickness of 1.5 μm. Size 23.61 ± 1.4 μm.
14 15 16 17
V VP V VP
VE V
14. Asteraceae, Perezia ciliosa, monad grain, oblate spheroidal shape, circular field, tricolporate, long
and narrow colpos, elongated pores. Micro-reticulated–tilted structure, staffs 1.5 μm long. Exine
thickness of 1.5 μm. Size 27.6 ± 4 μm.
15. Asteraceae, Werneria glaberrima, monad grain, oblate spheroidal shape, circular field,
tricolporate, large and long colpos, circular pores. Equine structure, conical equines, 3 μm base,
length of 4 μm, equine separation of 2 μm. Exine thickness of 2 μm. Size 23.43 ± 1.48 μm.
16. Asteraceae, Werneria pygmaea, monad grain, oblate spheroidal shape, circular field, tricolporate,
long and relatively narrow colpos, circular pores with a diameter of 3 μm. Equine structure,
conical equines, 2 μm base and length of 2 μm, equine separation of 1.5 μm. Exine thickness of
1.5 μm. Size 21.83 ± 1.45 μm.
17. Asteraceae, Xenophyllum incisum, monad grain, oblate spheroidal shape, circular scope,
78
10 μm
t-----------i
10 μm
t-----------i
10 μm
f-----1
10 μm
f--------i
222
14. Asteraceae, Perezia ciliosa, monad grain, oblate spheroidal shape, circular
field, tricolporate, long and narrow colpos, elongated pores. Micro-reticulated–
tilted structure, staffs 1.5 μm long. Exine thickness of 1.5 μm. Size 27.6 ± 4 μm.
15. Asteraceae, Werneria glaberrima, monad grain, oblate spheroidal shape,
circular field, tricolporate, large and long colpos, circular pores. Equine
structure, conical equines, 3 μm base, length of 4 μm, equine separation of 2
μm. Exine thickness of 2 μm. Size 23.43 ± 1.48 μm.
16. Asteraceae, Werneria pygmaea, monad grain, oblate spheroidal shape,
circular field, tricolporate, long and relatively narrow colpos, circular pores
with a diameter of 3 μm. Equine structure, conical equines, 2 μm base and
length of 2 μm, equine separation of 1.5 μm. Exine thickness of 1.5 μm. Size
21.83 ± 1.45 μm.
17. Asteraceae, Xenophyllum incisum, monad grain, oblate spheroidal shape,
circular scope, tricolporate, long and relatively narrow colpos, elongated pores.
Equine structure, conical equines, base 3 μm, length 4 μm, equine separation 3
μm. Exine thickness of 2 μm. Size 21.62 ±
1.76 μm.
19
18
20
VP
VE
18. Loasaceae, Caiophora coronata, monad, radiosymmetric sub-prolate shape, circular field,
tricolporate, long colpos, pores at the equator of the colpos (Heusser, 1981). Size: 18.89 ± 0.97
μm.
19. Hydrophyllaceae, Phacelia nana, monad pollen grain, prolate shape, circular field, tricolporate,
long and narrow colpos. Micro-reticulated structure. Exine thickness of 1.5 μm. Size 23.26 ± 1.84
μm.
20. Poaceae, Puccinellia frigida, monad grain, spherical shape, monopod, circular pore,
inconspicuous angle, micro-striated exine. Size 23-24 μm. 79
10 μm
VP
10 μm
1-----------l
10 μm
223
18. Loasaceae, Caiophora coronata, monad, radiosymmetric sub-prolate shape,
circular field, tricolporate, long colpos, pores at the equator of the colpos
(Heusser, 1981). Size: 18.89 ± 0.97 μm.
19. Hydrophyllaceae, Phacelia nana, monad pollen grain, prolate shape, circular
field, tricolporate, long and narrow colpos. Micro-reticulated structure. Exine
thickness of 1.5 μm. Size 23.26 ± 1.84 μm.
20. Poaceae, Puccinellia frigida, monad grain, spherical shape, monopod,
circular pore, inconspicuous angle, micro-striated exine. Size 23-24 μm.
ANNEX 4
Results of the 14C Analysis
80
224
96
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
ANNEX 4
Results of the 14C Analysis
81
Beta Analytic Inc Mr. Darden Hood
4985 SW 74 Court President
~ Beta Analytic M,am,, Flonda 33155
~ RADIOCARBON DATING Tel 305 667 5167 Mr. Ronald Hatfield
Fax 305 663 0964 Mr. Christopher Patrick
beta@rad,ocarbon com Deputy Directors
1S0/IEC 2005 17025 Accred11ed Testing Laboratory
REPORT OF RADIOCARBON DATING ANALYSES
Katerine Escobar Torrez
Herbario Nacional de Bolivia
Report Date: May 16, 2018
Material Received: April 18. 2018
Laboratory Number
Beta • 492440
mm
CoovenlJOMI AOOIOC8fbon Age (BP) or
Percem Modem ceroon (pMCJ & Slable Isotopes
Sample Code Number
Calel'ld&r Cololll'&led Reslllls 95 4 'Pfobabllity
High Probabtll!y OenSlty Range Method (HPD)
BSP2 7 103.29 +!- 0.39 pMC
(95.4%) 1956 - 1957 cal AD(-7 - -8 cal BP)
Submitter Material· Organic Sediment/Gyttja
Pretreatment: (Ol"ganic sediment) acid washes
Analyzed Material: Organic sediment
Analysis Service: AMS-Standard delivery
Conventional Radiocarbon Age: -260 +/- 30 BP
Fraction Modern Carbon: 1.0329 +I• 0.0039
D14C: 32.90 +/· 3.86 o/oo
614C: 24.44 ..-,. 3.86 oJ00(1950:2.018.00)
Raw pMC: (without d13C correction): 102.76 +/· 0.39 pMC
Calibration: BetaCal3.21: HPD method: SHCAL 13 + SHZ1_2
Beta Analytic
RADIOCARBON DATING
Beta Analytic Inc
4985 SW 74 Court
Miami, Florida 33155
Tel: 305-667-5167
Fax: 305-663-0964
[email protected]
150/IEC 2005:17025-Accredited Testing Laboratory
lRMS 613C: -27.5 o/oo
Mr. Da rden Hood
President
Mr. Ronald Hatfield
Mr. Christopher Patrick
Deputy Directors
REPORT OF RADIOCARBON DATING ANALYSES
Katerine Escobar Torrez
Herbario Nacional de Bolivia
Report Date: May 16, 2018
Material Received: April 18, 2018
Laboratory Number
Beta - 492442
Conventional Radioclirt:>on Age (BP) or
Percenl Modem Carbon (pMC) &. Stable Isotopes
Sample Code Number
C•leodar C• llbrated Results: 95 4 % Probability
High Probability OfflSlly Range Mettlod (HPO)
BSP2 38 240 +/· 30 BP
(64.9°ft ) 1726 - 1806 cal AD(224 - 144 cal BP)
(30.5°1.) 1640 - 1692 cal AD(310 - 258 cal BP)
Submitter Material· Organic SedimenVGyttja
Pretreatment: (organic sediment) acid washes
Analyzed Material: Organic sediment
Analysis Service: AMS-Standard delivery
Percent Modem Carbon: 97.06 +/. 0.36 pMC
Fraction Modem Carbon: 0.9706 +I- 0.0036
D14C -29.44 +I- 3.62 o/oo
614C· -37.39 +I- 3.62 o/00(1950:2,018,00)
Measured Radiocarbon Age· (without d13C correction): 260 +/- 30 BP
Calibration· BetaCa13.21: HPD method: SHCAL13
!RMS 613C: -26.1 o/oo
225
97
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
82
Beta Analytic Inc Mr. Darden Hood
4985 SW 74 Court President
~ Beta Analytic M,am, Flonda33155
~ RADIOCARBON DATING Tel 305 667 5167 Mr. Ronald Hatfield
Fax 305 663 0964 Mr. Christophor Patrick
beta@rad1ocarbon com Deputy Directors
150/IEC 2005 17025 Accredited Testing Laboratory
REPORT OF RADIOCARBON DATING ANALYSES
Katerine EsoobarTorrez
Herbario Nacional de Bolivia
Report Date· May 16, 2018
Material Received April 18. 2018
Laboratory Number
Bela •492443
Sample Code Number
Ceo:w~R~lbOn,l,,g'I (8P)0<
i>.fclfll~Cwt,on(pMC) &SIKI•~&
C-arCalit>ratt<IR-ll5.~%Problbaly
High Probebilit)o Oemity Range Method (HPOJ
BNP7 4 133.82 +/. 0.S0 pMC IRMS 613C: -28.0 o/oo
(89.7%) 1976 -1978 cal AD(-27 • .29 cal BP)
( 5.7%) 1963 cal AD(-14 cal BP)
Submitter Material: Organic SedimenUGyttja
Pretreatment: (organic sediment) acid washes
Analyzed Material; Organic sediment
Analysis Serviee: AMS-Standard delivery
Conventional Radiocart>on Age -2340 • f- 30 BP
Fraction Modern Carbon: 1.3382 +/- 0.0050
D14C· 338.17+1- 5.00o/oo
a.14C 327.21 +I- 5.00 oloo(1950:2.018.00)
Raw pMC: (without d13C COHecbon): 133.01 +/- 0.50 pMC
Galibration: BetaCal3.21: HPD method: SHCAL 13., SHZ1_2
Beta Analytic Inc Mr. Darden Hood
4985 SW 74 Coun. President
~ Beta Analytic M,am,, Flonda 33155
~ RAD10CARBONDATING Tel 3056675167 Mr. Ronald Hatfield
Fax 30$ 663 0964 Mr. Christopher Patnck
beta@rad1ocarbon com Deputy Directors
1S0/IEC 2005 17025 Accre d ited T est1ng La b o ratory
REPORT OF RADIOCARBON DATING ANALYSES
Ka1erine Escobar Torrez
Herbario Nacional de Bolivia
Report Date: May 16. 2018
Material Received: April 18. 2018
Labofatory Number
Beta - 492444
Convention,,I R--'~lbon AQe {8P) Of
Percent Modem C..t>on (pMCJ & Stable lsotop,,s
Sample Code Number
Calendar C11litm1te<1 R:n.Jts: 95.4 ~ Probability
High Pfobablii!y 0.0111ly Rqe Method (HPD)
BNP7 45 860 +/- 30 BP
(95.4%) 1176 1274 cal AD(774 676cal BP)
Submitter Material· Organic SedimenlfGytlja
Pretreatment: (organic sediment) acid washes
Analyzed Material: Organic sediment
Analysis Service: AMS-Standard delivery
Percent Modern Carboo· 89.85 +/- 0.34 pMC
Fraction Modern Carbon: 0.8985 +f- 0.0034
D14C· ·101.53 .. ,. 3.36 o/oo
D.14C -108.89 +/. 3.36 o/00(1950:2,018.00)
Measured Radiocarbon Age: (without d13C correction): 870 +/- 30 BP
Calibration· BetaCal3.21: HPD method: SHCAL 13
IRMS 613C: -25.9 o/oo
226
98
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
83
Beta Analytic Inc Mr. Darden Hood
4985 SW 74 Court President
~ Beta Analytic M,am, Fiend, 33155
~ RADIOCARBON DATING Tel 305 667 5167 Mr. Ronald Hatfield
Fax 305 663 0964 Mr. Christopher Patrick
beta@radiocarbon com Deputy Directors
1S0/lEC 2005 17025 Accredited T est1ng Laboratory
REPORT OF RADIOCARBON DATING ANALYSES
Katerine Escobar Torrez
Herbario Nacional de Bolivia
Report Date· August 09. 2018
Material Received: July 20, 2018
Laboratory Number
Beta . 499941
Convem.,,..i Radiocafbon Age (SP) or
Percent Modem Cafboo (pMC) a Stable lsotope,s
Sample Code Number
Clleodaof C.llbm ed Results: 95,4 'Ii, Pl'obabr!,ty
High Probal)itity Oeoaily Raf!Q9Method (HPO)
(84.6%)
(10.8%)
BNP14 17.5-18
1981 - 1984 cat AD
1962 cal AD
Submitter Material: Peat
124.50 +/. 0.46 pMC
(-32. -35 cal BP)
(-13 cal BP)
Pretreatment (organic sediment) acid washes
Analyzed Material· Organic: sediment
Analysis Service: AMS-Standard delivery
Conventional Radiocarbon Age: -1760 +/. 30 BP
Fraction Modem Carbon- 1.2450 +/ - 0.0046
D14C: 244.95 +/. 4.65 o/oo
ll14C: 234.76 +/. 4.65 o/00(1950:2,018.00)
Raw pMC: (without d13C correctioo): 123.76 +/. 0.46 pMC
Calibration: BetaCal3.21: HPO method: SHCAL 13 + SHZ1_2
IRMS 013C: -27.9 o/oo
Beta Analytic Inc Mr. Darden Hood
4985 SW 74 Court President
~ Beta Analytic M,am,, Fiend, 33155
~ RADIOCARBONDATING Tel 3056675167 Mr. Ronald Hatfield
Fax 305 663 0964 Mr. Christopher Patrick
beta@rad1ocarbon com Deputy Directors
150/tEC 2005 17025 Accredited Testing Laboratory
REPORT OF RADIOCARBON DATING ANALYSES
Katerine Escobar Torrez
Herbario Nacional de Bolivia
Report Date: August 09. 2018
Material Received July 20, 20'8
Laboratory Number
Beta - 499942
Col'lVMlt!Onal Radiocarbon Ao,, (BP) 0(
Percent Modern Carbon (pMC) ~ Su ble 15Qtopes
Sample Code Number
Calendar Calibrated Result$· 95 4 ~ Probablrty
High Prob.ability Density Range Mttnod (HPD)
BSP14 9-9.5 1300 +f- 30 BP
(95.4%) 680 - 862 cal AO (1270 - 1088 cal BP)
Submitter Material: Peat
Pretreatment (organic sediment) acid washes
Analyzed Material: Organic sediment
Analysis Service: AMS-Micro-sample Analysis; Standard delivery
Percent Modem Carbon: 85.06 +/- 0.32 pMC
Fraction Modern Carbon: 0.8506 +f-
014C: -149.42 +/· 3.18 o/oo
d 14C: -156.39 +/- 3 .18 o/00( 1950:2,018.00)
Measured Radiocarbon Age: (without d13C correction): NA
Calibration: BetaCal3.21: HPO method: SHCAL 13
IRMS !513C: NA
227
100
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Results of metal analysis (XRD)
Results of the BSP2 Profile
Depth Years BP Years AD-BC Fe Ni Br Pb Si/Ti Fe/Ti Mn/Ti Mn/Fe
0 -62 2012 15006 5482 2330 1498 2.6482 14.3051 1.1592 0.081
0.5 -58 2008 55734 4756 3159 3430 1.6679 26.2525 0.715 0.0272
1 -55 2005 97063 5032 3119 3208 1.5275 32.4083 0.7002 0.0216
1.5 -51 2001 153692 4893 2579 3414 1.2931 32.1061 0.6236 0.0194
2 -47 1997 158513 5080 3211 3439 1.3021 28.1051 0.6181 0.022
2.5 -43 1993 140579 5043 3662 2720 1.3468 29.3178 0.7218 0.0246
3 -39 1989 95234 6278 7265 1871 1.6318 30.7603 0.8107 0.0264
3.5 -35 1985 124048 6205 6426 2672 2.1689 34.8058 0.7685 0.0221
4 -31 1981 148331 6563 8438 3117 1.8627 41.9844 0.9825 0.0234
4.5 -28 1977 176571 6558 8420 5160 1.7019 51.4484 0.6952 0.0135
5 -24 1973 228167 6638 9027 7865 1.823 56.7862 0.5042 8.88E-03
5.5 -20 1969 276511 6484 8052 6440 1.2735 50.9228 0.3576 7.02E-03
6 -16 1965 314769 6444 8781 9707 1.509 70.1513 0.3633 5.18E-03
6.5 -12 1962 353338 5624 7423 8934 1.4246 54.2013 0.3086 5.69E-03
7 -8 1958 326932 6136 10162 7157 1.1271 46.738 0.2097 4.49E-03
7.5 -4 1954 440230 6196 8773 13922 1.3012 66.21 0.2313 3.49E-03
8 0 1950 493123 6043 6527 13910 1.0339 62.3417 0.2339 3.75E-03
8.5 4 1946 466451 5474 5470 9636 0.887 53.1992 0.2636 4.95E-03
9 8 1942 453969 4816 3500 7692 0.9552 47.546 0.2275 4.78E-03
9.5 12 1938 524233 5471 3234 10514 0.9946 64.331 0.2766 4.30E-03
10 16 1934 415598 4638 3837 13177 1.0804 93.5821 0.3783 4.04E-03
10.5 20 1930 297649 4135 2848 7271 0.927 63.1951 0.2675 4.23E-03
11 24 1926 271253 3878 2957 8168 1.0343 84.6872 0.3437 4.06E-03
11.5 28 1922 274825 3964 2910 6357 0.9172 70.2698 0.3125 4.45E-03
12 32 1918 369414 4106 2617 6919 0.7483 59.6406 0.2879 4.83E-03
12.5 36 1915 421817 4479 3168 6145 0.6511 42.9461 0.2546 5.93E-03
13 40 1911 503855 4916 3273 7931 0.6182 40.2762 0.2301 5.71E-03
13.5 44 1907 663727 5070 3401 11215 0.6313 36.8553 0.1976 5.36E-03
14 48 1903 625039 5212 2910 9130 0.6759 31.4358 0.1722 5.48E-03
14.5 52 1899 590762 5250 2874 6847 0.5932 29.853 0.1841 6.17E-03
15 56 1895 579671 5024 2725 6467 0.5469 34.5948 0.2091 6.04E-03
15.5 60 1891 634268 5167 2787 8755 0.4654 36.9104 0.189 5.12E-03
16 64 1887 621626 5277 2947 8681 0.4684 37.4835 0.2001 5.34E-03
16.5 68 1883 607599 5306 2909 9105 0.5347 45.479 0.2487 5.47E-03
17 72 1879 565430 5196 2728 7185 0.5334 40.5094 0.2427 5.99E-03
84
228
101
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
Results of the BSP14 Profile
Depth Pb Fe Ni Br Si/Ti Fe/Ti Mn/Fe Mn/Ti
0 2325 20542 4149 2087 2.1349 16.1114 0.0319 0.5137
0.5 5200 59168 6422 4885 1.876 25.6583 0.0396 1.0169
1 7184 83115 6930 7367 2.58 49.7993 0.02 0.9964
1.5 5390 71533 6436 5680 2.0332 43.2224 9.09E-03 0.3927
2 5241 82370 6157 5754 2.8539 67.6273 6.73E-03 0.4548
2.5 4627 76543 6025 5795 2.1556 52.2478 7.68E-03 0.4014
3 4823 140272 5933 6682 1.9878 85.4796 3.78E-04 0.0323
3.5 5101 182580 6025 7409 1.6305 107.085 4.07E-03 0.4358
4 4726 151227 5909 7443 1.8125 96.4458 5.74E-03 0.5536
4.5 5293 157113 5524 7274 1.7093 95.1623 4.77E-03 0.4543
5 5511 138821 5430 7084 1.8494 85.0098 4.11E-03 0.3497
5.5 5244 128600 5202 7011 1.171 51.0317 5.26E-03 0.2687
6 5294 105808 5243 7303 1.8963 75.6853 6.07E-03 0.4592
6.5 5273 86298 5605 6772 1.8981 63.2683 5.72E-03 0.3622
7 5420 103992 5558 7095 1.8698 73.5966 4.97E-03 0.3659
7.5 6814 109532 5538 6536 1.6571 67.1975 4.56E-03 0.3067
8 8116 117998 5929 6342 1.445 59.5348 3.69E-03 0.2195
8.5 8700 104468 5612 6559 1.8244 67.4422 5.51E-03 0.3719
9 9073 122752 5627 6527 1.1685 46.1821 6.06E-03 0.2799
9.5 9800 127563 5469 5511 1.1674 49.7904 6.41E-03 0.3193
10 7153 136692 4626 3520 1.0617 40.9257 7.81E-03 0.3195
10.5 4234 175358 4301 2373 0.9127 34.8624 8.74E-03 0.3046
11 2510 228106 4105 1684 0.8614 30.9087 9.20E-03 0.2844
11.5 1819 235946 3978 1449 0.7566 27.2361 9.06E-03 0.2468
12 2608 234324 4376 1946 0.7363 25.04 9.15E-03 0.2292
12.5 2856 264240 4532 1862 0.6612 25.8628 8.40E-03 0.2172
13 3827 192459 4741 2254 0.8052 26.9853 8.76E-03 0.2363
13.5 4004 201360 4714 2293 0.7429 23.8578 7.81E-03 0.1864
14 5259 190189 4872 2280 0.8975 26.0497 8.70E-03 0.2267
14.5 5091 242968 4630 2217 0.7515 28.4506 8.25E-03 0.2347
15 5023 333389 4465 2001 0.5228 25.3991 9.16E-03 0.2327
15.5 3773 252454 4481 2156 0.6893 27.9263 8.97E-03 0.2504
16 5175 221122 4507 2445 0.7635 29.4084 7.69E-03 0.2262
16.5 9240 213520 4661 3014 0.7676 35.7775 8.07E-03 0.2887
17 6633 102473 5478 4903 1.1345 36.8475 7.95E-03 0.2931
17.5 4337 129171 5078 4053 1.2139 27.5477 8.58E-03 0.2363
18 3731 110657 5491 4291 3.1235 31.4188 8.43E-03 0.2649
18.5 3633 185907 5038 3934 1.1924 39.8685 8.52E-03 0.3397
85
229
86
18.5 3633 185907 5038 3934 1.1924 39.8685 8.52E-03 0.3397
19 2630 193638 4598 3259 0.9801 36.9891 9.51E-03 0.3519
19.5 4690 151702 5342 4152 1.183 34.0139 7.67E-03 0.261
20 3776 138289 4434 3012 1.2473 37.7942 8.90E-03 0.3364
20.5 4377 110107 5192 3788 1.5289 45.3862 7.24E-03 0.3285
21 7096 124274 5674 5417 1.6507 55.2329 5.41E-03 0.2987
21.5 7421 94532 5625 5004 1.6744 59.0825 7.02E-03 0.415
22 8634 95869 6032 6043 1.3958 42.345 5.10E-03 0.216
22.5 10394 92615 6482 6535 1.3217 40.4786 8.47E-03 0.3427
23 8678 119565 6058 5563 1.0416 31.6477 5.85E-03 0.1853
23.5 4766 138418 5035 3334 0.9841 37.9227 8.34E-03 0.3162
24 2614 109106 3893 2406 1.0784 28.8031 8.60E-03 0.2476
24.5 6356 128599 4665 3460 0.9374 28.3445 8.77E-03 0.2486
24.5 6464 128256 4598 3734 0.941 28.4444 8.37E-03 0.2382
24.5 6416 128096 4616 3721 0.9603 27.9442 7.60E-03 0.2125
24.5 6306 127698 4411 3390 0.9977 29.1615 8.55E-03 0.2494
25 4350 148174 4524 3084 0.9972 27.8575 9.43E-03 0.2626
25.5 5539 174132 4271 2963 1.0331 27.6049 7.99E-03 0.2207
26 13243 152591 4723 3856 1.15 25.8366 8.72E-03 0.2252
26.5 4819 192550 4603 2755 1.5455 28.6447 8.77E-03 0.2513
27 3089 191058 4547 2729 1.1134 24.0173 9.60E-03 0.2307
27.5 2561 221974 4460 2457 1.0069 23.6823 9.67E-03 0.2291
28 2883 228981 4419 1887 0.9748 23.0039 8.57E-03 0.1971
28.5 2193 217467 4469 2298 0.9636 19.8148 8.86E-03 0.1756
29 2729 217337 4444 2439 1.0322 20.9947 9.01E-03 0.1891
29.5 1917 270226 4445 1880 1.063 22.7616 9.45E-03 0.215
30 2010 266750 4399 2024 1.0643 24.0532 9.18E-03 0.2207
30.5 2457 214052 4274 2064 1.1663 26.3028 0.0104 0.2739
31 1996 233933 4415 1846 0.9969 21.9573 9.15E-03 0.201
31.5 2522 210485 4219 2183 0.9771 21.5484 0.0102 0.2208
32 3150 178712 4254 2281 0.7342 21.3006 9.15E-03 0.195
32.5 1789 159398 4229 1759 0.8675 22.9614 9.76E-03 0.224
33 1696 139153 4251 1906 0.9291 18.6582 9.78E-03 0.1825
33.5 2241 185864 4338 2083 0.9986 22.0767 9.80E-03 0.2164
34 2756 182420 4179 2047 1.0873 23.7341 9.37E-03 0.2224
34.5 2869 158386 4274 2086 1.2222 23.9761 0.0101 0.2425
35 2024 172567 4160 1895 1.1694 23.8188 9.82E-03 0.2338
35.5 2588 166584 4404 2415 1.1398 23.5521 0.0105 0.2467
36 3337 179362 4588 2673 0.7593 23.3757 9.32E-03 0.2179
36.5 4355 191905 4689 2660 0.9816 25.2706 9.04E-03 0.2283
37 3435 207693 4489 2244 1.0117 23.9858 9.12E-03 0.2188
86
230
19 2630 193638 4598 3259 0.9801 36.9891 9.51E-03 0.3519
19.5 4690 151702 5342 4152 1.183 34.0139 7.67E-03 0.261
20 3776 138289 4434 3012 1.2473 37.7942 8.90E-03 0.3364
20.5 4377 110107 5192 3788 1.5289 45.3862 7.24E-03 0.3285
21 7096 124274 5674 5417 1.6507 55.2329 5.41E-03 0.2987
21.5 7421 94532 5625 5004 1.6744 59.0825 7.02E-03 0.415
22 8634 95869 6032 6043 1.3958 42.345 5.10E-03 0.216
22.5 10394 92615 6482 6535 1.3217 40.4786 8.47E-03 0.3427
23 8678 119565 6058 5563 1.0416 31.6477 5.85E-03 0.1853
23.5 4766 138418 5035 3334 0.9841 37.9227 8.34E-03 0.3162
24 2614 109106 3893 2406 1.0784 28.8031 8.60E-03 0.2476
24.5 6356 128599 4665 3460 0.9374 28.3445 8.77E-03 0.2486
24.5 6464 128256 4598 3734 0.941 28.4444 8.37E-03 0.2382
24.5 6416 128096 4616 3721 0.9603 27.9442 7.60E-03 0.2125
24.5 6306 127698 4411 3390 0.9977 29.1615 8.55E-03 0.2494
25 4350 148174 4524 3084 0.9972 27.8575 9.43E-03 0.2626
25.5 5539 174132 4271 2963 1.0331 27.6049 7.99E-03 0.2207
26 13243 152591 4723 3856 1.15 25.8366 8.72E-03 0.2252
26.5 4819 192550 4603 2755 1.5455 28.6447 8.77E-03 0.2513
27 3089 191058 4547 2729 1.1134 24.0173 9.60E-03 0.2307
27.5 2561 221974 4460 2457 1.0069 23.6823 9.67E-03 0.2291
28 2883 228981 4419 1887 0.9748 23.0039 8.57E-03 0.1971
28.5 2193 217467 4469 2298 0.9636 19.8148 8.86E-03 0.1756
29 2729 217337 4444 2439 1.0322 20.9947 9.01E-03 0.1891
29.5 1917 270226 4445 1880 1.063 22.7616 9.45E-03 0.215
30 2010 266750 4399 2024 1.0643 24.0532 9.18E-03 0.2207
30.5 2457 214052 4274 2064 1.1663 26.3028 0.0104 0.2739
31 1996 233933 4415 1846 0.9969 21.9573 9.15E-03 0.201
31.5 2522 210485 4219 2183 0.9771 21.5484 0.0102 0.2208
32 3150 178712 4254 2281 0.7342 21.3006 9.15E-03 0.195
32.5 1789 159398 4229 1759 0.8675 22.9614 9.76E-03 0.224
33 1696 139153 4251 1906 0.9291 18.6582 9.78E-03 0.1825
33.5 2241 185864 4338 2083 0.9986 22.0767 9.80E-03 0.2164
34 2756 182420 4179 2047 1.0873 23.7341 9.37E-03 0.2224
34.5 2869 158386 4274 2086 1.2222 23.9761 0.0101 0.2425
35 2024 172567 4160 1895 1.1694 23.8188 9.82E-03 0.2338
35.5 2588 166584 4404 2415 1.1398 23.5521 0.0105 0.2467
36 3337 179362 4588 2673 0.7593 23.3757 9.32E-03 0.2179
36.5 4355 191905 4689 2660 0.9816 25.2706 9.04E-03 0.2283
37 3435 207693 4489 2244 1.0117 23.9858 9.12E-03 0.2188
37.5 2094 216141 4156 2088 1.0436 23.9385 9.50E-03 0.2275
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
102
87
231
38 1813 277605 4380 1804 1.0266 24.8238 9.52E-03 0.2363
38.5 1567 286329 4306 1634 1.0341 23.1583 9.35E-03 0.2165
39 1703 319763 4425 1552 1.2065 24.276 0.0101 0.2457
39.5 1505 321057 4574 1778 1.0283 21.9256 9.70E-03 0.2126
40 1510 304032 4177 1671 1.0971 22.9736 9.95E-03 0.2285
40.5 1443 337886 4323 1832 0.976 21.5365 9.47E-03 0.204
41 1511 328818 4377 1644 0.8929 20.5114 0.0102 0.2095
41.5 1297 356157 4415 1711 0.8148 19.9483 9.76E-03 0.1947
42 1467 349798 4211 1855 0.7947 21.1627 0.01 0.2121
42.5 1397 341594 4299 1302 0.9031 24.1341 0.0109 0.2636
43 1484 317331 4146 1510 0.6592 25.6616 0.0103 0.2631
Results of the BSP7 Profile
Depth Years BP Years AD-BC Fe Ni Br Pb Si/Ti Fe/Ti Mn/Ti Mn/Fe
0 -61 2018 11581 4706 1804 2680 2.3368 8.57216876 0.3235 0.0377
0.5 -60 2016 27259 7950 3483 1483 2.2895 16.0725236 0.6757 0.042
1 -59 2008 45051 8042 4873 1483 1.8425 19.6557592 0.6357 0.0323
1.5 -49 1999 59395 7510 5022 1456 2.1588 31.6435802 0.8998 0.0284
2 -40 1989 33623 7552 4341 1040 2.6322 22.4452603 1.3685 0.061
2.5 -31 1980 29125 7669 5060 1114 3.5256 23.6981286 2.4052 0.1015
3 -21 1971 27465 7609 4314 1367 3.0007 18.6709721 1.7988 0.0963
3.5 -12 1961 28520 7496 4179 1021 3.4725 20.084507 1.093 0.0544
4 -3 1952 40044 7894 4410 1452 2.8696 21.0536278 0.7739 0.0368
4.5 7 1943 52662 7661 3514 822 2.263 20.7657729 0.6995 0.0337
5 16 1933 31039 7412 3448 1130 2.4265 19.4115072 0.8243 0.0425
5.5 25 1924 29690 7268 3378 871 1.9012 19.5586298 1.0303 0.0527
6 35 1915 28658 7117 4086 985 2.4036 23.6062603 1.9465 0.0825
6.5 44 1905 21440 7465 4386 653 2.0729 16.6330489 3.6649 0.2203
7 53 1896 23530 7229 5307 619 2.5416 22.5167464 4.0316 0.179
7.5 63 1887 24872 7195 5377 975 2.1903 18.2747979 4.252 0.2327
8 72 1877 30001 7107 4834 1034 2.6756 24.2726537 4.682 0.1929
8.5 82 1868 36919 7039 4116 1181 2.3462 25.356456 3.4979 0.138
9 91 1859 40234 7116 4329 1560 2.2567 25.6922095 2.2133 0.0861
9.5 100 1849 63206 6793 4783 2405 2.686 52.3661972 1.7829 0.034
10 110 1840 101716 6447 5362 6808 1.9475 67.5853821 0.8645 0.0128
10.5 119 1831 170927 6688 5215 12521 3.005 169.907555 1.175 6.92E-03
11 128 1821 96229 6755 4017 5947 2.6627 88.6903226 0.4691 5.29E-03
11.5 138 1812 65535 6356 4246 3740 2.7467 67.492276 0.4573 6.78E-03
12 147 1803 65779 6638 3776 2986 2.5194 62.1142587 0.3805 6.13E-03
English translation prepared by DIREMAR. The original-language text remains the authoritative one.
103
88
232
12.5 156 1793 77606 6824 4145 4203 3.0569 88.3895216 0.3417 3.87E-03
13 166 1784 89839 7588 4823 5937 2.4686 76.1347458 0.3119 4.10E-03
13.5 175 1775 65172 7635 4819 2950 2.3944 50.9953052 0.2793 5.48E-03
14 184 1765 63381 7456 4363 1553 1.665 26.8449809 0.2351 8.76E-03
14.5 194 1756 81736 7417 4542 1953 1.2483 27.9534884 0.2869 0.0103
15 203 1747 67144 7456 4552 2747 1.3907 28.7308515 0.1836 6.39E-03
15.5 212 1737 52948 7973 3767 2870 1.8121 30.712297 0.2291 7.46E-03
16 222 1728 50173 8331 3193 2289 1.5502 26.9312936 0.2496 9.27E-03
16.5 231 1719 58917 8468 3205 3804 1.584 29.2102132 0.2291 7.84E-03
89
Annex 23.5
F. Urquidi, “Technical analysis of geological, hydrological,
hydrogeological and hydrochemical surveys completed for
the Silala water system”, June 2018
(English Translation)