Andean Altiplano Research Articles

Diet, Mobility, Technology, and Lithics: Neolithization on the Andean Altiplano, 7.0–3.5 ka

Neolithization was a complex, protracted process of domestication, sedentarization, and technology change that occurred in various combinations in various times and places around the world. Understanding the causal relationships among those and other important human behaviors remains an analytical challenge. This study examines Neolithization through the lens of lithic artifact variation in the Lake Titicaca Basin, Peru. Drawing on previous lithics research, we outline a synthetic model linking changing diet, mobility, and projectile technology to predicted trends in lithic assemblages. The expectations are then compared to two large, well-dated lithic assemblages from the Titicaca Basin—one from the Middle/Late Archaic forager site of Soro Mik’aya Patjxa (8.0–6.5 cal. ka) and the other from the Terminal Archaic horticultural site of Jiskairumoko (5.2–3.4 cal. ka). We find that the strongest signal in lithic technology change is related to the introduction of archery technology. Signals for subsistence change and declining mobility are relatively weak. The results suggest an early but unconfirmed adoption of archery technology in the Terminal Archaic Period with major transitions in mobility and diet likely to have occurred subsequently in the Terminal Archaic or Formative periods. The findings are consistent with a behavioral model in which changes in projectile technology played a prominent role in the evolution of resource intensification and residential sedentism as well as resource privatization and sexual division of labor in the high Andes.

Limnological response from high-altitude wetlands to the water supply in the Andean Altiplano

The Andean Altiplano-Puna is located at an elevation of approximately 4000 m.a.s.l. and is delineated by the Western and the Eastern Andes Cordillera. The high-altitude wetlands (HAWs) in the Central Andes are unique ecosystems located in the Altiplano that provide many ecosystem services. The objective of this study was to characterize the spatial heterogeneity of the environmental conditions associated with varying hydrology of the HAW, Salar de Tara, in the Andean Altiplano. Sediment samples of up to 20 cm in depth were obtained from various salt flat sub-environments. The samples were analyzed using proxies for mineralogical and chemical composition, thermal analysis, and magnetic susceptibility. Diatom and ostracod communities were also identified and analyzed. The results reflected changes in the geochemistry, carbon content, mineralogy, and magnetic properties of the sediments that can be explained by variations in the sources of water input to the Salar de Tara. The sub-environments depend on the supply of water via the groundwater recharge of springs adjacent to the streamflow from the Zapaleri River, which promotes greater diversity and richness of genera. Our results suggest that water extraction at industrial levels greatly impacts the persistence of hydrologically connected HAWs, which concentrate a worldwide interest in brine mining.

Genome‐wide DNA and phenotypic information supports recent colonization of South American grasslands by Correndera Pipit (Aves, Motacillidae)

AbstractAnthus correndera has a wide distribution in southern South America with several subspecies assigned to the taxon. We take an integrative approach, analysing genome‐wide single‐nucleotide polymorphism (SNP) data collected using ddRAD sequencing, songs and linear morphological data, to evaluate the evolutionary history of A. correndera and divergence of each subspecies. The final genomic data set of 11,467 SNPs for 40 individuals supports a primary divergence of two main lineages: one in the Andean highlands and another in the lowlands. Estimated divergence times suggest the Andean and lowland groups diverged around 135.5 to 99 thousand years ago (Ka), whereas divergence among populations within each group was much more recent, ranging from 54.7 Ka among the Andean populations to as recent as 20.6 Ka among the lowland populations. Analyses of territorial songs showed slight differences between all operational taxonomic units; however, morphological differences were apparent only between geographically distant populations (i.e. Puna vs. South Georgia). Based on multiple lines of evidence, we propose to reduce the number of subspecies within the correndera complex to three: A. c. calcaratus on the Andean Altiplano (treating A. c. catamarcae as a junior synonym), A. c. correndera in the lowlands (treating A. c. chilensis and A. c. grayi as junior synonyms), and A. c. antarcticus on South Georgia.

On the origin of saline compounds in acidic salt flats (Central Andean Altiplano)

Volcanism, aridity, and endorheism converge in the central zone of the Andean Cordillera (Bolivia, Chile, and Argentina, between latitudes 19° S and 27° S). The Gorbea and Ignorado basins are pristine Andean sites in which the transfer of saline compounds from endogenous to exogenous environments occurs. In this area the regional volcanic rocks display strong argillic alteration, with Al and Fe (alunite, jarosite) and Ca (gypsum/anhydrite) sulfates. Native sulfur is also present in paleosolfataras. The Gorbea salt flat is covered by a discontinuous layer of selenitic gypsum of varying thickness (maximum 2 m). The discontinuity of the layer as well as its variable thickness is due to the fact that the original bed has been partially destroyed mainly by dissolution but also by deflation. Saline pond brines (Cl-SO4-Na [-Mg]) are strongly acidic reaching pH values lower than 2. The high temperature processes that caused the hydrothermal alteration in the Gorbea and Ignorado basins occurred in the Miocene (14 Ma) coinciding with a wet period that reached 9 Ma. Subsequently, the weather up to 120 ka was predominantly hyper-arid with a less arid interval between 6 and 3 Ma and the epithermal sulfates were recycled in saline lakes mainly in the Late Pleistocene wet period (120 to 11.7 ka). Evolution into the current salt flat occurred in the mid-early Holocene (11.7 to 4 ka), through a salt lake that first evolved into a ‘salina’ environment that gave rise to a selenitic gypsum layer (6.4 ka), and later to the final dryness. The highest values of δ34SVCDT and δ18OVSMOW found in the selenitic gypsum layer (+20‰ and + 28‰, respectively) show that the recycling was locally produced, mainly from isotopically heavier hypogene sulfates. The δ18OVSMOW (and less clearly, δ34SVCDT) values are higher in the basal part of the gypsum crust (about +27‰), which suggests an initial hypogene source that decreased towards the top due to mixing with supergene sulfate inputs. Bacterial activity, although catalyzing the supergene reactions, does not appear to have had a significant influence on the isotopic composition of sulfates. The crystallization water of the gypsum is isotopically lighter in the basal part of the selenitic layer (δ18OVSMOW ≈ +7‰), which indicates that the brines of the saline lake were still poorly evolved. These brines evolved to heavier (approximately +13‰) towards the top of the layer and towards the center of the salt flat, before the final drying. The partial destruction of the selenitic gypsum layer occurred during more recent wet periods over the last 4 ka that have been identified in wetlands and lakes in the Central Andean area. Isotopic data (δ34SVCDT and δ18OVSMOW) clearly suggest that sulfates in the saline compounds and evaporites from the entire Central Andean arid area have mostly a thermal origin with contributions from atmospheric deposition and locally, near the Pacific coast, marine aerosols. In addition, the great difference in altitude (approximately 3000 m) between the Altiplano and the lands located to the west, up to the Pacific coast, generated a constant flow of groundwater containing saline compounds that gave rise, to the salt flats of the basins located in lower topographic areas (Atacama, Punta Negra, Hilaricos, Soledad, Tamarugal, Salar de Pintados, Salar Grande) throughout the Cenozoic. Such salt flats have lower δ34SVCDT and δ18OVSMOW values mostly for two reasons: the secular mixing with atmospheric sulfate, and the isotope fractionation related to repetitive dissolution (or leaking)—migration—precipitation along the hydraulic gradient, a process that occurred throughout a large part of the Cenozoic. The last process also explains that the evaporites of some of these salt flats (e.g., Salar de Atacama, Salar Grande) display very high Cl/SO4 ratios.

Comparative Mitogenomics in Hyalella (Amphipoda: Crustacea).

We present the sequencing and comparative analysis of 17 mitochondrial genomes of Nearctic and Neotropical amphipods of the genus Hyalella, most from the Andean Altiplano. The mitogenomes obtained comprised the usual 37 gene-set of the metazoan mitochondrial genome showing a gene rearrangement (a reverse transposition and a reversal) between the North and South American Hyalella mitogenomes. Hyalella mitochondrial genomes show the typical AT-richness and strong nucleotide bias among codon sites and strands of pancrustaceans. Protein-coding sequences are biased towards AT-rich codons, with a preference for leucine and serine amino acids. Numerous base changes (539) were found in tRNA stems, with 103 classified as fully compensatory, 253 hemi-compensatory and the remaining base mismatches and indels. Most compensatory Watson–Crick switches were AU -> GC linked in the same haplotype, whereas most hemi-compensatory changes resulted in wobble GU and a few AC pairs. These results suggest a pairing fitness increase in tRNAs after crossing low fitness valleys. Branch-site level models detected positive selection for several amino acid positions in up to eight mitochondrial genes, with atp6 and nad5 as the genes displaying more sites under selection.

Postcranial anatomy of the extinct terrestrial slothSimomylodon uccasamamensis(Xenarthra, Mylodontidae) from the Pliocene of the Bolivian Altiplano, and its evolutionary implications

AbstractExtinct terrestrial sloths are common elements of the late Cenozoic South American fossil record. Among them, Mylodontinae species were particularly abundant in the Americas throughout the Pleistocene epoch, and their anatomy is relatively well known. In contrast, less information is available from the Neogene record and particularly from localities at low latitudes, with an additional and considerable bias in favour of craniodental rather than postcranial remains. In this contribution, we provide comparative descriptions of several postcranial bony elements ascribed toSimomylodon uccasamamensis, a moderate‐sized extinct mylodontine from the Andean Altiplano. This species was particularly abundant during latest Miocene – late Pliocene times in the high altitudes of the Andean Cordillera, and so far represents the best known mylodontine from the Neogene of South America. Its anatomy is compared with that of several extinct terrestrial sloths, with the aim of using the observed morphologies to elucidate taxonomy, phylogeny, and locomotion. From a morphofunctional perspective, the postcranium ofS. uccasamamensis is consistent with that of a terrestrial graviportal quadruped, with moderate climbing and digging capabilities.

Vicuñas (Vicugna vicugna), Wild Andean Altiplano Camelids

In these case studies, vicuñas are presented as biocultural components of the Andean altiplano’s socioecological landscape. The environmental history of vicuñas is related to the multiple values of the species, especially of its appreciated fiber as a nature contribution to people. Vicuñas were in risk of extinction, but thanks to conservation policies, the engagement of local communities, and the efforts of scientists and naturalists, this species has recovered to an extent than allows sustainable, community-based management via chakus, a traditional method involving the capture and release of wild vicuñas to harvest their fiber. We describe two cases where the VICAM research team (former MACS) was summoned by local institutions in Cieneguillas and Santa Catalina, both localities belonging to the Pozuelos UNESCO MAB Biosphere Reserve in Jujuy, Argentina. The process to launch and maintain the sustainable use of vicuñas is presented, focusing on the emerging challenges, dilemmas, and conflicts that shaped decision-making processes. The obstacle that seemed the most challenging beforehand—the capture itself and its biological consequences for the animals—was overcome with the development of adaptive management. Vicuña management has great potential for the sustainable development of indigenous peoples and local communities, but achieving this goal is a process ridden with difficulties, including the commercial interests of non-Andean actors. For vicuña management to become a driver of sustainable local development, a series of challenges must be overcome: power asymmetries between local communities and other stakeholders due to the monistic economic valuation of vicuña fiber, the incorporation of relational values with strict welfare protocols recognizing vicuñas as sentient beings, and the intrinsic valuation of the ecological role of the species, also considering their indisputable position as Andean ancestral biocultural heritage.

A partially complete skeleton of Hippidion saldiasi Roth, 1899 (Mammalia: Perissodactyla) from the late Pleistocene of the high Andes in northern Chile

ABSTRACT South America is well known for its abundance of Quaternary fossiliferous deposits, but well-preserved fossil remains from well-dated sites are scarce in the Atacama Desert and adjacent arid Andes. Here we report on a partially complete skeleton (46%) of a single young (ca. 3–4 years old) extinct horse discovered in the Salar de Surire, a salt flat located on the Andean altiplano of northern Chile (4,250 m asl). Comparative and osteometric morphological analyses identify the specimen as a South American endemic horse Hippidion saldiasi Roth, 1899. A direct AMS radiocarbon date on bone collagen yielded a calibrated age of 13,170 cal yr BP (2σ range: 13,300–13,060 cal yr BP) indicating that it lived near the end of the last glaciation. The body mass of the individual was calculated at approximately 326.4 kg, close to the upper limit of the larger sizes reported for the genus. Stable isotope evidence shows that the Salar de Surire horse relied on an almost 100% C3 diet that is mostly consistent with Hippidion specimens from other environments that also consumed either mixed C3/C4 or fully C3 diets. This finding is now the southernmost high-elevation record for this species and provides further evidence for the broad geographic and ecological distribution of this genus throughout southern South America.

A woman hunter in the early Andes

Archaeology The ethnographic record of modern hunter-gatherers indicates that men were the primary, almost exclusive, hunters of big game. However, to what extent this pattern existed in prehistory has been challenged on both empirical and theoretical grounds. To examine this question, Haas et al. studied the artifacts recovered from a burial of a young woman at a site on the Andean Altiplano dated to more than 8000 years ago. Found with her was a tool kit used in animal processing and numerous projectile points, strongly indicating that she hunted. Additional examples of female hunters at late Pleistocene and early Holocene sites in the Americas were also identified, findings that support a model of relatively undifferentiated subsistence labor among early populations in the Americas. Sci. Adv. 10.1126/sciadv.abd0310 (2020).

Ascotán and Carcote salt flats as sensors of humidity fluctuations and anthropic impacts in the transition zone of the Andean Altiplano

The Altiplano-Puna plateau is a climatic transition zone between the Atacama Desert, the aridest worldwide, and the Amazon basin. The salt flats of the Altiplano are hydrogeological and ecological systems highly dependent and sensitive to seasonal, interannual and inter-decadal variations in humidity; they may be markedly affected by anthropic activities. We focused on Ascotán and Carcote, two nearby salt flats located at more than 3,600 m of elevation at the border of Chile and Bolivia, to determinate the relationship between the depositional environments and recent hydrological conditions, which can be used as sensors of the particular climatic conditions of the Altiplano and anthropic activities in these systems. Results of analysis of sediment properties (mineralogical, geochemical and magnetic), the water (elemental composition) and diatom communities of the different springs in the salt flats showed that the water and sediments of Ascotán and Carcote salt flats were heterogeneous in granulometric, chemical, mineralogical and magnetic grain composition, both intra- and inter-salt flat. The content of saline facies tended to increase in zones furthest from the edge and close to the depocenter of the basin, whose sediments were composed mainly of finer size grains. Diatom diversity and species richness differed between salt flats, which were associated with characteristics of the brine composition, grain size and magnetic properties and were mostly affected by local abiotic factors of each spring. Four sub-environments were identified based on the variables measured: alluvial, marsh, lacustrine and evaporitic, mainly defined by the recharge of water input dominated by summer rainfalls and snow melt. Our results suggest that Ascotán and Carcote salt flats constitute excellent sensors of the air moisture from the Amazon Basin, both current and through the Last Glacial Maximum and the Holocene. Therefore, further studies using Ascotán and Carcote as model systems may be focused on identifying hydro-geo-ecological changes in millennia-term variability of humid periods, in addition to short-term pressure from mining activity.

High methylmercury uptake by green algae in Lake Titicaca: Potential implications for remediation

Anthropogenic pressure in the high altitude lakes such as Titicaca and Uru (Bolivia) may favor the production of methylmercury (MeHg) known to accumulate in trophic chains. Periphyton associated with emerged aquatic plants (totoras) from the lake shores accumulates and demethylates MeHg providing a potential cost-effective water treatment technique. In this laboratory study, we measured the MeHg uptake kinetics of a consortium of green algae isolated from Lake Titicaca totora's periphyton. The most abundant algal consortium, composed of Oedogonium spp., Chlorella spp., Scenedesmus spp., was exposed to rising MeHg concentrations (from 5 to 200 ng·L−1) to assess their maximum potential capacity for MeHg accumulation. Various algal biomass concentrations were tested to choose the optimal one. Results provided a net MeHg uptake rate by this algal consortium of 2.38 amol ng−1·h−1·nM−1 (the total uptake was 2863 ng MeHg·g−1) for an initial concentration of 200 ng MeHg·L−1 with an algal biomass concentration of 0.02 g·L−1. This initial MeHg concentration is 1000 times higher than the one measured in the eutrophic Cohana Bay of Lake Titicaca, which shows the high accumulation potential of these green algae. Our data suggest that periphyton has a high potential for the treatment of Hg contaminated waters in constructing wetlands in the Andean Altiplano.

Precipitation trends over the southern Andean Altiplano from 1981 to 2018

This study undertakes a spatio-temporal assessment of the annual and seasonal precipitation trends over the Desaguadero-Poopó (DP) system in Bolivia for the period 1981–2018. Given the insufficient spatial density of meteorological stations in the study, the high-spatial resolution Climate Hazards group Infrared Precipitation with Stations (CHIRPS) satellite product was used. CHIRPS precipitation data was validated against 7,636 gauge measurements and used to map the spatial distribution of precipitation trends. In addition, the temporal changes in the onset, duration and average intensity of the wet season were explored. Results showed a good, statistically significant agreement between CHIRPS data and onsite records of monthly precipitation at the pixel and regional scales. The spatio-temporal precipitation assessment revealed that statistically significant increases in annual precipitation (2–6 mm yr−1) occurred in two zones at the north and north-western part of the DP system. Only the southern part showed decreasing precipitation trends at a rate of −1 mm yr−1 while the central part did not show significant changes. Overall, a general increasing trend of about 2.5 mm yr−1 was observed for the entire DP system during the 38-year study period, with the months of December and February showing the highest significant increases. The analysis of the onset and cessation times of the rainy season indicated a statistically significant decrease in its duration at a rate of −0.4 day yr−1 and an increment of the average precipitation intensity. Our results reveal trend in the temporal concentration of precipitation in a water scarce region, which highlights the need for the management of the resource, so it can meet societal and environmental demands throughout the year.

HLA study in Amerindian Bolivia La Paz Aymaras

Aymara people has been a relatively homogeneous group since Spanish Conquest by 1,532 CE, even if previously represented a group of various cultural defined populations who gave rise to them. They were and are established in Andean Altiplano around Titikaka Lake (Bolivia, Peru), Argentina and Chile neighborhood, speak Aymara language and have been maintained after Europeans arrival at a lower social status than Quechua (Inca) speaking people. However, both Aymara and Quechua populations acknowledge Titikaka Lake as center of their origins; both languages are also related. Specific high frequencies of HLA-A*02, -A*24 and -A*68, HLA-B*35, -B*39 and -B*48, HLA-DRB1*08:02, -DRB1*09:01, and -DRB1*14:02, and HLA-DQB1*04:02, -DQB1*03:02 and -DQB1*03:01 alleles are found in Aymaras and HLA class II haplotypes common to Andean Amerindians (DRB1*08:02-DQB1*04:02 and DRB1*04:03-DQB1*03:02), like Quechua, Aymara, Uros, Lamas and Mapuche are also found in Easter and other Pacific Islands. Giant human head stone statues at Tiwanaku (Titikaka Lake, Bolivia) are also found at Easter Island. Thus, it is possible a gene and cultural flow between Andean Amerindians and Easter and other Pacific Islands, as it was demonstrated by Thor Heyerdahl in his Kon-Tiki expedition which reached Pacific Islands sailing from El Callao Harbour (Lima, Peru).

Morphological and molecular species boundaries in the Hyalella species flock of Lake Titicaca (Crustacea: Amphipoda)

The Hyalella species diversity in the high-altitude water bodies of the Andean Altiplano is addressed using mitochondrial cox1 sequences and implementing different molecular species delimitation criteria. We have recorded the presence of five major genetic lineages in the Altiplano, of which one seems to be exclusive to Lake Titicaca and nearby areas, whereas the rest occur also in other regions of South America. Eleven out of 36 South American entities diagnosed by molecular delimitation criteria in our study are likely endemic to the Titicaca and neighbouring water bodies. We have detected a remarkable disagreement between morphology and genetic data in the Titicacan Hyalella, with occurrence of several cases of the same morpho-species corresponding to several Molecular Operational Taxonomic Units (MOTUs), some even distantly related, and other instances where a particular MOTU is shared by a morphologically heterogeneous array of species, including species with body smooth and others with body heavily armoured. Species diversification and incongruence between morphological and molecular boundaries within this species assemblage may be associated to the sharp changes in hydrological conditions experienced by the water bodies of the Altiplano in the past, which included dramatic fluctuations in water level and salinity of Lake Titicaca. Such environmental shifts could have triggered rapid morphological changes and ecological differentiation within the Hyalella assemblage, followed by phenotypic convergence among the diverse lineages. Factors such as phenotypic plasticity, incomplete lineage sorting or admixture between divergent lineages might lie also at the root of the morphological-genetic incongruence described herein.

Pelmatellus amicorum Delgado and Ruiz-Tapiador (Coleoptera: Carabidae), a New Species from the Andean Altiplano of Peru

A new species of ground beetle, Pelmatellus amicorum Delgado and Ruiz-Tapiador (Coleoptera: Carabidae), from the Andean Altiplano of Peru is described. The state of knowledge of the genus and the relationship of the new species with known congeneric species are reviewed.

Exposure to geogenic lithium in ancient Andeans: Unraveling lithium in mummy hair using LA-ICP-MS

The ancient Andeans, who lived along the coastal region of the arid Atacama Desert in present day Chile had access to scarce freshwater via a few small rivers originating from the Andean Altiplano. Due to volcanic-derived lithium minerals and their solubility in water, the surface water in the Atacama Desert region is rich with lithium (Li); often many orders of magnitude higher than that of other rivers in the world. The goal of this study was to examine whether ancient Andean mummy individuals (n = 145) from four burial areas in northern Chile (Azapa, Camarones, Lluta and Morro) were exposed to geogenic lithium by conducting laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) on a single strand of hair per individual. The resulting concentrations for Li in mummy hair [Site, Median, Range (μg/g), n: Azapa, 0.38, 0.04–2.91 μg/g, n = 98; Morro, 0.33, 0.03–0.65 μg/g, n = 14; Camarones, 0.61, 0.07–12.8 μg/g, n = 31; Lluta, 2.9, 2.7–3.1 μg/g, n = 2] had the following order: Lluta > Camarones > Azapa > Morro. Hair-Li concentration of the Andean mummies were nearly 20 times elevated when compared to concentrations of Li in the hair of contemporary populations in other regions. Exposure to Li as revealed in hair appears to be depend in part on where ancient Andeans were buried, and generally correlates well with dissolved Li in associated rivers.

Hydrogeological research in the Tuyajto Lake at the Flamingo National Reserve (Atacama, Chile)

The Tuyajto Lake is a saline lake located in the Andean Altiplano of northern Chile, at the foot of the volcano of the same name. It is fed by springs located on its eastern and northern boundaries. These springs discharge groundwater from a volcanic aquifer. Arid conditions dominate in the area, with average precipitation less than 200 mm/year. The tritium content in some groundwater samples shows the contribution of modern recharge to the total groundwater flow. Recharge occurs by infiltration of snowmelt in the austral winter months and to a lesser extent by short but intense precipitation events during the summer. The vertical gradients of rainfall isotopic content (δ18O, δ2H) and precipitation points to the recharge zone of the springs being located at the northern area of the lake, above 4,900 m a.s.l. along the slopes of the Tuyajto volcano, whereas recharge to the springs discharging on the eastern area of the lake originates in the adjacent basins of Pampa Colorada and Pampa Las Tecas at altitudes between 4,400 and 4,700 m a.s.l. The water of these springs may contain measurable tritium. The chemical composition of groundwater is the result of meteoric water evaporation processes, high temperature water-rock interaction and dissolution of buried old salt flat deposits. The groundwater flow is shallow, due to the presence of a regional low permeability ignimbrite formation that precludes the formation of deep convective groundwater flow cells due to the high density of brines. At a local scale, the Tuyajto lake behaves as a flow-through system with respect to the regional groundwater flow. The persistence of the springs is essential for the existence of the brine sheet and maintaining the ecological conditions for the waterfowl.

Groundwater recharge and hydrodynamics of complex volcanic aquifers with a shallow saline lake: Laguna Tuyajto, Andean Cordillera of northern Chile

Estimating groundwater recharge in arid regions with seasonal snow cover, as in the Andean Altiplano of northern Chile, is important for sustainable development policies and the effective management of scarce resources in a high water demanding zone, as fragile ecosystems depends on a stable water contribution. This research aims to evaluate and quantify rainfall and snowfall contribution to aquifer recharge while assessing the factors that control the hydrodynamics in such areas, based in the knowledge of the better documented Tuyajto Lake in the Tuyajto catchment/basin. The modeling framework involves an energy balance of the snow cover, a soil water balance and a groundwater flow and chloride transport model. The basin average annual recharge is about 23% of average precipitation. Snowmelt contribution to recharge is important at altitudes above 4700 m a.s.l. during September, while rainfall is more important in February and March, during short intense precipitation events. The hydraulic conductivity of ignimbrites and other volcanic formations are the most important hydrogeological parameters controlling lake level and spring flow rates, while albedo and snowpack surface roughness length on the energy balance causes the greatest variation of lake level. Evaporation is the process controlling the variability of the lake level, as aquifer contribution remains relatively constant and springs flow variability is not enough to cause the observed variations, except during November. Possible buried salts deposits on the eastern edges of Pampa Colorada and Tuyajto Lake, together with volcanic HCl contribution, justify the high measured groundwater chloride concentrations. A recharge 2–3 higher than the current one is necessary to justify a lake level 40 m above its modern value during the Last Glacial period, giving insight into past hydrological changes in the basin due to climate variability. The knowledge gained can be applied to other high altitude volcanic basins with seasonal snow cover.

Land tenure and the sustainability of pastoral production systems: a comparative analysis of the Andean Altiplano and the East African savannah

Abstract Pastoral communities are facing mounting pressure on their livelihoods due to misconceptions about pastoralism and global trends including population growth and climate change. In this context, this article seeks to establish a correlation between pastoral land tenure systems and the sustainability of pastoralism as a production system. Using a comparative approach, we develop a taxonomy to first categorise the tenure regimes - collective and individual - of pastoralist societies of the Andean altiplano and the Kenyan savannah, and then we explore how these different regimes enable or hinder the performance of productive strategies that are key to the sustainability of pastoralism. We find that collective land tenure is positively correlated with the sustainability of pastoral production systems.

ACCD-producing rhizobacteria from an Andean Altiplano native plant (Parastrephia quadrangularis) and their potential to alleviate salt stress in wheat seedlings

1-Aminocyclopropane-1-carboxylate deaminase (ACCD)-producing rhizobacteria are widely studied as plant growth-promoting rhizobacteria (PGPR) to alleviate a variety of stresses in plants. However, the presence of ACCD-producing rhizobacteria in plants that naturally occur in stressful ecosystems as well as the potential PGPR activity in agriculturally relevant plants has been poorly explored thus far. We isolated and characterized ACCD-producing rhizobacteria from Parastrephia quadrangularis, a native plant from the Andean Altiplano in Chile. The effects of selected ACCD-producing rhizobacteria on biomass and superoxide dismutase (SOD) activity of wheat seedlings subjected to salt stress (0.25 M and 0.45 M NaCl) were also evaluated. Ten out of 30 isolates showed ACCD activity (0.83–3.32 μmol α-ketobutyrate mg−1h−1) and were identified as members of the Enterobacteriales order (mainly Serratia and Klebsiella). The ACCD-producing rhizobacteria also showed salt tolerance (from 2.5 to 7.5% NaCl) and other PGPR traits, such as the production of auxin (from 20.3 to 41 μg mL−1) and siderophores (from 3.35 to 67.7%). Wheat seedlings inoculated with two selected ACCD-producing Klebsiella isolates (8LJA and 27IJA) significantly (P ≤ 0.05) increased the biomass (45–62%) content and SOD activity in roots (18–35%) with and without salt stress. This study demonstrated that PGPR were associated with native plants in the Andean Altiplano and offers a promising potential source of novel PGPR to alleviate salt stress in plants.