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Study region: Andes central Chile (32ºS-36ºS) / Lakes Study focus: Mountain lakes play a key role in the terrestrial freshwater reservoir, both for storage of snow melt and precipitation. Although lakes are sensitive to climate variability, the effect of global warming on water availability remains uncertain. Semiarid regions are especially sensitive to relatively small changes in temperature and precipitation as these have disproportionately large impacts on lake hydrologic budgets. Here, we mapped 12 lakes from the Andes of central Chile (32º-36ºS) using Landsat mission and Sentinel-2 satellites images from 1984 to 2020 and compared these results with the available climate data (precipitation, temperature, and evaporation). New hydrological insights for the region: This approach provides a high-resolution temporal and spatial analysis for changes in lake surface over the last 36 years. Our results indicate that the number of lakes and respective surface area decrease latitudinally from south to north across central Chile, which is consistent the present-day rainfall gradient. Over the study period, lake surface areas decreased significantly between 7% and 25% during the so-called ‘megadrought’ (2010–2020). As lakes continue to dry up, the implications for freshwater availability are of considerable societal and environmental importance. Our results can assist with water management decisions and improve our understanding of future water availability across the region. more...

The abundance of the southern Pacific mollusk loco (Concholepas concholepas), among other conspicuous marine supplies, are often cited as critical resources behind the long-term cultural and demographic fluctuations of prehistoric hunter-gatherers in the coastal Atacama Desert. These societies inhabited one of the world's most productive marine environments flanked by one the world's driest deserts. Both of these environments have witnessed significant ecological variation since people first colonized them at the end of the Pleistocene (c. 13,000 cal yr BP). Here, we examine the relationship between the relative abundance of shellfish (a staple resource) along a 9,500-year sequence of archeological shell midden accumulations at Caleta (a small inlet or cove) Vitor, with past demographic trends (established via summed probability distributions of radiocarbon ages) and technological innovations together with paleoceanographic data on past primary productivity. We find that shellfish extraction varied considerably from one cultural period to the next in terms of the number of species and their abundance, with diversity increasing during periods of regionally decreased productivity. Such shifts in consumption patterns are considered community based management decisions, and for the most part they were synchronous with large and unusual regional demographic fluctuations experienced by prehistoric coastal societies in northern Chile. When taken together with their technological innovations, our data illustrates how these human groups tailored their socio-cultural patterns to what were often abrupt and prolonged environmental changes throughout the Holocene. more...

Archaeological and palaeoecological studies throughout the Americas have documented widespread landscape and environmental transformation during the pre-Columbian era. The highly dynamic Formative (or Neolithic) period in northern Chile (ca. 3700-1550 yr BP) brought about the local establishment of agriculture, introduction of new crops (maize, quinoa, manioc, beans, etc.) along with a major population increase, new emergent villages and technological innovations. Even trees such as the Algarrobos (Prosopis section Algarobia) may have been part of this transformation. Here, we provide evidence that these species were not native to the Atacama Desert of Chile (18-27°S), appearing only in the late Holocene and most likely due to human actions. We assembled a database composed of 41 taxon specific AMS radiocarbon dates from archaeobotanical and palaeoecological records (rodent middens, leaf litter deposits), as well an extensive bibliographical review comprising archaeobotanical, paleoecological, phylogenetic and taxonomic data to evaluate the chronology of introduction and dispersal of these trees. Although Algarrobos could have appeared as early as 4200 yr BP in northernmost Chile, they only became common throughout the Atacama over a thousand years later, during and after the Formative period. Cultural and natural factors likely contributed to its spread and consolidation as a major silvicultural resource. more...

Socio-economic and environmental changes are well known causes of demographic collapse of agrarian cultures. The collapse of human societies is a complex phenomenon where historical and cultural dimensions play a key role, and they may interact with the environmental context. However, the importance of the interaction between socio-economic and climatic factors in explaining possible breakdowns in Native American societies has been poorly explored. The aim of this study is to test the role of socio-economic causes and rainfall variability in the collapse suffered by the Aymara people of the semiarid Andean region of Tarapacá during the period 1820-1970. Our motivation is to demonstrate that simple population dynamic models can be helpful in understanding the causes and relative importance of population changes in Andean agro-pastoral societies in responses to socio-environmental variability. Simple logistic models that combine the effects of external socio-economic causes and past rainfall variability (inferred from Gross Domestic Product [GDP] and tree-rings, respectively) were quite accurate in predicting the sustained population decline of the Aymara people. Our results suggest that the depopulation in the semiarid Tarapacá province was caused by the interaction among external socio-economic pressures given by the economic growth of the lowlands and demands for labor coupled with a persistent decline in rainfall. This study constitutes an example of how applied ecological knowledge, in particular the application of the logistic equation and theories pertaining to nonlinear population dynamics and exogenous perturbations, can be used to better understand major demographic changes in human societies. more...

El área del Salar de Atacama, Provincia de El Loa, segunda Región de Antofagasta del norte de Chile, es una de las más secas del mundo, correspondiendo al área de máxima penetración del Desierto de Atacama en la costa Pacífica de Sudamérica. En efecto, y en concordancia con la disminución de las lluvias en sentido NW-SE, desde los Andes de Arica (18°S), hacia los de Antofagasta (24°S), se observa que la vegetación se retrae paulatinamente hacia mayores altitudes. Así, extensas áreas al interior de la ciudad de Calama, representadas por el Salar de Atacama, Cordillera de Domeyko y sectores bajos de la vertiente occidental andina corresponden a desiertos ‘absolutos’, con valores de coberturas de plantas vasculares prácticamente nulos. La hiperaridez de la región es interrumpida por oasis, como San Pedro de Atacama y Toconao, y algunas quebradas que cuentan con agua permanente, hábitats que permiten el desarrollo de agricultura en el sector. Así, y a pesar de la extremada aridez y aislamiento, subsisten en la región poblaciones con tradición atacameña que han desarrollado un acabado conocimiento y uso de los precarios recursos bióticos del desierto. El objetivo de este trabajo es acceder al conocimiento de las plantas en los territorios de estas culturas y definir sus singularidades etnobotánicas, en correspondencia con su situación tan especial dentro de los Andes del norte de Chile. Con este propósito, se realizó una recolección exhaustiva de la flora del área y un muestreo sistemático de la vegetación, este último siguiendo un transecto altitudinal desde el Salar de Atacama (2.700 m) hasta el Salar de Aguas Calientes (4.500 m). Posteriormente, se entrevistaron 38 personas provenientes de San Pedro de Atacama, Toconao, Talabre, Camar, Socaire y Peine. Para las 173 especies de plantas consultadas se registraron 416 nombres vernaculares, correspondiendo la mayor proporción al español (53%) o una combinación indígena-español (12%). Entre los nombres indígenas destacan los provenientes de los idiomas atacameño o kunza (8%), quichua (5%), aymara (2%) o una combinación de estas tres lenguas (16%). Un rasgo interesante es la existencia de nombres múltiples, y en varias lenguas, para una cierta cantidad de especies, probablemente una expresión del multilingüismo que caracteriza a la región. Se ha registrado también diferenciación de nombres de plantas dentro del área de estudio, existiendo un conjunto de nombres vernaculares de plantas restringidos al sector sur del Salar de Atacama, específicamente a las localidades de Peine, Socaire y Camar. Estos nombres son definidos por algunos informantes como correspondientes a las denominaciones antiguas de las plantas (“nombres que daban los abuelos”) y pertenecerían al idioma atacameño o kunza. En lo que se refiere a la etnoclasificación de las plantas, y tal como ha sido documentado en otros estudios etnobotánicos andinos, la denominación de las especies, y la distinción de grupos de especies, se basa principalmente en el contraste de características morfo-fisionómicas. Entre las clases de agrupaciones de plantas registradas, categorías etnogenéricas, destacan las construidas sobre la base de formas de crecimiento (agrupaciones de formas de vida); por parecido morfológico general (agrupaciones “taxonómicas”); por comparación con otras plantas importantes o útiles (agrupaciones en torno a un referente); por similitud de algún atributo morfológico, terapéutico, alimenticio, u otros (agrupaciones por similitud en alguna propiedad). En los Andes del norte de Chile, las dos últimas clases de agrupaciones son exclusivas de la región del Salar de Atacama. De las 173 especies consultadas en Atacama, 165 tenían uno o más usos (94,8%), distribuyéndose los distintos tipos de usos en las siguientes 10 clases principales: Forrajero, 35%; Medicinal, 24%; Alimenticio, 9%; Combustible y Leña, 6%; Construcción y Artesanías, 6%; Adorno, 5%; Tintóreo, 4%; Perjudicial, 3%; Ritual, 2%, y Otros usos variados, 6%. Generalmente, las especies tienen de uno a tres usos aunque, para varias especies, se registraron usos múltiples (e.g. la chillka, con siete usos; el algarrobo, con seis). La utilidad de la flora de los distintos pisos de vegetación muestra las siguientes tendencias: El Piso Altoandino es predominantemente forrajero (52%) y los Pisos Puneño y Prepuneño son principalmente forrajero (Puneño, 31%; Prepuneño, 44%) y medicinal (Puneño, 25%; Prepuneño, 13%). También, en ambos pisos, las especies de plantas tintóreas y alimenticias son más abundantes que en el resto de la vegetación del área. La flora azonal de las quebradas, riberas de ríos, salares y chacras muestra un uso más diversificado, hecho que corresponde a la heterogeneidad vegetacional que caracteriza estas formaciones. Se discuten los resultados etnobotánicos en el contexto de la cosmovisión, percepción ambiental, control de recursos naturales y transformaciones, por parte de las comunidades estudiadas. ABSTRACT The Atacama salt flat, or salar, lies in northern Chile’s second region of Antofagasta, and is one of the driest areas in the world as it corresponds to the maximum penetration of the Atacama Desert into the interior from the Pacific coast. This is observed as well in the vegetation gradient which retreats to greater altitudes following the precipitation gradient that decreases from the NW towards the SE, from the Andes of Arica (18°S) to the Andes of Antofagasta (24°S). Absolute desert, areas with practically no plant vascular plants, occurs near the city of Calama to the interior, such as the Salar de Atacama, the Domeyko cordillera or other low lying piedmont regions of the western slope of the Andes. This hyperaridity is interrupted by only a few oases such as San Pedro de Atacama and Toconao, and a few ravines supplied with flowing water on a permanent basis that allow for agriculture to be sustained on a regular basis. Despite these factors, the few atacameño traditional communities that subsist in the area have developed a thorough knowledge and use of the biotic resources present in the desert. Our objective in this paper was to access the plant knowledge of these cultures as well as defining their ethnobotanical uniqueness, particularly when seen from their special viewpoint within the Andes of northern Chile. With this goal we set out to exhaustively collect the flora of the area as well as working on systematic surveys of the vegetation through an altitudinal transect from the Salar de Atacama (2.700 m) to the Salar de Aguas Calientes (4.500 m). We also obtained 38 interviews from the inhabitants of San Pedro de Atacama, Toconao, Talabre, Camar, Socaire and Peine. For the 173 species of plants consulted in these interviews, we registered 416 common names, with the largest proportion of these originating from spanish (53%) or a native-spanish combination (12%). Among those pure native names encountered, these have their origins in atacameño or kunza (8%), quichua (5%), aymara (2%) or a combination of these three languages (16%). One interesting feature is the existence of multiple names in several languages for certain species, possibly an expression of the many languages present in the region. Name differentiation within the study area was also observed, with a set of common names restricted to a certain locality, such as Peine, Socaire and Camar. These names were described by a few informants as originating from “ancient” names (“names used by our grandfa9 thers”) and correspond to the atacameño or kunza languages. Regarding plant ethnoclassification, the naming of different species as well as differences between groups of species is based primarily on contrasting morpho-phisionomical traits, as documented in other Andean ethnobotany studies. Among the different classes of groups of plants recorded (ethnogeneric categories), the most prominent are those based on different growth forms (life form groups); morphological similarity (“taxonomic” groups); comparisons to different other important or useful plants (reference groups); or by a common attribute such as morphology, therapeutic value, food, etc. (groups with shared properties). These last two groups are unique to the Salar de Atacama region within northern Chile. Of the 173 species consulted in Atacama, 165 had one or more uses (94.8%), with the different types of uses distributed in 10 main classes: Fodder 35%, Medicinal 24%, Alimentary 9%, Fuel and Wood 6%, Building and Crafts 6%, Decoration 5%, Dyes 4%, Harmful 3%, Ceremonial 2%, Other uses 6%. On average, species had from one to three uses although some species had truly multiple uses (e.g. the chilka, with seven uses and the algarrobo with six). Also, the uses of the flora from different vegetation belts showed certain tendencies. The High Andean belt was predominantly for fodder (52%) while the Puneño and Prepuneño belts were primarily fodder (Puneño 31%, Prepuneño 44%) and medicinal (Puneño 25%, Prepuneño 13%) in use. Higher numbers of plants are used as dyes and food in these latter two belts as compared to vegetation from other areas. The azonal flora from ravines, river floodplains, salars, and fields has a more diverse use, observation that coincides with a more heterogeneous vegetation that is present in these areas. We discuss these ethnobotanical results in the light of the cosmovision, environment perception, control and transformation of natural resources on behalf of the communities studied. more...