Evaluating the resilience of semi-arid vegetation and ecosystem function during the late Holocene in the south-central Andes

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Over 30% of the Earth’s surface is classified as arid lands. Arid lands are vulnerable to small changes in precipitation. People that rely on arid lands are also vulnerable to changes in precipitation amount and timing. The Andes Mountains of South America contain arid lands that are one of the most extreme environments in the world. The region is expected to experience more frequent severe droughts in the coming decades, causing concern about the impacts on available natural resources and livelihoods. The goal of this project is to investigate the climatic and human controls on ecosystems in the arid lands of the Andes beyond the historical record. This research aims to improve our ability to predict changes in these ecosystems in the future because of climate change and land-use pressure. This project is providing training opportunities for early career scientists to conduct research as well as through training workshops. This project is also developing an international collaboration to connect scientists with Indigenous groups and park rangers at the Sajama National Park in Bolivia. Data generated from this project are archived at the Neotoma Paleoecology Database and the Global Charcoal Database.This research investigates the resilience of Andean drylands to climate, fire, and human land-use through the analysis of fossil plant material recovered from rodent middens and peatland sediment cores. The resulting data are used to test the hypothesis that human disturbance coupled with changing climate leads to reduced stability and longer recovery times of natural ecosystems. Combining paleoecological information from middens and cores as well as anthropogenic indicators directly derived from the archaeological record allows reconstruction of ecosystem dynamics. Two sites in the southcentral Bolivian Andes are studied. Vegetation reconstructions are combined with fecal biomarkers and human demographic reconstructions to assess the ecological legacies of past changes to human-land use. This project helps determine the relationships between climate variability and human activities as well as the resilience of arid lands over the last few thousand years.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.