Past Vegetation Changes in the Context of Land use and Late Holocene Expansion of the Jê Pre-Columbian Cultures in Southern Brazil

Palaeoecological research can provide important insights into the impacts of humans vs climate change upon ecosystems in the past, which can inform land-use and conservation planning. Our international project aims to reveal past dynamics of the iconic Araucaria forest in the context of land use by the pre-Columbian Jê culture in southern Brazil over the last c. 2000 years. Our palaeoecological research is based on three bog cores collected within archaeological sites representing different land uses associated with the mixed-economy Jê culture. We use modern and fossil pollen, charcoal, isotopes and geochemical analysis of the sediments to reconstruct vegetation, fire, land-use histories, as well as past agricultural practices at the sites. We also integrate this information with local archaeological and independent palaeoclimatic data to understand the relationship with climate change. Our results show varied vegetation development within the same region that seems to be related to the type of land-use. For example, we find that Araucaria forest expansion occurred at habitation sites but not at funerary sites. Where we do observe Araucaria forest expansion, it was less pronounced than the previously recorded, interpreted as climate-driven, regional-scale Araucaria expansion ca. 2000 yr BP. Our study therefore suggests that pre-Columbian human land-use had significant and diverse impacts on Araucaria forest at the local scale – through ritual practices, habitation and agriculture – nested within a long-term, regional scale trend of Araucaria expansion. This expansion of the forest correlates in part to the increasing rainfall, as revealed by comparison with previously published speleothem data. This case study reveals complex human-vegetation-climate dynamics, and provides key information about baseline ecological conditions relevant for conservation policy and land-use planning.