Past vegetation reconstruction maps and paleoclimatic variability inferred by pollen records in southern Patagonia Argentina since the Late Glacial-Holocene transition

Abstract

Palaeoecological reconstructions document past vegetation distribution with estimates of the communities boundaries shifts. This work presents a compilation of palaeoecological studies from southern Patagonia Argentina as a contribution to a better understanding of the composition and distribution of Andean and extra-Andean plant communities. Paleoenvironmental reconstructions are based on pollen sequences from different types of deposits located in the forest, forest-steppe ecotone and steppes between 46° and 51°S. The comprehension of modern pollen and its relation with the actual vegetation is a critical component of palaeoecological research. Models of the current relationship pollen-vegetation-climate were applied to interpret these sequences. Their integration made it possible to reconstruct the spatio-temporal patterns of vegetation and past climatic changes since the Late Glacial-Holocene transition. Four areas were selected to map past vegetation communities; three lake basins: Pueyrredón, San Martín and Argentino, and the Deseado Massif. The local conditions given by the geomorphology of each site were also taken into account. The vegetation reconstruction during the Pleistocene-Holocene transition came from records located in the Deseado Massif only, and indicated steppes, without modern analogues, linked to arid and cold conditions. During the Holocene, plant communities were sensitive to moisture conditions related to westerly winds or Atlantic-derived precipitation events. Taxa related to the anthropogenic impact of the past centuries were found at all sites, both in Andean and extra-Andean Patagonia.