Vegetation–Climate–Megafauna Interactions During the Late Glacial in Pilauco Site, Northwestern Patagonia

Abstract

We present a vegetation reconstruction based on high-resolution analysis of two pollen, seeds, and charcoal records between ∼16,000 and 12,800 cal yr BP. Pollen records show the dominance of non-arboreal and aquatic pollen types, mainly Poaceae, Asteraceae, Cyperaceae, and Sagittaria. At ∼16,000 cal yr, BP recorded high percentages of the aquatic fern Isoetes sp., characteristic of shallow and oligotrophic water. The arboreal component of the pollen assemblages is represented by north Patagonian taxa. Pollen and seeds of Prumnopitys andina are recorded between ∼14,000 and 12,800 cal yr BP, representing mild summers and very cold winters. Among the non-arboreal assemblage, taxa like Gunnera, Acaena, and Amaranthaceae could indicate some seasonality in water availability. A second detailed record was made only below and above of an erosional unconformity dated on ∼12,800 cal yr BP. The sediments on top of the unconformity show the decline of pollen concentration, extremely high fire activity, and elevated sedimentation rates, probably related to intense colluvial erosion/transport. The high abundance of pioneer species and open-forest taxa during the complete record is not comparable to other pollen records from the region and can be interpreted as a high disturbance regime induced by megafauna and human activities.