Late Pleistocene glacial forest elements of Brazilian Amazonia.

Pollen data recovered from the sedimentary record of western Amazonia is still inadequate to fully address climate changes over the Last Glaciation in this region. The present work focuses vegetation dynamics from an area of southwestern Amazonia during the past 42,000 cal yr B.P. based on the integration of previous and new pollen data. Sediment cores were sampled from two sites covered by tropical rainforest in fluvial terraces of the Madeira River, a major southern Amazonian tributary. The results indicated a significant proportion of cold-adapted Andean tree species, represented by Alnus (0–20%), Hedyosmum (1–15%), Podocarpus (0–5%), Illex (1–11%) and Weinmannia (0–1%) at least between > 43,163–42,018 cal yr B.P. and 10,394–10,240 cal yr B.P. During the Holocene, only pollen representative of herbs and modern Amazonian vegetation persisted. The new pollen record confirmed previous documented results that vegetation communities presently restricted to Andean areas at altitudes higher than 2000–3000 m, occupied this region of the Amazonian lowlands close to the onset and probably also during the Last Glacial Maximum. [ABSTRACT FROM AUTHOR]