Palaeoecological background: Neotropics

Abstract

Strong changes of temperature and rainfall effected tropical South America during the last few millions of years; the sequence of the last glacialinterglacial cycle is relatively well known. Humid and cooler climates occurred in the period between >50 000 and approx. 25 000/30 000 B.P. A cold and very dry climate occurred in the period of approx. 21 000-14 000 B.P. Between 13 000 and 10 000 the climate became warmer and more humid, and from 10 000 B.P. to the present, the climate is more like the present, but there are still changes of temperature and especially rainfall. The climatic changes had a profound effect on the vegetation, especially in the mountains, but data from the tropical lowlands are now increasing and show that the effect on lowland vegetation may also have been considerable. Very recent data from Eastern Brasil (Carajas, see postscriptum) indicate that the rainfall in that area was lowered at least 500 mm during several dry phases of the Late Pleistocene, savanna vegetation replacing forest. If this lowering of rainfall was a regional phenomenon, the Amazonian forest may have been split up in at least two large forest areas separated by savanna and/or dry forest.