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The fate of Amazonia’s tropical evergreen rainforests over the 21st century, under different climate change scenarios, is a topic of widespread scientific debate and global concern (Betts et al. 2008). Most climate models simulate increased drought and reduced available moisture for Amazonia over this century, but the magnitude of drought, and the ability of the rainforest biome to withstand and accommodate such drought, is uncertain (Malhi et al. 2008). One might predict that evergreen rainforest species would be most susceptible to increased drought at ecotones (Fig. 1) towards the highly seasonal margins of the Amazon basin, where they are under greatest moisture stress. An understanding of the response of rainforest ecotones to past climate change may help inform understanding of their likely response to different climate change scenarios for the future. Given the vast geographic area encompassed by Amazonia’s rainforest biome, stretching from~ 3 N to 14 S, and across the breadth of the South American continent, one would not expect that the magnitude, or even direction, of climate change would be uniform across the basin, especially with respect to the seasonal distribution of rainfall. It is therefore unlikely that the spatio-temporal pattern of ecotonal rainforest dynamics in one part of Amazonia will be representative of ecotones across the basin as a whole.

In this review paper, the aim is to compare and contrast fossil pollen evidence for Holocene rainforest ecotonal dynamics at opposite ends of the Amazon basin–the southern ecotone in NE lowland Bolivia versus the northern ecotone in lowland Colombia. During the Holocene …