Results confirm a relatively dry setting during the last glacial (MIS 3 and LGM) in Carajás,Amazonia: A comment on Guimarães et al.

Abstract

Recent pollen rain data from lake Amendoim in Carajás (southeastern Amazonia) revealed a dominant forest formation spectrum where, locally, montane savannas occupy a larger proportion of the lake’s basin (>90%). From this surprising result, we learn that local savanna coverage may not necessarily be enough to influence and dominate the pollen spectrum recorded in the lake sediments when rainforest is widespread in the surrounding areas. Therefore, even a minor proportion of tall forest in a savanna environment can have a significant influence on pollen deposition, masking the savanna signal in the stratigraphic record. Thus, when interpreting the last glacial pollen record of Carajás, the increased abundance of savanna taxa is an unequivocal indicator of local to regional savannas expansion. The postulation of a continued rainforest formation during the glacial times is an unsustainable alternative.