Hydroclimate and vegetation changes in southeastern Amazonia over the past ∼25,000 years

Stable isotope analysis of plant waxes (delta C-13(wax) and delta D-wax) along with detailed pollen data provide a new perspective on vegetation and precipitation variability in Serra Sul de Carajas, southeastern (SE) Amazonia, over the past similar to 25 cal kyr BP. The delta D-wax record indicates drier conditions during the Last Glacial Maximum (LGM) and a transition to wetter conditions into the Holocene, while the delta C-13(wax) data reveal that vegetation did not experienced C-3/C-4 shifts and remained dominated by C-3-plant communities. Under glacial conditions C-3-savanna was prominent on the Serra Sul plateau with tropical forest areas limited to the lower slopes. Tropical forests expanded upslope and forest patches developed on the plateau as a response to more humid and warmer conditions during the Holocene. Pollen data indicate a shift towards more open landscape of savanna, woodlands, and open forests during the mid-Holocene. The delta D-wax record exhibits a distinct moisture variability during the Holocene, not always coherent with the vegetation data (pollen), especially during the mid-Holocene interval. Our study confirms the complexity and the overall lack of coherence among Holocene moisture proxy records throughout the monsoon domain in South America and suggest that Holocene local moisture conditions might not follow the regional monsoonal variability. Our data further stress the need for more multi-proxy reconstructions of hydroclimate patterns in SE Amazonia. (C) 2022 Elsevier Ltd. All rights reserved.