Vegetation and environmental changes in tropical South America from the last glacial to the Holocene documented by multiple cave sediment proxies

Abstract δ 18 O values in speleothems have been utilized to document past changes in South American monsoon intensity. However, changes in regional vegetation and ecosystems have not been part of this discussion, and other cave proxies such as speleothem δ 13 C values, a useful proxy for vegetation reconstruction, have been neglected due to interpretive complexities. Here we report δ 13 C values and 87Sr/86Sr ratios in stalagmites, together with XRF-derived elemental chemistry, δ 13 Corg values and carbon content from a sedimentary profile from the same cave where the stalagmites were collected. In combination with a previously published δ 18 O record, this enables us to clarify climate and environmental shifts that occurred between the Last Glacial Maximum and the Holocene in central South America. We show that vegetation was sparse during the last glacial period in spite of a previously inferred strong monsoon, and that changes in atmospheric pCO2 combined with local hydrological and temperature feedbacks may have determined vegetation development during this time.