Vegetation and climate of the Last Glacial Maximum in Sulawesi

Lake Towuti, a large lowland tectonic lake situated within the Indo-Pacific Warm Pool, is perfectly situated to evaluate how large-scale changes in climate have manifested themselves in the Asian tropics. High-resolution geochemical data serving as proxies of surface runoff and vegetation for the last 60,000 years suggest that the Last Glacial Maximum (LGM) was extremely dry, bracketed by the much wetter conditions of marine isotope stage 3 (MIS3) and the Holocene. Existing pollen-based records for Sulawesi also suggest that the LGM was drier than present; however, these records are short and discontinuous over this time period. A pollen record, still being refined for Lake Towuti, also shows a sudden and profound response in the vegetation over the LGM period; however, the expected increase in grassland, in line with the enriched δ13C of terrestrial leaf wax in the geochemistry record, is not apparent. Instead, there is a loss of high-altitude taxa and the expansion of several lowland dicots that remain taxonomically unresolved. An expanded research program under the auspices of Towuti Drilling Program has begun to improve our insight and understanding of this globally important region, enabling a better assessment of the potential threats that projected climate change and human activities pose for one of the most diverse rainforest ecosystems on Earth. While numerous questions of fine detail remain concerning LGM climate and its impact on these tropical forests, in the context of this monograph, palaeoenvironmental research, and in particular the palaeovegetation record, provides an important environmental backdrop to trajectories of human occupation in Sulawesi and the subsequent cultural changes and interactions that took place across the region