Biomass burning in Indonesia and Papua New Guinea: natural and human induced fire events in the fossil record

Microscopic charcoal preserved in sediments from ten wetlands in the Indone sian and Papua New Guinea region provide a proxy record of regional fire ev ents during the last 20,000 years. Two periods of high regional charcoal fr equency are encountered during the last glacial transition (17,000-9000 yea rs B.P.) and the middle to late Holocene (5000 years B.P. to the present). Despite the presence of humans in the region throughout the last 20,000 yea rs, there is no suggestion that, on a regional spatial scale, fire frequenc ies were solely related to changing subsistence patterns of the human popul ation. Pollen data from these same sites suggest that during times of high charcoal the rate at which vegetation changes, represented by the fossil po llen spectra, also increases. High climate variability may promote a greate r community turnover rate and in turn a more fire susceptible forest commun ity. Rapid climate change and high variability during the last glacial tran sition and intensification of El Nino-related climate variability during th e middle to late Holocene, may have been important mechanisms for promoting fire in rainforest environments and maintaining diversity of tropical rain forests. (C) 2001 Elsevier Science B.V. All rights reserved.