ABSTRACT
The three major tropical regions have contrasting histories of Holocene climate change. Each region reveals a complex interaction of climatic, environmental and cultural change that prompted modern land use and biogeographic patterns. The onset of the Holocene was marked by some changes of global scale, e.g. rising atmospheric CO2 concentrations, temperatures and sea-levels, whereas other factors were essentially local, e.g. precipitation, edaphic development and competition. Despite the profound environmental changes associated with the Pleistocene–Holocene transition, in general, lowland tropical forest communities formed modern communities earlier than their temperate forest counterparts. Following the initial warming of the Holocene, temperatures were fairly constant. Consequently, the largest Holocene climatic variables in the lowland tropics were the amount and seasonality of precipitation. Through much of the Holocene the El Niño Southern Oscillation (ENSO) strongly influenced precipitation in the neotropics and Asia. In Africa, orbitally-driven variability in insolation may have outweighed the influence of ENSO. Africa is also different from the other areas as it is the driest of the continents and is the only one to exhibit major biome range changes in the last 11,000 years. In the neotropics, local movement of ecotonal boundaries rather than broad biome change was the norm. In Southeast Asia, Holocene relaxation of island communities isolated by rising sea-level has probably been ecologically more significant than the direct consequences of climate change. The impact of human activities on tropical systems spans the entire Holocene in all the tropical continents. Land clearance with fire, proto-agriculture and hunting, all exerted an influence on systems. The development of larger societies both increased the rate of land disturbance and rendered those societies more susceptible to climate change. Increasing evidence points to a linkage between cultural turnover and periods of extended drought.
