Tropical rainforests, despite their locations, can suffer from drought, and during severe droughts, a rainforest can even become susceptible to fire. Evidence of past forest fires, in the form of charcoal deposits, can be found in many parts of the humid tropics, but there has been little documentation of the effects of such catastrophic disturbances on the ecology of tree species.
Van Nieuwstadt and Sheil have examined the effects of drought and fire in a lowland rainforest in East Kalimantan, Indonesia, by censusing live and dead trees in adjacent burned and unburned areas. The drought of 1997-1998, one of the most severe ever in a tropical rainforest, was followed by fire. The consequences of the drought were more pronounced in the larger, mature trees: Nearly half of the trees with trunk diameter >80 cm were lost, whereas less than one-quarter of trees <20 cm in diameter died. In contrast, fire killed smaller saplings disproportionately: Almost no individuals <10 cm in diameter survived. Some species (particularly dipterocarp and palm) withstood fire better than others. In sum, drought and fire both reduce biomass, alter patterns of forest dynamics by removing reproductive individuals and regenerating saplings, and change the relative abundances of species, but do so in different ways. -- AMS
J. Ecol. 93, 191 (2005).
