Effects of Fires on Peat Swamp and Lowland Dipterocarp Forests in Kalimantan, Indonesia

The effects of the fires that burned over 4.7 million ha of Indonesia’s tropical forests during 1997 and 1998 are largely unknown. We assess the immediate impacts of these fires on five forest areas representing several different habitats in Kalimantan 1-2 months after the fires went out. Comparisons of transects in burned and unburned forest areas were conducted at three sites: Tanjung Puting National Park, Kutai National Park, and Sungai Wain Nature Reserve. In general, burned forests had reduced canopy and ground cover, lower tree species richness and diversity, and higher canopy tree, seedling, and sapling mortality than unburned forests. Species richness in peat swamp forests at Tanjung Puting was reduced by 59% by the fires, and in two lowland dipterocarp forests by 24% (Sungai Wain) and 57% (Kutai). Resurveying of transects at Tanjung Puting 8 months after the first survey showed that burned forests suffer higher tree mortality and further species loss in the months following fires. In addition, species richness was lower in forests that had been logged prior to burning than in forests that had been undisturbed before the fires. The long-term ecological effects of burning on forest diversity, structure, and species composition are discussed, and the conservation implications of the high fire hazard in Indonesia are considered.