Regrowth of secondary vegetation after the ‘Borneo fire’ of 1982–1983

Abstract

The severe drought in 1982-1983 in south-east Asia caused wildfires in large areas of Borneo (Malingreau et al. 1985, Riswan & Yusuf 1986). In Sabah, Beaman et al. (1985) estimated that about 1 million ha of forest burned. Woods (1989) found that tree mortality after drought and fire was on average 2.5 times greater than that caused by drought alone and that mortality generally was higher in logged forests than in unlogged ones. He reported that the combined effect of drought and fire caused between 38 and 72% mortality in a forest selectively logged two years earlier. For saplings, the mortality on burnt plots exceeded 78% on all sites (Woods 1989). This paper describes the secondary vegetation after the 'Borneo fire' in a lowland rainforest area. Immediately after the fire it was almost devoid of green plants, except for a few surviving large trees which were more or less damaged. The area of 18.7 ha is located at an elevation of 650-750 m asl, c. 35 km south-east of Sipitang (1 150 5' E, 50 0' N) in the south-western part of Sabah. The soil type is an haplic acrisol on a bedrock consisting of mudstones, sandstones and carboniferous shales. The annual rainfall for the years 1985-1990 averaged 3352 mm (Malmer 1992). The vegetation before the Borneo fire was a lowland dipterocarp forest which was lightly selectively logged in 1981. In an adjacent area which was not burnt the number of trees per ha with dbh >20 cm was 145 and the volume 146 m3 ha-' (Sim & Nykvist 1991). The six most abundant families in terms of tree volume were Dipterocarpaceae, Lauraceae, Legumninosae, Sterculiaceae, Myrtaceae and Euphorbiaceae (Sim & Nykvist 1991). The distance between