STRUCTURE, COMPOSITION AND COMMERCIAL CHARACTERISTICS OF A PRIMARY DIPTEROCARP FOREST IN SABAH, MALAYSIA

Abstract

A primary dipterocarp forest in Sabah, Malaysia, dominated by steep and
broken terrain, was systematically sampled. A total of 88 clusters of four circular plots each (radius 10 m) were censussed for trees > 10 cm dbh, climbers > 2 cm dbh, and inclination over an area of approximately 600 ha. There was an average of about 400 stems ha^-1 of which dipterocarps accounted for 27%. Red seraya was the most common dipterocarp group. Mean basal area was 28.4 m2 ha^-1 (dipterocarps 56%), and mean volume 399 m³ ha^-1 (dipterocarps 62%). Diameter distribution was negatively exponential. Of dipterocarps, 23% were of poor quality, as were 58% of the nondipterocarps. There were 192 climbers ha^-1 > 2 cm dbh. One or more climbers were found on about 25% of the trees. Trees > 10 cm dbh were significantly aggregated but approached a random distribution with increasing dbh. Dipterocarps > 60 cm had a significantly uniform distribution. Stocking in general compares favourably to other parts of the region. Based on structure and composition data, diameter limit felling is cautioned against in favour of more elaborate selection systems.