Impacts of selective logging on spatial structure of tree species composition in Bornean tropical rain forests

Abstract

ABSTRACT We studied the impacts of selective logging on the spatial structure of tree species composition in the tropical rain forest of Sabah, Malaysia. We established 50 20-m radius plots (0.12 ha in area) across primary to highly degraded forests in each of two logging concessions with distances in between any two plots ranging from 0.2 to 40 km. In addition, we established one 100 × 200-m plot in each of primary, reduced-impact logged, and conventionally logged forest in other two logging concessions, and each plot was divided into 40 × 30-m quadrats (0.12 ha in area) for the further analysis of the spatial structure at the scale of less than 200 m. A decline of species-compositional similarity with increasing in-between distance was found in primary and moderately logged forest at both larger and smaller than 0.2-km scale. Such a spatial structure could not be detected in heavily logged forests at both scales. The heavily logged forests were rather characterized by mosaics of remnant stands and regenerating patches of pioneer species, leading to a high spatial variance of species composition without the distance-dependent spatial structure. Accordingly, high-impact conventional logging damages the distance-dependent spatial structure of species composition in canopy tree communities by creating random vegetation patches, while reduced-impact logging can maintain the spatial structure.