Effects of FELLING GAP proximity on residual tree mortality and growth in a dipterocarp forest in East Kalimantan, Indonesia

The effects of proximity to felling gaps on residual trees in a selectively logged forest were monitored for eight years after nine 4-ha plots (n = 3 per treatment) were subjected to one of two intensities of reduced-impact logging (RIL), i.e. either 50 or 60 cm diameter cutting limits, or conventional logging of 60 cm diameter cutting limit with three additional plots reserved as unlogged controls. Each residual tree 10 cm diameter at breast height (dbh) was classified as either being near ( 20 m from a gap centre) or far ( 20 m) from the nearest felling gap, defined as 20 m radii areas around the stumps of felled trees. Tree mortality rates did not vary with gap proximity, but were higher in logged than unlogged plots for the first two years after logging. In all logged plots combined, trees 50 cm dbh of all species and dipterocarps 30 cm dbh grew faster if they were near a gap. The observed increased growth rates of trees in the more intensively logged plots, regardless of the logging method used, was due to both higher proportions of trees near gaps and faster growth of trees in all locations.