Soil disturbance and post-logging forest recovery on bulldozer paths in Sabah, Malaysia

We examined the extent of soil disturbance associated with bulldozer yardin g and the regrowth of woody vegetation on bulldozer paths (skid trails) in selectively logged dipterocarp forest. In an area logged in 1993, using con ventional, i.e., uncontrolled, harvesting methods, about 17% of the area wa s covered by roads and skid trails. In contrast, in a 450-ha experimental a rea where reduced-impact logging guidelines were implemented, 6% of the are a was similarly disturbed. Skid trails in the reduced-impact logging areas were less severely disturbed than those in conventional logging areas; the proportion of skid trails with subsoil disturbance was less than half that in conventional logging areas. Four years after logging, woody plant recove ry on skid trails was greater in areas logged by reduced-impact than by con ventional methods. Skid trails where topsoil had been bladed off had less w oody vegetation than skid trails with intact topsoil. In a chronosequence o f logging areas (3, 6, and 18 years after logging), species richness and st em densities of woody plants (>1 m tall, <5 cm dbh) were lower on skid trai l tracks than on skid trail edges or in adjacent forest. Both richness and density increased with time since logging, but even 18 years after logging, abandoned skid trails were impoverished in small woody stems compared with adjacent forest. Minimizing soil and stand disturbance during logging appe ars to allow a more rapid recovery of vegetation on bulldozed soils, but th e long-term fate of trees growing on compacted soils remains uncertain. (C) 2000 Elsevier Science B.V. All rights reserved.