Effect of skidder disturbance on commercial tree regeneration in logging gaps in a Bolivian tropical forest

The impact of skidder disturbance on recruitment of commercial tree regeneration within logging gaps was studied using paired scarified and unscarified plots as well as whole-gap surveys of scarified and unscarified areas in a Bolivian tropical humid forest. More than a year following gap creation, variability in the density of regeneration among logging gaps was high, but commercial tree regeneration density tended to be greater in scarified areas than in unscarified areas within gaps for most species. Height growth was also significantly greater for trees in scarified compared to unscarified areas, despite a near doubling of soil compaction in scarified areas. The principal species benefiting from soil disturbance by skidders was Schizolobium amazonicum, which had nearly 10x higher density and 2x greater height growth in scarified compared to unscarified areas. Although initially devoid of vegetation and litter cover, scarified areas had vegetation and litter cover levels similar to unscarified areas after 7 months. Vegetation cover on scarified areas tended to be dominated by early successional tree species while unscarified areas were dominated by forbs and grasses. (C) 2002 Elsevier Science B.V. All rights reserved.