Regeneration of timber species following selection logging in a Bolivian tropical dry forest

The establishment of commercial tree regeneration is currently a focus for concern regarding the sustainability of logging in the tropical forests of Bolivia. This study compared the density, species composition, and growth o f sawtimber species seedling and sapling regeneration 14 months following s election logging. Areas sampled included logging gaps, logging roads, skid trails, and log landings. Areas not disturbed by logging were also sampled as controls. The abundance and composition of competing vegetation in tree regeneration plots was also measured. The highest density and greatest init ial height growth rates of tree regeneration were observed on areas with th e greatest amount of soil disturbance, including log landings and logging r oads. This trend was largely due to the higher densities of two common, lig ht-seeded, shade-intolerant species, Anadenanthera colubrina and Astronium urundeuva. Despite having higher light availability than other sites, tree regeneration of all species was poor in logging gaps. Logging gaps were qui ckly colonized by competing vegetation, particularly lianas, where they had a percent cover 2.5 times that in undisturbed sites. Regeneration of some commercial species in these forests appears to respond more favorably to di sturbances that exceed those provided by single tree selection logging. Des pite the better initial establishment and growth of a few species on areas with soil disturbance caused by logging, the lack of regeneration of other commercial tree species and the increasing colonization of all sites by com peting plants indicate the need for post-harvest competition control treatm ents to ensure vigorous commercial species regeneration that will contribut e to the sustainable management of this forest. (C) 2000 Elsevier Science B .V. All rights reserved.