Environmental heterogeneity and dispersal processes influence post-logging seedling establishment in a Chiquitano dry tropical forest

摘要

Selective logging is becoming more and more influential in forest use in the tropics, especially as it provides local communities and regions with timber resources. Logging greatly alters abiotic and biotic factors which are fundamental in seedling establishment and spatial heterogeneity of tree recruitment. Niche and dispersal processes may affect post-logging seedling establishment, particularly in water-constrained tropical dry forests (TDF). To understand how selective logging affects tree recruitment and how forest exploitation can become a sustainable practice, a theoretical framework has been set up based on these processes. We assessed post-logging seedling establishment in a Bolivian Chiquitano TDF by: (i) characterizing logging microsites and the variability in abiotic (canopy openness, soil compaction and soil water content) and biotic (short and long-distance dispersal) factors among them, (ii) evaluating the roles played by those factors, here considered surrogates of niche and dispersal processes, on seedling establishment, and (iii) providing guidelines to ensure tree regeneration in similar logged TDFs. One year after logging, seedling establishment of five canopy tree species was assessed in four microsite types created by selective logging and in undisturbed TDF. Dispersal processes were described by interpolated kernel estimates of abundance of adult trees, i.e. potential seed sources. After logging, the abiotic environment was considerably altered, especially in the most disturbed logging microsites, leading to significant changes in canopy openness and soil compaction, the most important factors determining seedling establishment in four out of the five studied species. Dispersal processes also influenced regeneration in three tree species. Since the spatial distribution of adult trees influences post-logging regeneration, this should be considered to improve sustainability in logging operations across the tropics. (C) 2015 Elsevier B.V. All rights reserved.