Global-scale assessment of forest management impacts on biodiversity patterns

Abstract

Integrating biodiversity conservation into forest management has been highlighted as one of the means for halting and reversing the recent biodiversity loss. This integration requires that we understand the mechanistic linkage between anthropogenic disturbances and biodiversity patterns, and it is fundamental for implementing ecological management actions, such as impact mitigation and offsetting by restoration. The empirical evidence on forest management impacts on biodiversity has been accumulated mostly locally, but the response of biodiversity patterns to anthropogenic disturbances remains poorly known. Furthermore, there is no consensus about how diversity patterns of local communities differently shift among forest biomes with different taxonomic composition and regional species pools. Global-scale plot datasets, including both intact and managed forests provides an opportunity to test how vulnerable tree species assembly is to anthropogenic interventions under different biogeographical conditions. To assess disturbance impacts on maintenance of biodiversity across a variety of forest biomes, community phylogenetics, which can disentangle hierarchical species assembly processes from local to global scales, is a promising approach and may contribute to predicting restoration success for each local forest community. Here, we collected plot census data for 1101 plots with 23072 tree species from 293 published papers, and created tree species abundance datasets for individual plots and a phylogeny including all species. Using these datasets, we calculated taxonomic and phylogenetic measures for each plot: taxonomic diversity (Fisher's alpha), evenness (Pielou's E), abundance-weighted net-relatedness index (NRI) and nearest taxon index (NTI). NRI and NTI indicate the degree of species clustering or dispersion relative to a referred phylogeny and represent the influence of abiotic/biotic filtering on species assembly in local communities. Then, we examined disturbance impacts in each biogeographical realm (Neotropic, Afrotropic, Indo-Malay, Australia-Oceania, Nearctic and Palearctic) on the taxonomic/phylogenetic measures using generalized linear mixed model. For the disturbed forests, especially logged forests, the taxonomic diversity and evenness generally showed negative deviation from that of the intact forests. NRI and NTI of disturbed forests showed both positive and negative deviation from that of the intact forests: those were positive in the logged-forests in Australia, Indo-Malay, Neotropic and/or Palearctic, and negative in Africa and Nearctic. Our findings suggests management impacts on potential species assembly processes. Phylogenetic clustering in the logged forests, especially in Indo-Malay and Australia, indicated environmental filtering, which may reflect management-driven species re-assembly associated with similarity of phylogenetic niche among species. Phylogenetic over-dispersion in response to logging disturbances, especial