Impacts of selective logging on avian phylogenetic and functional diversity in the Amazon

Selective logging is the most extensive land use threatening tropical forests worldwide, making our understanding of its impacts on biodiversity vital for the conservation of these hyperdiverse ecosystems. We investigated the effects of selective logging on the phylogenetic and functional diversity (FD) of Amazonian forest avifauna. We sampled the overall and the understorey bird community using point counts and mist-netting, respectively, in logged and unlogged forests. The overall bird community showed significantly lower phylogenetic diversity (PD) and FD in logged than unlogged forests, but significantly higher standard effect size (ses) of PD, ses mean pairwise distance (MPD), mean nearest taxon distance (MNTD), ses functional MPD (sesfMPD) and functional MNTD (fMNTD) in logged sites. Evolutionary distinctiveness, sesMPD, sesFD, fMNTD and sesfMNTD of understorey birds were significantly higher in logged forests. Higher logging intensity affected some metrics negatively and others positively, although the relatively small changes in phylogenetic and FD suggest limited overall effects from logging at lower intensity. In combination, selective logging brings deleterious effects for some components of phylogenetic and FD of the overall Amazonian bird community. Nonetheless, selectively logged forests retain important avian diversity, underscoring their high conservation value. Relatively, low impacts of selective logging may be due to the reduced-impact logging (RIL) techniques used, high connectivity with well-preserved unlogged forests or focus on short-term logging impacts. Because even low-intensity RIL causes some losses in evolutionary history and functional traits, an optimal approach for conserving phylogenetic and FD requires incorporating some land-sparing logging to protect more old-growth patches within the logged matrix.