Effects of land-use change on avian taxonomic, functional and phylogenetic diversity in a tropical montane rainforest

Aim: Although land-use change is a leading cause of biodiversity loss worldwide, there is scant information on the extent to which it has affected the structure and composition of bird communities in the Afrotropical region. This study aimed to quantify the effects of habitat transformation on taxonomic, functional, and phylogenetic diversity in Afrotropical bird communities. Location: Nyungwe landscape, a montane rainforest with adjoining farmland in south-west Rwanda. Methods: Data on bird occurrence, abundance, and functional traits were collected in 2017/18 using point-counts. We also collected data on habitat and morphological traits for all bird species recorded. We quantified bird diversity using a range of metrics, including the Inverse Simpson index, functional dispersion and the standardized effect size of mean nearest taxon distance. Results: In comparison to primary forest areas, even low levels of land-use change altered species composition, and reduced species diversity. Although overall functional and phylogenetic diversity were similar across land-use types, we found a significant contraction of trophic and locomotory trait structures of bird communities in restored areas and cultivated areas, respectively. Soil moisture, elevation, and lower vegetation height were major factors influencing taxonomic, functional and phylogenetic dimensions of bird communities, although their effects varied across these dimensions. Main conclusions: The sensitivity of forest species to minor habitat disturbance emphasises the value of conserving primary vegetation. Long-term conservation of bird communities in Afromontane ecosystems requires halting wide-scale destruction of primary forest, promoting vegetation heterogeneity in the ecological restoration of degraded habitats, and adopting wildlife-friendly agricultural practices. Our results suggest that monitoring and conservation in these landscapes can be refined using taxonomic, functional and phylogenetic diversity metrics to provide complementary information about the current and likely future impacts of land-use change.