Multifaceted diversity-area relationships in avian assemblages: insights from naturally fragmented Southern Mistbelt Forests

Traditional species-area relationships (SARs) provide limited insights into biodiversity by focusing solely on species richness. This study examined multifaceted diversity-area relationships (DARs) in naturally fragmented Southern Mistbelt Forests of South Africa, incorporating species richness, functional diversity (FDARs), and phylogenetic diversity (PDARs). We used model averaging to fit multiple models across 32 forest fragments, revealing distinct and non-uniform responses of DARs to fragment area. The SARs showed a positive relationship with area, whereas FDARs and PDARs displayed weak or even negative associations. Community assembly patterns were largely driven by environmental filtering and neutral processes, without evidence of competitive exclusion. These findings emphasise the importance of preserving functional and evolutionary diversity, alongside species richness, to maintain ecosystem function. Conservation strategies must account for diverse biodiversity facets to protect avian communities in naturally fragmented landscapes.