Impact of Climate Change on the Multiple Facets of Forest Bird Diversity in a Biodiversity Hotspot Within the Atlantic Forest

Abstract

Aim: Climate change is driving species to either shift their ranges or face extinction. While its effects on taxonomic diversity (TD) are relatively well understood, the impacts on functional diversity (FD) and phylogenetic diversity (PD) remain less explored. Among the biological metrics considered in protected area (PA) selection, TD is the most common, yet its effectiveness in also capturing high FD and PD under future climate scenarios is uncertain. Here, we assess the implications of future climate scenarios for the conservation of TD, FD and PD of forest birds. Location: Central Corridor of the Atlantic Forest (CCAF), Brazil. Methods: We used ecological niche models to project the species distributions of 292 forest birds for baseline and future (2050 and 2070) scenarios. We generated binary maps of suitable areas for each species and calculated alpha and beta diversities for TD, FD and PD. We also evaluated spatial overlaps between highly diverse areas and the current PA network. Results: Most species are projected to experience range contractions, leading to declines in TD, FD, and PD. The western CCAF, a subregion with low diversity, is expected to face the greatest losses, while coastal areas show greater resilience with fewer declines. FD and PD exhibit distinct spatial patterns, including functional type replacements in the northwestern CCAF and variations in phylogenetic lineages in the central-eastern subregion. Northeastern PAs may retain higher diversity in the future, while the southern CCAF remains underrepresented in the current PA network. The eastern CCAF is identified as a subregion of community stability across TD, FD and PD. Main Conclusions: Incorporating multiple facets of diversity offers a comprehensive framework for conservation strategies. Beta diversity highlights critical stable areas connecting highly diverse subregions of the CCAF. Therefore, a better understanding of these patterns can guide the preservation of species, their ecological roles and evolutionary heritage in a changing world.