Multidimensional β-diversity responses to global change: a meta-analysis highlighting divergent effects on plant communities.

In the Anthropocene, global change is reshaping biological communities, potentially leading to widespread biotic homogenization-a worrying erosion of biological distinctiveness. However, the extent to which human activities have homogenized plant communities worldwide remains a pivotal unresolved question. To address this gap, we conduct a global meta-analysis of 1604 experimental and observational comparisons from 256 studies to assess the impacts of major global change drivers on plant β-diversity across its taxonomic, functional, and phylogenetic dimensions. The findings indicate no significant net change in plant β-diversity globally, with responses varying markedly across global change factor types, biogeographic regions, ecosystems, and plant life forms. Specifically, climate change and biological invasions are consistently associated with reduced β-diversity, while land management (e.g., ecological restoration, reduced grazing, and controlled burning) is associated with increased β-diversity. The effects of land-use change (e.g., urbanization, habitat fragmentation, and infrastructure development) and multiple interacting factors are variable. Crucially, impacts differ across biodiversity dimensions. For instance, climate change is associated with reduced taxonomic and functional β-diversity but is associated with increased phylogenetic β-diversity. Our study calls for a shift in conservation focus from solely preventing species extinctions to addressing compositional changes in communities. It emphasizes the importance of functional and phylogenetic processes and the need to integrate all three biodiversity dimensions into monitoring and planning to maintain ecosystem resilience and evolutionary potential.