Phylofloristic regionalization of woody plants in East Asia and the drivers of phylogenetic structure

East Asia is characterized by a rich flora with many relictual and endemic plant taxa. However, the floristic subdivision of East Asia remains debated due to differences in data sources, methodological approaches, and spatial scales, among other reasons. Furthermore, the roles of environmental factors and evolutionary history in shaping its diversity patterns are still poorly understood. Compared with traditional regionalization which is mainly based on taxonomic composition, modern phylogenetic regionalization relies on molecular phylogeny to provide a more explicit and quantitative evolutionary perspective on floristic differentiation. Woody plants are considered as the ideal indicators for identifying stable floristic boundaries and large-scale biogeographic patterns because they have long life spans, resilient ecological stability, and well-preserved phylogenetic signals. In this study, we have integrated distribution and phylogenetic data of 1161 woody plant genera across East Asia (covering ∼88% of woody genera in East Asia) and quantitatively delineated regional floras using phylogenetic dissimilarity approaches. The result show that East Asia can be subdivided into seven major floristic subregions of woody plants. Our environmental analyses suggest that phylogenetic diversity (PD) exhibits the strongest correlation with environmental variables among the five phylogenetic metrics, and that the current climate is the leading driver of phylogenetic structure. In contrast to the metrics of deep evolutionary history (MPD and MPDses), the indicators of shallow lineage divergence (PD and PDses) display a more pronounced response to environmental factors. Our results highlight how contemporary environmental drivers and historical evolutionary processes jointly shape the diversity patterns of East Asian woody plants, offering new insights into the mechanisms underlying the formation of regional biogeographic patterns, and also laying a solid foundation for biodiversity conservation in East Asia. • We conducted a phylogenetic regionalization of woody flora in East Asia, and identified seven floristic subregions. • The phylogenetic diversity of the woody flora in East Asia shows the strongest environmental associations, with current climate being the main driver. • The influence of environmental factors on phylogenetic structure varies markedly among subregions, reflecting substantial spatial heterogeneity.