Anthropogenic Factors Dominate Taxonomic Diversity of Urban Street Trees While Climate Drives Phylogenetic Diversity

Urbanization profoundly alters ecosystems, yet urban areas, home to more than half the world’s population, also support a wide range of biodiversity. Urban street trees, a crucial component of urban green space, are among the most frequently encountered green infrastructure in city environments for urban residents. Despite their vast range of benefits to urban quality of life, the taxonomic diversity and phylogenetic diversity patterns at the regional scale, and the underlying drivers, remain insufficiently understood. To address this, we explore and map geographic patterns of taxonomic and phylogenetic diversity of street trees across 116 county-level cities of Yunnan province and further analyze the factors influencing these patterns. Urban street trees comprise 180 species (119 genera, 47 families), with distribution highly uneven (81 species occurring only once and 30 species in over 10 cities). We found that climatic and anthropogenic (i.e., socio-economic and urbanization metrics) factors jointly influenced taxonomic and phylogenetic diversity, with anthropogenic factors primarily driving taxonomic diversity and climatic factors dominating phylogenetic diversity. Although urban expansion can introduce more species, the phylogenetic structure of street trees is still shaped by climate. Enhancing diversity requires introducing climate-resilient species that can adapt to current and future environmental stresses.