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.<b> </b>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 patters at regional scale, and the underlying drivers, remains 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 analysis the factors influencing these patterns. Urban street trees comprise 180 species (119 genera, 47 families), with distribution highly uneven (81 species appeared only once and 30 species in over 10 cities). We found that climate and anthropogenic factors jointly influenced taxonomic and phylogenetic diversity, with anthropogenic factors primarily driving taxonomic diversity and climate 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.

城市化进程深刻改变着生态系统，而占全球人口半数以上的城市区域，同时也维系着丰富多样的生物多样性。城市行道树作为城市绿地的核心组成部分，是城市居民日常接触最为频繁的城市绿色基础设施之一。尽管城市行道树对提升城市生活品质有着诸多裨益，但目前学界对区域尺度下其分类多样性与系统发育多样性的分布格局，以及背后的驱动机制仍缺乏足够认知。为此，本研究针对云南省116个县级市的行道树分类与系统发育多样性的地理分布格局展开探究与制图，并进一步解析影响该格局的相关因素。本次研究涉及的城市行道树共计180种（隶属于119属、47科），其分布极不均衡：81个物种仅在1个城市出现，另有30个物种分布于10个以上的城市。研究发现，气候与人为因素共同作用于行道树的分类与系统发育多样性：人为因素主要驱动分类多样性格局，而气候因素则主导系统发育多样性格局。尽管城市扩张可引入更多物种，但行道树的系统发育结构仍受气候因素塑造。若要提升行道树多样性，需引入能够适应当前及未来环境压力的气候适配性物种。