Warming alters plant phylogenetic and functional community structure

Climate change is known to affect many facets of the Earth's ecosystems. However, little is known about its impacts on phylogenetic and functional properties of ecological communities. Here we studied the responses of plant communities in an alpine grassland on the Tibetan Plateau to environmental warming across taxonomic, phylogenetic and functional levels in a 6‐year multiple‐level warming experiment. While low‐level warming did not alter either plant species richness or phylogenetic/functional community structure, high‐level warming significantly decreased species richness. Higher level warming more strongly reduced soil moisture and caused stronger environmental filtering, consequently changing species composition and community structure. At the plant functional trait level, high‐level warming promoted species turnover through altering the effects of traits such as plant height on species extinction and SLA on species colonization. As a result, high‐, but not low‐level warming drove phylogenetic/functional community structure from overdispersion to randomness, by filtering out species that were functionally dissimilar and distantly related to the resident species. Synthesis. Our study provides evidence that the responses of plant phylogenetic and functional community structure to low warming differ from those in the future scenarios of increasing temperature. Importantly, the extinction of species that was functionally dissimilar and distantly related to the resident species contributed to alterations in plant community structure under high warming. Our study underscores the need to incorporate the phylogenetic and functional perspectives to gain a more complete understanding of community responses to climate warming. 摘要 众所周知, 气候变化影响着地球生态系统的许多方面。然而, 其对生态群落系统发育和功能特性的影响尚不清楚。为此, 我们在青藏高原高寒草地开展了6年的多水平增温实验, 研究了高寒草地植物群落在分类、系统发育和功能水平上对环境变暖的响应。 我们发现, 低水平增温对植物物种丰富度和系统发育/功能群落结构均无影响, 而高水平增温显著降低了物种丰富度。增温幅度越高, 土壤水分减少越强烈, 环境过滤作用越强, 最终导致物种组成和群落结构发生变化。在植物功能性状水平上, 高水平增温通过改变株高对物种灭绝和比叶面积对物种定植等性状的影响, 促进了物种更新。高水平增温, 通过过滤掉与现存物种在功能上不相似或远亲的物种, 驱动系统发育/功能群落结构从过度分散向随机。 我们的研究提供了证据, 表明植物系统发育和功能群落结构对低水平增温的反应不同于未来高水平增温的情景。重要的是, 那些与本地物种功能上不相似且亲缘关系较远的物种的灭绝导致了在高增温条件下植物群落结构的改变。我们的研究强调需要结合系统发育和功能的特性, 以获得对气候变暖下植物群落反应的更全面的理解。 Here we reported on a 6‐year two‐level warming experiment conducted in a Tibetan Plateau alpine grassland, approximately 4,600 m in elevation. We found high warming altered plant phylogenetic and functional community structure by filtering out species that were functio