在过去的50年里，青藏高原经历了普遍而明显的变暖趋势，而且高海拔的变暖程度更强。目前，全球变暖对青藏高原高寒草地生态系统影响的研究取得了较大进展，但是这些研究大多是在单一地点开展的，因而无法解决不同生态系统对全球变暖响应差异的问题。本申请项目利用在青海海北高寒草甸已建立的高、中、低3个海拔的增温控制实验，试图回答（1）增温是如何影响群落多样性和生态系统功能的？（2）不同海拔生态系统对增温的影响是否具有显著的差异？为此，设计的研究内容为：增温对高寒草甸群落多样性（物种、功能和谱系多样性）和生态系统功能（生产力、氮循环和凋落物分解）的影响，探讨增温是如何通过改变种间关系（竞争和互惠）与养分的可利用性而影响生态系统功能的。通过这些研究，揭示增温是如何改变高寒草甸群落多样性和功能的，理解不同海拔高寒草甸生态系统响应增温的差异，为未来全球变暖背景下青藏高寒草地的可持续发展提供管理依据。

In the past 50 years, the Tibetan Plateau has experienced a universal and significant warming, and the warming is more prominent at higher elevations. A great progress has been made on the effects of global warming on alpine grassland’s ecosystem on the Tibetan Plateau, however, most of these studies were carried out only in one single site, and could not figure out the issue about the difference in the sensitivity of different ecosystems in response to global warming. In the current project, using the manipulative warming experiments on high-, mid- and low-elevation which had been built in alpine meadow in Haibei, Qinghai province, we attempt to address two issue: (1) how does warming influence community diversity and ecosystem functioning? (2) Is there an apparent difference of ecosystems across different elevations in response to warming? For this purpose, we will focus on the following issues: (1) the impact of warming on community diversity (i.e. species, functional and phylogenetic diversity) and ecosystem functioning (i.e. production, nitrogen cycling and litter decomposition) in alpine meadow; (2) how warming influence ecosystem functioning directly, and indirectly through shifting plant-plant interactions (competition vs. facilitation) and soil nutrient availability. Results from the current project will improve our understanding of how alpine grassland's ecosystem on the Tibetan Plateau would shift under future global warming.