三江源区高寒草地生态环境脆弱、对气候变化敏感、生态作用重要。高寒草地的碳库作用及在区域碳收支平衡中占有重要地位。在环境因素和人为扰动共同作用下，高寒草地退化广泛且严峻，草地植物功能群结构及功能发生变异，引起土壤碳汇变化，破坏了高寒草地碳的收支平衡甚至反馈到陆地生态系统的碳平衡。因此，以具有一定科研基础的青海三江源核心区高寒草地为研究区，通过野外观测、室内测定等，分析和阐明高寒草地不同退化演替阶段植物功能群数量特征和生态功能特征的时空变异规律以及土壤碳汇对其的响应机制，对于回答在未来气候变化背景下，高寒草地退化演替导致植物功能群结构和功能发生怎样的时空变异，植物功能群碳输入输出机制发生怎样的改变，进而对土壤碳汇产生怎样的影响，土壤碳收支发生转变时对应的植物功能群结构与功能阈值等关键科学问题具有重要科学意义，也为高寒退化草地植被恢复与重建、减轻高寒草地温室气体排放提供科学依据。

Alpine grassland in the Yellow River, Yangtze River and Lancangjiang River, Qinghai Province, China ecological environment is fragile, sensitive to climate change and ecological function is important. Alpine grassland carbon pool function and regional carbon balance have important position. Under the effect of environmental factors and human disturbance, alpine grassland degeneration was extensive and serious, and structure and function of Grassland plant functional groups changed, and caused the soil carbon sink changed. Alpine grassland carbon balance destroyed even feedback to the terrestrial ecosystem carbon balance. Therefore, in this study, alpine grasslands in source area of three major rivers of China were selected as research area because they have certain scientific research foundation. Through field observation and indoor measurement, analyze and illustrate plant functional groups quantitative and functional characteristics of spatial and temporal variation pattern in the alpine grassland different degradation succession stages and soil carbon pool to its response mechanism. They have important scientific significance to answer some questions under the background of climate change in the future. For example, what kind of spatial and temporal variation will happen that alpine grassland degradation succession leads to plant functional groups structure and function, what change that carbon input and output mechanism of plant functional groups, and then what kind of impact on soil carbon sink, soil carbon input and output changing correspond to structure and function threshold of plant functional groups. Also for alpine grassland vegetation restoration and reconstruction, reducing greenhouse gas emissions to provide scientific basis.