青藏高原典型生态系统碳氮水循环过程及其气候效应

青藏高原海拔高、面积辽阔，其独特的地理地形特征对区域环境和气候变化具有极为重要的影响，其影响的程度主要取决于高原生态系统的碳氮水循环过程，这不仅因为碳氮水对全球温室气体潜能具有很大贡献，同时也因为植被覆盖的变化会影响高原能量平衡，进而影响局部甚至全球气候。本研究以青藏高原典型生态系统为对象，聚焦最关键的生态系统过程，即碳氮水循环过程。我们将利用当雄和海北建立的高海拔和大海拔跨度研究平台以及在刚察建立的多时期热融冻土系列的研究平台，通过长期观测、移植或开放圆顶箱式增温、放牧围封控制实验、并利用以植物功能性状为核心的过程模型和以光合作用蒸腾作用的海拔效应为关键的机理模型，阐明青藏高原不同功能性植物的碳氮水代谢和典型生态系统的碳氮水循环过程，模拟这些过程在不同气候变化情景下的动态，预测碳氮水循环以及温室气体潜能，为探讨青藏高原生态系统过程的气候效应提供科学依据。

The geographical and topographical characteristics of the Qinghai-Tibetan Plateau, the highest plateau in the world with an extensive area, play a critical role in the regional and global climate systems. The climatic influences of the plateau are highly dependent on the carbon, nitrogen and water cycles in the plateau ecosystems, because these cycles contribute to not only the global warming potential but also the climatic system through changes in land surface processes. We will focus on these key ecosystem processes of the major vegetation at three ecological observatory platforms at Dangxiong, Haibei and Gangcha. We are to clarify the metabolism process of carbon, nitrogen and water in major plant functional types, and to characterize these processes in major ecosystems, through the long-term observation, manipulation experiments including the warming experiment through down-ward mini-ecosystem transplantation at Dangxiong and Haibei along altitudinal gradient, and the OTC warming experiment at the Gangcha permafrost. Using the data obtained from these approaches and from other resources, we will improve three current models, by including plants trait into a process based model, adding attitudinal effects into a physiological model (P-model) and combining soil processes to the VISIT model, to simulate the carbon, nitrogen and water cycles, and to make projections using climatic scenarios provided by IPCC 2013, to assess the effects of the ecosystem processes on the global warming potential.