Abstract: The source region of the Yangtze River, located in the middle region of the Tibetan Plateau, is characteristic of highaltitude and cold environment, and is a sensitive area to global change. As a major part of the National Three River Sources Nature Reserve, it is one of the principle areas of alpine wetlands as well. While in recent decades, in the influence of improper human activities and global climate changes, climate in this region has become warmer and drier in an obvious way. Accordingly, the glaciers and lakes have been retreating. Grassland has been degrading because of overgrazing. As a result, land desertification and soil erosion are increasingly expanding. These will be a threat to the Yangtze River Valley, and to the ecological security of the whole Yangtze River Basin. The alpine meadow is one of major highaltitude cold ecosystems in this region. In the influence of global change, undoubtedly, the alpine meadow dominated by cold resistant Kobresia plant will have to face ecological menace. Therefore, to discuss the impact of global change on the alpine meadow is of high value for understanding global change and reducing its negative influence. The alpine meadow in the source region of the Yangtze River is taken as a study case in this paper. Firstly, the ecological and environmental characters in the source region were clarified. Then the authors employed CENTURY model, a popular biogeochemistry model to simulate alpine meadow ecosystem, in terms of its longterm dynamics in productivity and carbon balance. Grazing, a main human activity in the plateau, was taken into account to simulate probable impacts on the ecosystem as well. In accordance with climate change scenarios from RCMs, possible impacts of climate change on ecosystem were analyzed. Finally, proper adaptation countermeasures were proposed in order to reduce the negative impact of climate change.

Key words: the alpine meadow, global climate change, CENTURY model, the Source Region of the Yangtze River, Tibetan Plateau