The effects of climate change on different types of grassland in Maqu County in Northeast Tibetan Plateau

The Maqu County, located in the eastern Tibetan Plateau, is an important ecological function protected area on the state level in China, because of its typical grass type, geographic conditions and ecological environment. In this paper, the dynamic change of climate factors and the change characteristics of three types of grassland NDVI in the Maqu, and the relationships between the NDVI and the climatic factors were studied by using GIMMS NDVI data and meteorological data from January 1982 to December 2006 and the data of grassland types in the Maqu. The results showed that, the monthly temperature is increasing from 1982 to 2010 in the Maqu. There is no clear trend in the monthly or quarterly precipitation. The reference evapotranspiration trend for every month has displayed increasing trend. The NDVI for the most of the months were increasing in the growing season, with increase most significant in July and October. But the increase of NDVI in August was not significant. Among the three types of grassland, the NDVI in the Alpine grassland increased the most obviously and the trends for marshed grassland increased the least significantly. Climate change may be the main reason for the change of the NDVI. Human activities (such as overgrazing) was one of the reasons for the degradation of vegetation.