关键词: 若尔盖, 土地沙化；空间变化；沙化强度；分类

Abstract: Land desertification is the first in the global top ten environmental problems. It is the most serious eco-environmental problem in China. Lying in the source area of the yellow river .Ruoergai county on the eastern Tibet Plateau is also threatened by desertification. In recent decades, under both natural and human effects, eco-environment has degraded in Ruoergai, resulting in desertification area expanding. In order to accurately grasp the status of desertified land in Ruoergai County and the necessary information for prevention, using geographic information systems technology and five-grade land desertification classification system, based on the survey data in 2004 and 2009, this paper analyzed the desertification rate, trend and classification. The results show that the desertified area in 2009 is 72569.05ha; with an increase of 24.01% compared with 2004.Annual growth rate is 4.8%.New desertified land is mainly distributed in the northwestern county. On the other hand, the desertification control practice had achieved to some extent from 2004 to 2009, the land area with persistent desertification was less than that with alleviating desertification. Desertified land in 2009 is divided into four categories, and 72.23% of the desertified land belongs to protection zone.

Key words: the Ruoergai Plateau, land desertification；spacial variability；desertification intensity；Classification