Change in the Spatial Structure of Grassland Vegetation in the Xilin River Basin from 1985 to 1999

Using Landsat TM images of 1985 and 1999, and through field investigation, the monitoring and analysis on the change of grassland vegetation types and distribution in the Xilin River Basin from 1985 to 1999 were made.Due to overgrazing and cultivating,the area of grassland plant community has changed. Comparing with 1985, the area of Leymus chinensis,Stipa grandis meso xero forbs steppe and Stipa grandis, Leymus chinensis xero forbs steppe decreased by 20.2% and 28.4%, and the area of Artemisia frigida steppe increased by 46.6%. In the past two decades, the area of grassland cultivated increased by 34.8%. In whole, the grassland vegetation in the Xinlin River Basin is in a state and trend of degradation.