Grassland degradation in the Western of Songnen plain

Based on RS and GIS techniques, three-period (1986, 1995, 2000) remote sensing images are interpreted in order to gain spatial information about grassland landscape in the Western of Songnen plain, then spatial-temporal dynamics of grassland and the natural, human factor of grassland degradation are analyzed. The results show that grassland area decreased 24.7%. Grassland degradation is serious. Grassland is mainly converted into forestland, cropland, unused land and saline-alkalized land. During 1986 to 1995, low coverage grassland developed rapidly, while high coverage grassland declined a lot during 1995 to 2000. From 1986 to 2000, both natural factors and human activities result in grassland degradation in the studying region. Natural factors are basic condition of grassland degradation, and human activities are crucial factors.