Analysis of China grassland resource dynamic under different aridity based on GIS and RS

This paper studies on dynamics of Chinese grassland resources during 1995 and 2000 under different aridity supported by GIS and RS based on TM images. We get the grassland dynamic coverage under MGE environment by contrasting 1995 and 2000 TM images. The results show there is an obvious zonal distribution under different aridity; grassland is changed to farmland in high cover grassland, especially at 4,5,6 degree which mainly distributes in west and north of China; grassland was replaced by urban areas at each aridity and grassland degradation. The change area between grassland changed into farmland and grassland is about same, but shifting into farmland shows the grassland decrease; a lot of grassland is changed into forest. With the aridity degree increasing, the degradation becomes serious, especially at 4,5 degree. But at I degree, the main change is that grassland changed to forest. The urban takes place of grassland in each aridity. But the mainly change is becoming farmland and grassland and grass resource having different degree degeneration. The main reason of grassland changing into farmland is population pressure; grassland degradation is caused by over graze etc.