Grassland resource dynamics in aridity area in China
我国不同干燥度区域草地资源动态变化研究

This paper studies the dynamic of the Chinese grassland resource in different aridity areas supported by GIS and RS based on TM images. The results show thai there is an obvious zone under different aridities where the high cover grassland is changed 10 farm land especially at 4, 5 . 6 degrees which are mainly distributed in the west and north of China and in these zone the grassland is being replaced by urban at each aridity area and the grassland is being degradated. The area between the grassland changing into farmland and farmland changing into grassland is about the same in middle cover grassland, but the area occupied by the farmland shows that the grassland decreases and a lot of grassland arc changed into forest. With the increasing aridity degree, the degradation becomes serious in low cover grassland, especially at 4, 5 degrees. But at 1 degree, the main change is that the grassland is changed to forest. The main reasons of grassland changing into farmland are the population pressure and over graze, etc. Grassland degradation will lead to the environment of north China worsen.