Land cover and macro ecological changes in source region of the Yellow River in last 30 years

摘要

By using MSS image and TM image, the 5 period spatial data set of land cover in yellow river source region has been achieved. Then the paper analyzes the spatial pattern of land cover changes in last 30 years, and Ecological changes and trends in the area by extracting varieties landscape index, land cover conversion index and land cover state index etc. The results show: the land cover state index is 5 in last 30 years; in 1977–1986, 1985–1995 two periods, the land cover conversion of the area mainly transform from high ecological level to the low, in the period of 1995–2000, changes are little, and there are transformation from low ecological level to the high from 2000 to 2006; It can be reflected that the macro-ecological condition of the area through the series indexes, generally experienced following process: variation (1977–1995)-market variation (1985–1995)-little change (1995–2000) — slight improvement (2000–2006).