STUDY ON THE LAND-USE CHANGE AND ITS SPATIAL DISTRIBUTION : A CASE STUDY IN ANKANG DISTRICT

Land-use change is a key component for global environment change, and indicates the influence of human activities on physical environment. Supported by the techniques of Remote Sensing and GIS, the struc tural features and spatial patterns of land-use change in Ankang district from 1985 to 2000 has been analyzed based on Landsat TM digital data. Some interesting and significant findings have been obtained. (1) During 1985-2000, the land-use change mainly occurred in farmland, forest land, grassland and water areas, the conversion amounts of the above-mentioned land-use types accounted for 94.95%, 38.55%, 48.07%and 3.89% of the total conversion amounts respectively. Farmland increased conspicuously, meanwhile, the decrease of forestland, grassland and water areas was obvious, the unused land was kept no change. The increment of built-up areas was 215.94 hm2, mainly transformed from farmland and forestland, accounting for 60.20% and 38.80% respec-tively; (2)The net change of each kind of land-use types is easily found in each county, while there exists a con-spicuous differentiation of the net change of farmland, forest land and grassland in altitudinal direction. Delimit-ed about at l 600 meters, areas of farmland decrease with the increase of elevation while those of forest land and grassland increase along the altitudinal direction; (3)The net change of each kind of land-use types differs from each other during the three periods in Ankang district. During the period of 1985-1995, farmland was mainly transformed from other land-use types, and the amounts transformed from grassland ranked the first, which accounted for the 96.02% of the total conversion amounts of farmland(835.67 hm2). Because of the implementation of natural forest protect project and returning farmland to forestland or grassland, farmland was mainly transformed into other land-use types during 1995-2000. In this period, farmland about l 503.21 hm2 were transformed into others, and the amounts of farmland to forestland and farmland to grassland accounted for 15.64% and 78.77% of the total conversion amounts of farmland respectively.