CHARACTERISTICS OF VEGETATION EVOLUTION IN ARID LAND OF WESTERN CHINA USING REMOTE SENSING IMAGES FROM 1982 TO 1990

In this article we got some classification rules by using 1km resolution of FVC combining with DEM to classify vegetation in arid land of western China, these rules are also used to classify all FVC images with 8km×8km resolution from 1982 to 2000. Thus, the classified results for every year can be obtained. From these classified results, three majority values of 1982～1988, 1989～1994 and 1995～2000 are calculated. Based on ARC/INFO software, every cell value at same location in the three serial maps are compared and know which cell turns to decrease or increase, and then the vegetation evolution in this area are mapped. From that, some results have been obtained as follows: 1) vegetation turns to increase in all of arid land of western China; 2) in plain area, the rate is larger than that in all study area. But in mountainous area, the increased cell almost equals the decreased one; 3) There have two types of increased patches in plain area, one distributes around old oasis; another distributes sparsely in desert; 4) In plain, the decreased patches distribute in the lower reaches of Tarim River, Cherchen River, Jungger basin and the southern Alxa Right County of Inner Mongolia; 5) In mountainous area, most of all increased cells distribute in south Tianshan Mountains and Pamier High Plain, and decreased cells present a long narrow region locating on slope of north Kunlun Mountains, and large patches in Aljin Mountains and on the north slope of Qilian Mountains.