关键词: 宁夏中部生态脆弱区, 分形模型, 土地利用动态度, 沙漠化, 盐池县

Abstract:

Land use and land cover change research needs to pay more attention to its environmental response, especially to its desertification response. The study area is typical in the agro-grazing ecotone, where desertification is a serious threat to agricultural economy. Based on three land use maps, which were identified by using 1985, 1995 and 2000 TM remote sensing images, this paper analyzed the land use change and its desertification response in the central Ningxia Hui Autonomous Region. Supported by spatially statistical function of GIS technology, land use indices and landscape indices, including single land use dynamic index, patch density, fractal index, etc., the analysis tried to discuss the relationship between the pattern of land use change and desertification trajectory during recent 20 years. The results suggested:1)General land use change analysis showed that the middle-covered grassland and lower-covered grassland decreased obviously, and woodland presented a trend of protection and reconstruction after previous destruction. 2) Hotspots of desertified land shifted from northern sandy region to central region from 1985 to 2000. The region near Yanghuang trench should be paid much more attention in terms of its desertification condition. 3) Desertification of grassland was extremely serious among all the other land use types. The desertification of middle-covered grassland gathered in the northern region, where there were more agricultural activities. The patch cohesion index of middle-covered grassland in that region was relatively large. The desertification of low-covered grassland appeared around original sandy land, and it was more sensitive to physical change than human activities. 4) Considering instability of different agricultural land use activities in the study area, the middle-covered and low-covered grassland were more instable than other types, especially the middle-covered grassland. It was indicated that the middle-covered grassland was the most sensitive land use type in the region in response to physical and human disturbances, and it needed effective management and scientific pattern of ecological reconstruction.

Key words: ecological fragile region in central of Ningxia, fractal index, land use dynamic index, desertification, Yanchi County