以宁夏中部生态脆弱区典型县为研究对象,利用1985、1995、2000年三期TM影像提取的土地利用数据,基于GIS空间统计分析功能,结合土地利用指数及分形模型、景观破碎度等景观分异测度指数,探讨近20年来该县土地利用时空分异特征及其沙漠化响应,结果表明:①土地利用变化整体上表现为中低覆盖度草场减少,林地为先破坏而后治理;②1985~2000年沙地扩展区域从北部风沙地貌区转移到中部波状高原区,尤其是扬黄灌渠附近需加强管理和防治;③草场沙化比例最大,中覆盖度草场沙化集中在北部农作活动密集区,其沙化斑块连通性强,低覆盖度草场沙化大部分紧临原沙地,受自然因素干扰更为明显;④中、低覆盖度草场斑块不稳定性程度较高,中覆盖度草场属该区域中对自然条件变化和人为干扰最为敏感的类型,需要加强管理和建立科学的生态恢复重建格局。

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.