近30年玉门市土地利用与景观格局变化及其驱动力

干旱内陆河流域生态环境非常脆弱,是土地利用和景观格局变化的敏感区域,也是全球环境变化响应比较突出的区域。采用1976年、1989年、2000年和2010年的Landsat遥感影像,利用GIS技术和景观格局分析方法,系统地分析了疏勒河中游玉门市的土地利用和景观格局变化的时空特征,为研究区土地可持续利用政策的制定提供参考和依据。研究结果显示:近34a来,玉门市土地利用和景观格局发生了剧烈变化,土地利用变化经历了"缓慢变化—急剧变化—显著变化"的过程。研究区景观密度增大,多样性和均匀度先减小,后增加;不同斑块间的分离度减小。农业人口增长和经济发展是玉门市土地利用景观格局变化的最直接驱动力,同时还受气候因素和政策因素的影响。

Land use ＆ landscape pattern change and its driving forces in Yumen City

The quantitative evaluation on land use change and its influence on landscape pattern caused by land exploitation and reorganization at a large scale is significant to the sustainable use of local land resources.The study area in this research,the middle reaches of Shule River Watershed in Gansu,belongs to a typical area with dramatic exploitation and use of water and land resources in the arid area of Northwest China.Yumen City is a resource-exhausted city.Combined with the integrated technology of ecological quantity analytical method and GIS technology through ArcGIS and Fragstats,based on the MSS images in 1976,TM images in 1989 and 2010,and ETM+ images in 2000,this paper analyzed the changes of land use/cover and landscape pattern in Yumen County from 1976 to 2010.The conclusions are as follows.(1) The trend of LUCC is that the area of farmland increased obviously,and the areas of grassland and glacier decreased.The area of sandy land reduced at first and then expanded.Its area was the smallest in 2000 and increased in 2010.The major patterns of land use change were the conversions of grassland and Gobi to farmland,farmland to construction land,and grassland to Gobi.Land use change underwent a process of slow change—tremendous change—obvious change.(2) Landscape change was also obvious in the decades.Totally,landscape density increased,the largest path index expanded at first and then decreased,the weight area index increased and the shape of landscape became irregular.The shortest distances decreased,and the patch became more complex.Diversity of landscape and the Interspersion Juxtaposition Index decreased at first and then increased.The degree of diversity landscape and fragmentation increase also shows that the land uses became more complex.(3) Driving force analysis shows that the agricultural population growth and economic development are the most direct driving force of land use/cover changes in Yumen City.Climatic factors and policy factors have also affected land use change in the study area.