长江上游地区土地利用/覆被和景观格局变化分析

利用1980年、1990年和2000年3个时期土地利用数据，将GIS和景观生态学的数量分析方法相结合，运用Arc Info和Arc View以及Fragstats(栅格版)，分析了长江上游地区1980~2000年间的土地利用/覆被和景观格局的变化。结果表明：研究期间，林地和耕地大幅度减少，草地和建设用地面积显著增加，水域和未利用地相对变化幅度不大。研究区土地利用类型转移的主要方向是林地转化为草地和耕地、耕地转化为建设用地和草地、草地转化为未利用地。通过对该区斑块类型级别指标的分析，得出水域、建设用地和未利用地分离度和破碎度较大，而耕地、林地和草地在宏观政策和人类活动强烈干扰下，分离度和破碎度呈现先降低后升高的趋势。通过对景观级别指标的分析，得出整个区域景观结构日趋破碎，景观异质性也逐渐提高，土地向着多样化和均匀化发展。长江上游地区脆弱的生态体系对土地利用变化响应强烈，造成水土流失和沙漠化程度加剧，自然灾害频发等景观生态效应。可通过调整景观尺度上的土地利用方式，使长江上游地区生态建设及水土资源实现可持续发展。

Analysis of the changes of land use/cover and landscape pattern in the upper reaches of the Yangtze River

Combined the integrated technology of ecological quantity analytical method with GIS techology through Arc Info, Arc View and Fragstats, the changes of land use/cover and landscape pattern had been analyzed in this paper in the upper reaches of Yangtze River, using the land use data of 1980, 1990 and 2000. The results show that the areas of grassland and farmland obviously decrease, while the areas of forest land and construction land increase, and the areas of water and unused land keep stable. The major patterns of land use change are the conversions of forest to grassland and farmland, farmland to construction land and grassland, and grassland to unused land. The analysis on the index of patch show that the value of the fragmentation and isolation of water areas, construction land and unused land are bigger than other landscape types. Under the adjustment of macro policies and intensive human activities, the fragmentation and isolation of farmland, forest and grass decreased gradually and then increase. The analysis on index of landscape show that the landscape is becoming more fragmental, and the diversification and evenness of landscape pattern are more obvious. The eco-environment in the study area is very vulnerable to the land use change, resulting in distinct landscape effects, such as loss of water and soil, land desertification, nature disaster and environmental quality declining. The mode of land use should be adjusted in landscape scale to rehabilitate and reconstruct the landscape ecosystems in the upper reaches of Yangtze River.