滇西北生态脆弱区土地利用变化及其生态效应——以云南省永胜县为例

Land Use Change and Its Ecological Effect in the Ecotone of Northwest of Yunnan Province, China:A Case Study of Yongsheng County

土地利用/土地覆被变化及其生态环境效应研究是当前地理学全球变化研究的核心内容,而生态系统服务功能则是生态学、生态经济学研究的热点问题。作者利用滇西北生态脆弱区———永胜县1988年、1994年和1999年的TM遥感影像,采用景观生态学的空间格局指数分析研究区近10年来的土地利用动态变化特征,并以生态系统服务功能衡量相应土地利用类型的相对生态价值,评价区域土地利用/土地覆被变化的生态效应,尝试将二者有机结合起来。研究表明,全县景观总体构成表现为景观破碎度较高,斑块数目较多;林地和未利用地一直占很大比重,林地的不断增加与未利用地的迅速减少是研究时段内土地利用变化的突出特征;研究时段内全县土地利用变化带来了较好的生态效应,土地利用生态效益持续提高,并表现出了较大的空间差异。

Research on land use/land cover change and associated effects on eco-environment is the key content of geographical research on global change today. And ecosystem services are the hot issues of ecology and ecological economics. In this paper, we put ecosystem service values in use to weigh the ecological values of corresponding land use types, so as to evaluate the ecological effect of regional land use change. Yongsheng county, situated in the northwest of Yunnan province, also an ecotone, is taken as our research area. Based on TM images in 1988, 1994 and 1999, the landscape component maps of Yongsheng county were conducted through methods of supervised classification and interactive modification. The landscape type transition matrix and three kinds of indices for spatial patterns including patch-level index, class-level index and landscape-level index were calculated by models and GIS to examine the spatial patterns and dynamics of regional landscape in Yongsheng county. The results show that, due to human activity, the unused land decreased rapidly during the past 12 years; because of the limitation of physical geographic condition, the proportion of steady farmland is not high; the inter-changes of farmland and unused land happened frequently. And index for landscape diversity has showed a tendency of increasing, which means that the proportion of each landscape component changed to average. Also, the decreasing of fractal dimension of unused land shows that human activity effects are increasing. And land use change in Yongsheng county from 1988-1999 has got a good ecological effect, where the ecological benefit of land use is always increasing, and shows a distinct spatial difference.