上海城市土地利用变化及生态风险研究

A Study on Land Use Changes and Ecological Risk in Shanghai

基于上海市1987年和2007年的Landsat—TM遥感数据，采用监督分类方法，获得2个时相遥感土地利用分类数据；在此基础上，构建了区域土地利用综合生态风险指数，通过普通克里格插值方法，编制上海区域生态风险等级图。研究结果表明：20年来，上海市土地利用的总体趋势是城市建设用地面积大幅增加，农田面积大幅减少；对半变异函数曲线中块金值、基台值和块金基台比3个主要参数的分析，表明上海市生态风险指数的空间相关距离在逐年增加；1987年和2007年的生态风险指数分别在0．15～0．31和0．12～0．32之间，该指数从市中心向郊区呈圈层状递减，且高生态风险区面积在大幅扩大；通过缓冲区分析得出土地利用类型的时空格局变化对生态风险的空间结构有着很大程度的影响。这对于城市生态风险研究提供了案例，研究结果对城市可持续发展具有重要意义。

The ecological risk based on land use is a hot issue in academia currently. In this paper, Shanghai City was selected for case study. Land use information obtained from TM image during two periods of 1987 and 2007 was used as main data source. The authors determine the weight values of the ecological risk from different land use patterns by analytic hierarchy process and construct integrated ecological risk index of different periods.Then the semivariogram analysis and block Ordinary Kriging were conducted to gain the map of distribution of eco-logical risk. The result indicates that the area of building land has been increasing continually, while the area of cultivated land has been reducing without stop. Ecological risk index decreases from the city to the country with circle layers, and the area of high ecological risk expands substantially. Through analyzing the three main parameters of the semivariogram curves, we know space-related range of ecological risk index in Shanghai increased year by year. Through using buffer analysis method, the changes of the patterns of land use have significant effects on the structure of ecological risk. The paper provides a case study of city ecological risk, and the results have great significances to the sustainable development of the city.