Ecological Security in the Tabular Mountainous and Hilly Rural Area of Western Chongqing City

Landscape patterns in Zhangjia valley of the low tabular mountains and hills in Western Chongqing City are studied by using five sets of land use data in 1957,1976,1982,1992,and 1998,quantitative methods of landscape ecology,and techniques of RS GIS.Firstly,landscape is classified into the six types of irrigable land,dry land,orchard,woodland,village,and watershed by using remote sensing images.Secondly,depended on spatial analysis function of GIS,indexes of fragment,isolation,dominance,disturbance,frangibility,and risk of each landscape in different periods are calculated.Thirdly,according to the causality of ecological risk and landscape pattern,the relation of ecological security to landscape pattern is build and index of integrated ecological security is calculated.Results showed that(1) from 1957,ecological security has been favorable in Zhangjia valley and a series of engineering for ecological construction have positive effects on environment.However,human activities aggravate natural degeneration step by step.(2) With the time elapsing and the economic development,the change of the landscape indexes in Zhangjiagou valley in different periods are complicated and anomalistic.The rhythm of the changes is consistent with agricultural policies,population increase,and economic development.