渝西方山丘陵农村社区生态安全动态分析

以渝西方山丘陵农村社区张家沟小流域为研究区,基于RS和GIS技术,运用破碎度指数、分离度指数、优势度指数、干扰度指数、脆弱性指数和风险指数等景观生态学量化指标分析了该农村社区1957,1976,1982,1992和1998年景观格局的演变规律;同时,根据生态风险与景观格局之间的联系,建立了生态安全与景观格局之间的关系,计算得出了研究区不同年份生态安全综合指数值.结果表明:(1)1957年以来,研究区生态安全状况整体较好,国家一系列生态建设工程对当地生态环境保护起到了积极作用,但人类活动进一步加剧了生态环境的退化,生态安全呈弱化趋势;(2)随时间推移和经济发展,研究区各景观指数发生了较为复杂的不均匀变化,其变化的节律性与该区农业经济政策、人口增长和经济发展具有很好的对应性.

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

Landscape patter ns in Zhangjia valley of the low tabular mo untains and hills in Western Chongqing City are studied by using five sets of land use data in 1957, 1976, 1982, 1992, and 1998, quantitative metho ds 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 perio ds 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 eco nomic develo pment, the change of the landscape indexes in Zhangjiagou valley in different periods are complicated and anomalistic. The r hythm of the changes is consistent with agricultural policies, population increase, and economic develo pment.