Ecological security in downtown area of Chongqing City

Landscape pattern in downtown area of Chongqing City is studied by using four sets of land use data in 1978, 1988, 1993 and 2006, quantitative methods of landscape ecology and techniques of RS & GIS. Firstly, landscape is classified into six types of City, woodland, Non-irrigated field, Lake-reservoir, Irrigable land, and Bush by using remote sensing image. 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 and landscape pattern is build and index of integrated ecological security is calculated. Results showed that: (1)Form 1978, ecological security is favorable in downtown area of Chongqing city and a series engineering for ecological construction have positive effects to environment. but human activities and city expand are aggravate natural degeneration step by step. (2) With the time elapsing and the development of economy, the change of the landscape indexes in different periods downtown area of Chongqing city are Complicated and anomalistic. The rhythm of the changes is consistent with city expand, population increase, and economy development.