Assessment on urban ecological security spatial differences based on causal network:a case of Dalian City

The urban ecological system is a fragile and an unstable ecosystem. Compared with the natural ecological system, the urban ecological system has many disadvantages, such as high consumption of energy and material, environmental pollution problems and low amounts of natural resources. Because of rapid urbanization process has resulted in innumerable ecological environmental problems, to make things even more severe, eco-environmental security in the cities of spatial differences is being outlined. The paper analyzes the pros and cons of some causal chain structure model, such as PSR, DSR and DPSIR, and raises a new ecological security assessment model-causal network model of DPSRC model, after while combines GIS spatial analysis method is used, researching the ecosystem health status of Dalian City. The following conclusions are: First, it proposes the network model by way of studying the disadvantages of chain models during the past, according to the complexity of urban ecosystem. It also makes assessment indicators system of the "Driving force-Pressure-State-Response-Control" model and applies fuzzy Analytic Hierarchy Process (AHP) and indicates weights by a comprehensive compared method for results. Secondly, it does a field survey and collects the detailed data about the urban ecological security system and digitizes the correlative information of urban ecological security. Finally, it expounds the states of ecological health and spatial differences of urban ecological security by spatial analysis of GIS.