An urban ecosystem health assessment method and its application

A city is a complex system and it is of great importance to study the urban ecological problems with complex ecosystem theory. The concept of health was introduced into urban ecosestem research, which could describe the conditions of system and sub\|systems clearly to provide useful information for decision\|making of the ecological city construction.To express the absoltue and reletive status of systems and sub\|systems,distance index and coordination index were suggested relied on the discussing of concept of urban complex ecosystem health. A health assessment model was established by integrating the distance index with the coordination index. The city's status was quantified with a scale of 5 grades as very healthy, healthy, less healthy, unhealthy and diseased and the grade of each level was established. An indicator system was developed based on the characteristics of urban complex system. An application of this model to Ningbo City revealed the urban ecosystem health state and health heterogeneity. The results indicated that this method could distinguish the complex and spatial properties of urban ecosystem. Thus it could give the appropriate directions of implementing the urban sustainable development strategy by showing the key action fields of ecological city planning and constructing.