Ecosystem Health Assessment and Regulation for Urban Ecosystems: A Case Study of the Yangtze River Delta Urban Cluster, China

Abstract

Methods and indicators need to be developed to investigate urban ecosystem health to mitigate eco-environmental problems and develop holistic policies for integrated urban ecosystem management. Considering the importance of energy and materials flows in urban ecosystems, the emergy synthesis model was applied to organize the urban ecosystem health indicators from the biophysical perspective in this paper, through which a better understanding of urban ecological patterns and processes can be obtained. Set pair analysis was combined to conduct the data processing of health indicators and promote objectivity of ecosystem health criteria. Set pair analysis defines the approximate degree of a real index set relative to an optimal one, which is evaluated to describe the relative urban ecosystem health levels in view of the emergy-based health indicators. Six cities in the Yangtze River Delta urban cluster in China (Shanghai, Suzhou, Wuxi, Changzhou, Nanjing and Hangzhou) were selected as case studies using 2005 data. The evaluation showed that the urban ecosystem health states of Shanghai and Hangzhou are relatively good, while the health states of Wuxi and Suzhou are relatively poor. The health states of the cities based on the factors (vigor, structure, resilience, ecosystem service maintenance and environmental impact) and individual indicators were also analyzed to identify regulatory directions and measures for improving the health status of those cities with relatively poor ecosystem health. This paper presents a meaningful comparison between different urban ecosystems at different indicator levels and provides a useful framework for urban ecological management with respect to urban ecosystem health status.