Limiting factor analysis of urban ecosystems based on emergy—A case study of three cities in the Pearl River Delta in China

The development of urban ecosystems is usually restricted by a few key limiting factors, including both the natural resource condition and the socioeconomic performance. To link the natural, economic and social subsystems together and uniformly measure the multiple ecological flows within and amongst these subsystems, emergy analysis was applied in this paper to describe the status quo of urban ecosystems in terms of energy and materials metabolism. Three typical cities, namely Guangzhou, Shenzhen and Zhuhai all in the Pearl River Delta urban cluster in China, are chosen as the cases, regarding the urban cluster as an important developmental pattern and trend of urban ecosystems. Using the data in 2005, an emergy-based analysis was conducted for the three cities from aspects of emergy structure, emergy intensity, emergy welfare, environmental pressure and ecologic economic interface. Based on the comparative results, the limiting factors of these urban ecosystems were further analyzed. This paper presents a meaningful comparison among different urban ecosystems in the same region, and provides a useful framework for urban ecological management based on limiting factors analysis of urban ecosystems