A material flow-based approach for diagnosing urban ecosystem health

A healthy urban ecosystem should be able to support urban development and have enough resilience to recover from ecological environmental stress. Healthy material flow can support the function of the system. Therefore material flow can be regarded as a key factor that reflects the health of an urban ecosystem. This paper explores the mechanism for material flow between urban and natural ecosystems and reveals the main problems that affect urban ecosystem health. A material flow model of urban ecosystems is established by using this mechanism. By using this model, a diagnosis framework is developed for diagnosis of urban ecosystem health. The framework consists of function analysis, input-output flow analysis, health assessment, and function optimization. It focuses on developing a material flow-based diagnosis approach and an indicator system including function-based indicators and effect-based indicators. Case studies show that this approach can not only diagnose the health problems of an urban ecosystem but can also identify the main causes of the problems. Therefore our approach can aid decision makers in making a timely and informative diagnosis of urban ecosystem health to support planning and management decisions.