Hanzhong Urban Ecosystem Health Assessment

With the changes in global temperature, ecosystem (including urban ecosystem) health has attracted much attention. Urban ecosystem is an artificial ecosystem, which takes the human as a main body and combines nature, economics and society together. A healthy city must have capability of self-sustaining and update, and meet the urban residents'reasonable demands. In recent years, with the accelerated process of urbanization in china, "urban disease"-problem of urban ecosystem health-occurs in many cities. These corresponding problems will hinder and constraint the development of urban ecosystem, and further affect the survival of human beings. Therefore, it is important to establish a reasonable assessment system of urban ecosystem.This article discusses the basic theory and research progress of ecosystem health, and gives a mathematical model for the assessment of ecosystem health, and makes the calculation and analysis by taking Hanzhong city (in Shanxi province) as a study area. The main conclusions are as follows:1. In view of the ten-year data from 2000 to 2009. which embodies the ecosystem health of Hanzhong city. I establish an evaluation index system that is a collection of 24 indicators including five aspects:vigor, organizational structure, resilience, ecosystem services and human health.2. By the fuzzy AHP. I first determine the weight of each index, and then use two different methods to evaluate Hanzhong city ecosystem health. One method is comprehensive evaluation method, the other is the one which is from the gray system theory, and is combined with the actual situation in Hanzhong. and applies the improved model of gray geometric correlation to evaluate Hanzhong ecosystem health over the past decade. From the two evaluation methods, it is concluded that the Hanzhong ecosystem health becomes better year by year, which is consistent with the actual situation in Hanzhong city. Hence, it is feasible to apply these two methods to evaluate the urban ecosystem health in Hanzhong. 3. The results also show some indicators that constraint the Hanzhong urban ecosystem health, and can be used as a theoretical basis to establish the Hanzhong urban ecosystem management mechanisms.