关键词: 评价模型, 指标体系, 城市生态安全, 评价, 深圳

Abstract:

This paper aims at exploring the urban ecological security level and assessment methods, and providing the scientific basis for the policy of the assessment and management on the urban ecological security. Shenzhen and four municipalities are taken as case studies to contrive an evaluating index system of urban ecological security depending on the Pressure-Status-Response (PSR) model. Firstly, the authors use four kinds of assessment models to simulate urban ecological security levels for those cities in 2006. A comparison is made between these models, based on the optimal method in combination of the subjective preference (Analytic Hierarchy Process) and the objective information (the modified Entropy), so as to identify the weights of all assessment indexes comprehensively. Then the ecological systems of Shenzhen and four municipalities are evaluated by applying the modified Grey Relational Analysis, the Matter-Element extension, the Fuzzy Comprehensive method and Main Constituents Projection method. The results are shown as follows: (1) Shenzhen's ecological security level is the highest, followed by Beijing, Tianjin and Shanghai, and Chongqing. Shenzhen, Beijing and Tianjin are labeled as relative safety at ecological security level, Shanghai is critically secure, and Chongqing is unsafe; Shanghai possesses the most developmental potentiality, while less in Shenzhen, Beijing and Tianjin, and still the lowest in Chongqing. From the conclusions above, the differences can be found in terms of ecological environmental pressures, the states of ecological systems and the responses of human beings for different cities. (2) In the studying method of urban ecological security evaluation, every model can obtain a similar result and can reflect the applicability on ecological security assessment. The results of Fuzzy Comprehensive method and Matter-Element Extension method are more comprehensive, and more differentiations can be revealed in Fuzzy Comprehensive method which can analyze the problems and offer the targeted measures than in the Matter-Element Extension. The conclusion of level judgment drawn by the Grey Associative Analysis is not possessed of comparability and cannot reflect the gaps among the cities. The Main Constituents Projection method cannot directly demonstrate the ecological security levels, although it can simplify the data structure, reduce the information loss of the original data and avoid the subjective arbitrariness as well as only showing the high or low level of ecological security. Thus there are some limitations in this method on ecological security assessment.

Key words: assessment model, indexes system, urban ecological security, assessment, Shenzhen