Urban eco-security and its dynamic assessment method
城市生态安全及其动态评价方法

Eco-security is a challenging issue to human survival and development. Cities are a concentration of human activities for efficiency and interaction.Traditionally,urban development places human beings at the center and is driven by human interests,so following urbanization,natural ecosystem is facing great stress,and the carrying capacity for cities is over loaded.As a result,serious urban eco-security problems rise up.Resource shortage blocks urban further development,and ecological refugees as well as environmental health problems influence human survival.Urban eco-security is menacing urban sustainable development.There is an urgent need for appreciating urban eco-security,and urban eco-security assessment is among the most important problems.Through the assessment,decision makers can get more information of the status of urban eco-security so that they can make sound strategies to resolve the problems.People can get timely information and then take decisive actions to protect themselves.However, existing methods are too limited in their ability to meet the objective.This paper focuses on urban eco-security assessment and proposes the basic concept of urban eco-security,which is a kind of status and trend of urban development whose eco-environment conditions can meet the needs of urban development and human living sufficiently.It identifies the factors of urban eco-security including resource shortage,environment pollution and ecological disaster,analyzes the dynamic characteristics of urban eco-security,and points out that there are different eco-security level in different temporal and spatial scales.Based on the factors,characteristics of urban eco-security,and the analytic hierarchy process(AHP) model,the paper discusses the assessment principles for urban eco-security;establishes the indicator system which includes 23 indicators involving in resource and eco-environment;poses a dynamic assessment method based on status assessment and trend analysis including fuzzy synthesis status assessment model, assessment grades and trend analysis model.A case study on a city shows that the dynamic assessment gives more objective information to decision makers than traditional assessment.This research develops a vehicle to promote urban eco-security study,provides a way to establish a practical assessment method,and facilitates to achieve urban sustainability.