Regional ecological security anddiagnosisof obstaclefactors in underdevelopedregions：acasestudy in Yunnan Province,China

In order toclarify regional ecological security status and formation mechanism of regional ecological security barriers in underdeveloped regions of China,we took Yunnan province as a case to evaluate its regional ecological security by using entropy matter-element model,comprehensive index and GIS spatial method,and we diagnosed itsobstacle factors through obstacle degree model. We found a low overall level of regional ecological security in Yunnan. Only Kunmingfell into the good level, 68% of the regions were below the critical safe level. For the vast majority of regions in Yunnan, their regional ecological security was unstable. The indexes related to per capita resources, geological and topographyenvironment, economic, and technologywere at the unsafe or dangerous level.The indexes related to urban expansion, level of income, cultivated land quality were at the level of critical safety. The indexes concerning urban management capacity, airqualityand waterenvironment were at the good or ideallevel. Yunnan's regional ecological security was not good due to natural obstructive environment itself, simultaneously lower backward economic and social level restricted the ability of ecological security response to manage ragile ecological environment. The results of the composite index wereroughly consistent with those of the entropy weight matterelement model. The mean values of the classification index,from high to low, were: the state index>the response index>the pressure index. The state index and the response index had a significant mutual promotion to each other.The regions with good composite index, state index and response index mainly distributed in the central regions of Yunnan Province. Spatial autocorrelation of regional ecological security level in Yunnan was not obvious. Water resources, economic and social development were main obstacle factors of the regional ecological security.When distinguishing with obstacle type, Kunming belonged to natural ecological environment barrier type, while other regions belonged to economic and social barrier type.

Quantitative analysis of the dynamic change and spatial differences of the ecological security: a case study of Loess Plateau in northern Shaanxi Province

Using the theory and method of the ecological footprint, and combining the changes of regional land use, resource environment, population, society and economy, this paper calculated the ecological footprint, ecological carrying capacity and ecological surplus/loss in 1986-2002 on the Loess Plateau in northern Shaanxi Province. What is more, this paper has put forward the concept of ecological pressure index, set up ecological pressure index models, and ecological security grading systems, and the prediction models of different ecological footprints, ecological carrying capacity, ecological surplus and ecological safety change, and also has assessed the ecological footprint demands of 10,000 yuan GDE The results of this study are as follows： （1） the ecological carrying capacity in northern Shaanxi shows a decreasing trend, the difference of reducing range is the fastest; （2） the ecological footprint appears an increasing trend; （3） ecological pressure index rose to 0.91 from 0.44 during 1986-2002 on the Loess Plateau of northern Shaanxi with an increase of 47%; and （4） the ecological security in the study area is in a critical state, and the ecological oressure index has been increasing rapidlv.