Assessment method of regional ecological security based on Pressure-State-Response model

Ecological security is defined as the goal of stakeholder to create a condition where resources and environment of a region are provided for the needs of economy and social development without diminishing its resource stock.Although the Pressure-State-Response(PSR) framework together with Analytic Hierarchy Process(AHP) was widely adopted to assess ecological security at present,it has inherent limitations and need to be improved.Based on PSR model,the paper selected boreal forest,opening forest,cropland,desert shrubs and desert as reference system for evaluating regional ecological security,and made the per unit area amount of vegetation of tropical rainforest per year to be a standard unit,then gave the method of computing the ecological state index.The paper proposed the new conceptions of subjective response degree and objective response degree,and built up the method of calculating ecological response index.The paper established the method of calculating ecological pressure index through the junction of ecological footprint(EF) method and emergy theory.The paper proposed a new model of comprehensively evaluating the status of ecological security,which makes evaluation results more objective and more comparative.The paper analyzed the relation among ecological state,ecological pressure and ecological response:ecological rehabilitation from ecological system with the lower grade to ecological system with the higher grade needed to throw in the more ecological response.The index value of ecological response will be 1665,18 and 4 if ecological state is changed from the critical state of ecological security,namely crises state,security state and relatively good state to ideal state.Taking Changdao county in Shandong province as an example,the paper researched the ecological security trend at time scale(1990-2005) by the improved model,and drew the curve in three dimensions to reflect the ecological security tendency,and then inquired into the requirement of continually enhancing ecological security status.The results show that Changdao's area of plant is gradually increasing,but the amount of vegetation is decreasing from 1990 to 2005;the index value of ecological state has decreased by 0.266,0.219,0.176 and 0.152,respectively;the index value of ecological pressure has increased by 0 and 0.19;the index value of ecological response has been 0.266,0.336,0.330 and 0.304,respectively;the index value of ecological security has decreased by 0.070756,0.067506,0.057971 and 0.038830,respectively.The current status of ecological security presents a declining trend.Even if the size of the forest area was added,ecosystem health status directly was not improved.So the amount of vegetation,especially forest area is an important factor for enhancing a regional ecological security.This suggests that further measures,such as reducing ecological pressure,adding ecological rehabilitation investment and increasing the mass of plant,must be adopted to reverse the current situation of Changdao' s ecological security.The improved models in this paper could make an important contribution to decision-making for Changdao' s governors and to the development of the island regional planning incorporation assessment and prediction of ecological security.This study demonstrates the potential of the improved model for assessing ecological security.