Study On Ecological Carrying Capacity Of Ordos City Based On Principal Component Analysis And Entropy Weight Method

Ecological carrying capacity(ECC)is composed of three subsystems:ecological elastic force,supporting force of bearing media and pressure of bearing object.It is of indicative importance for us to discuss the key factor which affected by condition of the three subsystems,and judge the interrelation between social productive behavior and ecological environment.Ordos City is a typical coal resource-based city,most coal mining is open-pit mining.On the one hand,taking coal mining and processing as the major leading mode of production to maintain rapid gross domestic product(GDP)growth is harmful to the ecological environment,and the further development is troubled by the pollution and destruction of land,air and water.It is an important premise to ensure the sustainable development of cities to understand the ecological carrying capacity and the key factors affecting its changesThis study is aimed to shed light into the ECC of Ordos City based on the theory of ecological carrying capacity and sustainable development,and applied comprehensive grading evaluation method.A total of 31 indexes were selected from ECC including ecological elastic force,supporting force of bearing media and pressure of bearing object to construct the comprehensive evaluation index system of ecological carrying capacity of Ordos City.Principal component analysis method and entropy weight method were used to determine the index weight.Besides,linear regression equation was used to calculate the development of each subsystem based on the evaluation results of ecological carrying capacity.The main results are as follows:1.Ordos City ecological elastic force index increased from 0.372 to 0.401.Before 2011,it basically showed a declining state,and in 2011,reached the lowest value of 0.233 in the research period,and then up,reached 0.737 in 2013.the highest value in the study period,but after 2013,declined again.The development of ecological environment played a positive role in the self-maintenance and regulation of the natural ecosystem in Ordos Citv.The situation of water resources was the main reason of unstable ecological elastic force in Ordos City.Light condition had potential effect on the change of ecological elastic force in Ordos City.2.The support force index of Ordos City showed a fluctuating and rising state,from 0.445 to 0.595,and showed a phased change feature.From 2008 to 2010,it fell from 0.445 to a lower level of 0.341,and then to 2012,the supporting force index increased year by year and reached a high level of 0.606.However,it decreased to an intermediate level of 0.569 in 2014,and then rose to a high level of 0.595 in 2015.The development of social economy improved the supporting function of the complex ecosystem of Ordos City,but the decline of environmental governance ability became the primary factor hindering the development of supporting force,and the change of average resource quantity affected the change of supporting force.3.From 2008 to 2015,the pressure index increased from 0.504 to 0.531,so pressure fluctuate declining trend.The pressure was at its lowest in 2014,then there was a strong increase in 2015.but always less pressure than in 2008.Economic consumption and the consumption of resources and environment brought by the industrial pollution were the main cause of ecological system pressure fluctuations in Ordos City,and changes in the structure of population and the population pressure also increased the pressure on ecological system.but the change of consumption patterns prompted the economic growth to alleviate the pressure of ecosystem.4.The overall index of ecological carrying capacity increased slightly,from 0.444 to 0.501.During the study period,in addition,it reached a high level of 0.624 in 201 3.the index of ecological carrying capacity in other years was intermediate,with small but frequent fluctuations.From 2008 to 2010.the ECC first increased and then decreased,and then continued to increase until 2013.when it reached the maximum value during the study period.However,the ECC decreased to an intermediate level in 2015.The change trend of the ECC index and the ecological elastic force index was basically the same.The pressure index of the carrying object had a good correlation with the change trend of the ecological carrying capacity index.Based on the evaluation results of ecological carrying capacity,the development of Ordos City during the study period was determined to be sustainable through the analysis of sustainable development.