Study On Evaluation Of Land Use And Ecological Security Change In Changsha City

Land resources are the basic materials and labor objects for human production and life,the development and utilization of land resources has always run through the process of human social and economic development.In recent years,with the continuous advancement of urbanization,population keeps increasing and social economy develops rapidly,the way people use land resources is constantly changing,and irrational land use happens frequently and leads to a series of ecological problems.These ecological problems have a negative impact on the regional land ecological security,and then lead to a potential ecological crisis.In this context,it is of great significance to study the land use change and land ecological security in the region,and to analyze the relevant factors causing the regional land ecological security crisis.Taking Changsha City as an example,this paper studied the land use change and land ecological security evaluation in the study area from the following three aspects:(1)the land use situation of Changsha City and each district(city,county)in different periods was obtained through the interpretation of Changsha four periods(2007,2010,2013,2017)remote sensing image data,and on this basis,the scale change,structure change and degree change of land use were quantitatively explored and analyzed;(2)this paper analyzed the influence mechanism of landecological security change,constructed the evaluation index system of land ecological security by using DPSIR(" Drive force-Pressure-State-Impact-Response " model)model,and used entropy weight method to weight the evaluation indexes of each criterion sub-system;(3)the improved TOPSIS method was used to analyze and calculate the land ecological security index,the change of land ecological security in different periods was discussed by using CFSFDP(a fast clustering method),the correlation between land use change and ecological security was analyzed by cosine similarity method.The findings of this paper were as follows:(1)From 2007 to 2017,in terms of the change range of land use scale,except for construction land,the cultivated land,woodland,water area,water conservancy facilities land and other land in Changsha City showed a trend of decreasing area;from the perspective of the change speed of land use scale,the change speed of land use scale in Changsha City showed a gradually decreasing trend;from the perspective of the change of land use structure,the information entropy value decreased sharply first and then gradually increased,and the land use structure of Changsha tends to be more balanced gradually,the order degree of land use in 2007-2010 is better,and the land use structure is relatively stable;from the perspective of the change of land use degree,the comprehensive index of land use degree in Changsha City from 2007 to 2017 wasrelatively large,and the land use degree of Changsha City was on the high side,which was in the development period and showed a trend of gradual increase.(2)From 2007 to 2017,the land ecological security index of Changsha City was mainly in three ecological security levels: unsafe level,less safe level and critical safe level,and the overall land ecological security level was low.From the perspective of the five sub-systems,the driving force system of Changsha City showed an upward trend in the study period,and the land ecological security index fluctuated in the range of unsafe and safer levels;the land ecological security index of the pressure system showed a gradual decrease trend,while the state system ecological security index showed an upward trend;the ecological security index of the impact system decreased from 2007 to 2010,but increased in other years;the ecological security index of the response system was generally stable,mainly fluctuated among the less safe levels,and the overall change was not significant.(3)By using CFSFDP and cosine similarity method,the results showed that although the average ecological security index of each land ecological security cluster in Changsha City decreased first and then increased,the difference among different clusters continued to decrease,and the coordination value between the land ecological security index of each district(city,county)and the land use change gradually decreased,but coordination enhanced.It was found that the main reasons for the gradual decrease of land ecological security differences among districts(cities and counties)were ecological protection,investment in environmental governance and intensified supervision of pollutant treatment.The correlation degree of land ecological security and land use change in each district(city,county)was gradually reduced,which was related to the measures of Changsha City,such as greatly reducing the emission of main pollutants,promoting the comprehensive improvement of rural environment,promoting environmental protection education and publicity,and enhancing public awareness of environmental protection.