Research On Spatio-Temporal Changes And Analysis Obstacle Indicators Of Cultivated Land Ecological Security In Dongting Lake Ecological Economic Zone

Cultivated land is a precious basic natural resource,the source of human food and clothing,the basis of survival,and an important material basis for sustainable social and economic development.Cultivated land ecological security plays an important role in ensuring national food,social and economic security,especially in major grain-producing areas of China.The cultivated land ecological security is of greater strategic significance in ensuring national food security.Dongting lake ecological economic zone(part of Hunan)is an important grain-producing area and the second largest economic sector in Hunan province.With the acceleration of industrialization and urbanization,the phenomenon of unreasonable utilization of cultivated land occurs frequently.Regional economic development and cultivated land ecological environment protection present an unbalanced situation,and the pressure of cultivated land ecological environment protection is huge.Therefore,it is of great significance to carry out the evaluation of cultivated land ecological security and the diagnosis of obstacle factors to realize the maintenance of cultivated land ecosystem and sustainable utilization of cultivated land resources in the ecological economic zone of Dongting lake,and to build ecological and green Dongting.Based on the quantity,quality and ecological environment of Dongting cultivated land resources in Dongting lake ecological economic zone,the "P(pressure)-s(state)-r(response)" model was introduced,and 19 indexes were selected to construct the evaluation index system of cultivated land ecological security in Dongting lake ecological economic zone.Through entropy value method and comprehensive index method,the cultivated land ecological security level in Dongting lake ecological economic zone from 2008 to 2017 was quantitatively evaluated.Based on the comprehensive scores,the paper carried out the analysis of the characteristics of the changes in the time series of cultivated land ecological security in Dongting lake ecological economic zone from2008 to 2017,the analysis of the characteristics of spatial aggregation and the diagnosis of the obstacle factors of cultivated land ecological security in Dongting lake ecological economic zone,and the main conclusions are as follows:(1)from the point of temporal changes in county cultivated land ecological security,AnXiang,HanShou,ShiMen,PinJiang,eight such as TaoJiang county belong to the cultivated land ecological security level rapidly rising area,ding city,LinLi,Li County,TaoYuan,LinXiang 11 county cultivated land ecological security level in a slow rise area,and the WuLing,HeShan,WangCheng6 counties such as cultivated land ecological security levels haven’t changed much,belong to basic stability region,in general,the study period of Dongting lake ecological economic zone of cultivated land ecological security level to get a degree of improvement.(2)from the perspective of the change of cultivated land ecological security grade in the whole region,the cultivated land ecological security grade in the county went through the change process of sensitive level,critical level and relatively safe level.During the study period,the area of sensitive counties decreased from 3,603.90 hectares to 758.87 hectares,and the proportion of the area decreased from 77.83% to16.39%.The critical safety level county area increased from 785.90 hectares to3,126.02 hectares,accounting for 67.51% of the total area,up from 21.28%.The area of relatively safe counties increased from 41.25 hectares to 745.75 hectares,and the proportion of the area increased from 0.89% to 16.10%.(3)from the perspective of the change of comprehensive index of cultivated land ecological security in the whole region,from 2008 to 2017,the level of cultivated land ecological security in Dongting lake ecological economic zone has been continuously improved,with the comprehensive index of cultivated land ecological security rising from 0.4983 to 0.6483,and the grade of cultivated land ecological security rising from the critical level to the relatively safe level.The cultivated land ecological security pressure index decreased from 0.3452 to 0.1863,the cultivated land ecological security status index increased from 0.1406 to 0.1962,and the cultivated land ecological security response index increased from 0.0125 to 0.2637.(4),2008-2017,the county cultivated land ecological security space correlation analysis results show that at 0.5% significance level,the cultivated land ecological security level of global Moran’s I index(except 2008)is a spatial correlation,namely each county(city,area)the cultivated land ecological security level there is anobvious spatial agglomeration effect,according to LISA clustering figure,the main research area high value ghettos in WuLing,YueYangLou,WangCheng county,relatively developed economic level low zones are mainly distributed in the north-central pingnan,ruanjiang,we and other regions.(5)through the county from 2008 to 2017 the cultivated land ecological security system obstacle factor diagnosis,using minimum variance method combined with pressure,state and response degree scores,county cultivated land ecological security barrier will be divided into P > S > R(pressure obstacles obstacles state > > response),P > R > S disorders(pressure barrier > > response state),R > P > S obstacles obstacles > pressure > state(response),R > S > P disorders(response state > > stress disorder),S > P > R(state obstacles obstacles > pressure > response)5 kinds of resistance model.The spatial distribution change of resistance type indicates that the system response obstacle degree in the western part of the region is greater than that in the eastern part.(6)the following results were obtained through the diagnosis of obstacle factors of cultivated land ecological security in the whole region: environmental pressure is the primary obstacle factor restricting the cultivated land ecological security in the Dongting lake ecological economic zone,mainly involving the application amount of chemical fertilizer per unit cultivated land area,the application amount of pesticide per unit cultivated land area,and the application amount of agricultural film per unit cultivated land area;(2)social pressure and population pressure is an important obstacle to the ecological security of cultivated land,involving urbanization level,population density,natural population growth rate three obstacles;The social response and cultivated land quality state are also the key factors restricting the improvement of cultivated land ecological security level,mainly including agricultural science and technology personnel and the proportion of irrigated land in paddy fields.