| The environment is the place where human beings live and inhabit.With the acceleration of urbanization and the deterioration of the ecological environment,protecting the ecological environment and maintaining environmental security is a key and important research topic in the process of sustainable development.Studying the ecological security of our region is of particular importance.Located in the upper reaches of the Yangtze River,Chongqing is an important link between the "Belt and Road" and the Yangtze River Economic Belt.?t is an important ecological barrier in the upper reaches of the Yangtze River.?t has a high ecological status,rich forest resources,and important ecological service functions.Therefore,this paper is based on Chongqing.The important ecological status of the city,combined with the PSR model to construct the evaluation index system,using the grid unit as the evaluation unit,using the comprehensive index method to calculate the ecological security index of the study area and grade it,combined with exploratory spatial analysis tools and geo-detectors.The tool aims to find out the dynamic change characteristics,spatial correlation characteristics,spatial pattern differentiation characteristics,and driving mechanism of ecological security in Chongqing.The research objective is to better understand the basic characteristics and laws of ecological security changes in Chongqing.The city's ecological environment improvement put forward targeted opinions,and then enrich and promote the comprehensive research of China's ecological security evaluation.The main research conclusions of the thesis are as follows.1.Spatial and temporal evolution characteristics of ecological security in Chongqing(1)The dynamic change of ecological security indexThe average ecological security index of Chongqing from 2000 to 2015 was 0.5181,0.5292,0.5399,and 0.5316 respectively,all of which were at the critical safety level.However,from 2000 to 2015,ecological security showed a gradually better trend.From the perspective of spatial distribution,the overall ecological security level of the study area has a large spatial difference,showing a gradually decreasing trend from east to west.From the perspective of districts and counties,there are significant differences in the average ecological safety indexes among all districts and counties,among which the ecological safety indexes of Yuzhong,Tongnan,and Dadukou are relatively low,while the ecological safety indexes of Chengkou,Shizhu,Nanchuan,and Wulong are relatively large and the ecological environment conditions are relatively good.(2)The changing trend of ecological security levelThe regional ecological security level ?,namely the critical safety level,accounts for the largest proportion,and the rest are in the order of ecological security level ?,?,?,and ?.The overall ecosystem is relatively fragile.Level ?,? and ? of ecological security are mainly distributed in clusters to the west of the study area,while level ? and ? of ecological security are distributed in belts in the four mountains in central Chongqing and the areas with abundant forest resources such as the northeast and southeast of Chongqing.From the time point of view,from 2000 to 2015,the ecological security level ? and ? area is increased.The ecological security level ? increase amplitude is greater than the increase rate of the ecological security level ?,that such as returning farmland to forest and afforestation improving ecological,environmental quality policy,the implementation of the ecological security situation in the study area presents a good trend gradually.2.Spatial correlation analysis of ecological security in Chongqing(1)Trend surface analysisThe changing trend of ecological security in the study area was roughly the same from 2000 to 2015,but there were differences in the change rate.?n the east-west direction,the value of ecological security increased gradually from west to east,while the northsouth direction showed a trend of high on both sides and low in the middle.?n 2005,the changing trend of ecological security was relatively steep,while in the other three years,the change was relatively gentle.(2)Spatial autocorrelation analysisThe ecological security of the research area has a strong spatial autocorrelation.?n 2000,2005,2010,and 2015,the global Moran's ? index of the comprehensive index of ecological security was respectively 0.7977,0.8100,0.7877,and 0.7768.Ecological security composite index in the study area mainly concentrated in HH and LL area,a small amount of distributed in the area LH and HL.High concentrated areas mainly distributed in the southeast and northeast of Chongqing,and scattered distribution in its surrounding area.Low concentrated areas mainly distributed in Yuxi region and central city nine urban core area heartland.3.The spatial differentiation of ecological security in ChongqingThe distribution difference of each ecological security level in each land use type is obvious,the ecological insecurity level is mainly distributed in the construction land,the less security is mainly distributed on the cultivated land,and the ecological security and the more security is mainly distributed on the woodland and grassland.Ecological Security and elevation and slope show clear vertical differentiation.With the increase of elevation and slope,the better the ecological environment quality is,the safer the ecology will be.The differentiation of ecological security and slope direction is the least ecological security on the plain,and the ecological security from north to east to south to west presents a gradually better trend.The difference between ecological security and population density is obvious.4.Analysis of the driving force of ecological security change in ChongqingThe main driving factors for ecological security in the study area are the human disturbance,land use level,ecosystem service value,ecological resilience,biological abundance,and regional development index.The overall situation can be summarized as human and natural factors.From the rational urban layout and the improvement of the ecological environment,the ecological security of the study area will be greatly improved.The interaction between driving factors presents a non-linear enhancement,and the interaction between any two factors has a greater impact on ecological security than the single one.Through ecological exploration,the influence of each driving factor on the ecological security index can be further divided into two categories: significant and insignificant.Among them,population density,application amount of agricultural fertilizer per unit area,annual rainfall,annual average temperature,slope,topographic relief,human disturbance index,land use degree factor,and regional development index have a significant influence on ecological security index. |
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