| As the basis for the development of all economic and social activities,land plays a decisive role in human daily life.Especially in the era of rapid economic development,social modernization and continuous progress of science and technology,problems such as environmental pollution,imbalance of land pattern,which seriously affect the life of human beings and the utilization of sustainable resources for social development.In the face of such a severe situation,it is of great value and significance to make a reasonable evaluation of the ecological security of land and make accurate prediction of the future through scientific research on the ecological security of land.This is very important to ensure the coordinated development of the society,promote the sustainable use of land resources and pronstruction of ecological civilization in the region.Based on the Bohai Rim Economic Zone Bridge and one of the central cities along the?Belt and Road?,Hohhot was selected as the research area.According to relevant research at home and abroad,the relevant statistical data and RS technology reflecting the land ecology of Hohhot were selected and calculated by NDVI,WET,The LST and NDBSI parameters are composed of 30 safety indicators through the RSEI index synthesized by the principal components.The index weights are determined by AHP,objective entropy method and game theory method,and the index system of land ecological security evaluation is constructed based on DPSIR-EES model.Then,using impact TOPSIS method and RSEI index,according to the different situations of urban areas and county,respectively,revealed the evolution trend of remote sensing ecology and land ecological security,and further used the obstacle degree model to analyze the characteristics of land ecological security evolution in each district According to the classification of characteristics,the spatial autocorrelation analysis of the overall land ecological security situation in Hohhot was carried out using GIS technology.Finally,the basis function neural network model RBF with high simulation accuracy was used to predict RSEI and land ecological security.The main conclusions are as follows:(1)Overall,the land ecological safety value of Hohhot kept increased from 2009to 2018,the D~+gradually decreased and the D~-gradually increased,and the safety value approached the positive ideal solution.Among them,the degree of C in urban area increased from 0.4573 to 0.6709 in 2009-2018,the safety level increased from"critical level"to"satisfactory level",while the county level increased from 0.3736 to0.5804,and the safety level increased from"risk level"to"critical level".In the development of overall land ecological security,the influence of various indicators is that the negative factors have been reduced.Specifically,the negative factors in urban areas from 2009 to 2013 mainly include the urbanization rate,the use of fertilizers and pesticides,etc.From 2013 to 2018,the negative factors mainly include population size,land surface temperature,etc;From 2009 to 2013,the negative factors in county mainly include the number of livestock and Energy consumption per unit of GDP.From 2013 to 2014,the negative factors mainly include population number and industrial wastewater discharge.From 2014 to 2018,the negative factors mainly include vegetation coverage and the number of industrial units.The influencing factors of land ecological security in urban areas and county are different and similar to the situation development.The main manifestations are that urban modernization develops faster,vegetation coverage has a greater impact on the environment,and wet is higher.The surface temperature in county is higher,and the development of agriculture and animal husbandry is greater.In the performance of the criteria,the driving force is different from the development of the status criteria,and the urban ecological security changes in the urban area are more volatile than those in county;the pressure criteria and the correlation between the criteria levels are similar.At the same time,it can be seen that the development of the natural ecological situation and the land ecological security situation are different,indicating that the development of the land security ecology does not represent the natural ecology and has the same trend.(2)In the case of obstacle resistance to land ecological security at each criterion level,the difference among urban codes remained basically the same from 2009 to2018.The county took 2014 as the node after which the driving criterion and pressure kept upward,while the influence criterion and response decreased.The state criterion began increased from 2017.Among all the indexes,the indexes with fewer obstacles to the change of land ecological security in Hohhot are per capita GDP and per capita park green area.The major indexes are industrial wastewater discharge and urbanization rate.Taking 2009to 2013 as the first stage and 2013 to 2018 as the second stage,the obstacle resistance was divided into districts.In the first stage of each urban,the main obstacle index is industrial water and gas emissions,clean energy utilization rate,etc.while the second stage was mainly sewage discharge,urbanization rate,etc.In the first stage of each county,the main obstacle index is the proportion of tertiary industry,the number of medical beds,etc,and the second stage is mainly the pollution of agricultural and livestock number,sewage discharge,etc.It can be seen that the most important impact on the land ecological security of various districts and counties in Hohhot is the economic development represented by the pressure criterion.(3)In 2009,2014,2018,3 period in global spatial autocorrelation analysis Moran'I index value of 0.3620,0.1072,0.0499,respectively,was a positive correlation suggests that Hohhot land ecology safe space,global land ecological safety of spatial correlation is obtained by a scatter diagram is reduced.In the local spatial autocorrelation,through Hohhot 2009,2014,2018,3 local land ecological security gathering for LISA,the situation of land ecological security in Hohhot city has developed from obvious spatial autocorrelation aggregation between the urban area and the county to insignificant aggregation.The overall development towards balance,and the districts land ecology safe difference is narrowing.(4)In the 2019-2021,Hohhot city remote sensing ecological situation dropped to0.503 after up to 0.561,still in the"critical level";County remote sensing ecological index from 0.422 to 0.535 step by step,the whole is more stable than the city.In terms of land ecological security,the urban area keeps the same state of about 0.66.County increased slightly from 0.624 to 0.641,with a slow upward trend at the?satisfactory level"boundary.On the whole,the land ecological security of Hohhot city will increase slowly from"critical level"to"satisfactory level"in the future,but the situation of land ecological security and the natural ecological still do not reach the ideal state.Therefore,it is necessary to carry out targeted land ecological security protection work according to the current specific problems in the future development,so as to reach the ideal state as soon as possible. |
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