| "The mountains of gold and silver are green water and green mountains".The construction of ecological civilization is related to the future of the nation and human well-being.Ecological security is the original driving force and continuous guarantee of economic development and social progress.Land is an extremely important material carrier for human production and life.Only when the land resources are in a green and healthy state can the survival and development of human beings be ensured,the coordinated development of nature,economy and society can be realized,and the harmonious coexistence of humans and nature can be guaranteed.The Guanzhong Plain urban agglomeration is the second largest urban agglomeration in western my country,and it has an important strategic position to lead t lead the western region’s economies take-off.Guanzhong Plain urban agglomeration was officially approved in 2018,and economic development is facing unprecedented new opportunities.With the rapid development of urbanization and industrialization,the economy of various counties and districts in the Guanzhong Plain urban agglomeration has different development trends,and the ecological environment of the land is also in a different state.There are also unreasonable land development,land waste and land pollution in the area.Under the background of changes in the land ecological environment of various counties in the Guanzhong Plain urban agglomeration,if the reasons for the changes are not diagnosed,the relationship between the land ecological environment and economic development is not identified,and the land ecology is not effectively protected,the deterioration of the land ecology is bound to affect all economic and social development of counties and districts.Therefore,construct a reasonable evaluation system,use reasonable methods and models to analyze the spatial and temporal distribution pattern of land ecological security in the Guanzhong Plain urban agglomeration counties,explore the factors affecting land ecological security,and diagnose the coupling and coordination types of land ecological security and economic development in each county It is of great significance to promote the coordinated development of land ecological civilization construction and land ecological economy in the regional.In this study,based on the understanding and discussion of land ecology,human-land relationship and ecological economy,a DPSIR model was constructed from five aspects:drive force,pressure,state,impact and response.It takes 90 counties and districts in the Guanzhong Plain urban agglomeration as the research objects,and selects a total of 19 evaluation indicators,using the CRITIC method to determine the weight of the indicators,using the TOPSIS model to calculate the comprehensive score of land ecological security from 2009 to 2018 and carry out grading evaluation,and combine the spatial autocorrelation analysis and the obstacle degree model to analyze the time and space of the county land ecological security dynamic changes,spatial agglomeration state and driving mechanism,and then introduce night light data,analyze the spatiotemporal pattern of economic development and the distribution of cold and hot spots through the standard deviation ellipse and Gi*statistical method,and finally use the coupling coordination model to analyze the coupling coordination types of the land ecosystem and economic system in each county.With a view to maintaining and improving the land ecological security and economic development of the Guanzhong Plain urban agglomeration,targeted countermeasures and suggestions will be put forward.The main conclusions drawn through the research are as follows:（1）From 2009 to 2018,the land ecological security of the urban agglomeration in the Guanzhong Plain was generally at a critical safety level,showing an upward trend of fluctuations,and the land ecological security of various counties and districts showed a pattern of alternating peaks and lows,with little fluctuation.From 2009 to 2018,the land ecological security level of 90 counties and districts was basically critically safe and relatively safe,and spatially safer areas gradually gather in the middle of the Guanzhong Plain urban agglomeration.For all counties,the changes in land ecological security of the five sub-systems are relatively small.Among them,many counties show that the land ecological security value of the state sub-system is much larger than that of the other four sub-systems.（2）The land ecological security of the urban agglomeration in the Guanzhong Plain has a strong positive correlation and agglomeration in space.The level of urbanization,the erosivity of precipitation,the total power of agricultural machinery,the proportion of the tertiary industry and the afforestation area of the year are the key obstacles affecting the ecological security of the land in all counties.The overall value of Moran’s I in the urban agglomeration of the Guanzhong Plain were greater than 0 from 2009 to 2018.The value of land ecological security was spatially clustered,but the overall value of Moran’s I showed a downward trend,reflecting that the difference in land ecological security between adjacent counties in the region has increased.In the counties and districts of the Guanzhong Plain urban agglomeration,the ecological security of land is concentrated in high-high agglomeration and low-low agglomeration,with a small number of high-low and low-high agglomerations.In the past 10 years,the main threats to land ecological security have come from the three aspects of drive force,state and response.The key obstacles to land ecological security in the counties of the Guanzhong Plain urban agglomeration vary significantly.The main driving factors（higher frequency）are:the level of urbanization,the erosivity of precipitation,the total power of agricultural machinery,the proportion of the tertiary industry and the afforestation area of the year.（3）The economic development of the counties and districts in the Guanzhong Plain urban agglomeration presents a northeast-southwest spatial distribution pattern,and the regional economy manifests itself as a radiant development from Xi’an City.Compared with 2009,in 2018,the economic development of the counties in the Guanzhong Plain urban agglomeration showed an overall upward trend.The economic dispersion of counties was greater,and the overall degree of agglomeration declined.It has the characteristics of local clustering and multiple spots.The hot spots for economic development are concentrated in the cluster area with the central area of Xi’an as the core.The cold spot and the sub-cold spot are mainly distributed in the border areas of the Guanzhong Plain urban agglomeration,and the counties at the junction of Shaanxi and Gansu.（4）In the past 10 years,the coupling coordination degree of land ecological security and economic development in the counties and districts of the Guanzhong Plain urban agglomeration has shown a downward trend and then an upward trend,which is basically in a state of coordination as a whole.The degree of coupling coordination between the two in space is represented by a pattern of "high in the east and low in the west,low in the north and south,high in the middle",and it is mainly divided into two types:moderate coordination and high coordination.During the study period,the land ecological security and economic development of 90 counties and districts generally had a system lag,which is mainly manifested in the lagging economic development and the land ecological lag,and there was a shortage of counties and districts with synchronous and coordinated development. |
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