Study On Green Land-use Of Beijing-Tianjin-Hebei Urban Agglomeration

The continuous industrialization in China intensifies the contradiction between supply and demand of resources,and increases the pressure on the ecological environment.The traditional development model has hindered the healthy development of the current economy,thus the transformation of the economic development mode is extremely urgent,while the implementation of green development is of no delay.Land,as an important carrier in resources,ecology and material space,runs through the whole process of human social and economic activities.Under the new situation of economic development,a new land-use mode is urgently needed to conform to the direction,speed and quality of social and economic development.Therefore,on combing previous land-use patterns,this study introduces the concept of green development in land-use under the current situation of our economy,puts forward the model of green land-use,and builds quantifiable evaluation models according to the implementation of theoretical analysis of green land-use on the basis of theoretical assumptions,constraints and benefit function construction.Taking urban agglomeration as a unit,this study explores the spatial distribution and evolution rules of green land-use,the overall and stage-driven mechanism,and the coupling stress relationship with economic development,specifying the characteristics of green land-use in cities at different developmental stages.The CART algorithm model in decision tree is employed to predict the future green land-use level of Beijing,Tianjin and Hebei,and the optimization Suggestions are put forward according to the specific constraints of specific cities.The main research contents,process and conclusions are as follows:Firstly,the green land-use model is proposed.On the basis of theoretical analysis,land,energy and environment are taken as endogenous economic variables to build the green land-use efficiency evaluation model.Taking Beijing-Tianjin-Hebei urban agglomeration as the research unit,SSBM model is used to evaluate and analyze its green land-use efficiency.Overall,the green land-use efficiency of Beijing-Tianjin-Hebei urban agglomeration tends to rise,with energy and environment as the main constraints.However,there is a large gap between the efficiency of each city,which is basically the same as the distribution of economic centers.There are global weak spatial positive correlation effects and local spatial agglomeration phenomena.Secondly,direct effect model and indirect effect model are constructed to analyze the driving mechanism of green land-use.The direct effect model analysis shows that the level of economic development is the main factor affecting the green land-use efficiency of Beijing-Tianjin-Hebei urban agglomeration,the intermediate effects of industrial structure optimization are not obvious,and the scientific and technological progress has masking effects.Different developmental stages require different urban development needs,and the driving factors of green land-use are also different: in the middle stage of industrialization,the main driving factor is economic growth;in the late stage of industrialization,the effects of foreign investment began to appear,with the economic development and the adjustment of industrial structure;In the post-industrial period,environmental regulations and government efforts became the main driving forces of green land-use,under the negative effects of land-use intensity and GDP per capita.Therefore,cities of different developmental stages should adopt different development strategies to promote the efficiency of green land-use.Thirdly,this study analyzes the coupling and coordination relationship between green land-use and economic development in Beijing-Tianjin-Hebei urban agglomeration,as well as the relative situation between green land-use and economic development.The analysis shows that,the grey correlation degree between the two is in the running-in range on the whole.The economic strength has the greatest promotions on green land-use,while the green land-use has restrictions on the economic development mainly through its bearing constraints and pollution influences in the process.Among them,Beijing and Tianjin have entered a coordinated and synchronous state,while the other cities are in advanced or backward improving and running-in state respectively,which also verifies the hypothesis that green land-use is an inevitable choice of the maturity of economic development,and green land-use and economic development go from interactive stress to final coordination.Fourthly,the CART algorithm model in decision tree is used to predict the future green land-use level of Beijing,Tianjin and Hebei.The prediction shows that Beijing,Tianjin,Tangshan and Shijiazhuang,which have achieved the state of efficiency,will present a downward trend in the future,while the rest of the cities will present an upward trend,indicating that the overall level of green land-use in Beijing-Tianjin-Hebei city group will present a centralized trend in the future.Accordingly,weight factors of each city are further calculated,internal mechanisms influencing and restricting the use of green land are located,and optimizing suggestions are proposed in terms of specific cities and their corresponding constraints.According to the constraints,the forecast of the developmental trend of urban land-use transformation in the future can give a better interpretation to the mechanism of green land-use transformation,a further explanation to the law of green land-use transformation of Beijing-Tianjin-Hebei city group,as well as a scientific provision for land-use planning and policy formulation of Beijing-Tianjin-Hebei city group.