Study On The Spatiotemporal Change Of Urban Land Use Efficiency And Its Influencing Factors In Northwest China

Urban land is not only the carrier of urban economic activities,but also the basic living space of urban residents.Urban land utilization efficiency has a profound impact on the level of urban land intensive use and the coordinated development of economy and society.For a long time,there has been a problem of large population,less land and insufficient land resources in China.Since the reform and opening up,with the rapid development of urbanization,urban construction land expands rapidly.Some cities are expanding outward in the form of "big pie".By the end of year 2018,China's urban construction land area was 56100 square kilometers,about 7.80 times that of year 1981,and the urban expansion coefficient(land use growth rate/population growth rate)was as high as 2.17,which is far higher than the international ideal coefficient of 1.12.Northwest China has a vast territory,fragile ecological environment,and because of the climate,topography and water and soil resource conditions,there are less land for urban construction.However,although the available land in the Northwest is less,compared with other regions,the urban land use level in the Northwest is more extensive.In addition,after a long period of rapid development,the level of economic and industrial development in the eastern region has reached a higher level.Under the background of speeding up the formation of a double cycle pattern and the development of the national industrial chain,with the rising costs of land,human resources and environmental constraints in the eastern region,it is necessary to transfer the industry and technology to the backward areas in the northwest,which also gives the urban land in the northwest new pressure.The research of the urban land use efficiency in Northwest China is of great significance for the economical and intensive use of land in Northwest China,narrowing the gap between the East and the west,improving the ecological environment in Northwest China,and boosting the high-quality development of Northwest China.In view of this,on the basis of expounding the scale,structure,benefit and other land use status of urban land in Northwest China,this paper first constructs the theoretical analysis framework and index system of urban land use efficiency,and makes an objective evaluation of urban land use efficiency of 39 cities in Northwest China from 2004 to 2018 by using Super-SBM model,GML index and efficiency loss model.Then,combining static and dynamic,time and space,the paper analyzes the differences,temporal evolution,spatial correlation and spatial-temporal dynamic characteristics of urban land use efficiency in Northwest China.Moreover,this paper establishes the theoretical analysis framework of the influencing factors of urban land use efficiency,identifies the specific influencing factors,analyzes the mechanism of each influencing factor on urban land use efficiency.Finally,this paper constructs Tobit model and spatial econometric model to empirically test the influencing factors of urban land use efficiency in Northwest China,and the conclusions and suggestions are drawn.The main conclusions are as follows:(1)The urban land use efficiency in Northwest China is at a low level.From2004 to 2018,the overall trend of urban land use efficiency is fluctuating and rising,and the change trend is similar to the "N" curve.In 2018,the high efficiency values gather in the southeast of Northwest China,and the agglomeration of urban agglomeration is enhanced.During the study period,the growth rate of urban land use efficiency in provincial capital central cities is the fastest,followed by resource-based cities,and the growth rate of other cities is the slowest.From the perspective of efficiency loss model,the redundancy rate of labor input,land input and environmental pollution in Northwest China is relatively high,and the deficiency rate of environmental benefits is relatively large,while the deficiency rate of economic benefits and social benefits is relatively small.(2)From 2004 to 2018,the difference of urban land use efficiency in Northwest China is significant,which first decreases rapidly and then rises slowly.The difference between groups is very small,while the difference within groups is absolutely dominant.Moreover,the difference of the efficiency level in resource-based cities is the largest,followed by provincial capital cities,and the smallest in other cities.The kernel density function curve reveals that the urban land use efficiency in Northwest China has the characteristics of polarization and spatial disequilibrium.The agglomeration type is low value agglomeration at first,and then high value agglomeration.The evolution characteristics of provincial capital central cities,resource-based cities and other types of cities are quite different.The results of Markov chain transfer show that there is a "club convergence" phenomenon in urban land use efficiency in Northwest China,which weakens after 2012.The probability of maintaining the efficiency level in the "low" and "high" types is the largest,the probability of upward transfer is greater than that of downward transfer,and the probability of jump transfer is smaller.(3)The urban land use efficiency in Northwest China has a significant spatial correlation,and the local spatial correlation presents a state of "small aggregation,large dispersion".In2018,the aggregation area will be closer to the southeast of Northwest China.The land use efficiency of resource-based cities has a more dynamic spatial structure,followed by other cities,while the spatial structure of provincial capital cities is more stable.(4)The regression results of Tobit model show that there is a "U" curve relationship between the economic development level and urban land use efficiency in Northwest China.The upgrading of industrial structure,the increase of population density,the introduction of foreign capital and the improvement of transportation infrastructure will significantly promote the improvement of urban land use efficiency in Northwest China.However,the urbanization of land,the level of environmental regulation,the proportion of industrial land and the proportion of facility land have a negative impact on the efficiency of urban land use in Northwest China.The proportion of residential land and the level of land marketization have no obvious impact on the urban land use efficiency in Northwest China.There are differences in the influencing factors of urban land use efficiency among capital cities,resource-based cities and other cities in Northwest China.(5)The spatial econometric model shows that there is a positive spatial spillover effect of urban land use efficiency in Northwest China.Considering the spatial spillover effect,the regression results of population density and land urbanization level change from significant promotion and significant inhibition in Tobit regression to insignificant in the spatial econometric model,respectively.The effect of other factors are similar to that in Tobit regression results.(6)According to the conclusion of this paper,the policy recommendations to promote the efficiency of urban land use in Northwest China are summarized as follows: first,control the land supply area and realize the internal tapping of the stock of construction land;second,to play the gathering role of urban agglomerations and promote the "high-high" gathering of urban land use efficiency;third,reduce pollutant emissions and reduce the burden of urban land;fourth,continue to promote the upgrading of industrial structure in the northwest region and orderly undertake the industrial transfer in the eastern region;fifth,improve the construction of transportation facilities in the Northwest,and further expand the level of opening up;finally,to implement classified policies according to local conditions and according to the differences among various cities.