Spatiotemporal Evolution And Optimal Allocation Of Construction Land Of Shrinking Cities In Northeast China

In the midst of rapid urbanization,shrinking cities are a category of municipalities that cannot be disregarded;in recent years,they have been a focal point of international and domestic urban research.During the nearly forty years of rapid economic development during the reform and opening-up process,China’s shrinking cities have encountered a paradoxical development pattern characterized by the simultaneous expansion of space and multidimensional contraction under the traditional growthist planning and land development model.The northeastern region has undergone a significant reduction in its social and economic structure since the turn of the 21 st century as a result of the combined effects of external environment change and internal transformation pressure,which have led to shrinking city agglomeration and a particularly acute incongruity between human-land relationships.The external environment changed due to a change in the national economic development pattern.The internal transformation was caused by the mineral resources and ecological environment damage resulting from the industrial structure of the transformation of lagging behind and the lack of successor industries.In this context,comprehensively sorting out the characteristics and patterns of shrinking cities in Northeast China,in-depth analysis of the characteristics of the evolution of construction land in shrinking cities,and optimization of the spatial layout of typical shrinking cities are the epitome of exploring the sustainable development of shrinking cities.Based on the relevant theoretical foundations of geography,sociology,management,and other disciplines,this paper proposes a multi-indicator shrinkage city identification model with "one main indicator,two secondary indicators ",which overcomes the limitations of previous studies that utilized a single indicator or multi-dimensional juxtaposition of indicators as a criterion for measuring shrinkage cities.Concurrently,it constructs a framework system for studying the evolution law of construction land in shrinking cities,which provides analytical paradigms and pathways for a comprehensive interpretation of the problem of land use in shrinking cities.Taking the northeastern region as an example,on the basis of identifying shrinking cities,this study conducts a systematic analysis of the scale,structure,utilization efficiency and driving mechanism of construction land in shrinking cities,and the PLUS-SD coupling model is utilized to simulate and optimize the typical shrinking city’s construction land and its internal structure.In order to provide a theoretical foundation and empirical evidence for optimizing the urban humanland relations of shrinking cities and maintaining sustainable development of construction land,and to furnish a decision-making reference for the revitalization of Northeast China.The main conclusions of this study are as follows:(1)There is a discernible upward trend in both the quantity and severity of urban contraction in the Northeast region,with the full dimension of shrinking cities appearing centrally in 2010-2020.From 2000 to 2010,only four demographically and one demographically-economically shrinking cities were identified;there weren’t any fulldimensionally shrinking cities in the Northeast.From 2010-2020,the region shows a full shift from uni-dimensional or bi-dimensional shrinking cities to full-dimensional shrinking cities.We identified 17 full-dimensional shrinking cities,of which 29.41% are mildly shrinking,47.06% are moderately shrinking,and 23.53% are severely shrinking.Spatially,the shrinking cities show a pattern of "more in the east and less in the west,higher in the north and lower in the south",and are centrally and serially dispersed in the eastern and northern regions of Northeast China.The attributes of shrinking cities are varied.When considering the size of shrinking cities,41.18% are medium-sized cities,and 29.41% are small cities of type I.With regard to location constraints,border-shrinking cities and border-"siphon"-shrinking cities comprise 23.52% of the total,while "siphon"-shrinking cities account for 35.29%.From the viewpoint of resource dependence,88.24% are resource-type shrinking cities.According to development history,64.71% of shrinking cities are oldindustrial.(2)From 2000 to 2020,more than 70% of the shrinking cities’ construction land in the Northeast region exhibited a trend of continuous growth,with sluggish expansion constituting the predominant rate of expansion.During the study period,the high rate of expansion in the region is concentrated in the distribution of the cities along the HarbinDalian economic belt,exhibiting a spatial configuration characterized by a "high in the south and low in the north" trend.Throughout the duration of the study,the construction land in the region exhibited a consistent southwestward displacement of its center of gravity.Additionally,each shrinking city possessed one or more dominant expansion wings in its construction land,and the expansion pattern tended to be concentrated from diffusion;the utilization efficiency was generally low,with weak spatial agglomeration in over 80% of the shrinking cities and an intensive utilization level that requires improvement in over 60%of the shrinking cities.The evolution of construction land in shrinking cities is a comprehensive result of the interaction of the natural environment,population-economic and infrastructure factors,and the core driving factors of shrinking cities across various study periods and types have both commonality and uniqueness.Demographic,economic,and transportation infrastructure and public service facility factors were the main core drivers of construction land expansion in shrinking cities between 2000-2010.The main core driver of construction land expansion in shrinking cities in 2010-2020 was public service facilities.(3)The information entropy of the construction land structure in most of the shrinking cities in the Northeast region exhibits a "rising-falling" trend.After 2010,the order of the cities’ construction land structure gradually increased,the diversity and equilibrium continued to decline,and the dominant role of a single dominant structure increased significantly.Public utility land,road traffic land,municipal utility land,green space and plaza land from 2000 to 2010,and public utility land,industrial land,and road traffic land from 2010 to 2020 are the growth structures,and they are the primary drivers of the rapid increase in construction land in the Northeast region’s shrinking cities.The regional shift in construction land structure shows significant spatial non-equilibrium,with high-value areas concentrated in the shrinking cities in Liao-Zhong-South and Ha-Chang urban agglomerations.(4)The coordinated relationship between population and construction land in the shrinking cities of the Northeast has progressed from "lack of coordination" to "uncoordinated",exhibiting notable stage characteristics.In 2010-2020,the "strong decoupling" of population shrinkage and growth in construction land was polarized within the region.The coordinated relationship between population and construction land in shrinking cities is a systematic process in which multiple factors interact in an integrated manner,and there are significant differences in the degree of influence of various driving factors on this coordinated relationship in different research periods.From 2000 to 2010,the relationship between population and construction land coordination in shrinking cities was predominately determined by infrastructure,living standards,and employment structure.From 2010 to 2020,it would be primarily influenced by the deteriorating efficacy of land utilization in urban construction,delayed industrial restructuring,employment outflows,and waning economic strength.(5)In this paper,Baishan City,a typical shrinking city with an uncoordinated humanland relationship,urgent spatial governance,and diverse urban attributes that can be used as the epitome of a border shrinking city,a resource-based shrinking city,and an old industrial shrinking city to improve the efficiency of construction land use,is selected as a case city.The PLUS-SD coupled model,which outperforms the PLUS model in simulation,is utilized to simulate and analyze the differences in the spatial pattern and utilization efficiency of construction land in Baishan City under the three development scenarios of natural growth,traditional planning,and smart shrinkage in 2030.The results show that under the three scenarios,the areas with more changes in each land use type in Baishan City will be mostly located at the edges of the land use category,and the dominant expansion wing of the construction land uses will extend along the southeast–northwest axis,with a significant trend of reciprocal expansion between city districts.In both the natural growth scenario and the traditional planning scenario,there will be a trend of rapid expansion of construction land in Baishan City,with a decrease in the degree of construction land intensification,and a larger area of expansion of construction land in Baishan City under the traditional planning scenario compared to the natural growth scenario.Under the smart shrinkage scenario,Baishan City will present a small increase in city construction land and an increase in the level of intensive utilization of construction land.Therefore,the concept of smart shrinkage planning can help to optimize the quantitative structure,hierarchical structure,and benefit structure of the land resources in shrinking cities.It is a scientific and feasible plan for the realization of efficient and sustainable utilization of the construction land in shrinking cities.