Construction land expansion and influencing factors of typical river valley cities in Northeast China: Taking Jilin City as an example

Jilin City is a typical river valley city in Northeast China.In this paper,the authors studied the spatial and temporal expansion characteristics of the built-up areas in Jilin City from 1990 to 2020 using the analysis of expansion speed and strength,fractal dimension,barycenter coordinate transfer index and sector analysis.The ultimate-goal is to analyze the driving and restrictive factors that affect the spatial expansion of river valley cities.The results indicate that(1)the expansion speed of urban land in Jilin City has been re-latively slow in the past 30 years,while only slightly faster in 2010–2020;(2)in the spatial dimension,Jilin City mainly expanded to the south,then to the west,and extensive expansion has resulted in complex mor-phology with little stability and compactness;(3)the expansion is affected by multiple factors,of which the positive factor is industrial development,while the restrictive factors include natural factors,population loss,etc.This study provides a case for the formulation of land use policies and land space planning in river valley cities.

不同类型城市建设用地扩张驱动机制比较研究——以京津冀地区为例

Different types of urban construction land are different in terms of driving factors for their expansion.Most existing studies on driving forces for urban construction land expansion have considered the construction urban land as a whole and have not examined and compared the differentiated driving forces for different types of construction land expansion.This study explored the differentiated driving mechanisms for two types of urban construction land expansion by selecting key driving factors and using spatial econometric regression and geographical detector models.The results show that there are significant differences in the driving forces for expansion between the two types of urban construction land.The driving factors of urban land expansion do not necessarily affect industrial parks.And the factors acting on expansion of both types are different in influence degree.For urban expansion,economic density growth,the value-added growth of tertiary industries,and proximity to urban centers have a negative effect.However,urbanization levels and value-added growth of secondary industries have a positive effect.The explanatory power of these factors is arranged in the following descending order:value-added growth of tertiary industries,value-added change of secondary industries,urban population growth,economic density growth,and proximity to urban centers;road network density has no significant effect.For industrial parks expansion,the value-added growth of secondary industries and road network density has a positive effect,while economic density growth has a negative effect.The explanatory power is arranged in the following descending order:value-added growth of secondary industries,road network density,and economic density growth.The findings can help implement differentiated and refined urban land use management policies.

2000-2020年中国建设用地扩张侵占耕地的时空特征及其与粮食产量的空间关系

Construction land expansion is a key driver of urbanization and industrialization,yet it poses the risk of losing farmland and cascading impacts on food supply.The spatial char-acteristics of farmland occupied by construction land and its association with grain yield in China were unclear.We analyzed the characteristics of farmland converted into construction land,and its relationship with grain yield in China for 2000-2020.Construction land increased in area in central and western regions of China,and farmland decreased in area in south-eastern China.The expansion of construction land in the North China Plain,Northeast China Plain,and the Loess Plateau,occurred at the expense of farmland.Except the southeast coast of China,grain yield increase was only weakly dependent on farmland area.Patterns in which farmland was converted into construction land and grain-yield change were highly coupled in southeastern coastal China,Sichuan Basin,Shandong Peninsula,and the Hu Huanyong Line.It should be noted that expansion in construction land area does have some influence on grain production;ultimately it is greatly affected by yield per unitarea.