增长下的收缩:长三角城市群局部收缩的演化分析

Shrinkage under Growth:Evolution Analysis of Local Shrinkage of Yangtze River Delta Urban Agglomeration

近年来,“流空间”效应逐渐重塑区域城市体系,使得快速城镇化地区的部分城市发生相对收缩。长三角城市群整体增长区域内部的局部收缩现象有其特殊性与普遍性。本研究基于“人口运动”的视角,着重关注人口流动的特征与本质,构建以人口为核心的收缩测度标准,通过分析人口规模增长、人口流动状态以及人口变化趋势三项指标的增减变化情况及组合关系,将长三角城市群各区县单元的发展状态划分为绝对增长、发展型相对收缩、衰退型相对收缩与绝对收缩四种类型,进而识别增长与收缩的演化特征,并根据人口流动的驱动机制揭示在城市发展的不同阶段收缩发生的动因与机制。研究结果显示:第一,就各区县单元发展状态的类型占比而言,长三角城市群依次经历了以绝对收缩和衰退型相对收缩并存、绝对收缩、发展型相对收缩为主体的三个阶段;从地理分布上看,增长单元主要以上海、南京、杭州等核心城市及其近圈层区域为空间载体,绝对收缩、发展型相对收缩以及衰退型相对收缩的空间分布呈现出阶段性波动特征。第二,人口流动受行政机制与市场机制驱动。伴随着市场机制主导下的就业供给变革以及行政机制主导下的就业环境优化,长三角城市群流动人口的地理分布呈现出鲜明的阶段性特征,进而表现为增长与收缩的差异化演化。

In recent years,the effect of"space of flows"has gradually reshaped the regional urban system,bringing a relative shrinkage in the development of some cities in rapidly urbanizing areas.In this context,the local shrinkage phenomenon under the growing Yangtze River Delta urban agglomeration has its particularity and universality.Based on the perspective of"population movement",this researchfocuses on the characteristics and nature of population mobility,and constructs a populationcentric shrinkage measurement standard.By analyzing the growth and shrinkage relationship of the three indicators(population growth,population mobility,and demographic trends),the development status of each district and county unit in the Yangtze River Delta urban agglomeration is defined as four types,including absolute growth,growth-type relative shrinkage,declining-type relative shrinkage,and absolute shrinkage.The study then identifies the evolutionary characteristics of growth and shrinkage,and reveals why the shrinkage occurs in each stage according to the driving mechanism of population flow.The research shows:first,the shrinkage pattern of the Yangtze River Delta urban agglomeration has experienced three stages,with absolute shrinkage and declining-type relative shrinkage,absolute shrinkage,and development-type relative shrinkage;from the geographical distribution,the growth units are mainly core cities such as Shanghai,Nanjing and Hangzhou as well as their nearby regions.The spatial distribution of absolute shrinkage,growth-type relative shrinkage and declining-type relative shrinkage is with periodic changes;second,the population flow is driven by administrative and market mechanisms.Along with the employment supply reform led by the market mechanism and the employment environment optimization led by the administrative mechanism,the geographical distribution of the floating population in the Yangtze River Delta urban agglomeration presents distinct periodic characteristics,and then manifests the evolutionary characteristics of growth and shrinkage.