人口集聚与扩散是诠释区域形态和空间结构的重要方面,对其研究有助于理解区域空间结构特征及演变趋势。本研究使用区域密度函数考察京津冀都市圈人口集聚与扩散的特征、趋势及模式,并在其基础上建立计量模型,分析人口集聚与扩散的影响因素。多中心区域密度函数的估计结果显示,京津冀都市圈空间发展正逐步由20世纪80年代的少数核心城市主导的向心集聚阶段,向90年代的多中心集聚与核心城市腹地扩散并存的阶段转变。而且,不同层次的中心城市表现出不同的人口集聚与扩散模式,即去中心化扩散、中心增长型扩散和向心集聚。多中心区域密度函数综合考虑多个中心城市对区域人口密度分布的影响,可以更准确地反映京津冀都市圈人口集聚与扩散的特征及变化趋势。同时,本研究建立动态VPM(Varying Parameter Model)模型,考察区域中心城市的社会经济属性对人口集聚与扩散的影响。其结果显示,区域中心城市人口集聚与扩散主要受城市规模、经济发展及结构调整以及对外交通条件等因素的影响。

The distribution of population is of great importance to regional economic studies, which helps reveal the characteristics and the development trends of regional spatial structure. This paper applied the regional density function approach to study the concentration and the decentralization of population in the Beijing-Tianjin-Hebei Metropolitan Region, one of the largest extended metropolitan regions in North China. Besides, the polycentric regional density function is used to analyze the population growth patterns of the study region. Compared with the classic monocentric density function, the polycentric density function is more appropriate for modeling the modern metropolitan regions, like the Beijing-Tianjin-Hebei region, which usually presents a polycentric pattern. The estimation of the polycentric density function shows the concentration of population into the core urban centers during the 1980s, the coexistence of the concentration of population into multi-urban centers and the decentralization of population from the core urban centers during the 1990s. At the same time, it is shown that three different growth patterns for the urban centers have formed at different levels, namely, the dispersion pattern through decentralization, the dispersion pattern through growth and the concentration pattern. Finally, a dynamic varying parameter model is proposed to identify the determinants of the spatial dynamics of the population distribution and growth, which indicates that the concentration and the decentralization of population within urban centers are influenced by the size, the economic structure and the transportation facilities of urban centers and their changes.