バブル経済期以降の東京23区における人口変化の空間的パタ一ン

摘要

This study examines the spatial patterns of population change in the 23 Special Wards of Tokyo after the period of the bubble economy in the late 1980s. To this end, we analyze grid square data suitable for time-series analysis between 1985, when the bubble economy started, and 2005, the latest year for which data are available, using the geographic information system (GIS). After selecting major indicators representing three dimensions of the social area analysis -family status, socioeconomic status, and ethnic status-we map each indicator and make quantitative comparisons of six zones, classified by distance from the city center, and of four sectors classined by direction from the city center. The indicators used in this study are three variables representing family status (ratio of young population, ratio of elderly population, and ratio of single-person families), three variables representing socioeconomic status (ratio of blue collar workers, ratio of managers and officials, and ratio of professional and technical workers), and one variable representing ethnic status (ratio of non-Japanese people). Before analyzing these data, we examine the spatial pattern of population change in the 23 Special Wards between 1985 and 2005. This analysis reveals that a population recovery has occurred since the latter half of the 1990s in central Tokyo, where a previous population decline had continued until 1995. On the basis of this trend of population change, we examine the spatial pattern of each indicator in the social atlas. Concerning age and household composition (representing family status), spatial distribution has gradually shifted from a zonal pattern to a sectoral pattern due to the migration of nuclear families to the area surrounding the city center. The spatial distribution of socioeconomic status represented by the occupational structure maintained a sectoral pattern characterized by a contrast between the eastern and western parts of Tokyo although this distinction has blurred. In particular, the number of managers and officials in the 23 Special Wards has decreased, and the distribution shifted to a zonal pattern, which indicates a polarization of white-collar workers. The distribution of non-Japanese shows a zonal pattern in which the highest value appears in the area surrounding the city center. However, spatial autocorrelation analysis of the distribution of four major ethnic groups by nationality reveals a clustered pattern, supporting the findings of previous studies in Western countries.