Spatial patterns and the age profiles of rural population decline in plain agricultural areas: A case study of the Songnen Plain

Rural population is both crucial participants and beneficiaries in rural revitalization, and changes in its quantity and structure have profound impacts on agricultural and rural development. This study, based on Chinese population census data in 2010 and 2020, categorizes rural population into linked cohort, the post-1995 cohort, the post-1985 cohort, the post-1970s cohort, and the post-1955 cohort by employing the life cycle theory. Drawing on "Thünen ring" model, it classifies county-level units into core, proximal, and peripheral types according to their distance gradients from the central cities, namely, Harbin and Changchun, so as to reveal the spatial patterns of rural population decline and its age profiles across different spatial gradients. The findings show that: (1) During 2010-2020, the rural population age structure in the Songnen Plain underwent rapid changes, evolving into its later stages and trending toward fewer children and severe aging. (2) The rural population decline shows remarkable characteristics of spatial universality and all-cohort encompassing. The rural population decline intensity across different regional types exhibits a trend of initial increase followed by a decline with advancing age. Shaped by public service accessibility and employment market stability, significant disparities exist in the decline intensity among age cohorts across regional categories. (3) The age profiles disparities in rural population decline across the Songnen Plain fundamentally stem from the interplay between spatial disparities and family life cycle dynamics. This phenomenon not only mirrors the uneven allocation of regional public service resources but also underscores the contemporary transformation of intergenerational responsibilities and its profound impacts on migration patterns.