Neglected idle rural residential land (IRRL): A challenge in achieving rural restructuring in metropolitan suburbs

Idle rural residential land (IRRL) is an important manifestation of changes in the human-land relationship during rural development. Studies on this topic are an important field in the study of sustainable land use, but quantitative analyses of IRRL in the academic community are still lacking. In this paper, we take the Pinggu, which has rapid urbanization, to analyse the spatial differentiation of IRRL and explore the spatial differentiation in the impact of different factors on IRRL. Results showed that IRRL was a common phenomenon in metropolitan suburbs with rapid urbanization. It had a spatial pattern of "one belt, three cores" in Pinggu, and its scale decreased from southeast to northwest. Industrial areas, semi-mountain ecotourism areas and urban fringe areas were the high-incidence areas of IRRL, while the idle rate of rural residential land in mountainous areas and plain agricultural areas was relatively low. The IRRL was the result of a combination of different factors, and there were differences among the different factors and regions. The transfer of rural labour, non-agriculturalization of industrial structure and mode of production and lifestyle caused by urbanization and industrialization were the major driving forces, and the lagging village planning and imperfect land use system increased the risk of IRRL. Our study contributes to filling the gap in quantitative research on IRRL to enrich the land use research system by exploring the interaction between humans and land in rural areas and thus has significance for rural restructuring and sustainable use of land in China.