Nowadays, the reorganization of rural land-use space exhibits a dynamic process of expansion and shrinkage. Taking the Wuhan Metropolitan Area as an example, this study used the InVEST model to quantitatively assess changes in rural built-up land between 1995 and 2020 and its impact on regional carbon storage. Combined with the PLUS model, further simulations were carried out to predict the heterogeneous mechanisms of shrinkage and expansion of rural habitable space under three scenarios in 2030. The results indicate that the area of rural built-up land in the Wuhan Metropolitan Area showed an overall increasing trend, with shrinkage mainly concentrated in the Wuhan-Ezhou border, Tianmen, and southern Xiantao, while expansion displayed a decentralized point distribution. The PLUS model predicts that, in the scenario of rural built-up land expansion, a significant amount of cropland is encroached upon. This study provides a new perspective for understanding the impact of rural habitat changes on the carbon cycle. Future land management and planning should pay more attention to maintaining ecosystem services and considering the environmental effects of changes in rural built-up land layout.

The uneven distribution of populations within urban and rural built-up areas restricts balanced regional development. This study employs statistical data from 296 cities in China covering the years 2010, 2015, and 2020 to analyze the coupling coordination relationship of population density in urban and rural built-up land and its influencing factors. The findings reveal the following: (1) Throughout the study period, population density in urban built-up areas (PUL) experienced a slow increase, whereas population density in rural built-up areas (PRL) declined rapidly. (2) Spatially, high levels of coupling coordination in population density between urban and rural built-up areas are primarily concentrated in the southwestern region, particularly in Sichuan, demonstrating a trend of gradual diffusion from the core to the periphery. Overall, a southwest-high to northeast-low pattern emerged. (3) The regression results indicate that economic development, agricultural structure, public services, and urbanization significantly affect the coupling coordination of population densities in urban and rural built-up areas. Among natural conditions, both elevation and temperature show significantly positive effects. This research provides theoretical foundations and policy recommendations for promoting urban-rural integrated development and achieving regional sustainable development.