Urban shrinkage and habitat quality in the Beijing-Tianjin-Hebei urban agglomeration: a regional linkage perspective on coupling coordination and network optimization

Urban shrinkage leads to population loss, economic decline, and spatial contraction, thereby exerting significant effects on urban sustainable development and the ecological environment. This study focuses on the Beijing-Tianjin-Hebei urban agglomeration (BTH) and examines the coordinated development of urban shrinkage and habitat quality from a regional linkage perspective between 2010 and 2020. First, a multidimensional urban shrinkage index was constructed, and habitat quality was assessed using the InVEST model. Then, the Local-Tele Coupling Coordination Degree Model (LTCCDM) and GeoDetector were applied to reveal the coupling coordination between urban shrinkage and habitat quality and its driving mechanisms. Finally, a coordinated development network was constructed using a gravity model, and a spatial organization pattern was proposed based on the results of complex network analysis, providing a practical framework for addressing regional imbalances. This study provides scientific support for the coordinated development of the BTH and other urban agglomerations. Key findings include: (1) The spatiotemporal differentiation of multidimensional shrinkage and habitat quality was significant. Urban shrinkage intensified over time, shifting from a dominance of relative shrinkage to absolute shrinkage, particularly in the population and spatial dimensions. The central counties of Beijing and Tianjin exhibited resistance to shrinkage, while counties in Hebei faced greater shrinkage pressure. Habitat quality improved locally, but spatial differences intensified. (2) Coordination across periods improved, shifting from “internal coordination–external incoordination” to a more balanced state. Climate stress, air pollution, aging, and landscape connectivity were important driving factors. (3) The density of the coordinated development network increased, with more integrated communities and a more multicentered nodal structure, indicating enhanced regional cooperation. However, the western and northern regions still lagged behind.