Research on the Coupling Coordination and Spatial Differentiation of Ecological Suitability and Economic Development in the Beijing–Tianjin–Hebei Region

Coordination between ecological suitability and economic development is essential for sustainable urban growth. This study examines the spatiotemporal evolution, spatial differentiation, and driving mechanisms of ecological–economic coupling coordination in the Beijing–Tianjin–Hebei (BTH) region from 2014 to 2023 using four cross-sectional datasets (2014, 2017, 2020, and 2023). A comprehensive evaluation framework integrating natural and socioeconomic indicators was established, combining the entropy weight method, coupling coordination degree (CCD) model, spatial statistics, and the XGBoost-SHAP machine learning framework. Results revealed stepwise improvement in CCD over the decade, with low-coordination zones declining from 82.25% to 43.52%, while medium-coordination zones became the dominant spatial component. A concentric pattern emerged, featuring high-coordination agglomeration in the Beijing–Tianjin–Xiongan core, medium-coordination transition in the peri-Beijing ring, and contiguous low-coordination zones in northern Hebei. Global spatial agglomeration followed a trajectory of decline followed by rebound, whereas local agglomeration shifted from fragmentation toward homogenization. Population density and GDP alternately dominated as core socioeconomic drivers, with natural factors playing stable constraining roles. Both factors exhibited nonlinear threshold effects: population density showed diminishing marginal returns, while GDP displayed continuously strengthening positive effects. This study offers scientific support for high-standard spatial governance and sustainable development in the BTH region and other urban agglomerations.