Coupling coordination between urbanization and ecosystem services value in the Beijing-Tianjin-Hebei urban agglomeration

While urbanization has increased people's well-being, it has also caused ecological problems, such as resource shortage, land degradation, and environmental pollution. As the highest form of spatial organization at the mature stage of urbanization, an urban agglomeration (UA) can be a key area for studying this urban-ecology interaction. This study integrated the urbanization evaluation, ecosystem services value (ESV) assessment, and optimized coupling coordination degree (CCD) models to explore the coupling coordination of urbanization and ESV at the UA scale. Analyzing data from the Beijing-Tianjin-Hebei UA (BTHUA) from 1985 to 2020 revealed that: (1) urbanization continues to increase and ESV fluctuates; however, both exhibit significant spatial heterogeneity. (2) The CCD is increasing annually but remains relatively low overall; spatially, it is high in the northeast and low in the southwest. (3) The main driving factors of the CCD are urbanization rate and slope, while all five selected factors have a positive effect. (4) Government decision-making can guide the CCD. For which, the development pattern of "One Belt-Four Zones-Multi Cores" and zoning strategies for improving the CCD are proposed. Overall, these findings suggest balancing development and protection to promote the coordinated development of BTHUA and provide valuable insights for enhancing the sustainability of UA.