The Synergy Between Ecosystem Services and Biodiversity Depends on the Ecosystem Type and Evaluation Scale

Biodiversity and ecosystem services are essential to human well-being, yet their complex interactions remain poorly understood, particularly in highly urbanized areas subject to significant anthropogenic disturbances. This study investigates the spatial relationships between biodiversity and five key ecosystem services: crop production, soil conservation, carbon sequestration, water yield, and habitat quality across the rapidly urbanizing Beijing–Tianjin–Hebei Urban Agglomeration (BTHUA). We utilize a biodiversity index based on species richness and an ecosystem services index that integrates the value of these five services to examine their spatial distribution and coupling coordination. A coupling coordination degree model is applied to assess interactions between the two systems. Our results indicate that most ecosystem services are positively associated with biodiversity, with habitat quality showing the strongest correlation. In contrast, water yield is negatively associated with crop production, primarily due to urban expansion and hydrological constraints that limit agricultural output. Coupling coordination analysis reveals stronger coordination at broader spatial scales. Land use and Average annual precipitation are identified as the dominant drivers, especially in coastal areas. These findings fill a crucial gap in understanding the spatial dynamics of ecosystem services and biodiversity, offering valuable insights for regional ecological management and policy-making.