An ecological perspective for understanding regional integration based on ecosystem service budgets, bundles, and flows: A case study of the Jinan metropolitan area in China.

Regional integration can contribute to co-occurring benefits of different parts of an urban agglomeration by managing these parts as a whole. However, current regional integration mainly focuses on the socioeconomic rather than the ecological dimension. To interpret regional ecological integration, we firstly selected six typical ecosystem services (ESs) to represent ecological benefits that potentially need to be improved by ecological integration for further analysis. Then we used ES budgets, bundles, and flows to investigate the potential, basic analysis unit, and occurring manners of ecological integration, respectively. Our results show that supply-demand mismatches were observed in all the ES types. Meanwhile, coexisting ES surpluses and deficits on the town scale were found in supporting biodiversity, soil retention, water yield, green space recreation, and crop yield, which indicates that their supply-demand mismatches can be mitigated with ecological integration. Furthermore, all the towns were classified into five spatial clusters with distinct ES budget bundles, which acted as the basic analysis unit of ecological integration. ES flows with three flow characteristic types were observed between different clusters, and all the clusters had ES provider-beneficiary relationships with each other. Based on the ES approach, we provided an ecological perspective for understanding regional integration, which has the potential to promote regional ecological sustainability.