A multiscale analysis of urbanization effects on ecosystem services supply in an urban megaregion.

The rapid and large-scale urbanization leads to drastic land-use conversion and impacts on ecosystem services. The relationship between urbanization and ecosystem services not only depends on the characteristics of the study area, but is closely related to the selected ecosystem services types and the indicators to measure urbanization level. Exploring the relationship in specific study area is necessary to support regional planning for sustainability. In this study, we analyzed the impacts of urbanization on ecosystem services from 2000 to 2010 in the Beijing-Tianjin-Hebei (BTH) urban megaregion in China. We quantified four critical ecosystem services, food production, carbon sequestration and oxygen production, water conservation, and soil retention, and identified the hotspots of ecosystem service provision. We measured the urbanization level from three aspects, namely, population growth, economic development and developed land expansion. The impacts of urbanization on the selected ecosystem services were examined at the hotspots scale and urban megaregion scale. We found both ecosystem services and urbanization level in the BTH region increased. There was an obvious spatial heterogeneity in the hotspots of ecosystem services, showing hotspots of food production aggregately distributed in the southern plain while hotspots of regulating services mainly located in the north mountainous areas with dense forest. The relationship between population growth, economic development and food production were represented by an inverse U-shaped curve, while it displayed a decreasing trend with regulating services. Both food production and regulating services decreased dramatically with urban land expansion. Additionally, the relationships between urbanization and ecosystem services were consistent across scales. Effective measures should be implemented for the hotspots of different types of ecosystem services to mitigate the loss of ecosystem services during rapid urbanization. The results can provide insights for enhancing urban sustainability in the BTH region, as well other urban megaregion with similar characteristics throughout the world.