Indirect impacts of future urban expansion on ecosystem services in the transnational area of China, North Korea, and Russia

Assessing the indirect impacts of urban expansion on ecosystem services is important for understanding the cascading effect of urbanization on the environment. However, few studies have assessed the indirect impacts of urban expansion on ecosystem services. In this study, the indirect impacts of urban expansion on ecosystem services refer to the impacts of cropland displacement on ecosystem services, which is triggered by urban expansion. Taking the transnational area of Changbai Mountain as a study area, we assessed the indirect impacts of urban expansion on ecosystem services during 2015-2050. We first quantified three key ecosystem services, that is, carbon storage (CS), water retention (WR), and air purification (AP). Then, the future urban expansion and cropland displacement were simulated by using the Shared Socioeconomic Pathways (SSPs) and the zoned Land Use Scenario Dynamics-urban (LUSD-urban) model. Finally, the indirect impacts of urban expansion on ecosystem services were assessed. The results indicated that influenced by the cropland displacement, the CS, WR, and AP will decrease by 0.03%-0.16%, 0.01%-0.06%, and 0.03%-0.16%, respectively. The Democratic People's Republic of Korea's (DPRK) side will be the foremost region of ecosystem service indirect losses. The indirect losses of ecosystem services on the DPRK's side will be significantly higher than those on the Chinese side and Russian side. Meanwhile, on the DPRK's side, the indirect losses of CS and AP will be 1.01-1.74-times and 1.01-1.67-times the direct losses of these two ecosystem services, respectively. In addition, cropland displacement will cause significant trade-offs between food provisioning services and regulation services. To promote sustainable development in this transnational area, we propose to make effective land-use policies to optimize cropland displacement and take ecosystem services as effective tools to guide land-use planning.