Simulation and spatiotemporal dynamic analysis of air-mediated ecosystem service flows: A case study of Guanzhong Plain urban agglomeration

Analyzing the relationship between supply and demand of ecosystem services (ESs) from a spatiotemporal flow perspective is crucial for in-depth insight into flow process of ESs, and ensuring regional ecological security, optimizing resource allocation, and promoting sustainable development. However, previous studies have primarily focused on the flow of ecosystem service mediated by tangible substances (e.g., water, soil, animals etc.) with specific physical channels, the flow of ecosystem services mediated by intangible carriers (especially by air) remain rare and are lack of methods. Thus, taking the Guanzhong Plain urban agglomeration (GPUA) as a case, we proposed a flow analysis framework for air-mediated ecosystem service flows (AMESFs), quantified the supply–demand relationship of five ESs, simulated the air-mediated ESs flow field, determined the flow direction, volumes and paths, and analyzed their spatiotemporal dynamics. The results showed significant spatial mismatches of ESs in GPUA. High surplus areas were primarily distributed in forest-covered mountainous regions, while high deficit areas were concentrated in the cultivated regions of the Fenwei Plain and parts of the Loess Plateau, particularly in urban and adjacent areas. The flows of above ESs exhibited a similar pattern with minimal interannual variation during 2000–2020. Overall, five primary flow pathways were identified, extending from the northeastern and southeastern parts of GPUA toward the west, northwest, and southwest. Although the total supply of services was greater than the total demand, most of surplus service flowed out of the study area and the demand was not satisfied locally. The AMESFs were predominantly driven by the local prevailing wind rather than the supply–demand relationships. The framework is crucial for revealing the spatial flow characteristics and dynamic processes of ESs mediated by air and applicable to other regions. That also provides an assessment method for regional air pollution prevention and control, and green infrastructure development.