Spatial and temporal patterns of supply and demand risk for ecosystem services in the Weihe River Main Stream, NW China

The rapid development of society and economy in the post-industrial era has exacerbated the spatial matching contradiction between the demand of humans and the supply of the natural environment, while ecosystem service (ES) as a bridge linking nature and society, identifying and assessing its supply–demand risk, was beneficial to ecosystem management and promoted regional high-quality development. Based on the data of multi-source remote sensing and statistics, the supply and demand levels of four ESs, which contain food supply, carbon storage, soil conservation, and water yield in the main stem of the Weihe River in 2000, 2010, and 2020, were quantitatively measured. The spatial and temporal analysis of the supply, demand, and supply–demand ratio of each service was carried out using spatial mapping. The spatio-temporal pattern of the supply–demand risk was recognized by the method of spatial overlay, which means overlaying the supply and demand for material quality, ratio, trend, and the degree of trade-off coordination together between each service. The results showed that (1) the demand for water yield decreased slightly while the demand for food and the supply of carbon storage remained stable. In addition, the supply and demand of other services showed an upward trend. (2) The spatial distribution of the supply–demand ratio of each service shows “high in the south and low in the north” and “high in the east and low in the west,” among which the supply–demand ratio of carbon storage is decreasing. (3) The overall supply–demand risk of soil conservation in the study area is low with characteristics of small range and high degree, the risk distribution characteristics of the other services are high in the east and low in the west, and the risk is high in the city center and low around. Otherwise, the supply–demand risk of food supply showed a downward trend, the risk of carbon storage showed an upward trend, the risk of soil conservation remained stable, and the risk of water yield showed a significant downward trend. Based on static supply–demand risk identification, this study assesses supply–demand risk over two periods and analyzes the trend of supply–demand risk changes over time. It clarifies the extent and direction of supply–demand risk shifts, as well as provides improved theoretical support for ecosystem service management.