Quantitative assessment of the supply, demand and flows of ecosystem services in the Yangtze River Basin, China

Ecosystem service flow is essential for transporting, transforming, and maintaining ecosystem services and connecting supply and demand. This study attempted to quantitatively assess the supply and demand flows of ecosystem services in the Yangtze River Basin in 2000, 2010, and 2020; assess the evolution of the spatial patterns of ecosystem service flow at the provincial, watershed and urban agglomeration scales; and design a zoning standard for ecosystem service flow. The results showed as follows. 1) Between 2000 and 2020, the Yangtze River had a progressive drop in its freshwater supply, water conservation service and carbon sequestration service flows. The decline rates for these services were measured at 10.90%, 11.11%, and 5.17%, respectively. The climate regulation service flow exhibited a pattern of initial fall followed by a subsequent increase, characterized by a decline rate of 35.53%. 2) The lowest was the ecosystem service flow in the lower reaches of the Yangtze River and the Yangtze River Delta urban agglomeration. Freshwater supply service flow and water conservation service flow were the highest in the upper reaches of the Yangtze River and the Chengdu-Chongqing urban agglomeration. Carbon sequestration service flow and climate regulation service flow were the highest in the middle reaches of the Yangtze River Basin and the urban agglomeration in the middle reaches of the Yangtze River. 3) From 2000 to 2020, the change ratios of the area proportion of the confluence, flow, and outflow areas in the Yangtze River Basin were 1.06, 3.17, and 0.86, respectively. The results of this research could offer decision support for regulating ecosystem services in the Yangtze River Basin, promoting sustainable regional development and achieving rational use of the basin resources.