Ecological compensation based on multiscale ecosystem carbon sequestration service flow

Scientific assessments of the supply, demand and flow of ecosystem services and the formulation of ecological compensation policies are important for the promotion of sustainable regional development. Based on the supply-demand ratio model, breakpoint model, field strength model, geographic information system spatial analysis and statistical methods, we assessed the supply, demand and supply-demand relationships of carbon sequestration services on the Loess Plateau for 2000, 2010 and 2020. We also analyzed the interregional flow of carbon sequestration services at multiple scales and accounted for horizontal ecological compensation. The results revealed that from 2000 to 2020, both the supply and demand of carbon sequestration services increased, with a greater increase in demand. The high-supply areas were mostly in the central and northwestern parts of the Loess Plateau, and the high-demand areas were mostly in areas other than the central part. The supply-demand ratio for carbon sequestration services declined, with a large increase in the number of deficit counties and surplus counties, mostly in the central and western parts of the study area. The flow rates of carbon sequestration services within the Loess Plateau increased. The intercounty flow rates within the same city were the highest but decreased. Decreasing intercity flow rates appeared within the same province although they initially increased. Finally, interprovincial flow rates were the lowest, but they were increasing. The outflow of carbon sequestration services from the Loess Plateau to external regions was greater than the inflow from external regions, but the outflow decreased in 2020 compared with 2010, while the inflow from external regions increased. Most cities actually received or paid less ecological compensation than that accounted for based on the basis of flow rates after considering willingness to pay and ability to pay. Moreover, the number and total compensation of cities receiving ecological compensation were greater than the number and total compensation of payers in the 44 cities within the Loess Plateau. This study provides a theoretical basis for not only understanding the spatial transfer patterns of ecosystem services at multiple scales but also formulating ecological compensation policies, thereby promoting the realization of regional sustainable development.