Quantification of basin-scale multiple ecosystem services in ecologically fragile areas

•Lack of an approach that quantifies basin-scale ecosystem services.•Modified an existing method by introducing the regional difference coefficient.•Valued ecosystem services of a debris flow alluvial fan in Awang basin.•Ecosystem function of the water area is more significant in debris flow area.•Proposed method valuable for ecosystem services and ecological restoration. Despite the increasing awareness regarding the importance of ecologically fragile areas in maintaining human well-being, there is a lack of understanding of the comprehensive quantification of the basin-scale ecosystem services. In this study, based on risk zoning, the regional difference coefficient (RDC) was introduced into an existing method proposed by Costanza to value the ecosystem services. The modified method was then applied to value the ecosystem services of a debris flow alluvial fan in Awang basin, Yunnan, China from 2012 to 2018. The results indicated that in the debris flow area, the ecosystem service of water area is of great value; however, because of the limited area, the transformation between the adjacent land types can be easily triggered owing to human or natural influence. During this period, the ecosystem service demonstrated a downward trend, which could attribute to a decrease in the water area with a larger ecosystem service and an increase in the area of the construction land that led to the considerable depletion of the ecosystem service. The proposed modified method to value ecosystem services can be a valuable means to reflect the present situation of a basin-scale ecosystem and the effect of ecological restoration.