GIS-based analysis for hotspot identification of tradeoff between ecosystem services: A case study in Yanhe Basin, China

Although the quantification and valuation of ecosystem services have been studied for a long time, few studies have specifically focused on the quantification of tradeoffs between ecosystem services and tradeoff hotspots. Based on previous studies of ecosystem service assessment, we proposed a feasible method to analyze the tradeoffs between ecosystem services, including determination of their relationship, quantification of tradeoffs, and identification of tradeoff hotspots. Potential influencing factors were then further analyzed. The Yanhe Basin in the Loess Plateau was selected as an example to demonstrate the application process. Firstly, the amounts of net primary production (NPP) and water yield (WY) in 2000 and 2008 were estimated by using biophysical models. Secondly, correlation analysis was used to indicate the tradeoffs between NPP and WY. Thirdly, tradeoff index (TI (NPP/WY)) was established to quantify the extent of tradeoffs between NPP and WY, and the average value of TI (NPP/WY) is 24.4 g/(mm center dot m(2)) for the Yanhe Basin between 2000 and 2008. Finally, the tradeoff hotspots were identified. The results indicated that the area of lowest tradeoff index concentrated in the middle part of the Yanhe Basin and marginal areas of the southern basin. Map overlapping was used for preliminary analysis to seek potential influencing factors, and the results showed that shrub was the best suited for growing in the Yanhe Basin, but also was a potential influencing factor for formulation of the tradeoff hotspots. The concept of tradeoff index could also be used to quantify the degree of synergy between different ecosystem services. The method to identify the tradeoff hotspots could help us to narrow the scope of study area for further research on the relationship among ecosystem services and concentrate on the potential factors for formation of tradeoff between ecosystem services, enhance the capacity to maintain the sustainability of ecosystem.