[Trade-off and synergy among ecosystem services and the influencing factors in the Ziwuling Region, Northwest China.].

Ecosystem service (ES) bundle is a combination of various ecosystem services, serving as an indicator for the trade-off or synergy relationship among ecosystem services. Identifying the trade-off and synergy within ecosystem service bundles is helpful for realizing regional management and policymaking at the ES-bundle level. In this study, based on the InVEST model, the spatial composition, trade-off, and synergy of ES bundles, and their influencing factors were clarified using correlation analysis, cluster analysis, principal component analysis, and redundancy analysis. The results showed that the ESs in the Ziwuling Region (ZWLR) were generally improved from 2000 to 2017. The high-value area of soil conservation was concentrated in the northern part of the ZWLR, whereas other high-value areas of ESs were concentrated in the central and southern parts. According to the results of the cluster analysis, the ZWLR could be divided into four ES-bundles at pixel level. There was a strong tradeoff between water yield service and soil conservation in the core protected bundle, and a strong tradeoff between habitat quality, water yield service and food production in grain production bundle. The relationship between ESs in ecologi-cal transition bundle and ecologically fragile bundle was dominated by synergetic relationship. The ESs were affec-ted by both natural conditions and human activities. Vegetation cover, precipitation, and elevation had positive effects on the ESs, while temperature, the proportion of construction land, and population density had negative effects.