Multilevel modelling of impacts of human and natural factors on ecosystem services change in an oasis, Northwest China

Clarifying driving mechanisms of ecosystem services changes is key to sustainable ecosystem management. This study evaluated three key ecosystem services, including carbon sequestration (proxied by net primary production, NPP), water yield, and soil conservation in Zhanyge during 1990-2015, and applied multilevel modeling to examine the impacts of sub-watershed level natural factors and county level human factors on ecosystem services changes. The results showed the ecological vulnerable Qilian mountain area possessed high values of these ecosystem services. During 1990-2015, NPP and water yield increased, and soil conservation decreased. Results of the multilevel models indicated that natural and human factors drove ecosystem service changes in various degrees and directions and it was necessary to consider the scale dependence of the driving factors at different levels. Particularly, forest land, grassland and cultivated land expansion led to increase of NPP, water yield and soil conservation, grain productivity and agricultural machinery level had negative effects on water yield, while had positive impacts on soil conservation. Overall, it is necessary to strengthen ecological protection in the Qilian mountain area and strictly control cultivated land expansion balance to maintain sustainable development of ecosystem with comprehensively considering the effects of driving factors and local conditions.