Scale effect on spatial patterns of ecosystem services and associations among them in semi-arid area: A case study in Ningxia Hui Autonomous Region, China.

Identifying scale effect on spatial patterns of ecosystem services and associations among them has been recognized as critical to the sustainable management of ecosystem services. We proposed a method to conveniently integrate ecosystem services of small scale into different larger scales. Taking Ningxia Hui Autonomous Region in west China as an example, we analyzed the change regularity of spatial patterns of 7 ecosystem services under 22 different scales. Further, the tradeoffs and synergies among ecosystem services across all scales were compared. The results showed that all of the 7 ecosystem services had been characterized by stable spatial cluster patterns across all of the 22 scales in our study. However, the extent of aggregation decreased with the increase of scale owing to the 'peak cutting and valley filling' process of map scale synthesis. Most of the associations among ecosystem services were robust across scales. However, there was a trend that smaller scales had more pairwise correlations than larger scales. The formation of tradeoffs and synergies among ecosystem services can be attributed to one or more of the following three factors: land use conflict or consistency, common drivers, and interactions among ecosystem services. We attribute the change of relationships among ecosystem services with scales to that the role of factors causing tradeoffs and synergies among ecosystem services may change with scales. Food supply service synergizes with all of the 3 regulating services at almost all of the scales in our study area, indicating that well managed farmlands with high net profit are beneficial to soil conservation and organic matter accumulation in semi-arid area.