Effect of grazing exclusion on ecosystem services dynamics, trade-offs and synergies in Northern Tibet

The relationships between different ecosystem services are key to regional ecological stability and security, and their trade-offs and synergies are affected by many factors, especially on the Qinghai-Tibet Plateau (QTP), which is susceptible to human activities. Norther Tibet, located on the QTP, has built fences for grazing exclusion in recent years. However, how grazing exclusion affect the ecosystem service variability and their mechanism remains still unclear. Based on the net primary productivity (NPP) quantitative index method, hotspot analysis, geographically weighted regression (GWR) model, this study analyzed the effects of grazing exclusion with fencing on ecosystem services dynamics, trade-offs and synergies. Results showed that the values of biodiversity conservation, water conservation and soil conservation were all higher in the fencing region than in the nonfencing region. Most counties experienced increasing trends in the fencing region with higher biodiversity conservation, water conservation in the fencing region than that in the non-fencing region from 2006 to 2015. Except for the relationship between soil conservation and water conservation in the non-fencing region in Cuoqin county in 2015, the relationships among all ecosystem services were synergistic, and the overall trends were weakening. The county number percentage with higher synergistic relationships in the fencing region than that in the non-fencing region showed gradually increasing trends. Land use intensity, grazing intensity, precipitation and altitude were the main factors that affecting spatial heterogeneity of three ecosystem services in the nonfencing region, while distance to road, distance to town, land use intensity and temperature were the main influencing factors in the fencing region. This study contributes to exploring the effect of grazing exclusion on ecosystem services and their relationships, thus providing guidance for the formulation of grassland restoration measures