The response of total grassland biomass in Sanjiangyuan to future climate change scenarios

The DNDC (denitrification–decomposition) model was calibrated using 2 055 field monitoring data collected from 2005 to 2016 in Sanjiangyuan, and the model parameters suitable for the region were established. The dynamics of total grassland biomass in Sanjiangyuan were studied based on a process-based model and changes under different periods and different future climate scenarios (representative concentration pathways: RCP 4.5 and RCP 8.5) were analyzed. Therefore, the influence of climatic variables on total grassland biomass was explored, and the countermeasures of grazing and utilization of grassland in different regions of Sanjiangyuan under the future climate scenarios were discussed. Our results showed that this model could accurately capture the variation of total grassland biomass under different climates, and the model explained 69% of total biomass variation, while the RMSE was 96.414 g·m^–2; When comparing the two climate scenarios, the temperature increase in the climate scenario of RCP8.5 was higher than that of RCP 4.5, while the precipitation increase was lower; Under both the RCP 4.5 and RCP 8.5 scenarios, total grassland biomass tended to decrease significantly in the study area, with the simulated values of total grassland biomass decreasing by 16.91%～18.51% and 23.82%～26.44%, respectively. Climate change is the main factor leading to changes in total grassland biomass. Grassland management should actively respond to the potential climate change effects and formulate corresponding countermeasures to achieve sustainable development in this region.