Simulation and prediction of nitrous oxide emission by the water and nitrogen management model on the Tibetan plateau

Process-based simulation models have been used to assess the characteristics of N₂O emission and to examine the potential impacts of climate change in grassland ecosystems. Temporal N₂O fluxes from the soil-atmosphere interface were monitored in this study continuously for two years by using flux chamber measurements and were simulated by using the water and nitrogen management model (WNMM_NSWDPI version) on the Tibetan plateau. The model predictions of N₂O flux in an alpine meadow agreed well with the observed values in 2013 and 2014 at daily and monthly scales. Annual emissions of the model output and the measured data agreed closely with lower than 4% relative deviation. Therefore, we concluded that the model captured the key driving process of N₂O formulation in which nitrification was the predominant process, contributing to 72.8% and 64.8% in 2013 and 2014, respectively. The average annual N₂O emission flux from 1961 to 2014 was 2.02 ± 0.04 kg N₂O-ha^-1. We further identified that future moderately increases in precipitation could partially reduce the positive response of N₂O flux to global warming on the Tibetan Plateau.