Dominant process and mechanism of nitrous oxide flux in an alpine meadow on the Tibetan plateau

摘要

Nitrous oxide emission (N_2O) and its main process in a Kobresia humillis meadow were measured by acetylene inhibition during the growing season in 2009, and the DNDC model was validated by the N_2O fluxes of 2004 and 2005. The average fluxes were 2.91+0.46 and 1.97+0.58 |ug/m~2/h from nitrification-denitrification and soil denitrification process, thus indicating that the potential nitrification might be the dominant process in the alpine meadow. DNDC model also revealed that nitrification contributed 52.85% to N_2O flux, while denitrification contributed about 47.15%. The N_2O flux could be well captured considering the main affecting factors by a linear regression model (r~2=0.663), which demonstrated that soil temperature and biomass played a large part in N_2O emission, while biomass, soil organic matter and mineral nitrogen concentration could also simulate the emission. Nevertheless, warming and increasing precipitation would mitigate the emission.