Cao Guangmin

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

Nitrous oxide emission (N2O) 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 N2O fluxes of 2004 and 2005. The average fluxes were 2.91±0.46 and 1.97±0.58 μg/m2/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 N2O flux, while denitrification contributed about 47.15%. The N2O flux could be well captured considering the main affecting factors by a linear regression model (r2=0.663), which demonstrated that soil temperature and biomass played a large part in N2O emission, while biomass, soil organic matter and mineral nitrogen concentration could also simulate the emission. Nevertheless, warming and increasing precipitation would mitigate the emission.