No significant nitrous oxide emissions during spring thaw under grazing and nitrogen addition in an alpine grassland.

A recent study (Wolf et al., 2010) suggests that short-lived pulses of N2O emission during spring thaw dominate the annual N2O budget and that grazing decreases N2O emissions during the spring thaw. To verify this we conducted year-round N2O flux measurements from June 2010 to May 2011 in Tianshan alpine grassland in central Asia. No pulse emissions of N2O were found at grazing management sites and nitrogen addition sites during the spring thaw. The contribution of the spring thaw to the total annual N2O budget was small and accounted for only 6.6% of the annual fluxes, with winter emissions accounting for 16.7% and growing season emissions accounting for 76.7%. The difference in N2O emissions attributable to grazing management was not significant ( P > 0.05). Nitrogen input tended to increase N2O emissions at N addition sites during the grass growing season compared with those at unfertilized sites. N2O fluxes showed a significant correlation with air temperature and also with both soil temperature and soil water content at 10 cm depth. [ABSTRACT FROM AUTHOR]