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

Abstract A recent study (Wolf et al ., 2010) suggests that short—lived pulses of N 2 O emission during spring thaw dominate the annual N 2 O budget and that grazing decreases N 2 O emissions during the spring thaw. To verify this we conducted year—round N 2 O flux measurements from June 2010 to May 2011 in Tianshan alpine grassland in central Asia. No pulse emissions of N 2 O were found at grazing management sites and nitrogen addition sites during the spring thaw. The contribution of the spring thaw to the total annual N 2 O 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 N 2 O emissions attributable to grazing management was not significant ( P > 0.05). Nitrogen input tended to increase N 2 O emissions at N addition sites during the grass growing season compared with those at unfertilized sites. N 2 O fluxes showed a significant correlation with air temperature and also with both soil temperature and soil water content at 10 cm depth.