Fungi regulate response of N 2 O production to warming and grazing in a Tibetan grassland

Lack of understanding of the effects of warming and winter grazing on soil fungal contribution to nitrous oxide (N 2 O) production has limited our ability to predict N 2 O fluxes under changes in climate and land use management, because soil fungi play an important role in driving terrestrial N cycling. Here, we examined the effects of 10 yearsu0027 warming and winter grazing on soil N 2 O emissions potential in an alpine meadow. Our results showed that soil bacteria and fungi contributed 46 % and 54 % to nitrification, and 37 % and 63 % to denitrification, respectively. Neither warming nor winter grazing affected the activity of enzymes responsible for overall nitrification and denitrification. However, warming significantly increased the enzyme activity of bacterial nitrification and denitrification to 53 % and 55 %, respectively. Warming significantly decreased enzyme activity of fungal nitrification and denitrification to 47 % and 45 %, respectively, while winter grazing had no such effect. We conclude that soil fungi could be the main source for N 2 O production potential in the Tibetan alpine grasslands. Warming and winter grazing may not affect the potential for soil N 2 O production potential, but climate warming can alter biotic pathways responsible for N 2 O production. These findings indicate that characterizing how fungal nitrification/denitrification contributes to N 2 O production, as well as how it responds to environmental and land use changes, can advance our understanding of N cycling. Therefore, our results provide some new insights about ecological controls on N 2 O production and lead to refine greenhouse gas flux models.