Nitrogen addition turns a temperate peatland from a near-zero source into a strong sink of nitrous oxide

Peatlands, as important global nitrogen (N) pools, are potential sources of nitrous oxide (N2O) emissions. We measured N2O flux dynamics in Hani peatland in a growing season with simulating warming and N addition for 12 years in the Changbai Mountains, Northeastern China, by using static chamber-gas chromatography. We hypothesised that warming and N addition would accelerate N2O emissions from the peatland. In a growing season, the peatland under natural conditions showed near-zero N2O fluxes and warming increased N2O emissions but N addition greatly increased N2O absorption compared with control. There was no interaction between warming and N addition on N2O fluxes. Pearson correlation analysis showed that water table depth was one of the main environmental factors affecting N2O fluxes and a positive relationship between them was observed. Our study suggests that the N2O source function in natural temperate peatlands maybe not be so significant as we expected before; warming can increase N2O emissions, but a high dose of N input may turn temperate peatlands to be strong sinks of N2O, and global change including warming and nitrogen deposition can alter N2O fluxes via its indirect effect on hydrology and vegetation in peatlands.