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

Abstract

Peatlands, as important global nitrogen (N) pools, are potential sources of nitrous oxide (N<sub>2</sub>O) emissions. We measured N<sub>2</sub>O 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 N<sub>2</sub>O emissions from the peatland. In a growing season, the peatland under natural conditions showed near-zero N<sub>2</sub>O fluxes and warming increased N<sub>2</sub>O emissions but N addition greatly increased N<sub>2</sub>O absorption compared with control. There was no interaction between warming and N addition on N<sub>2</sub>O fluxes. Pearson correlation analysis showed that water table depth was one of the main environmental factors affecting N<sub>2</sub>O fluxes and a positive relationship between them was observed. Our study suggests that the N<sub>2</sub>O source function in natural temperate peatlands maybe not be so significant as we expected before; warming can increase N<sub>2</sub>O emissions, but a high dose of N input may turn temperate peatlands to be strong sinks of N<sub>2</sub>O, and global change including warming and nitrogen deposition can alter N<sub>2</sub>O fluxes via its indirect effect on hydrology and vegetation in peatlands.