N2O Fluxes from Peatland Buffer Areas after High N Loadings in Five Forested Catchments in Finland

Peatlands are becoming increasingly used as buffer areas to reduce nutrient transport into watercourses, but knowledge on the dynamics of the element cycle, particularly in gas phase is scant. We investigated if peatland buffer areas significantly contribute to emissions of nitrous oxide (N2O) from forested catchments. We used an artificial addition of 150 kg NH4NO3 per buffer area (146–750 kg NH4NO3 ha−1) and quantified the N2O emission before and after the N loading. We conducted an extensive study with eight sampling positions and sampling interval of 1–5 weeks at five buffer areas, and an intensive study using 14 sampling positions and sampling frequency of 1–7 days at one area. In the extensive study, the average fluxes were −0.33–0.14 mg N2O m−2 d−1 before the N addition, and after the N addition they were 0.99–5.30 mg N2O m−2 d−1. During the intensive study, overall loss of N2O was estimated to be 0.74 kg N2O or 0.15 kg N2O ha−1. Considering the impacts on stratospheric ozone depletion and global warming, the study indicated low N2O emissions even when N loading increased to higher level than is likely to occur under actual conditions in forested catchments.