Methane Emission Heterogeneity and Its Temporal Variability on an Abandoned Milled Peatland in the Baltic Region of Russia

Methane fluxes in disturbed peatlands can exhibit significant heterogeneity with regard to land cover composition on abandoned peat extraction areas. The temporal and spatial variability of CH4 fluxes is considered in this paper in the context of a detailed vegetation classification on a typical milled peatland in the Baltic region of Russia (Kaliningrad oblast, Rossyanka Carbon Supersite). The findings are derived from the analysis of 12,000 air samples obtained by the opaque emission chamber method at 10 peatland sites with different environmental characteristics during regular measurement campaigns of 2022–2024. The emission data have been mapped using a multilevel B-spline interpolation procedure. The mean cumulative methane flux was found to be 18.7–28.8 kg ha−1yr−1, which is close to the IPCC conventional value of 32.9 kg ha−1yr−1 estimated for boreal and temperate zones. However, environmental distinctions across the peatland sites result in considerable emission heterogeneity ranging from −0.02 to 11.5 kg ha−1month−1. Temperature is considered a principal factor responsible for the baseline CH4 emission level in seasonal scale, while hydrology defines emission rate during the warm period of the year and in the inter-annual scales. Five peatland site types have been defined according to a level of methane emissions.