Soil CH4 Fluxes in Typical Tundra of the Taimyr Peninsula, Siberia

Abstract

Among the most climate-vulnerable biomes, Arctic tundra contains large amounts of soil organic carbon stored in perennially frozen ground (permafrost), which can be released into the atmosphere as carbon dioxide (CO₂) and methane (CH₄) in a warmer climate. Given the 25–30 times higher global warming potential of CH₄ compared to CO₂, CH₄ release from permafrost degradation could account for ~ 50% of the future total radiative forcing. Currently, tundra ecosystems constitute a weak CH₄ source, however strong spatio-temporal variations of CH₄ fluxes observed across the tundra biome contribute the uncertainty range in predicting climate feedbacks in the Arctic. We investigated spatial patterns and magnitudes of soil CH₄ fluxes within different landscape units and vegetation types in typical tundra of the Taimyr Peninsula, Siberia. CH₄ fluxes were measured during the growing seasons of 2023 – 2024 using the chamber method. In general, mean soil CH₄ flux reached 0.86 µmol m^-2 h^-1, ranging across tundra landscapes from -0.01 µmol m^-2 h^-1 (consumption) in patches of barren ground to 9.75 µmol m^-2 h^-1 (source) in sedge vegetation. The highest mean rates (2.39 µmol m^-2 h^-1) were attributed to the overwetted marsh tundra, while significantly lower records were observed across frost-heaved (0.09 µmol m^-2 h^-1) and moss tundra (0.19 µmol m^-2 h^-1). In areas disturbed by all-terrain tracks, the mean CH₄ flux was 3-fold higher than in the undisturbed tundra and achieved 2.24 µmol m^-2 h^-1, ranging from 0.97 to 2.99 µmol m^-2 h^-1 in moss and marsh tundra, respectively.