Observations of methane net sinks in the Arctic tundra

Abstract. This study focuses on direct measurements of CO₂ and CH₄ turbulent eddy covariance fluxes in tundra ecosystems in the Svalbard Islands over a two-year period. Our results reveal dynamic interactions between climatic conditions and ecosystem activities such as photosynthesis and microbial activity. During summer, pronounced carbon uptake fluxes indicate increased photosynthesis and microbial methane consumption, while during the freezing seasons very little exchange was recorded, signifying reduced activity. The observed net summertime methane uptake is correlated with the activation and aeration of soil microorganisms, and it declines in winter due to the presence of snow cover and because of the low soil temperatures, but then rebounds during the melting period. CH₄ fluxes are not significantly correlated with temperature, but are instead associated with wind velocity, suggesting that electron acceptor limitation may be stimulating methanotrophic communities. High temperature anomalies increase CO₂ emissions, which may have the effect of limiting summer productivity and carbon sequestration. Positive methane fluxes (emissions) were observed during warm anomalies in winter. These findings emphasise the necessity of comprehending the dynamics of greenhouse gases in tundra ecosystems in order to mitigate climate change. Further research is required to elucidate the sources and sinks of greenhouse gases in dry tundra ecosystems.