Carbon Dioxide Emission and Organic Carbon Stocks of Tundra Soils on the Coast of the Chosha Bay of the Barents Sea

The carbon budget of the coasts of the seas in the Arctic Ocean basin is still poorly understood, especially in the transitional zone from the continent to coastal meadows. We estimated CO2 emissions and organic carbon pools in the Podzols of tundra ecosystems of the ecotone zone on the southeastern coast of the Barents Sea, and revealed the relationships between the distribution of these phenomena and the relief morphometry. The studied soils in the upper 10-cm-thick layer were characterized by significant reserves of total carbon and low reserves of extractable and microbial carbon: 44.40 ± 0.26, 0.08 ± 0.02 and 0.16 ± 0.01 t/ha, respectively. The combined use of morphometric characteristics of relief, hydrothermal parameters of soils, and characteristics of the carbon cycle components (content and reserves of total, extractable and microbial carbon) in the regression model allows us to describe 50% of the CO2 emission variance. Atypically high values of CO2 emissions from soils of southern tundra ecosystems (3.35 ± 0.17 g C/(m2 day)) are largely due to the weather conditions of the 2024 growing season: high air temperature and low precipitation, as well as high wind speed. In the northeast of European Russia, a positive anomaly of the mean annual and average summer air temperatures has been observed for several years as one of the consequences of climate change. The results of the study contribute to a better understanding of the role of ecotone ecosystems in the coast of the western sector of the Russian Arctic in the carbon budget, pointing to a high potential for further use of relief morphometry in predicting CO2 emissions from soils.