Soil Respiration under a Short-Term Drought on the Example of Typical West Siberian Middle-Taiga Mires

The response of soil respiration (R_soil) to drought was studied for six typical oligotrophic mire biotopes in the middle taiga of Western Siberia: hollows with a dominance of Eriophorum vaginatum (hollow E) and Scheuchzeria palustris (hollow Sh), sphagnum bog with sparse low pine trees (open bog), and forested oligotrophic bogs (ryams) covered with dwarf shrub–pine–sphagnum vegetation (tall ryam and ryam). For this purpose, a regression model linking R_soil with the level of bog water was constructed. Cumulative soil respiration (R_soil(cum)) was measured in June–August 2021 and 2022. In the dry summer of 2022, R_soil(cum) values increased from waterlogged (hollow E) to better drained (tall ryam and ryam) biotopes and comprised 135 ± 2.3, 139 ± 2.4, 275 ± 7.8, 279 ± 7.5, 466 ± 16.4, 510 ± 18.5 g C/(m² season) for the considered sequence, respectively (mean ± standard deviation). An extremely low precipitation in July 2022 (6 mm) led to a sharp decrease in the water table level in August and an increase in the thickness of aerated zone with a corresponding increase in soil respiration. The R_soil(cum) values in summer 2022 were 29 to 54% higher than those in the same period in 2021. The most active growth of R_soil with a decrease in the water table level was observed at the periphery of the mire massif (tall ryam, ryam, and open bog biotopes) in contrast to its central parts.