Sequential (S) and equal-time (ET) methods were applied to assess the temperature sensitivity of respiration of peat soils in different terrestrial ecosystems: southern tundra, northern taiga, and mixed coniferous–broadleaved forests. The Q10 values varied widely (1.3–4.8) and in case of the ET method decreased from northern to temperate latitudes. In the cold range (5–15°С), Q10 increased from the southern tundra (3.5) to the northern taiga (4.8) and then sharply decreased in the zone of mixed forests (2.5). Meanwhile, warm range (15–25°С) showed a clear decline of Q10 from northern to temperate latitudes: southern tundra (2.6) > northern taiga (1.6) > coniferous–broadleaved forests (1.3). Application of the S method resulted in low variability of Q10 values. Our results demonstrate a higher temperature sensitivity of the respiration of peat soils in northern latitudes as compared to that in the temperate zone. The Q10 values obtained in this study can be useful for calibration of regional carbon cycle datasets that consider the contribution of peat soils.

Dissolved inorganic carbon is an essential component of the carbon cycle, especially in the northern regions; however, its loss through water bodies is still rarely included in regional carbon models. The tasks of the work comprise a detailed coverage of the methodological approach of “headspace equilibration” for assessing the concentration of dissolved CO2 in soil and surface waters and estimation of the CO2 concentration range in waters of different geneses in the landscapes of northern Western Siberia. The performed methodological work has allowed a headspace equilibration protocol for measuring the CO2 concentration in waters to be elaborated and described with detailed calculations. The CO2 concentration in soil (suprapermafrost) and surface waters (river, bog, lake, etc.) ranges from 13 to 2983 µmol/L (274 to 57 000 µatm), and the vast majority of objects are supersaturated with CO2 relative to the atmosphere. The maximum concentrations are characteristic of suprapermafrost soil and bog waters, and the minimum concentrations are in the waters of aquatic ecosystems (thermokarst and forest lakes). A high variability of CO2 concentrations in waters necessitates a large number of measurements to provide adequate estimates.

Frozen peat soils in the north of Western Siberia are vulnerable to the on-going climate changes. The increase in temperature which affects the permafrost thaw returns the huge carbon stocks to the global element cycle. Its export in the form of dissolved organic matter from peatlands is determined by a number of factors, among which hydrological conditions are the least studied. The influence of hydrological regimes on carbon export from oligotrophic peat soils in discontinuous permafrost zone was investigated in laboratory conditions. The model column experiment allowed estimating the carbon yield from undisturbed (monolithic) peat samples of different degrees of decomposition. Three types of mesocosms were considered: undisturbed samples of the TO horizon, as well as the TO horizon with underlying material of different texture (sand and loam). The concentration of dissolved organic carbon in the lysimetric waters of a fibric peat does not differ for the “precipitation” and “snowmelt” simulating modes, and in the “stagnation” mode it is 1.4 times less. Sapric peat lysimetric waters show no differences under simulating hydrological regimes. The total export of organic carbon for three successive extractions for fibric peat is 32% higher than for sapric peat. An increase in carbon in the sandy material after three cycles of the experiment was revealed, the loamy material did not show significant differences. The carbon adsorption by mineral soil layers of the study area can be a protective mechanism that prevents increased runoff from the soils.

Modern research proves the need to include waterbodies in regional and global models of carbon exchange. The concentration of carbon dioxide in surface waters is generally higher than that upon the equilibrium state with a partial atmospheric pressure of 400 µatm. The study of the functioning and regional role of aquatic systems, especially in regard to inorganic carbon dynamics, is insufficient, especially in circumboreal regions. The review highlights the theoretical foundations and relevance of studies of dissolved carbon dioxide; methodological approaches to assessing this indicator, as well as the role of dissolved CO2 in natural waters of boreal and arctic regions. Soil organic matter and dissolved carbon dioxide are the main sources of CO2 in surface waters, but this contribution has not yet been quantified. This is due to the underestimation of the abiotic aspects of soil gas exchange, the absolute predominance of studies of gas exchange at the soil/atmosphere interface without taking into account the interaction with groundwater, and methodological difficulties in measuring gas concentrations in ground and surface waters. Instrumental measurement methods are not standardized, and the calculated values have very high systematic and analytical errors. The conclusion points to the need to study the hydrological continuum: from a source (terrestrial ecosystems) to large rivers and lakes, with particular attention to the incorporation of CO2 from groundwater into the carbon budget of the entire watershed.

The influence of the moisture content on the CO2 emission from peat soils of palsa mires in the discontinuous permafrost area was studied in the north of Western Siberia (Nadym region). The СО2 flux was measured in Histic Cryosols of permafrost peatlands (palsas) and Fibric Histosols of surrounding bog using the closed chamber method for four years at the peak of the growing season (August). Despite a significant difference in the soil moisture (34.8 ± 13.2 and 56.2 ± 2.1

The study area in the north of Western Siberia is located in the southern tundra–taiga ecotone near the southern boundary of discontinuous permafrost zone. Three contrasting ecosystems—pine forests with Albic Podzols; palsa with Histic Oxyaquic Turbic Cryosols, and bogs with Fibric Histosols—predominate in this area. The objectives of the study included evaluation of the CO 2 emission from soils in the growing seasons of 2019–2022 and analysis of the factors controlling spatial and interannual variability of the emission. The study included analysis of the soil respiration (static closed chamber method) data and soil hydrothermal parameters in August for four years. In the absence of definite trends in climatic parameters over the past 10 years, a gradual increase in the soil temperature in all ecosystems and an increase in the depth of summer thawing in palsa were observed. These changes were not accompanied by significant changes in the CO 2 emission. Its averaged values varied from 485 to 540 mg CO 2 /(m 2 h) in forest ecosystems and from 150 to 255 mg CO 2 /(m 2 h) in the palsa–bog complex with high coefficients of spatial variability. High CO 2 emission in forest ecosystems is determined by a favorable hydrothermal regime, high root biomass, and good water-physical properties. Part of the CO 2 produced by palsa soils is transported with suprapermafrost water flows toward the adjacent bog and is released from the surface of bog soils. Soil temperature interrelated with seasonal thawing depth proved to be a significant predictor of the spatial variability of CO 2 emission from the soils of the palsa–bog complex.

The study area in the North of Western Siberia is located at the southern limit of the distribution of surficial permafrost in the ecotone zone on the border of taiga and southern tundra. Area is characterized by the contrasting landscapes: pine forests with Albic Podzol; palsa with Histic Oxyaquic Turbic Cryosol and bog ecosystems with Fibric Histosol. The objectives of the study included evaluation the values of CO2 emission (SR) by soils of key landscapes in the growing seasons of 2019–2022, and evaluation the factors of spatial variability of this indicator and its interannual variability. The study included analysis of the RS database (static closed chamber method) and soil hydrothermal parameters for four years in August. In the absence of trends in changing climatic parameters over the past 10 years, a gradual increase in soil temperature in all landscapes and an increase in the depth of thawing in palsa were observed. These changes were not accompanied by significant changes in the SR value. It averaged from 485 to 540 mgCO2/(m2 h) in forest ecosystems, from 150 to 255 mgCO2/(m2 h) in the peat-bog complex with high coefficients of spatial variability. High values of SR in forest ecosystems are determined by a favorable hydrothermal regime, high reserves of root biomass, and good water-physical properties. Part of the CO2 produced by palsa soils is transported by supra-permafrost waters and released from the surface of bog soils. Soil temperature, regulated by seasonal thawing, was a significant predictor of the spatial variability of SR on the soils of the palsa-bog complex.

The effect of the moisture content on peat soils has been studied in discontinuous permafrost area in the north of the Western Siberia (Nadym region). СО2 flux was measured in palsa mire soils (Cryic Histosol) and surrounding bogs (Fibric Histosol) using the closed chamber method for 4 years at the peak of the growing season (August). Despite a significant difference in soil moisture (34.8 ± 13.2 and 56.2 ± 2.1% on average), no significant difference in CO2 emission between these ecosystems was found in any of the observation years (on average 199.1 ± 90.1 and 182.1 ± 85.1 mg CO2 m–2 h–1, respectively). Experimental wetting or drying (with two times difference in moisture content) of peat soil plots by transplantation method showed no significant effect on CO2 emission even 3 years after the experiment start. The absence of significant differences in CO2 flux between ecosystems and experiments was explained by the presence of permafrost and the influence of many multidirectional factors mitigating changes in CO2 production by soils. CO2 flux enhancing from the soils of the bog is possible due to the additional contribution of the methanotrophic filter, as well as the lateral runoff of dissolved CO2 over the permafrost table from palsa mire surrounding the bogs. The absence of a response of CO2 emission to a significant change in moisture may indicate a wide optimum of this parameter for microbiological activity in peat soils of the studied region. The results indicate that, in the study of cryogenic soils of hydromorphic landscapes, it is necessary, in addition to biogenic sources, to take into account additional factors, often of a physical nature, that change the balance of CO2 fluxes and CO2 emission by soils, respectively.

The study area in the North of Western Siberia is located at the southern limit of the distribution of surficial permafrost in the ecotone zone on the border of taiga and southern tundra. Area is characterized by the contrasting landscapes: pine forests with Albic Podzol; palsa with Histic Oxyaquic Turbic Cryosol and bog ecosystems with Fibric Histosol. The objectives of the study included evaluation the values of CO2 emission (SR) by soils of key landscapes in the growing seasons of 2019–2022, and evaluation the factors of spatial variability of this indicator and its interannual variability. The study included analysis of the RS database (static closed chamber method) and soil hydrothermal parameters for four years in August. In the absence of trends in changing climatic parameters over the past 10 years, a gradual increase in soil temperature in all landscapes and an increase in the depth of thawing in palsa were observed. These changes were not accompanied by significant changes in the SR value. It averaged from 485 to 540 mgCO2/(m2 h) in forest ecosystems, from 150 to 255 mgCO2/(m2 h) in the peat-bog complex with high coefficients of spatial variability. High values of SR in forest ecosystems are determined by a favorable hydrothermal regime, high reserves of root biomass, and good water-physical properties. Part of the CO2 produced by palsa soils is transported by supra-permafrost waters and released from the surface of bog soils. Soil temperature, regulated by seasonal thawing, was a significant predictor of the spatial variability of SR on the soils of the palsa-bog complex.

An assessment of the spatial variability of the biological activity of anthropogenic soils on the territory of the Lomonosov Moscow State University and the factors controlling it has been performed. The properties of the upper horizon of the studied soils expectably differ from those of natural zonal soils in higher pH values (6.1–7.2), a significant increase in the total carbon content (0.9–10.6%) and its stock in the upper 10-cm-thick layer (0.7–7.2 kg m –2 ). Most of the urban soils are characterized by increased values of microbial respiration (up to 8 mg C–CO 2 kg –1 h –1 ) in comparison with those in natural zonal soils at approximately the same values of the CO 2 emission from the surface (230–750 mg CO 2 m –2 h –1 ). A high spatial variability of soil properties, such as moisture content, CO 2 emission, total carbon content, microbial respiration, and cellulolytic activity in urban soils is controlled by both natural and anthropogenic factors. It increases in the following series: CO 2 emission < microbial respiration < cellulolytic activity. The high spatial variability of soil properties makes it difficult to determine criteria for allocating sampling sites. The closest correlative relationships with environmental factors have been found for microbial respiration. According to our data, the main predictors of microbial respiration are the contents of carbon and moisture, and the correlation with moisture is higher ( r = 0.87, р = 0.0002). A significant enrichment of urban soils with carbon determines the potential for an increase in the CO 2 flux upon changes in the parameters of soil functioning. Difficulties in the interpretation of the results arise due to the unaccounted anthropogenic factors of variability, which are not included to the common set for such studies.

We studied processes of ice-wedge degradation and stabilization at three sites adjacent to road infrastructure in the Prudhoe Bay Oilfield, Alaska, USA. We examined climatic, environmental, and subsurface conditions and evaluated vulnerability of ice wedges to thermokarst in undisturbed and road-affected areas. Vulnerability of ice wedges strongly depends on the structure and thickness of soil layers above ice wedges, including the active, transient, and intermediate layers. In comparison with the undisturbed area, sites adjacent to the roads had smaller average thicknesses of the protective intermediate layer (4 cm vs. 9 cm), and this layer was absent above almost 60% of ice wedges (vs. ∼45% in undisturbed areas). Despite the strong influence of infrastructure, ice-wedge degradation is a reversible process. Deepening of troughs during ice-wedge degradation leads to a substantial increase in mean annual ground temperatures but not in thaw depths. Thus, stabilization of ice wedges in the areas of cold continuous permafrost can occur despite accumulation of snow and water in the troughs. Although thermokarst is usually more severe in flooded areas, higher plant productivity, more litter, and mineral material (including road dust) accumulating in the troughs contribute to formation of the intermediate layer, which protects ice wedges from further melting.

The hydrothermal regime of soils, which are formed on the same type of parent rock under different plant communities in ecosystems of large lysimeters at the Soil Experimental Station of Moscow State University, is characterized. The inter- and intra-annual influence of the vegetation cover on the dynamics of temperature and moisture content in soil horizons is evaluated. It is shown that over a 60-year period after the start of the experiment, the studied soils significantly differ in moisture and temperature conditions. The greatest impact is exerted by the tree layer, due to the precipitation redistribution and the transpiration effect, which significantly decrease soil moisture and lysimetric runoff. There is a 2–3-time difference in the moistening of the upper 20-cm layer and more than 10-time difference in the runoff volume between the driest ecosystem (spruce forest) and the most humid one (fallow). The specific effect of the forest type on the temperature regime of soils is revealed. The temperature is minimal under coniferous ecosystem and is maximal under broad-leaved ecosystem (the difference in the mean annual temperature in the 10-cm soil layer is more than 1.6°С). The role of the grass cover, which reduces temperature extremes and evaporation from the soil surface, is shown. Seasonal features of the effect of the plant cover on the hydrothermal soil regime are assessed.

Peatland soils in permafrost area are among the major components of global carbon cycle. In the case of predicted climate change, they may act as a significant source of greenhouse gases efflux. A four-year transplantation experiment (transplantation of soil cores of 20 cm in height and 10 cm in diameter to other natural positions) with the peat horizon was arranged to assess the temperature sensitivity of CO2 efflux from palsa peatlands in the north of Western Siberia. The rise in temperature by 7°С caused a positive feedback (30–70%) of CO2 efflux (measured by the closed chamber method) from transplanted soils as compared with the control. Temperature dependence of CO2 efflux from transplanted soils had the highest value (R2 = 0.8) in the first two years as a result of maximum contrast of temperature conditions between sites and decreased in the next two years. On the contrary, the temperature sensitivity of CO2 efflux from transplanted soils showed a high value during most of observations (Q10 = 3–6) thus indicating the increased rate of organic matter mineralization in peat soils of permafrost area for a long (four years) period. Our results might be useful for calibration of regional carbon cycle data sets that consider the contribution of organic permafrost-affected soils.

The results of the four-year study of the temperature regime of soils of three common landscapes of northern taiga in Western Siberia, located in the area of discontinuous permafrost, are presented. The soils of lumpy peatlands are characterized by mild permafrost annual regime with very cold summer and moderately cold winter. Temperature regime of the forest soils may be characterized as cold long-time seasonally freezing mild with very cold summer and moderately cold winter. The soils of the investigated region are functioning in conditions of the narrow range of temperatures: at the depth of 20 cm for the soils of all of the landscapes, the temperatures vary within the range of -2.5 to 0°С. This occurs due to their high moisture, low thermal conductivity, specificities of snow cover regime and the freezing effect of permafrost rocks. Annual temperature soil indices are characterized by the weak correlation to the mean annual specificities of air temperature regime. We discovered the direct correlation of annual soil temperature regime and the dynamics of the snow cover (with average and maximal thickness, and thawing date), and with winter N-factor (surface temperature index), and accumulative positive temperatures. Since isolating activity of the vegetation is significantly lower than that of snow (summer N- factors 0.7-0.9), annual fluctuations of summer air temperatures will significantly affect the temperature regime of soils and geo-cryologic situation of the region in general.

In the course of studies in typical forest ecosystems of the northern, middle, and southern taiga of Western Siberia performed at the peak of the growing season, the spatial variation of soil CO2 emissions and their relationships with the content of extractable and microbial soil carbon and soil hydrothermic parameters were estimated. The studied parameters of the soil carbon cycle are characterized by the high spatial variability in all the studied ecosystems. This fact indicates the need for a detailed investigation of the greenhouse gas soil emission in all ecosystems typical of a given natural zone. There is a statistically significant difference between the soils of the green-moss pine forests and the soils of the lichen pine forest of the northern taiga. In the green-moss pine forest, the carbon content of microbial biomass is 1.5 times higher (195 ± 24 and 127 ± 16 mg C/kg soil, respectively), the content of extractable carbon is 4 times higher (157 ± 25 and 41 ± 5 mg C/kg of soil, respectively), and the CO2 emission is 1.7 times higher (324 ± 20 and 190 ± 10 mg CO2/(m2 h), respectively) than those in the lichen pine forest. In the northern taiga zone, carbon dioxide emissions from soils in the green-moss pine forests are largely determined by the soil temperature; the role of soil moisture is less significant. In the soils of lichen pine forests, the CO2 emission is mainly controlled by the content of extractable carbon. Significant factors influencing the soil СО2 emission in forest ecosystems of the taiga zone are the content of extractable and microbial carbon and hydrothermic parameters of the soils.

Snow cover distribution has a profound impact on ground temperature, on thickness of the active layer, and on permafrost. The purpose of this study was to evaluate the effects of snow cover on soil thermal regimes in West Siberia and to characterize the meso- and micro-scale spatial variation of winter ground surface temperature (GST). Maximum snow cover thickness (> 80 cm) and duration (similar to 8 months) were recorded for the lower elevation areas and in the forest site (using a vertical array of Muttons). Shallow snow cover and a late snow formation characterized open raised areas with shallow permafrost. Our results indicate that 20 cm snow cover thickness is the minimum for generating a significant insulating effect. Date of snow cover formation with thickness > 20 cm had the strongest influence on soil temperature regimes. We found a significant negative correlation between winter GST and elevation. This relationship is indirectly controlled by snow cover redistribution. We additionally have shown that elevation, n-factor and winter GST are the variables most significantly affecting thaw depth in permafrost-affected soils. This research dictates the need for taking into account snowfall, and its redistribution due to the variability of local factors, in predicting the effects of climate change on soil temperatures and active layer depth. According to long-term meteorological data for West Siberia, a temporal trend in snowfall is not observed. Nevertheless, considerable interannual fluctuations in snow cover thickness can lead to interannual variations in the soil thermal regimes.