Spatial Distribution of the Components of Carbon Cycle in Soils of Forest Ecosystems of the Northern,Middle, and Southern Taiga of Western Siberia

Eurasian Soil Science - 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...     

Biological Activity of Urban Soils: Spatial Variability and Control Factors

Eurasian Soil Science - 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...     

CO<Subscript>2</Subscript> Emission and Organic Carbon Pools in Soils of the Northern Taiga Ecosystems of Western Siberia under Different Geocryological Conditions

Statistical analysis of a vast body of data collected during five field seasons (2011–2015) was performed to characterize the biological activity of soils in the northern taiga ecosystems of Western Siberia. Automorphic forest soils, hydromorphic (oligotrophic bog) soils, and semihydromorphic (flat-topped and large peat mounds) soils were characterized. Statistically significant differences of average levels of CO₂ emission from the soils were identified at the ecosystem level. The CO₂ emission from podzols of automorphic forest ecosystems at the peak of the growing season (205 ± 30 to 410 ± 40 mg CO₂/(m² h)) was significantly higher than the emission from semihydromorphic soils of peat mounds (70 ± 20 to 116 ± 10 mg CO₂/(m² h)). The presence and depth of permafrost was a significant factor that affected ecosystem diversity and biological activity of northern taiga soils. Statistically significant differences in the total, labile, and microbial carbon pools were observed for the studied soils. Labile and microbial carbon pools in the organic layer (10 cm) of forest podzols amounted to 0.19 and 0.66 t/ha, respectively; those in the organic layer (40 cm) of peat cryozems of flat-topped peat mounds reached 1.24 and 3.20 t/ha, and those in the oligotrophic peat soils (50 cm) of large peat mounds were 2.76 and 1.35 t/ha, respectively. The portion of microbial carbon in the total carbon pool (C_micr/C_tot, %) varied significantly; according to the values of this index, the soils were arranged into the following sequence: oligotrophic peat soil < peat cryozem < podzol.     

The structure of the bacterial heterotrophic block in tundra soils of Yamal Peninsula

The tundra cryogenic soils of Yamal Peninsula have a high pool of prokaryote microorganisms characteristic of ecosystems where the environmental conditions are unfavorable for microbiological processes. The lowering of the cultivation temperature from 20 to 5°C did not affect the number of bacteria and their taxonomic structure. Psychrotolerant gram-negative bacteria represented by oligotrophs and copiotrophs predominated in the bacterial communities. Among the bacteria of the hydrolytic block, only bacilli were isolated upon cultivation on the media. The species spectrum of the Bacillus genus was determined by the capability of its representatives for growth at low temperatures. The bacteria isolated from the cryogenic soils had a high nitrogenase activity, which increased under the lower cultivation temperature. This fact shows that the majority of the bacteria in tundra soils has adapted to functioning at low temperatures.     

Temperature Sensitivity of СO2 Efflux from the Surface of Palsa Peatlands in Northwestern Siberia as Assessed by Transplantation Method

Eurasian Soil Science - 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...     

Seasonal dynamics of soil CO<Subscript>2</Subscript> production in the arboretum of the Moscow State University Botanical Garden

This paper tracks the annual dynamics of carbon dioxide production (emission and profile concentration) by soils of the arboretum in the Moscow State University Botanical Garden that are planted with Siberian spruce and common pine. The high biological activity of the studied soils is caused by the high content of organic matter, slightly alkaline reaction, and good structure and texture. Differences in CO₂ production by the soils of a spruce and pine forest (1.5–2 times higher in the latter) can be explained by different structures of soil profiles rather than a temperature regime. The seasonal dynamics of CO₂ production are the same for both soils and associated with seasonal changes in climatic parameters. In the cold season, there is noticeable production of carbon dioxide by soils.     

Specific features of the development of soils of hydromorphic ecosystems in the northern taiga of Western Siberia under conditions of cryogenesis

Differently directed and heterochronous cryogenic processes have contributed to the contrasting soil cover patterns and spatial heterogeneity of the properties of soils in hydromorphic ecosystems of the discontinuous permafrost zone of the northern taiga in Western Siberia. Frost heave and permafrost thawing within ecosystems of highmoor bogs have led to the development of specific cryogenic landforms, such as flat-topped and large peat mounds. A set of cryogenic soils is developed in these ecosystems; it includes different variants of cryozems, gleyzems (Cryosols), and peat soils (Histosols). The distribution of these soil types is controlled by the local topography and thawing depth, other factors being insignificant. Alternation of peat horizons of different types and ages, whirl-like patterns of horizon boundaries, considerable variations in the thickness of soil horizons, and inversions of soil horizons under the impact of frost cracking, frost heave, and cryoturbation are typical of the considered soils. Thawing depth is the most significant factor affecting the thickness of organic horizons, the soil pH, and the degree of decomposition of peat. As a result of the upward movement of bog ecosystems under the impact of frost heave, peat soils are subjected to considerable transformation: peat horizons undergo mineralization, and the thickness of organic horizons decreases; in some cases, eluvial–illuvial differentiation of the mineral horizons takes place, and peat podzols are developed. However, the opposite process of the return of the soils to the bog stage of pedogenesis with peat accumulation may take place in any time in the case of activation of thermokarst processes.     

Assessment of the Contribution of Root and Microbial Respiration to the Total Efflux of CO2 from Peat Soils and Podzols in the North of Western Siberia by the Method of Component Integration

Eurasian Soil Science - The method of component integration was tested in the course of studies in typical biogeocenoses of the north of Western Siberia. This method as applied for separate...     

Procedural Approaches to Field Determination of Root and Microbial Respiration Contribution to CO<Subscript>2</Subscript> Emission by Permafrost-Affected Soils

In the discontinuous cryolithozone in the north of Western Siberia in forest and tundra biogeocoenoses, two field methods for individual determination of root and microbial soil respiration were tested: plant shading and root exclusion (comparison of the plots with vegetation and without it). The proportion of of root respiration in the total soil respiration in the forest biogeocoenosis was 7–50%; in the tundra, 10–50%. The plant shading method has been physiologically substantiated, is the least time-consuming, and the least damaging to soil function (moisture and temperature do not change). The proposed modification of the method (root exclusion on natural objects) demonstrated a satisfactory result, but it is not universal due to the specifics of objects.