Nº 1 (2025)

The International soil classification system – WRB – was published every eight years starting with 1998; in its each version, the number, essence and status of qualifiers were more or less different. In accordance with the WRB principles, qualifiers, both principal and supplementary, are based on soil forming processes implemented in “diagnostics”. Analysis of the list of qualifiers in the last WRB version of 2022 (281 qualifiers) revealed the priority of diagnostic horizons as criteria for selecting both categories of qualifiers, less numerous were soil chemical properties. Among anthropogenic qualifiers, the technogenic ones are more numerous and diverse than those related to agriculture. The number of qualifiers per Reference soil group, mainly supplementary, is the greatest in the widely spread soils: Technosols, Cambisols, and Gleysols; it is minimal in soils confined to certain geographical sites, f.i. Nitisols. In relation to the Reference soil groups, qualifiers may be separated into “universal” being in the lists of almost all groups (indicating texture, gley, plowing) and “unique”, which are inherent to specific soils. Principal qualifiers’ function is creation of a central image of a Reference soil group based on major soil forming processes, and their number should be limited. Based on the calculation of taxonomic distances, the pairs of Referential groups with the most similar set of main qualifiers were Stagnosols and Planosols, Calcisol and Gypsisol, Alisols and Acrisols, which is determined by the similarity of the processes forming them. Referential groups Histosols and Gleysols are characterized by the most unique set of main qualifiers. As for the names of qualifiers, they are constructed of formative elements taken from 26 languages, along with the dominant Latin and Greek. Qualifiers in the Podzols Reference group are discussed as an example of approaches to soil diagnostic in WRB and Russian soil classification.

The search informative indicators of variation in soil carbon stock coniferous–broadleaf forest has a high predictive value. This article provides an assessment of the contribution of environmental factors to the variation of carbon stock in the forest soils. The study was carried out on the territory of the Bryansk Forest reserve on 45 sample plots located in different landscapes. Five groups of factors characterizing vegetation, macrofauna, landscape, relief, and history of environmental management were analyzed. Statistical relationships between carbon stock indicators and environmental factors were assessed using machine learning methods. The main factor determining the carbon stock in litter was the quality of litter, formed by the dominants of the trees, herbaceous and moss layers. Position in the landscape and other orographic characteristics were less informative. The highest carbon stock of the OL-subhorizon of the litter was in forests with a high proportion of pine. The most informative indicator for determining the variation in carbon stock FH-subhorizon of the litter was the projective cover of mosses. The results of regression analysis for the carbon stock in the A horizon and in the 0-30 cm layer demonstrated a significant contribution of indicators showing the increased hydromorphism, as well as characteristics connected with functional organization of forest ecosystems, namely the ecological-coenotic structure of plant communities (the proportion of nemoral species in the layer undergrowth and shrubs) and functional diversity of earthworms.

The results of studies of biological activity, concentrations of carbon-containing greenhouse gases and their emissions in eutrophic and mesotrophic swamps are presented. It was established that 4 years of research are characterized as long-term averages, levels marsh water in the swamps were close to the surface, and the humidity in the 0–30 cm layer did not fall below 0.8 of the total moisture capacity. It was revealed that the degree of heating of peat profiles of swamps is determined by their type and the level marsh water. The activity of oxidoreductases involved in the formation of humic substances has been revealed. The activity of catalase and polyphenol oxidase in the peats of a eutrophic swamp is identical to their activity in the peats of a mesotrophic swamp, and the activity of peroxidase in eutrophic peats is 1.5–6 times higher compared to the peats of a mesotrophic swamp. The dynamics of carbon-containing gases in the peat profile of swamps was studied, which showed similar values for both types of swamps from 0.07 to 1.4 mmol/dm³ for CO₂ and from zero to 0.65 mmol/dm³ for CH₄. The extreme values of the concentration of CO₂ and CH₄ gases in the eutrophic peat deposit were determined: for CO₂ – 0.07–1.40 and for CH₄ – 0.00–0.65 mmol/dm³, and in the mesotrophic: for CO₂ – 0.05–1.10 mmol/dm³ and for CH₄ – 0.00–0.62 mmol/dm³. In the eutrophic swamp, limits of emission values are observed: for CO₂ – 17.2–77.1 mg CO₂/(m² h), for CH₄ 1.3–11.3 mg CH₄/(m² h). In a mesotrophic swamp, the emission limits are: for CO₂ – 34.9–109.9 mg CO₂/(m² h), for CH₄ – 0.5–15.1 mg CH₄/(m² h). Quantitative indicators of biological parameters and their distribution along the peat profile of eutrophic and mesotrophic types were obtained. It has been proven that the activity of biological processes manifests itself throughout the peat profile of the swamp down to the mineral underlying rocks, but the degree of their activity is determined by the type of swamp and the botanical composition of the peat profile.

In the research of decomposition processes in the urban forest biogeocenoses of the Arboretum of the Botanical Garden of Moscow State University, the litter–bag technique was applied. To determine the leading factors of decomposition of the test materials, the study was carried out in various biogeocenoses of the zonal range: from the zone of mixed forest (Moscow region) to the zone of dry steppes (Volgograd region). Standardized samples of wood, cellulose, tea and native forest litters were placed on the soil surface (within or below the forest litter), then collected at different time intervals. For each study site the dynamics of mass loss were estimated, and some zonal and local decomposition patterns related to the decomposition factors were described. It was shown that the leading decomposition factors are specific to the different materials. Thus, the decomposition of wood and cellulose is controlled by temperature and moisture. The decomposition rate of tea in the initial stages depends on climate, but differs in deciduous and coniferous forests. The decomposition rate of native litters is not controlled by climate in the studied range. In the MSU Botanical Garden, the decomposition of wood is slowed to the rates that are typical for zonal forests located 320–440 km to the south. The native litters in coniferous forests of Botanical Garden, on the contrary, decompose faster than in natural biogeocenoses, which is consistent with previous data on litter-fall input and litter reserves. Thus, the specifics of the use of some test materials for decomposition studies in human–influenced biogeocenoses is shown; in addition, it is shown that the wood can be used as a test material.

Magnetic properties of soils depend on the initial properties of soil-forming material and a number of post-sedimentary processes. Within the uplands in the center and south of the East European Plain, the heterogeneity of spatial distribution of magnetic properties correlates closely with the soil-cover heterogeneity caused by the paleocryogenic microtopography. Differences in magnetic susceptibility are sufficient to form a pronounced geophysical contrast recorded by ground magnetic survey; however, that method has rarely been applied in soil studies. The origin and age of magnetic fraction in thin soil-sedimentary strata of mantle loam remain disputable. This study aims to determine the patterns of the spatial distribution of magnetic properties in surface Late Pleistocene–Holocene pedolithocomplexes by the example of the Suzdal Plateau. A set of magnetic methods was used, including field and laboratory measurements of volume and mass magnetic susceptibility parameters, as well as a detailed magnetic survey. As a result, datasets that characterize magnetic heterogeneity at scales from individual lithogenic units and morphological elements of soil profiles to elementary soil areals constituting a soil combination of texturally differentiated agrozems, agrogray, and agrosoddy- podzolic soils were obtained and compared. It is revealed that the magnetic fraction of pedogenic and pyrogenic origin concentrated in the material of humus horizons in the Late Glacial and Holocene soils represents the main source of magnetic anomalies. The results of this study can be used for soil-cover pattern studies, reconstruction of the Late Pleistocene—Holocene environment, and interpretation of geophysical data.

This review summarizes information about the properties of postagrogenic soils with a focus on the composition of soil organic matter (SOM) during the natural self-revegetation. Within one landscape zone, from the chronoseries of the plowed horizon with the poorest substrate to the richest, the contrast in changes in acidity, content and reserves of SOM, and its enrichment in N decreases. This trend is also typical for the series of postagrogenic soils “sandy and sandy loam in (sub)taiga – loamy in (sub)taiga – loamy in (forest-)steppe.” In the previously plowed horizon, with the natural self-revegetation, the pH value and the content of mobile K decreases in the (sub)taiga and remains unchanged in the (forest)steppe. The content of mobile P and exchangeable Ca and Mg decreases slightly in the sandy soils of the (sub)taiga and is constant in the loamy soils of the (sub)taiga and (forest)steppe. For the content of SOM and total N, multidirectional trends were noted in the sandy soils at the (sub)taiga and at the loamy soils, an increase or uniform distribution during the self-revegetation in (sub)taiga and (forest)steppe. The mobile fractions of transition metals and Ca as well as active forms of O play an important but not fully understood role in the stabilization and destruction of SOM. In the context of postagrogenic regradative changes in soils, only pilot assessments of the transformation of SOM composition have been carried out.