The article provides data on a comparative analysis of the features of vegetation restoration in areas of oligotrophic bogs with a high degree of oil product pollution, located on the territory of an oil field in the Middle Ob region, reclaimed according to standard schemes, widely used in the 2000s, and by cutting off oil-contaminated soil. The total projective vegetation cover (TPVC) of all reclaimed areas mostly reaches standard values (above 30%). The TPVC in areas without cutting is slightly higher than in areas with cutting due to the difference in recovery time in favor of the former. At the same time, the average number of all recorded species in areas with cutting is slightly higher, and they include some oligotrophic vascular plants (heather shrubs, Drosera rotundifolia, Eriophorum vaginatum), which spread much less frequently in areas without cutting. The projective cover of the herb-shrub layer is higher in areas without cutting. The content of oil products in the surface layer of 0-20 cm in areas with cutting is generally lower compared to areas reclaimed by traditional methods. However, even high concentrations (more than 250 g∙kg-1) do not have a significant negative effect on the total projective cover of the grass/herb-shrub layer, while its minimum values are primarily associated with a lack of moisture on high microrelief elements. Similarly, high concentrations of hydrocarbons do not serve as an obstacle to the development of moss cover dominated by sphagnum mosses in areas of cut-off hollows. At the same time, polytrichous and brown mosses were much more sensitive to oil pollution in the form of bitumen crust, and thus avoided areas without cutting.

Floodplain forage lands of the Pechora basin (Usinsky district of the Komi Republic) are experiencing a complex anthropogenic impact associated with both agricultural activity and pollution with petroleum products coming with flood waters. An ecological and agricultural assessment of the soil-vegetation cover of the Kolva floodplain used as hayfield (right-bank part) and pasture (left-bank part) was carried out. Soil combinations of the main part of the surveyed floodplain include alluvial sod, sod-meadow and meadow soils. Morphological signs of gley formation in meadow soils are observed in the lower part of the soil profile and are expressed moderately. Soils are characterized generally by favorable agrochemical and morphological properties, with the exception of areas subjected to pasture digression. The vegetation cover of the central and near-river part of the floodplain massif of the right bank is mainly represented by legume-cereal-grass communities formed both in inter-ridge depressions and on flat ridges. On the high floodplain of the left bank, legume-cereal-grass meadows, grass-clover and tufted hairgrass meadows are common, horsetail–butterbur, clover-cereal and cereal communities are common in the near-river part of the left bank. Despite the relatively high productivity and the presence of valuable forage species of cereals and legumes, the qualitative characteristics of hay deviate from optimal ones due to the participation of low-nutritious, unattractive, weedy and poisonous species in the herbage. On the pasture, as a result of pasture digression, there is a decrease in species diversity with the dominance of tufted hairgrass and low-value species of various grasses. In the most disturbed areas, the total projective vegetation coverage is reduced to 50%. The soil cover of the studied territory of the Kolva floodplain is currently not contaminated with hydrocarbons, with the exception of a few spots of petroleum products with a total area of 6 m2. The effect of oil pollution on the vegetation cover of the Kolva floodplain is not manifested. Background values of the content of petroleum products in soils are slightly higher in the left-bank part compared to the right-bank part.

One of the most valuable landscapes of the Krylatsky Hills Park are steppe meadows occupying the slopes of ravine-gully systems. In this work, we investigated the problem of the invasive spread of Manchurian walnut (Juglans mandshurica) in Krylatsky Hills Park, especially in areas of steppe meadows. Until the early 2000s, the species was not found in the park. In 2023, we discovered 125 specimens of Manchurian walnut in the park, measured their height and trunk diameter, and plotted the discovered specimens on a map. Most of the plant population is represented by plant undergrowth and young growth. Further intensification of invasion is possible due to the entry of plants into reproductive age, as well as warming and humidization of Moscow climate. Walnut may be one of the transforming species reducing the area of meadows. Among the positive phenomena associated with the spread of Manchurian walnut, the anti-erosion effect of afforestation of steep slopes of gully-beam systems can be considered.

The main milestones of the study of oil-contaminated soils at the Faculty of Soil Science of Moscow State University (Russia) in 50 years since its foundation are discussed from the perspective of the development of environmental regulation and new technologies of soil reclamation prospects. The main stages in the development of a procedural framework for the determination of oil and petroleum hydrocarbons in soils and studies of the soil properties and chemistry of oil and its components in soil and adjacent environments are considered. The development of legislation on the rationing of petroleum hydrocarbons in soils is provided. The important role played by the staff of the Faculty of Soil Science in adoption of a number of regional standards for the permissible residual content of petroleum hydrocarbons in soils is noted. The approaches to ecological rationing of oil and petroleum hydrocarbons in soils that take into account natural environments and types of land use are proposed. The importance of improving the regulatory and procedural framework and continuing activities in this direction are emphasized. The necessity of studies aimed at development of reclamation technologies for oil-contaminated lands and special use of oil-contaminated waste is indicated.

Peat soils of the taiga zone of West Siberia have historically been relatively poorly studied. In the diagnostics of peat soils, the question of the belonging of the sphagnum litter horizon to the soil profile, as well as the identification of its lower boundary, remains unresolved. In the WRB and Russian Soil Classification, sphagnum litter is considered as a vegetation cover, while in the Soviet classification it is considered as an integral part of the soil profile. The last point of view is also shared by the majority of Russian researchers. Using the material obtained in the study of peat soils in the basin of the river Kazym (subzone of the northern taiga, West Siberia), a comparative characteristic of the sphagnum litter horizon (0–20 cm) and the underlying peat horizon (20–50 cm) was carried out using three parameters: the botanical composition of peat, the degree of peat decomposition, and the color of the soil. All soils are differentiated into the litter horizon and the peat horizon by at least one parameter (5% of the profiles), but in 71% of cases, by three at once. The degree of profile differentiation into two horizons tends to increase in a series of soils formed, respectively, in oligotrophic pine-shrub-sphagnum, oligotrophic complex ridge-hollow, and mesotrophic biogeocenoses. In the overwhelming majority of oligotrophic peat soils, the transition from the litter horizon to the peat horizon is gradual, which does not allow a reproducible assessment of the boundary position in the soil profile. It is proposed to establish a fixed border of the litter horizon at 20 cm from the surface of the bog, referring it to the surface horizon of peat soil.

The problem of pedo- and biodiversity of mire ecosystems under the long-term multiple anthropogenic impact was studied in one of the most intensively technogenically transformed areas of Shaturskaya Meshchera, adjacent to power station Shaturskaya in the north and stretching along the route Kerva – Dolgusha – Severnaya Griva. For more than a hundred years, mires in the Shatura area have been under the influence of drainage, peat extraction, fires, attempts to create agricultural land, secondary watering and pollution, resulting from the power station, transport, and settlements wastewaters. Currently, the bio- and soil diversity of secondary ecosystems has increased significantly compared to undisturbed mires. Instead of bog, in some cases there appeared secondary meadow, grass-shrub communities, small-leaved forests, and dry sparse areas. The remaining bogs experience stable eutrophication, which leads to the formation of mesotrophic and eutrophic phytocenoses and, accordingly, peat mesotrophic and oligotrophic secondary eutrophic soils. In addition, the proportion of eutrophic mires is slightly increased by the peat formation in shallow lakes, which at the initial stage of peat extraction were used for storing wood waste. The phenomenon of secondary oligotrophization of the disturbed bogs of Meshchera, noted in the literature, is not observed in the area under consideration due to a significant anthropogenic load. To preserve the local flora of oligotrophic bogs, marginal areas of flooded quarries and cofferdams with undeveloped peat deposits are of great importance. The increase in pedodiversity was facilitated by the agricultural development of drained peatlands for the cultivation of perennial grasses, which resulted in the formation of torfozems and agrotorfyano-gleyzems.

The soil cover of mire plains is traditionally considered as fairly homogeneous, which is largely due to the difficulties of the systematics of peat soils in the modern Russian soil classification system. This article aims to analyze some characteristics of the soil cover patterns (soil cover composition, distribution of its components by classes of combinations and their association with mire biogeocenoses) of the northern taiga mire plain lying to the north of the Sibirskie Uvaly Ridge in the basin of the Kazym River, Khanty-Mansi Autonomous Okrug-Yugra. Soil maps of 34 key sites with a total area of 595.86 ha have been compiled on a scale of 1 : 5000. Overall, 33 soil mapping units are identified, including 30 units of different peat soils. Taiga soils are represented by iron-illuvial podzols and their combinations with gley soils. Thus, the main contribution to pedodiversity is provided by mire landscapes. The soil cover pattern of oligotrophic string bogs consists of low-contrasting combinations of oligotrophic peat soils differing in their thickness and the botanical composition of peat. In the areas of string bogs with water pools (lakes), low-contrasting combinations of oligotrophic peat soils differing in their botanical composition and contrasting combinations (complexes) of these soils with oligotrophic wet regressive peat soils of flarks. The importance of distinguishing between the soils of these combinations is related to different rates of the organic matter mineralization in them. Mesotrophic peat soils of key sites mainly compose individual elementary soil areas. In comparison with oligotrophic peat soils, they display a higher pedodiversity related to the botanical composition, degree of decomposition, and thickness of the peat layer. At the same time, the widespread distribution of complexes of oligotrophic and mesotrophic peat soils in the aapa mires, which was supposed in the 1980s, has not been confirmed; such complexes occupy 5.34% of the total mapped area.

Hydrocarbon-decomposing microorganisms identified as representatives of the genera Pseudomonas, Rhodococcus, Acinetobacter, Kocuria, Raoultella, and Candida have been isolated from the oil-contaminated soil samples of the Middle Ob region. They have been screened for the ability to decompose various classes of hydrocarbons in a wide temperature range (6–37°C), in acid media (up to pH 4), and at increased salinity (up to 3%), for the ability to produce biosurfactants, and for the presence of genes encoding enzymes responsible for hydrocarbon decomposition. A microbial consortium has been suggested as the basis of a biological preparation for bioremediation of oil-contaminated soils in the Middle Ob region, including strains of Candida fluviatilis 24p-51, Rhodococcus erythropolis 24-44, Acinetobacter calcoaceticus 7-43, and Pseudomonas extremaustralis 7-31. The modes of cultivation and lyophilization of biomass have been determined for these microorganisms. The efficiency of degradation of oil hydrocarbons by the developed microbial consortium has been evaluated in laboratory model systems. The degree of oil degradation by the microbial consortium in the liquid mineral medium was 56%; in the model soil, 22% in 10 days at 24°C.

In a laboratory experiment, the rate of mineralization of organic matter in samples of oil-contaminated and background soils formed in the main types of the middle-taiga biogeocenoses of Western Siberia was determined. The rate of mineralization was estimated by the amount of CO2 released from wet samples at room temperature. The cumulative curves had a linear form. Therefore, the values of the average daily CO2 release per 1 g of dry soil (Km) were used to estimate the mineralization rate. The Km values varied in the range of 0.1123–1.578 mg CO2/g per day. Minimum Km values (<0.2) were typical of the oil-polluted forest soils with the maximum content of oil products; high Km values (>0.8) were determined on the soils of uncontaminated background plots and oil-polluted plots of mesotrophic and eutrophic biogeocenoses with the neutral reaction and increased concentrations of biophilous elements. Moderate values (0.2 < Km <0.8) were typical of the plots confined to initially oligotrophic bogs (ryams, ridged-hollow bog complexes) moderately polluted with oil. The Km values negatively correlated with the contents of petroleum products (K = –0.50), n-alkanes (K = –0.73), and the coefficient of oil biodegradation (K = –0.72).

Despite the widespread use of the taxon “mesotrophic (transitional) peat soils” in the present-day Russian and foreign pedology, including some fundamental publications in this field, its diagnostic features are still uncertain, and this taxon is not included in the recent classification of Russian soils. The proposed criteria based on botanical features—botanical composition of peat soils and indicator plants—will allow separating mesotrophic type from eutrophic and oligotrophic types of peat soils. Special attention is paid to the distinction between mesotrophic and oligotrophic peat soils in accordance with the specific features of mires in northern West Siberia. Among 32 peat soil profiles studied in the Numto Nature Park, 19 profiles were classified as mesotrophic peat soils and 13 profiles, as oligotrophic soils. Owing to the spatial and temporal dynamics of vegetation in large- and flat-topped mound peat complexes, the soils of their hollows (flarks) were in most cases assigned to the oligotrophic type. The soils of aapa mires, as well as mires on low alluvial terraces, river floodplains, and runoff hollows dissecting slopes of the Sibirskie Uvaly Ridge were mainly classified as mesotrophic peat soils.

A digital version of the soil map of the Russian Federation, scale 1 : 2.5 M, is being prepared based on the analysis of the attributes of polygons with peat soils in the West-Siberian taiga and sub-taiga zones. The correction was perfomed in 795 polygons (with the total area of 179 483 km2) out of 1 711 polygons considered (with the total area of 262 204 km2). The currently formulated idea of the dominance of oligotrophic bogs in the West Siberian taiga region of mires served as the basis for suggestion to replace the mesotrophic peat soils by oligotrophic ones in 598 polygons of the total area of 87 250 km2. Similarly, the polygons of microcatenas comprising oligotrophic and mesotrophic peat soils (57 polygons, total area of 38 405 km2) were modified: only oligotrophic peat soils were considered to be the dominant ones there. At the same time, a number of polygons with prevailing oligotrophic soils, confined mainly to the sub-taiga zone were proposed to be replaced by polygons with mesotrophic peat soils. The thermokarst pools in ridge-hollow mire complexes that were shown on the soil map of Russia beyond the permafrost zone were eliminated from the map database; the mapping of destructive peat soils was rearranged in accordance with the new interpretation of this taxon in the Russian soil classification. This work should improve the quality of research in the field of assessing the resource potential of peat soils in West Siberia.

The process of natural remediation of oil- and soil-contaminated raised bogs reclaimed 14–16 years ago in Khanty-Mansiysk Autonomous Okrug–Yugra (KHMAO–Yugra) is analyzed. Revegetation is generally successful, although mesophytic grasses sown during reclamation almost completely disappeared in the grass stand. There is a gradual desalination of peat soil in salt-contaminated areas; it is accompanied by a succession change of halophytic (hemihalophytic) vegetation by communities that dominated by Calamagrostis epigeios, Eriophorum angustifolium, and Phragmites australis; a certain contribution is also made by sphagnum, green mosses, and liverworts. A characteristic feature of these habitats is the colonizing by a number of rare protected species (Heterogemma laxa, Thelypteris palustris, and Triglochin maritimum). In oil-contaminated bogs, hydrocarbons often enter from the underlying peat soil horizons during revegetation, resulting in the formation of a surface crust. Under these conditions, grass–sedge–cotton-grass and other communities are replaced by grass stands of Eriophorum angustifolium and some other species with strong root systems. A certain role in the overgrowth of crusted surfaces is also played by mosses (Sphagnum riparium, Warnstorfia fluitans, etc.). Unsuccessful restoration is observed in hollows with restricted runoff for salt-contaminated bogs and in most significantly drained segments for oil-contaminated ones.

A laboratory study of the solid phase of saline peats by X-ray fluorescence (XRF) analysis has revealed the presence of organic halogen compounds. Cl-organic compounds were found in one-third of peat samples; however, their proportion was low: 14–15% of the total chlorine content. In contrast, Br-organic compounds are formed more often and the Br org proportion is higher (from 12 to 23% of total Br). The relatively weak development of the halogenation of organic matter in the saline peatlands is explained by recovery conditions that prevent the synthesis of organic halogen compounds. An X-ray diffraction analysis (XRD) of the ash of saline peatlands has revealed four main minerals: halite, quartz, calcite, and gypsum. Halite absolutely prevails in low-ash peatlands. The XRD confirms the salinity of peatlands and gives the quantitative content of three minerals: halite, quartz, and calcite. However, analysis of peat ash may involve errors both due to the growth of minerals (gypsum) and due to the incomplete identification of the number of phases in high-ash peat samples. The second type of error can be corrected using data on the chlorine content in peat ash by X-ray fluorescence analysis. In addition to the construction of profiles of salt distribution in solution, it is necessary to determine the amount and composition of organic halogen compounds (some of them have herbicide properties) for characterizing the contamination of peatlands.

On the basis of the review of available literature sources, the approaches to the systematics of peat soils in different soil classifications systems (Russian, German, FAO-UNESCO, WRB, and Soil Taxonomy) are discussed and compared with the landscape-based classifications of boreal mires. Among the diagnostic criteria, the most important in the systematics of peat soils and peatlands are the peat thickness, trophic status as the availability of nutrients and as a botanical concept, and acidity (pH) of peat and peat waters. The following suggestions are made: (a) to establish the peat thickness ≥30 cm as a criterion for peat soils, (b) to exclude the contents of nutrients in the peat from the diagnostic scheme for peat soils, and (c) to develop this scheme on the basis of geobotanical indicators. The latter may include active peat-forming plants, as well as plant species settling on the regressive mires under conditions of a cessation or drastic slowdown of peat accumulation. It is also recommended that the type of mesotrophic peat soils should be added to the Russian soil classification system and that the subtype of wet regressive soils should be distinguished within the oligotrophic type of peat soils along with the existing subtype of destructive soils.

Currently, the taxonomy of peat soils is not given more attention, especially with regard to taxonomic units in the species rank. The diagnostics of 51 soil profiles in the various oligotrophic mire types in the Numto Nature Park (north taiga subzone of West Siberia) has brought about proposals to improve the existing soil classification. It is suggested to: 1) limit the peat horizon thickness in the peat-gleyzem type to 30 cm; 2) divide the peat-gleyzem type by the trophic status into oligotropic and eutrophic subtypes; 3) expand the list of taxa determined by the botanical composition of peat by means of the division of soil species into subspecies on the basis of classifications of peat and peat deposits; 4) use current vegetation as one of the main diagnostic (indicative) criteria in determining the soil type in mires; and 5) use the degree of decomposition of the peat layer underlying the peat soil for determining the variety of peat soil. The article draws attention to the difficulties in determining the classification position of soils of frozen large mounds in palsa bogs and proposes alternative solutions to this problem.

Currently, palsa mires in the southern limit of circumpolar permafrost zone are characterized by an increased intensity of thermokarst processes. In the south of Nature Park Numto the cyclic character of frozen mound formation was replaced by their unidirectional degradation as a result of thaw. We analyze plant indicators of various thermokarst forms occurring in mounds: denudation spots, slumps and funnels. Depending on the stages of thermokarst and type of palsas (flat mound or large mound ones) a number of plant indicators of thawing is revealed: “the drunken forest”, the loss of dwarf shrubs and lichens and their secondary colonization, eutrophication of communities, the emergence of the “ridges” of vegetatively mobile species and others. Brown mosses and secondary colonizing Cladonia lichens with cup-shaped and club-like podetia are indicators of slow thermokarst on patches of denudation in large mounds. Meanwhile, the role of Cladonia lichens with richly branched podetia is markedly reduced. Mesotrophic communities, dominated by mesotrophic sphagnum mosses, are formed in deep funnels on large mounds under the conditions of frozen bed existence. The development of eutrophic communities indicates the release of nutrients during the melting of peat. The stages of thermokarst on the flat palsa mounds correspond to the following succession row: lichens + dwarf shrubs → hygrophyte sphagnum mosses and / or brown mosses + liverworts → hygro-hydrophyte sphagnum mosses + Warnstorfia fluitans. Reliable and the most long-term indicator of thermokarst on large mounds is the downy birch (Betula pubescens).