Soil cover patterns in the Dzhida Depression and their representation on the soil map of 1: 500000 scale

A map of the soil cover patterns in the Dzhida Depression (Baikal region) has been compiled on a scale of 1: 500 000. The grouping of the soil cover patterns into larger categories makes it possible to retain the information contained on large-scale soil maps upon their generalization to the small-scale soil map. The latter displays the regularities of soil distribution at the levels of soil types and subtypes. The areas of the major soil groups have been calculated. It is shown that podburs predominate in the northern taiga ecosystems (72%), whereas acid soddy taiga soils (71%) and podburs (22%) predominate in the middle taiga zone. Minor areas in these zones are occupied by podzolic soils (9%) and permafrost-affected taiga gley soils (14%).     

Polycyclic aromatic hydrocarbons in background podzolic and gleyic peat-podzolic soils

The qualitative and quantitative composition of polycyclic aromatic hydrocarbons (PAHs) has been determined in the background podzolic and gleyic peat-podzolic soils of the middle and northern taiga zones of northeastern Europe using the methods of highly efficient liquid chromatography and chromato-mass spectrometry. The distribution of polyarenes in the soil profiles follows the eluvial-illuvial pattern. Organic and illuvial horizons are the biogeochemical barriers for PAHs migrating in the soils. The revealed regularities of the accumulation and redistribution of PAHs in the soil profiles are in agreement with the character of the soil-forming processes in the northern and middle taiga zones.     

Specific features of soil formation in the taiga zone of Western Siberia

Specific features of soil formation in the taiga zone of Western Siberia are considered. The polygenetic nature of podzolic and gley-podzolic soils in the middle taiga zone, soddy-podzolic and soddy gley soils in the southern taiga zone, and meadow soils in the subtaiga zone is related to the pre-Holocene transformation of the lithogenic matrix upon activation of denudation and accumulation processes and the complicated Holocene evolution of these soils. A soil profile can be subdivided into separate layers according to the geomorphic features of the cryogenesis, the indices of interruption of soil formation, and the differences in the composition of the organic matter in the relict and modern humus horizons.     

Soils and the soil cover of the taiga zone in the northern Urals (upper reaches of the Pechora River)

The territory in the upper reaches of the Pechora River is characterized by the predominance of Al-Fe-humus and metamorphic soils with gley features developing under the middle taiga fir-spruce forests rather than gley-podzolic soils as had been considered before. Some of the described soil profiles represent intergrades between brown taiga soils (burozems) and gleysols; these soils are absent in the new Russian soil classification system. General regularities of the soil cover are controlled by the geomorphic position of the soils on slopes and by the conditions of ground moistening and lateral soil water flows. The development of modern soil cover patterns is determined by the impact of herbaceous and woody vegetation, bioturbation of the soils by windfalls, the presence of dead tree trunks on the soil surface, and other factors.     

Altitudinal distribution of soil fauna in the Khibiny Massif

Data on the taxonomic and trophic composition, population density, and biomass of invertebrates in the soils of the main mountain vegetation zones of the Khibiny Mountains—taiga, subalpine, and alpine—are obtained. The degree of similarity between soil faunal complexes in different vegetation zones within the studied slope is higher than that between zonal biocenoses of Murmansk oblast. The mountain tundra zone differs from the zonal tundra in a higher population density and taxonomic diversity of invertebrates, which are similar to those in the northern taiga podzols. At the same time, invertebrate complexes in the mountain taiga zone are poorer than those in the zonal plain taiga soils. The analysis of invertebrate taxa present in all the studied mountain vegetation zones demonstrates similar effects of the altitudinal and latitudinal zonality on the species composition of invertebrates. A conclusion is made about a higher functional activity of saprotrophs in the high-humus soils enriched in biogenic elements of the Khibiny Mountains in comparison with the functional activity of saprotrophs in the zonal plain podzols.     

Geographic and genetic specificity of permafrost-affected soils in central Yakutia

The genesis, composition, and properties of the major types of permafrost-affected soils of central Yakutia were studied along a 30-km-long soil catena within the middle taiga zone near Yakutsk. It is shown that the distribution of different soils along the catena is controlled by the climatic zonality in the Yakutsk Depression; taiga soils are replaced by soddy forest-steppe soils and soddy meadow-steppe soils with a decrease in the absolute height of the territory.     

Automorphic soils of the central and southern Timan Ridge

Automorphic loamy soils developing from different parent materials in the central and southern parts of the Timan Ridge are described. Pale-podzolic soil and iron-illuvial texture-differentiated svetlozems are developed from silty covering loams underlain by moraine deposits. Podzolic, iron-illuvial, cryometamorphic, and clay-illuvial horizons are distinguished in the svetlozems; soils with such a complex morphology have been described in the taiga zone of European Russia for the first time. Humus-iron-illuvial podzols are developed from acidic slates. Raw-humus rzhavozems (iron-metamorphic soils) are developed from substrates with the high content of pebbles of mafic rocks. Such soils are typical of the middle taiga zone of Central Siberia and the south of Far East. In the northwestern part of European Russia, these soils occupy small areas.     

Soil catenas on denudation plains in the forest-tundra and northern taiga zones of the Kola Peninsula

Morphogenetic features of soils of two catenas developed on sandy to loamy sandy moraine deposits in the forest-tundra and northern taiga zones on denudation plains of the Kola Peninsula are discussed. It is shown that these catenas are similar with respect to the major directions of soil formation, regularities of soil distribution by the elements of mesotopography, and the factors of the soil cover differentiation. The differences between the catenas are of quantitative character and are related to the intensities of manifestation of the particular processes and features. Both catenas are characterized by the pronounced differentiation of soils with respect to their moistening with hydromorphic peat bog soils in the subordinate positions and Al–Fe-humus podzols in the automorphic positions.     

Microstructure of genetic horizons in automorphic soils of the Timan Ridge

Data are presented on the physicochemical composition and specific macro-, meso- and micro-morphological features of automorphic soils formed on silty loams in the northern and middle taiga subzones of the Timan Ridge. These soils have a texture-differentiated profile and are well aggregated, which is manifested at all levels of structural organization of the soil mass. The morphological structure of the middle soil horizons is characterized by the presence of specific nongleyed cryometamorphic horizon CRM. Its formation is due to the development of long-term seasonal cryogenic processes in relatively deep (up to 40 cm) light and medium loam deposits under conditions of the northern and middle taiga subzones. The processes of cryometamorphism, combined with Al-Fe-humus and textural differentiation, result in the formation of podzolic, iron-illuvial, cryometamorphic, and textural horizons (O-E-BF-CRM-BT). The textural horizons have a set of micromorphological features indicating that recent clay illuviation is a weak process.     

Microbial transformation of nitrogen compounds in middle taiga soils

The intensity of mineralization, nitrogen fixation, and denitrification in forest soils of the Karelian middle taiga ecosystems has been evaluated. Podzol-gleyish soil underlying a birch forest with gramineous plants and miscellaneous herbs was shown to have the highest nitrogen-fixing activity. The loss of gaseous nitrogen during denitrification was insignificant due to the low nitrifying activity of the soils named above. N₂O uptake by microorganisms was rather intensive in all the soils analyzed, and in illuvial-humo-ferric podzols underlying pine and spruce forests this process predominated. Podzolic sandy loam gley-like soil of a birch forest with gramineous plants and miscellaneous herbs had the highest potential for the mineralization of organic nitrogen; the rate of ammonification and nitrification in this soil was maximal.     

Modeling of the thermal influence of fires on the physicochemical properties and microbial activity of litter in cryogenic soils

Periodic surface fires in the cryolithozone (the northern taiga subzone) are the main factor determining the qualitative and quantitative characteristics of the soil organic matter. The specific features of the changes in the physicochemical parameters and microbial activity of the organic horizons in the cryogenic soils under larch forests of the northern taiga after the impact of high temperatures were revealed. The temperatures of fires of different intensity were simulated in laboratory conditions. The thermal impact on the litter organic matter during the surface fires may increase the CO₂ emission from the surface of the soil in the postfire communities due to the destruction of organic compounds only for a short time. After fires of high intensity with strong mineralization of the litters, during a period of more than 1 month, the pyrogenic effect on the organic horizons of the soils under the larch forests of the cryolithozone determined the reduction of the CO₂ emissions in the freshly burned areas as compared to the intact stands.     

Soils on hard rocks in the northwest of Russia: Chemical and mineralogical properties,genesis, and classification problems

Soil formation on hard rocks—nepheline syenite, amphibolite, metamorphized gabbro diabase, and their derivatives—was studied in the mountainous tundra and in the northern and middle taiga zones of the Kola Peninsula and Karelia (in the Kivach Reserve). It was found that the soils developing from these rocks could be classified into three groups: (1) petrozems with the O-M profile (the most common variant), (2) podzols and podzolized podburs on the substrates with an admixture of morainic derivatives of acid rocks, and (3) shallow (<5–10 cm) pebbly soils on the substrates without an admixture of allochthonous material (the rarest variant). In soils of the third group, the pedogenic alteration of the mineral matrix does not result in the appearance of phyllosilicates in the fine fractions if these phyllosilicates are initially absent in the rock. In these soils, the protion of the organic matter, and binding of iron released from the weathered silicate minerals into iron-organic complexes) are virtually undifferentiated by the separate soil horizons because of the very low thickness of the soil profiles. These soils have the Oao-BHFao-M profile; it is suggested that they can be classified as leptic podburs. An admixture of morainic material containing phyllosilicate minerals favors a more pronounced differentiation of the modern pedogenic processes by separate soil horizons even in the case of shallow soil profiles; the intense transformation of phyllosilicates takes place in the soils.     

Water-soluble low-molecular-weight organic acids in automorphic loamy soils of the tundra and taiga zones

The formation features of water-soluble low-molecular-weight organic acids (LMWOAs) in a zonal series of automorphic soils on loose silicate rocks from the middle taiga to the southern tundra (typical podzolic, gley-podzolic, and surface-gley tundra soils) were first revealed by gas chromatography mass spectrometry and gas-liquid chromatography. The content of LMWOAs varies within the range of 1–14 mg/dm³, which corresponds to 1–5% of the total carbon of the water-soluble soil organic matter. It has been shown that a subzonal feature of gley-podzolic soils in the northern taiga is the high content of LMWOAs, including primarily the strongest aliphatic hydroxyl acids. Possible mechanisms of their formation and accumulation in soils have been considered.     

The influence of fires on the properties of forest soils in the Amur River basin (the Norskii Reserve)

The influence of forest fires on the properties of taiga brown, gley taiga brown, and alluvial bog soils widespread in the area of the Norskii Reserve (the Amur River basin) was studied. During several years after the fire, the humus content increased, especially in the soils subjected to fires of high intensity. In the soils of steep slopes, the humus content decreased due to damage to the forest vegetation and activation of lateral runoff after the fire. As a rule, in the soils subjected to fire, the C ha-to-C fa ratio increased and correlated with the fire intensity. Some relationships between the forest fires and the acid-base properties of the soils were revealed. After the fires, the pH values often became higher. The stronger the fire, the higher the pH values. The stony soils differed from the other ones, since the reaction of their upper horizons turned out to be more acid after the fires. The analysis of the authors’ and literature data showed that the pyrogenic changes of some soil properties have been poorly studied and need further investigation, including their geographical aspects.     

Soils of northern spurs of the Cherskii Ridge in the area of the northern pole of cold: Morphology,properties, and classification

The soils in the area of the northern pole of cold located on the interfluve between the Yana and Adycha rivers within the spurs of Kisilyakh Ridge included in the mountain system of Cherskii Ridge have been studied for the first time. The profile-genetic approach has been applied to describe the soils and determine their classification position. It is found that the major soil types in this region are the soils of the postlithogenic trunk belonging to the orders of lithozems (Cryic Leptosols), gley soils (Gleyic Skeletic Cryosols), and Al–Fe-humus soils (Spodic Skeletic Cryosols). The ecological ranges of altitudinal zones— the taiga zone with various types of lithozems below 630–700 m a.s.l. and the tundra zone with combinations of gley and nongley cryogenic soils above these heights—have been established. The development of gley or nongley soils is specified by the local orogenic and lithological conditions and slope aspect, which, in turn, control the degree of drainage and the presence and character of permafrost. In the profile of mountainous gley soils (gleyzems) with shallow ice-rich permafrost, cryogenic processes and features typical of the analogues of these soils on plains—cryogenic cracking, cryoturbation, solifluction, thixotropy, oxiaquic features above permafrost, saturation of the soil profile with mobile humus, etc.—are typical.     

Diagnostics of hydromorphism in soils of autonomous positions on the Severo-Sos’vinsk Upland (Western Siberia)

The complex studies of hydromorphism features in taiga weakly differentiated soils using morphological (color), chemical (iron content in different extracts, indicators of reducing conditions (IRIS)), and geobotanic (using the Ramenskii scale) methods have led to ambiguous conclusions. In all the soils, surface gleying was manifested. According to the results obtained by different methods, the maximum reduction processes were related to either the sublitter or the next deeper horizon. The Schwertmann coefficient, the criterion of Bodegom, and the Ramenskii scale indicated an increase of hydromorphism in the soils studied in the following sequence: the lower part of the ridge slopes drained by the small gullies < the middle part of the slopes < the flat tops of the ridges < the depression between the ridges. The morphological diagnostics of gleying proved to be a less sensitive method, which can recognize only the most contrasting hydromorphic soils. The lower horizons in some taiga soils have a bluish gray color probably not related to the recent soil hydromorphism.     

Soil polygenesis in the northeast part of Vladimir opolie

Soil studies in cultural landscapes of the medieval epoch within the Vladimir opolie territory on the Russian Plain suggest that virtually all automorphic soils in this area were plowed in that period. The morphology of the profiles of studied soils depends on the composition of parent materials. If the parent material represents a pedocyclith that passed through the stage of periglacial pedogenesis in the Late Pleistocene, then the soil profile developed from this material is a heterochronous body with distinct features of polygenesis. If the parent material is a relatively homogeneous sediment that was not subjected to periglacial pedogenesis in the Late Pleistocene, then the soil profile developed from this material contains only the features of the Holocene pedogenesis, even in the case when the thickness of the homogeneous substrate does not exceed 0.5 m. It is hypothesized that the Holocene pedogenesis within the humid forest and southern taiga zones in the center of the Russian Plain cannot delete the features of the pre-Holocene pedogenesis and morpholithogenesis; these features are always inherited by the profiles of modern soils. The presence of these features ensures the development of a fully developed mature soil profile.     

A map of the soil cover patterns in the western part of the Transbaikal region (1: 500000 scale)

The results of soil surveys in the Khorinsk district of the Buryat Republic have been generalized on a map of the soil cover patterns on a scale of 1: 500000. The map reflects the soil cover patterns in the zones of mountainous tundra and taiga, mountainous forest-steppes, sand massifs on piedmonts, and plain steppes and dry steppes. The areas of each component of the soil combinations shown on the map have been calculated. In the course of the generalization of large-scale soil maps, information on the genetic types and subtypes of soils has been preserved. The new map adequately displays the real pattern of the soil distribution in the studied area.     

Hydrocarbons in the background soils of the southern- and middle-taiga subzones of the Komi Republic

The background content of hydrocarbons in soils of the southern and middle taiga has been assessed with consideration for the landscape and geochemical features of the area. Studies of hydrocarbons in soils of the taiga zone have showed that the position in the relief, particle-size distribution, and organic matter content are the main factors determining their content. The geochemical background of hydrocarbons is 50–100 mg/kg in the organic horizons of the soils on cover loams and 17–70 mg/kg in the soils on sandy deposits.     

Genesis and classification position of automorphic soils developed from mantle loams in the northern taiga of European Russia

Automorphic loamy soils of the northern taiga and forest-tundra zones in the northeastern part of European Russia are characterized. These soils are diagnosed by the presence of a paragenetic system of the podzolic (often, with gley features) and iron-illuvial horizons combined with a specific cryometamorphic CRM horizon. The podzolic horizon is considerably impoverished in the total and oxalate-extractable iron and slightly impoverished in aluminum and clay in comparison with the iron-illuvial horizon. A distinctive feature of the cryometamorphic horizon is its fine angular blocky, ooidal, or granulated structure in the dry state and curdled cryogenic structure in the wet state. The soil profile is relatively weakly differentiated with respect to the contents of clay and sesquioxides. The genesis of these soils is related to a combination of the gley-Al-Fe-humus mobilization, migration, and illuvial accumulation of substances and the cryogenic structuring. According to the new Classification and Diagnostic System of Russian Soils, these soils fit the criteria of iron-illuvial svetlozems in the order of cryometamorphic soils. In the studied area, these soils are found together with texture-differentiated gley-podzolic soils having the Bt horizon and belonging to the order of texture-differentiated soils.