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.     

Automorphic taiga soils of the Sredneobskaya Lowland

The morphology of the profile, some chemical properties, and particle-size distribution of the automorphic soils developed from lacustrine-alluvial loamy-clayey deposits in the Sredneobskaya Lowland are considered. The soils of the West Siberian middle taiga zone remain poorly studied. A comparison of our data with data on podzolic soils in the northeastern part of European Russia and with diagnostic characteristics of the soil type of svetlozems included in the new classification system of Russian soils (2004) allows to argue that the studied soils cannot be classified as podzolic soils; most of them also do not fit the diagnostic criteria of svetlozems. The obtained data on the particle-size distribution in the studied soils do not agree with the concept of the sedimentation zonality in the West Siberian Plain.     

Factors of the development of taiga and tundra soils with differentiation of Fe and Al oxides in the profile

Statistical data on the bulk contents of iron and aluminum oxides in iron-depleted and iron-enriched horizons of a wide range of taiga and tundra soils were compared. It was found that the soils could be arranged into the following sequence characterized by an increase in the relative contribution of iron oxides and a decrease in the relative contribution of aluminum oxides to the differentiation of sesquioxides in the soil profiles: sandy podzols—soddy-podzolic soils—loamy micropodzols and iron-illuvial svetlozems—cryogenic ferruginated gleyzems. It was concluded that the bleaching of eluvial horizons and the depletion of sesquioxides from them, as well as the accumulation of sesquioxides in the illuvial horizons, are controlled by different processes in different soils. In sandy podzols, the differentiation of sesquioxides is due to the Al-Fe-humus podzolization; in loamy micropodzols and iron-illuvial svetlozems, due to the redox-Al-Fe-humus podzolization; in podzolic and soddy-podzolic soils, due to the selective podzolization and lessivage; and, in cryogenic ferruginated gleyzems, due to the reduction-oxidation processes.     

Rheological Properties of Automorphic and Semihydromorphic Cryometamorphic Northern Taiga Soils in Northeastern European Russia (Komi Republic)

Soil pastes at the water content corresponding to the maximum swelling of samples from different genetic horizons of cryometamorphic soils―surface-gleyic iron-illuvial svetlozem (Folic Albic Stagnosol) and peaty and peat humus-impregnated gleyic svetlozems (Histic Gleyic Stagnosols)―have been studied with an MCR-302 modular rheometer (Anton Paar, Austria). It has been found that the strongest interparticle bonds are formed in the horizons of cryometamorphic soils characterized by high contents of humic substances and organomineral Al–Fe–humus compounds. These are horizons of podzol microprofile (Eg and BHF) in iron-illuvial svetlozem and a humus-impregnated horizon (ELhi,g) in peaty and peat svetlozems. Organomineral Al–Fe–humus compounds, as well as the seasonal freezing of soils, determine the elastic-brittle character of interparticle interactions. The contents of clay fractions, exchangeable bases, and organic and organomineral substances impart viscoelastic properties to these contacts. An enhancement of elastic-brittle properties of soil is observed under the impact of gleying and freezing. The threefold decrease of the structural interaction parameter (∫Z) when going from automorphic to semihydromorphic conditions indicates a decrease in the resistance of peaty and peat svetlozems to mechanical loads under increasing hydromorphism compared to iron-illuvial svetlozems.     

Soils of the northern part of the Subpolar Urals: Morphology, physicochemical properties, and carbon and nitrogen pools

The morphology and physicochemical properties of mountain-tundra and mountain-forest soils of the Subpolar Urals are analyzed. Gleyic humus-illuvial podburs, in combination with humus-illuvial podburs and raw-humus gleyzems, predominate in the mountain-tundra zone; permafrost-affected gleyzems and peat gleyzems with a shallow (30–50 cm) permafrost table are developed on colluvial fans at the foots-lopes. Iron-illuvial podzols, iron-illuvial svetlozems, eluviated burozems, texture-differentiated podzolic soils with a microprofile of a podzol, and gleyed peat-podzolic soils occur in the mountain-forest zone. The organic carbon and nitrogen pools in the soils considerably vary depending on the soil type and local landscape conditions. The organic carbon pool stored in the upper 50 cm of the soil profile varies from 7.7 to 39.3 kg/m² in the mountain-tundra soils and from 6.5 to 11.8 kg/m² in the mountain-forest soils. The corresponding values for the nitrogen pool are 0.4–2.4 and 0.4–0.8 kg/m², respectively.     

Changes in carbon pool and CO<Subscript>2</Subscript> emission in the course of postagrogenic succession on gray soils (Luvic Phaeozems) in European Russia

An analogous time series of fallow ecosystems (gray soils (Luvic Phaeozems) plowed and fallowed for 2, 7, 20, 60, and more than 120 years) in the broad-leaved forest zone of Orel oblast has been analyzed. Changes in carbon pool and CO2 emission in the course of postagrogenic succession during the vegetation and winter seasons have been estimated. The restoration of ecosystems on Luvic Phaeozems follows regularities revealed in analogous studies of southern taiga Podzols and forest-steppe Chernozems. Analogously to the other studied zonal chronosequences, total annual soil respiration on Luvic Phaeozems reaches the initial level of undisturbed ecosystems simultaneously with the restoration of phytomass reserve, although significantly earlier than the organic carbon reserve in soils is restored. According to regression models, among the zonal fallows in European Russia, including the southern taiga (Podzols), mixed forests (Luvisols), broadleaved forests (Luvic Phaeozems ), forest-steppe (Chernozems) and dry steppe (Calcisol–Solonetz soil complexes), the mean annual soil respiration is maximum in the zone of gray soils and Chernozems. The increase in soil respiration under artificial wetting (Birch effect) on fallows in the broad-leaved forest zone is minimum among the studied zonal chronosequences: 1.1 ± 0.6 (no effect), which corresponds to the optimal hydrothermal conditions in this zone.     

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.     

The relationships between the variability of soil carbon reserves and the spatial structure of the plant cover in forest biogeocenoses

This paper discusses the quantitative characteristics of the intrabiogeocenotic variability of litter carbon reserves, carbon content and reserves in the upper mineral layer of sod-podzol soils in forest biogeocenoses of the southern taiga of European Russia. Their dependence on forest type, parcel type, position in a tessera, and moisture degree is studied.     

The genesis,classification, and melioration of gleyed podzolic chernozem-like soils in the north of the forest-steppe zone of European Russia

Chernozem-like soils with light-colored acid eluvial horizons are widespread in the forest-steppe zone of European Russia. Their formation is related to gleying under the conditions of a stagnant-percolative water regime on leached rocks. It is closely associated with the evolution of salinized soils (Gedroits’s scheme). However, these soils have not been included in the soil classifications of the Soviet Union and Russia. Based on the principles of substantial-genetic classification, one of the authors of this article [3–5, 10] referred them to gleyed podzolic chernozem-like soils, which are considered as an individual genetic soil type. With respect to agroecological aspects, they are different from the leached chernozems in their low productivity and difficulty of tillage. This article covers the problems of genesis, classification, and melioration of gleyed podzolic chernozem-like soils in the north of the forest-steppe zone of European Russia and their possible association with dark-colored podbels.     

Characterization of vegetation and soils of rehabilitated sandy wastelands at the Usinsk oilfields (the Komi Republic)

The soils and phytocenoses developed over 13 years after four procedures of rehabilitation of sandy wastelands in the area of Usinsk oilfields (the northernmost taiga) are characterized. The planting of pine seedlings and especially the sowing of perennial grasses, along with the improvement of the substrate by application of peat and fertilizers, were the most efficient rehabilitation technologies as compared to the planting of only willow cuttings or 7-to 19-year-old pine wildings. On the plots where grasses were sown and pine seedlings were planted, the plant communities were at the preclimax succession stage (small-leaved tree species and shrubs) before the regeneration of the coniferous forest. The input of abundant plant residues have led to the formation of weakly developed soils with higher contents of organic carbon and hydrolyzable nitrogen as compared to their concentrations in the initial substrate. However, they were much lower as compared with the reference peaty-podzolic iron-illuvial soil. In the upper horizons of the weakly developed soils, the number of colony-forming units of bacteria and fungi and the mycobiota diversity were close to those in the reference soil, but the activity of the microbiological processes remained substantially lower in these horizons.     

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.     

Effect of the historical land use on the structure of forest soils in European Russia

The morphological structure of the soils in the forest areas of European Russia was analyzed. It was shown that most of the soils were formed under the impact of both biotic and anthropogenic factors. Soils with poorly differentiated profiles without podzolization features are typical for the least disturbed forest ecosystems. The presence of an eluvial (EL) horizon is associated with the signs of old plowing and (or) fires. The character and rate of the soil cover transformation under various impacts of the historical land use (felling, plowing, pasturing, burning, etc.) are discussed. The technologies of the main traditional farming systems in the forest zone of European Russia (slash-and-burn, fallow, and shifting farming systems) are considered; their effect on the long-term dynamics of the soil cover is estimated. Farming and the related impacts of historical land use can be a major reason for the formation of degraded soils in the forest zone of European Russia.     

Effect of Interannual Difference in Weather Conditions of the Growing Season on the СO2 Emission from the Soil Surface in the Middle-Taiga Cowberry–Lichen Pine Forest (Komi Republic)

Eurasian Soil Science - Data on the СО2 emission from the surface of iron-illuvial podzol (Albic Podzol) under an 84‑year-old cowberry–lichen pine forest of the middle taiga...     

Ecophysiological Characteristics of Psychrotolerant Actinomycetes in Tundra and Forest Landscapes

Eurasian Soil Science - Actinomycetic complexes of soils and plant substrates from tundra and taiga zones of Russia and Finland have been studied. A molecular cytogenetic...     

Genetic features of soils on sorted sand deposits of different origins in the Kola Peninsula

Differences in the chemical composition of soils developed from sorted sands of different origins are revealed. The iron-illuvial podzols on rich glaciofluvial and marine sands are characterized by well-pronounced Al-Fe-humus differentiation of the Si, Al, and Fe in the soil profile. These soils are relatively similar in their bulk elemental composition. The difference between them is seen in the degree of differentiation of the soil profiles; it is stronger in the soils developed from glaciofluvial deposits. This is particularly true with respect to the oxalate-soluble iron and aluminum hydroxides. The deposits derived from the red-colored Tersk sandstone and processed by the sea (in the coastal zone of the White Sea) have the poorest chemical composition. In the soils developed from them, the differentiation of oxalate-soluble compounds is slightly pronounced (for Fe) or completely absent (for Si and Al). These soils can be classified as podzolized ferruginous red-colored psammozems (within the order of poorly developed soils) with the following horizons: O-Ce-Cf-C. The Ce horizon has the features of podzolization, and the Cf horizon has some features attesting to the illuvial accumulation of Fe. The profile of these soils inherits a reddish tint from the parent material.     

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.     

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.     

Soil temperature regimes in the discontinuous permafrost zone in the east European Russian arctic

Temperature regimes of eleven plots with tundra soils were studied in the northeastern part of European Russia within the discontinuous permafrost zone. The duration of soil temperature records ranged from 1 to 9 years. The selected plots were representative of the diversity of landscape and soil conditions in the study area. Virgin tundra soils, a cultivated soil under sown grassland, and soils of secondary biocenoses that developed in place of the former sown grasslands were studied. It was shown that the winter and mean annual temperatures in the permafrost-affected soils drastically differ from those in the soils without permafrost, though the summer temperatures in the root zone of both soil groups are relatively similar. The soil temperature regimes were classified according to Russian (Dimo, 1972) and American (Soil Taxonomy, 1999) classification systems. The degree of detail provided by the Russian system proved to be somewhat greater; at the same time, in contrast to the American system, it does not make it possible to distinguish the soils with warm permafrost in the discontinuous permafrost zone from the soils without permafrost at all.     

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.     

Geographical features of the distribution and renewal of easily decomposable organic matter in virgin and arable zonal soils of European Russia

A decrease in the depth of organic surface horizons (forest litters and steppe mats), the reserves of organic matter in them, and an increase in their renewal rate were noted for virgin and fallow soils when going from the southern taiga to the dry steppe zone. Zonal changes in the content and reserve of easily decomposable soil organic matter showed a similar tendency: these parameters regularly decreased from soddy-podzolic soils of the southern taiga to chestnut and light chestnut soils of the dry steppe. An exception from this series is provided by fallow chernozems of the steppe zone noted for the lowest content and reserve of labile organic matter in the series of soils studied. Similar, although less pronounced, tendencies were observed for the arable soils.