Specific Features of Profile Distribution and Crystallochemistry of Phyllosilicates in Soils of the Cisbaikal Forest-Steppe

The mineralogical composition of agrogray, dark gray, and agro-dark gray soils (Luvic Greyzemic Retic Phaeozems); agro-dark gray residual-calcareous soils (Calcaric Cambic Phaeozems); clay-illuvial agrochernozems (Luvic Chernic Phaeozems); and agrochernozems with migrational–mycelial carbonates (Haplic Chernozems) developed in the forest-steppe of Central Siberia within the Irkutsk Depression has been studied. The clay (<1 μm) fraction separated from these soils consists of mixed-layer minerals with alternating layers of hydromica, smectite, vermiculite, and chlorite; the proportions between them change within the soil profiles. The clay fraction also contains hydromicas, kaolinite, chlorite, and some admixture of the fine-dispersed quartz. Each type of the soils is characterized by its own distribution pattern of clay material with specific alternation of layers in the mixed-layer formations. Mixed-layer minerals of the chlorite–vermiculite type predominate in the upper horizons of texture-differentiated soils. Down the soil profile, the content of mixed-layer mica–smectitic minerals increases. In the clay fraction of arable dark gray-humus soils with residual carbonates, the distribution of the clay fraction and major mineral phases in the soil profile is relatively even. An increased content of well-crystallized kaolinite is typical of these soils. The parent material of agrochernozems has a layered character: the upper horizons are generally depleted of clay, and the middle-profile and lower horizons are characterized by the considerable kaolinite content. In general, the clay material of soils of the Tulun–Irkutsk forest-steppe differs considerably from the clay material of foreststeppe soils developed from loesslike and mantle loams in the European part of Russia. In particular, this difference is seen in the proportions between major mineral phases and between biotitic and muscovitic components, as well as in the degree of crystallinity and behavior of kaolinite and chlorite.     

Dynamics of Soil Properties and Plant Composition during Postagrogenic Evolution in Different Bioclimatic Zones

The postagrogenic dynamics of acidity and some parameters of humus status have been studied in relation to the restoration of zonal vegetation in southern taiga (podzolic and soddy-podzolic soils (Retisols)), coniferous-broadleaved (subtaiga) forest (gray forest soil (Luvic Phaeozem)), and forest-steppe (gray forest soil (Haplic Phaeozem)) subzones. The most significant transformation of the studied properties of soils under changing vegetation has been revealed for poor sandy soils of southern taiga. The degree of changes in the content and stocks of organic carbon, the enrichment of humus in nitrogen, and acidity in the 0- to 20-cm soil layer during the postagrogenic evolution decreases from north to south. The adequate reflection of soil physicochemical properties in changes of plant cover is determined by the climatic zone and the land use pattern. A correlation between the changes in the soil acidity and the portion of acidophilic species in the plant cover is revealed for the southern taiga subzone. A positive relationship is found between the content of organic carbon and the share of species preferring humus-rich soils in the forest-steppe zone.     

Soil cover in the southern forest-steppe of the Central Russian Upland against the background of centennial climate fluctuations

Special approaches and algorithms for studying the response of zonal soils and the soil cover of the forest-steppe zone to climate fluctuations were developed on the basis of data of repeated soil surveys. They made it possible to analyze the particular transformations of the soil cover as indicators of short-term climate fluctuations in the southern forest-steppe of the Central Russian Upland. Vector soil maps and related databases on soil polygons were developed using GIS technologies. Changes in the climatic conditions between two rounds of large-scale soil surveys in 1971 and 1991 reflecting the so-called Brückner cycles were identified. A characteristic feature of climate change during that period was the rise in the mean annual air temperature by 0.2°C and an increase in the mean annual precipitation by 83 mm. In response to this change, the area of leached chernozems (Luvic Chernozems) on the interfluves somewhat increased, whereas the area of typical chernozems (Haplic Chernozems) decreased.     

Temporal changes of eroded soils depending on their agricultural use in the southern Cis-Ural region

Temporal changes of eroded soils in the southern Cis-Ural region (Republic of Bashkortostan) depending on their agricultural use during the period from 1975 to 2011 were studied. In the northern foreststeppe zone, the development of erosion processes was retarded upon the use of soil-saving management practices and grain-fallow-grass crop rotations. In slightly eroded light gray forest soils (Eutric Retisols (Cutanic)), the thickness of humus-accumulative horizons and the content of humus increased; the conversion of cropland into permanent fallow was found to be the most efficient measure to control soil erosion. In podzolized chernozems (Luvic Greyzemic Chernic Phaeozems) and typical chernozems (Haplic Chernozems) of the Cis-Ural steppe, the content of humus in the plow layer under grain-row crop rotation and classical soil management decreased, especially in moderately eroded soils. The development of water and wind erosion on slopes depended on the slope shape: the texture of soils at different degrees of erosion on slopes with free runoff became coarser by one gradation after 35 years; in the presence of linear obstacles in the lower part of slopes, the content of fine fractions in moderately and strongly eroded soils increased.     

Application of the Spectral Neighborhood of Soil Line Technique to Analyze the Intensity of Soil Use in 1985–2014 (by the Example of Three Districts of Tula Oblast)

The technique of separation of the spectral neighborhood of soil line (SNSL) makes it possible to perform quantitative estimates of the intensity of agricultural land use. This is achieved via calculation of the frequency of occurrence of bare soil surface (BSS). It is shown that the frequency of occurrence of BSS in 1984–1994 was linearly related to the soil type within the sequence of soddy strongly podzolic, soddy moderately podzolic, soddy slightly podzolic (Eutric Albic Glossic Retisols (Loamic, Aric, Cutanic, Differentic, Ochric)); light gray forest (Eutric Retisols (Loamic, Aric, Cutanic, Differentic, Ochric)), gray forest (Eutric Retisols (Loamic, Aric, Cutanic, Ochric)), and dark gray forest soils (Luvic Retic Greyzemic Phaeozems (Loamic, Aric)); podzolized chernozems (Luvic Greyzemic Chernic Phaeozems (Loamic, Aric, Pachic)) and leached chernozems (Luvic Chernic Phaeozems (Loamic, Aric, Pachic)). The intensity of exploitation of the least and most fertile soils in this sequence comprised 28 and 48%, respectively. In the next decade (1995–2004) the relationship between the type of soil and the intensity of its exploitation drastically changed; the intensity of exploitation of the leas and most fertile soils comprised 14 and 43%, respectively. Nearly a half of agricultural lands in the zones of soddy-podzolic and gray forest soils were abandoned, because the cultivation of the soils with the natural fertility below that in the podzolized chernozems became economically unfeasible under conditions of the economic crisis of the 1990s. The spatiotemporal relationships between the character of the soil cover and the intensity of exploitation of the agricultural lands manifest themselves by the decreasing frequency of occurrence of BSS from leached chernozems to soddy strongly podzolic soils and from 1985 to 2014.     

Dynamics of the agrochemical fertility parameters of arable soils in the southwestern region of Central Chernozemic zone of Russia

Data of the agrochemical survey of arable soils in Belgorod oblast during the period from 1964 to 2014 have been analyzed. The soil cover mainly consists of typical chernozems (Haplic Chernozems) and leached chernozems (Luvic Chernozems) in the forest-steppe zone and ordinary chernozems (Calcic Chernozems) in the steppe zone. Under long-term agricultural use (from 1964 to 2014), the content of mobile phosphorus in arable soils of the region under study has increased from 55 to 137 mg/kg, and the content of mobile potassium has increased from 105 to 147 mg/kg. During the period of 1976–2014, the share of acid soils has increased from 22.8 to 45.8%, including medium-acid soils from 1.5 to 12.6%. No significant changes in the weighted average content of soil organic matter are revealed for the period from 1985 to 2014. The value of this parameter is within the range of 4.8–5.0%. In the 2010–2014, 95.0% of arable soils belonged to the category of low supplied with mobile sulfur; 99.2, 96.9, 94.1, and 54.4% of soils were poorly supplied with zinc, copper, cobalt, and manganese, respectively. During the same period, the maximum average productivity of the crop area (3710 f. u./ha) was noted at the application of 4.8 t/ha organic fertilizers and 97.9 kg/ha organic fertilizers on the average. The maximum long-term yields of sugar beet (36.8 t/ha) and corn grain (4.97 t/ha) were obtained at the application of relatively low fertilizer rates.     

Soils of Different Land Use Categories in the City of Petrozavodsk

In the territory of the city of Petrozavodsk, the following categories of land use were distinguished: lands of common use, lands of urban and rural development, natural recreation zone, and reserved land. In each area, soil pits were made, and each full profile was analyzed for its morphological structure and physicochemical properties. Among soils, urbostratozems (Urbic Technosols) predominate, urbistratified natural soils (Plaggic Cambisols, Technic Podzols), and technogenic surface formations are spread to a lesser extent. The undisturbed natural soil cover is preserved in suburban forests and on lands of reserve and rural development. The urban soils differ in their physicochemical properties from the zonal natural soils by the elevated base saturation and high content of mineral nutrients. Heavy metal concentrations are mainly at the level of regional background characteristics. Maximum/tentatively permissible concentrations of lead, copper and zinc are exceeded on the lands of common use, building areas, and in the natural recreational zone of the city, which was influenced in the past by the activity of the city-forming plant.     

Soil formation in Greyzems in Moscow district: micromorphology, chemistry, clay mineralogy and particle size distribution

Greyzems (Grey Forest Soils) are zonal soils of the forest–steppe, in Russia geographically situated between the (Podzo) Luvisols of the southern taiga forest and the (Luvic) Chernozems of the steppe. Greyzems are characterized by a dark mollic horizon, with uncoated (bleached) silt and sand grains on pedfaces, and an argic horizon as diagnostic horizons. The FAO–Unesco soil map of the world shows Greyzems and Luvisols in Russia at this transition (the Russian soil map shows only Greyzems), while in similar geographic position in the USA and Canada the proportion of Greyzems is very small and Luvic Phaeozems/Chernozems and Albic Luvisols occupy those transitional zones of the grassland–forest interface. Three Greyzem profiles, presently under forest, and developed on loess-like mantle loams of Late Weichselian (Valday) age in the northern forest–steppe zone of the East European plain (Middle Russian Upland) were described and sampled near Pushchino, some 100 km south of Moscow. Micromorphology, particle size data, chemical data and clay mineralogy were studied. Based on the particle size distribution and the occurrence of fragments of a second humus horizon (SHH) the presence of two, rather similar, deposits in the solum is advocated. The following processes have been deduced from the study: (i) decalcification and secondary accumulation of carbonates; (ii) humus accumulation, including the significance of the SHH; (iii) clay illuviation, presumably two main phases; (iv) biological activity; (v) degradation of the mollic A: occurrence of bleached grains; (vi) downward migration of textural components and organic matter, in the Bt horizon along major pedfaces: occurrence of black organo-clay coatings and uncoated silt/sand grains; (vii) gleying. The tentative sequence of these processes during Late Weichselian and Holocene times leads us to conclude that Greyzems are polygenetic. They formed as Podzo(Luvisols) under forest, with fine clay coatings in the fine pores inside the blocky and prismatic peds, in the Late Glacial and Early Holocene. The change to tall grass steppe in the Atlanticum created a mollic horizon, that degrades when forest re-invades during the Subatlanticum. Fine clay, combined with organic matter forms black coatings on the major pedfaces. Uncoated silt and sand particles also migrate downward along those major pedfaces. Biological activity is involved in the very complex pattern of the transitional AhE and EBt horizons. Active gleying only occurs in the profile on the lowest topographic position. These latter processes are still active today. Similar soils do occur in the grassland–forest interface in North America, except where the younger age of the landscape and high CaCO3 content at shallow depth prevented their full development.     

Dynamics of denitrification and ammonification activities in the abandoned and intensely cultivated gray forest soils (Tula oblast)

The results of experimental study of daily dynamics of denitrification activity and the activity and population density of ammonifiers in the abandoned (converted to long-term fallow) and intensely cultivated gray forest soils (Luvic Retic Greyzemic Phaeozems (Aric)) are discussed. The potential denitrification activity in the arable soil is higher than that in the fallow soil, whereas the actual denitrification activity in the arable soil is lower. Data on the dynamics of ammonification do not show reliable differences between the activities of ammonifiers in the arable and fallow soils, though the number of ammonifying bacteria is considerably higher in the arable soil. Differences in daily dynamics of the numbers of ammonifiers in the fallow and arable soils are shown.     

Soil cover patterns and land assessment in the Baikal region of Buryatia using the example of the Kabansk district

The soil cover patterns in the Kabansk district (the Baikal region of the Buryat Republic), including the Selenga River delta, are analyzed. A soil map of this area has been developed on a scale of 1 : 500000. Stony organic soils are widespread in the tundra zone. Mountain-meadow soddy soils and tundra podburs (under dwarf pine) are formed at lower heights around lakes and in glacial valleys. Kabansk district includes taiga landscapes on the northern slopes of the Khamar-Daban Ridge with the predominance of podburs, podzols, soddy-taiga soils, and burozems. Agrolandscapes occur in the Nizhneselenginsk meadow-bog and forest-steppe natural region with a predominance of soddy forest, soddy gray forest, meadow, alluvial, meadow-bog, and bog soils. Data on the land evaluation in the agricultural part of the studied region are given.     

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.     

CO<Subscript>2</Subscript> emission from the surface of dark gray forest soils of the forest steppe and sandy soddy-podzolic soils of the southern taiga

Studies performed on dark gray loamy forest soils in an oak forest in the southern forest steppe and on sandy soddy-podzolic soil in a pine forest in the southern taiga showed that the annual emission of CO₂ from the soil surface in the pine forest was 16.3 t CO₂/ha, including 10.1 t CO₂/ha due to root respiration and 6.2 t CO₂/ha due to soil microbial respiration. In the southern forest steppe, the corresponding values were 17.8 t CO₂/ha due to root respiration at the optimum water content (20%) and 28.3 t CO₂/ha due to soil microbial respiration. With the insufficient soil water content (12.5%), 10.3 and 17.8 t CO₂/ha were due to root respiration and soil microbial respiration, respectively. Under strong drought conditions (water content of 10%), the emission of CO₂ decreased to 8.2 and 16.3 t/ha due to root respiration and soil microbial respiration, respectively.     

The effect of salinization on the biomass of microorganisms in the soils of different ages in the forest-steppe zone of Western Siberia

The study of soils of different ages developing on the drying bottom of the shallow-water Yudinsk reach of Lake Chany (Western Siberia) has shown that soil salinization is a powerful factor affecting the biomass and metabolic activity of microorganisms. Strong salinity of parent materials retards the development of microbial population in the young soils. With an increase the soil age of lake depressions, desalinization takes place, and the rate of the formation of microbial biomass increases. Its metabolic activity becomes more pronounced, though the specific rate of metabolic activity slows down. The carbon of the microbial biomass and basal respiration in the soils developing on drying lake bottoms in the forest-steppe zone reach the values typical of the zonal chernozemic soils in about 80 years.     

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%).     

The Effect of Historical and Regional Features of Land Use on the Size and Structure of Carbon Pools in the Southern Taiga and Forest-Steppe Zones of European Russia

An algorithm of regional assessment of the size and structure of the actual (corresponding to the modern state of ecosystems and land use patterns) and potential (for hypothetic natural ecosystems analogous to modern native ecosystems) pools of carbon has been developed and tested. A comparison between actual and potential values of carbon pools makes it possible to assess the integral result of land use in the studied region with multiple changes in the types of land use during the historical period. The calculations are made using a unified cartographic base and take into account the taxonomic position and texture of soil units, the types of modern land use, and the type and age structure of the reconstructed and actual vegetation. The results obtained for the southern taiga and forest-steppe zones of European Russian indicate that the modern actual carbon pool is 24% less than the potential carbon pool in Kostroma oblast (southern taiga zone) and 32% less than the potential carbon pool in Kursk oblast (forest-steppe zone). The actual phytomass reserves in these two regions have decreased by 40 and 75%, respectively, relative the potential phytomass reserves, so the portion of the soil carbon pool in the total carbon pool has increased. It is argues that the use of the territory for forestry and agriculture increases the role of the soil cover in sustaining the carbon budget of the region.     

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.     

Selective phytoamelioration of soils in Kursk oblast

Data on zinc accumulation by saperda mustard and common barley grown on typical chernozem (Voronic Chernozems) and gray forest soil (Greyic Phaeozems Albic) in Kursk oblast are given. The revealed high phytoextraction capability of saperda mustard on gray forest soil depends on the content of total and available zinc. It has been found that the accumulation capability of common barley is similar on both soil types. The phytoextraction rate of the root systems of the studied plants is greater than that of their sprouts. Biological removal of zinc from soil by plants is up to 4.46 kg/ha. Saperda mustard and common barley are potential phytoremediation plants for zinc-contaminated gray forest soil and typical chernozem.     

Soils of Mountainous Forests and Their Transformation under the Impact of Fires in Baikal Region

Data on postpyrogenic dynamics of soils under mountainous taiga cedar (Pinus sibirica) and pine (Pinus sylvestris) forests and subtaiga–forest-steppe pine (Pinus sylvestris) forests in the Baikal region are analyzed. Ground litter–humus fires predominating in this region transform the upper diagnostic organic soil horizons and lead to the formation of new pyrogenic organic horizons (Opir). Adverse effects of ground fires on the stock, fractional composition, and water-physical properties of forest litters are shown. Some quantitative parameters of the liquid and solid surface runoff in burnt areas related to the slope gradient, fire intensity, and the time passed after the fire are presented. Pyrogenic destruction of forest ecosystems inevitably induces the degradation of mountainous soils, whose restoration after fires takes tens of years. The products of soil erosion from the burnt out areas complicate the current situation with the pollution of coastal waters of Lake Baikal.     

The relationship between pedogenic and geomorphic processes in mountainous tropical forested area in Sierra Madre del Sur,Mexico

Both mature and underdeveloped soils are present in tropical mountainous landscapes. The spatial arrangement of mountainous soils is ascribed mainly to geomorphologic processes. We studied two soil toposequences (one on a convex, and the other on a concave slope with a gradient 40–60%) at the coffee-growing farm La Cabaña, situated in the mountains of the Sierra Madre del Sur, southern Mexico. Mature (Alisols) as well as moderately developed (Luvic Phaeozems) and underdeveloped soils (Fluvic and Skeletic Phaeozems) were detected in the study area. The sequence of sediments and soils is unusual for a classical soil catena. Buried clayey reddish soils are present on the shoulder of a slope; colluvial sediments with weakly developed soils form convex and concave footslopes. The peculiarity of the slopes and spatial distribution of soils in the studied toposequences were ascribed to intensive linear erosion (due to tectonic uplift), seismically induced landslides, and K-cycles of laminar erosion. The diversity of sediments leads to considerable variation in soil texture and mineralogical composition, and, thus, to the diversity of soil properties, which is considered to be a positive feature of a landscape.     

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.