No 7 (2023)

The ecological and coenotic structure of the living ground cover and the structural and functional features of forest litter for three types of forests were studied: hairy-sedge birch forest, birch-aspen hairy-sedge, soddy-pike birch forest, forming a sequential row as hydromorphism increases within the slope, gradually to the center of the drive-dividing depression. The ecological characteristic of the living ground cover is based on the grouping of ecological-coenotic formations according to A.A. Nitsenko and ecological scales L.G. Ramensky and H. Ellenberg. Increasing hydromorphism is accompanied by an increase in ecological and cenotic diversity. The total trophicity score also increases under conditions of increased hydromorphism – in the soddy pike birch forest – in combination with low Ellenberg acidity index. Conversely, the maximum scores for these indicators, with high variation, belong to the birch-aspen forest, which occupies intermediate positions in the series of increasing hydromorphism. It was established that the studied stands are characterized by destructive and fermentative litters. As hydromorphism increases, the litter deposit increases from 400 to 1400 g/m² with a simultaneous increase of detritus part in L subhorizon. About 60% of total organic matter deposit concentrated the litter of small-leaved plantations is accounted by easily decomposing fractions. With a regular increasing ash content in the system of subhorizons L–F, the maximum ash content is obtained for detritus fraction of L subhorizon. With a regular increase in the ash content in the system of subhorizons L–F, the maximum ash content is characteristic of the detritus fraction of the subhorizon L. The parameters of the ecological characteristics underlying the method of principal components showed a good grouping of the studied phytocenoses according to the degree of moisture, especially when using the general properties of litter (stocks, thickness, detritus content). The expediency of using the properties of litter to establish the similarities and differences of the studied phytocenoses as characteristics that integrally reflect the characteristics of moisture is revealed. The parameters of the living ground cover in conjunction with a number of structural and functional features of forest litter are adequate indicators of the degree of hydromorphism.

Statistical analysis of 3802 samples of saline soils from different regions of Russia made possible to substantiate observations of a higher proportion of magnesium in soils containing gypsum compared to saline soils without gypsum. Gypsum is not a toxic salt and its presence does not lead to an increase in salinity. The increase of the salinity degree is mainly associated with sodium and magnesium salts, with the proportion of sodium more often than the proportion of magnesium. The article statistically substantiates that in the studied saline soils that do not contain gypsum, among the cations in the water extract (1 : 5), sodium most often dominates at any degree of salinity. The appearance of gypsum in the soil profile is accompanied by a significant increase in the proportion of magnesium. With a low and medium degree of salinity in horizons containing more than 1% gypsum, according to the median, as well as the arithmetic mean, upper quartile and maximum, the proportion of magnesium from the sum of sodium and magnesium in the water extract (1 : 5) is often more than 50%. Even at a strong and very strong degree of salinity, the proportion of magnesium in gypsum-containing horizons is significant and amounts to 43 and 31%, respectively, on the median, which is 5.8–6.7 times higher than the proportion of magnesium in gypsum-free horizons of the same degree of salinity.

A comparative analysis of areal and profile measurements of magnetic susceptibility was carried out in order to improve methods of surface sensing of the earth, as well as to take into account small-scale mapping of soils and the identification of anomalies associated with anthropogenic pollution or violation of the surface layer of soils. Two sites with Haplic Chernozems and one Haplic Kastanozems (Endosalic, Cambic) were studied. Additionally, a catena was studied on the territory of the Ergeninsky upland with the inclusion of sites in various positions of the landscape (eluvial, transeluvial, transeluvial-accumulative). The comparison of the areal and profile magnetic susceptibility measured to a depth of 30 cm showed a direct correlation (R² = 0.7). It was found that the areal type of survey correctly captures the volumetric magnetic susceptibility (\({{\varkappa }_{{\text{s}}}}\)) to a depth of 30 cm. The variation of \({{\varkappa }_{{\text{s}}}}\) at sites with different types of soils reflects soil-climatic zonality and spatial lithological heterogeneity, expressed in different granulometric and mineralogical composition of the 0–30 cm layer on an area of 10 × 10 m. The areal magnetic susceptibility of soils can be an important additional indicator capable of reflecting the features of soil-forming, lithological and landscape geochemical processes occurring in the upper soil layer. Variation of \({{\varkappa }_{{\text{s}}}}\) at sites in different positions of the landscape occurs under the influence of planar flushing and a change in the direction of iron oxidogenesis processes depending on the position of the soil profile in the relief. The complex of measurements of areal and profile magnetic susceptibility can be used to study soil inhomogeneities caused by anthropogenic, paleocryogenic, geomorphological and lithogenic factors. Such an approach can be widely applied to the study of polluted soils and monitoring of agricultural land.

The effect of nitrate and potassium chloride salts, on the structure of the metabolically active prokaryotic community of oil-contaminated chernozem has been studied. Molecular biological approaches and bioinformatic methods of analysis were used in the study. The objects of the study were samples of chernozem selected in the Voronezh region (N 51°1′41″, E 40°43′31″). The phylogenetic and functional diversity of the prokaryotic complex of oil-contaminated chernozem was considered when introducing nitrate and potassium chloride under conditions of a slightly alkaline reaction of the medium. Contamination of chernozem with oil in an amount of 5% of the soil mass led to alkalinization of the medium from 7.1 to 7.9. The introduction of nitrate and potassium chloride, both separately and together in a total dose of 2 mmol/100 g of soil removed this negative effect. The combined addition of nitrate and potassium chloride led to a more than twofold increase in the biomass of metabolically active prokaryotic cells and the number of copies of functional genes responsible for the synthesis of alkanmonooxygenase enzymes involved in the decomposition of oil. In the presence of oil, the formation of a specific complex of bacteria was revealed, in which representatives of A-ctinobacteria (Rhodococcus erythropolis) and Alphaproteobacteria (Bradyrhizobium japonicum) prevailed. Rhodococcus erythropolis and Bradyrhizobium japonicum, being autochthonous organisms in uncontaminated soil, began to occupy dominant positions in oil-contaminated samples, and the introduction of nitrates enhanced this effect.

The high variability of the plutonium transfer factors presented in the literature makes it relevant to study the mechanisms that affect its migration ability and its availability for vegetation. The variability of transfer factors is explained by different properties of soils, since the redox potential and soil acidity can significantly affect the mobility of plutonium. In the vegetation experiment, the migration of plutonium in the “soil-agricultural plant” system was studied for different types of soils. The content of ^{239 + 240}Pu was analyzed by alpha spectrometry with preliminary radiochemical isolation. Plutonium migration parameters were determined using barley (Hordeum) and beans (Fabaceae) as test cultures. The plutonium accumulation coefficients obtained in the course of vegetation experiments are in the range of 3.1 × 10^–4–6.8 × 10^–3, with an average value of 3.8 × 10^–3 for the aboveground part of barley and 9.2 × 10^–3–7.6 × 10^–2, with an average value of 3.8 × 10^–2 – for the root system of barley. The transfer factor range was 1.5 × 10^–3–5.7 × 10^–3 with an average value of 3.7 × 10^–3 and 5.8 × 10^–2–6.5 × 10^–2 with an average value of 6.2 × 10^–2 for the aboveground part and the root system of the beans, respectively. It has been determined that the nature of the plutonium distribution over the vegetative organs of the crops under consideration is non-uniform. On average, the plutonium transfer factor for the aboveground part of plants is lower than for the root part by more than 40 times. It has been determined that the accumulation of plutonium in the aboveground parts of plants growing on different types of soil is not the same for individual species/organs of agricultural plants. For the aboveground part of the agricultural crops under consideration, the transfer factors differ up to several orders of magnitude. In general, the accumulation of plutonium by vegetation growing on different soils types is arranged in the following row: soddy-podzolic (Retisol) and gray forest soil (Phaeozem) > lowland peat-bog (Histosol) \( \gg \) typical chernozem (Chernozem). The smallest accumulation of plutonium by vegetation is observed in soils with a high content of organic matter. For the root system of plants, the dependence of the plutonium accumulation coefficients on the soil type is uncertain.

According to literary and archival data, the dynamics of the Tula region/province plowing as a whole, and its individual parts are revealed. It is established that the agricultural development of southern part of the modern Tula region began in the middle of the XVII century. According to the maps of different years of creation, changes in the area of arable land in the Lokna river basin (Plavsk district of the Tula region) from the end of the 18 to the present are determined. The reliability of the values of ploughing of the territory obtained by instrumental methods is confirmed by literature data. The composition of field crops and changes in farming systems during the period under review were reconstructed, significant conservatism of these indicators was revealed: the fallow three-field dominated throughout the XIX and the first half of the XX centuries, the predominance of rye in winter crops and oats in spring crops remained until the 1970s. According to the WaTEM/SEDEM, using historical data on the change in the main erosion factors as input parameters, the intensity and volume of rainfall run-off for the selected stages of agricultural development of the Lokna river basin were calculated. In order to compare the results with the literature data for the period 1980–1993 yr the snowmelt soil erosion rates were additionally calculated. The reliability of the obtained estimates for the last 40–50 years is confirmed by the literature data. It is established that the maximum plowing and intensity of the manifestation of erosion processes in the Lokna river basin was observed in the last quarter of the XIX–early XX centuries. The influence of the arable land location relative to the relief elements on the rates and volumes of run-off is revealed.