Počvovedenie

Five field surveys of the same territory were conducted to establish functional relationships between the content of soil organic matter (SOM) and multi-temporal spectral characteristics of the bare soil surface (BSS). The surveys differ in five methods for planning soil sampling sites. Three methods used traditional approaches using regular and irregular networks, and two methods used the coefficient C map of the multi-temporal (empirical) soil line (MSL). It is shown that it is difficult to obtain a stable relationship between the values of the spectral characteristics of remote sensing data and the SOM content using traditional methods. The determination coefficients of such dependencies are below 0.60, which does not allow to recommend the obtained dependencies for the purposes of SOM mapping. Organization of field work based on a pre-built map of the coefficient C of the MSL showed the possibility of establishing functional relationships between the SOM content and multi-temporal spectral characteristics of the BSS with a determination coefficient of 0.81. The reason for the different quality of regression models is the omission of a number of soil objects during traditional organization of field work and problems in positioning the sampling. Correction of traditional field surveys based on multi-temporal spectral characteristics of the BSS allows improving the quality of research and developing new methods for SOM mapping.

The article studies the structure and properties of permafrost-affected gleyzems and peat-gleyzems in the tundra landscapes of the Subpolar Urals, the southernmost mineral soils with insular permafrost that is particularly sensitive to present-day climate change. The study examines in detail the morphological and cryogenic structure, temperature regime, mineralogical composition, and physical-chemical properties of active layer and underlying permafrost. The thin active layer is characterized by the predominance of peat horizons and significant gleyization of mineral horizons; a high-ice transition layer is localized in the upper permafrost. Massive cryogenic textures were revealed in the active layer, and schlieren and ataxic textures were found in the underlying permafrost. Peat-gleyzem, in contrast to the colder gleyzem, is characterized by a relatively mild temperature regime, which is explained by the increased thickness of the heat-insulating peat horizon and a greater depth of snow cover. Permafrost-affected soils of the Subpolar Urals are confined to climate-driven ecosystem-modified permafrost. It was revealed that the predominance of the coarse silt fraction in soils with close underlying permafrost contributes to the significant thixotropy of gleyed active layer. Cryogenic-lithological heterogeneity of profiles in the conditions of the subarctic humid climate of the mountainous country determines the specific structure and properties of gley permafrost-affected soils of the Subpolar Urals.

The study is aimed at solving fundamental problems of soil science and ecology related to assessing the carbon balance in coastal soils and ecosystems of the Russian Arctic, as well as their functioning in a changing climate. The study estimated carbon dioxide emissions from soils of marsh ecosystems on the southeastern coast of the Barents Sea for the first time. Soils of marsh ecosystems are characterized by high values of carbon dioxide emissions (4.03 ± 0.17 g С/(m² day), June–July 2024), which indicates their high biological activity. The analysis of data on CO₂ emissions from soils of marsh ecosystems indicates mainly their high spatial variability. Soils at different levels of marsh ecosystems statistically significantly differ in the magnitude of CO₂ emissions and line up in order of increasing values: wadden, beaches < littoral pools, eroded benches of the marsh < ecotone zones, lower marshes, splash zones of backflow channels (creeks) < middle and upper marshes. It has been established that lower values of CO₂ emissions are observed on marshes subject to intense wind waves, which is due to the armoring role of coastal relief forms in the migration of thalassogenic matter. Despite the insignificant area of the coastal zone of the southeast of the Barents Sea, the contribution of soils of marsh ecosystems to the global flow of greenhouse gases cannot be neglected. The results of the study, obtained on the basis of statistical analysis of a large array of data, contribute to a better understanding of the role of marsh ecosystems of the western sector of the Russian Arctic in the carbon balance.

The physiology and taxonomic composition of prokaryotic communities of various volcanogenic deposits were studied. Samples of fumarole and pyroclastic deposits, as well as primitive soils (Leptic Cryosols) were collected in such poorly studied areas as fumarole fields on the summits of volcanoes in Kamchatka, the Caucasus, Japan, and cinder fields on the slopes of a volcanic structure in Antarctica. In this work, a microbiological characterization of cultured aerobic heterotrophic bacteria from the fumarole field of the Hertz crater on the summit of Ushkovsky volcano (Russia, Kamchatka) was performed for the first time. A collection of isolates was created, including 105 strains of aerobic heterotrophic bacteria representatives of Bacillus, Cupriavidus, Labedella, Microbacterium, Paenibacillus, Peribacillus, Plantibacter, Pseudomonas, Staphylococcus genus. Also, for the first time, an analysis of the physiological characteristics of the isolated strains was performed, such as temperature conditions of cultivation, pH of the medium, and NaCl concentration. The study found that tolerance to two or more stress factors was characteristic of 57.1% of the isolated strains, and tolerance to all three factors was characteristic of 24.8% of the isolated strains.

For a small catchment area in Tula region, a quantitative assessment of soil layers and volumes of soil erosion over the entire period of agricultural use was conducted. The assessment was based on the distribution of leached Chernozems (Luvic Chernic Phaeozems) and Podzols (Luvic Greyzemic Chernic Phaeozems). The total soil loss was determined by comparing the thickness of humified soil horizons on plowed slopes with those on nearby flat watersheds. The washout layer was calculated using the SERSAL model, developed at the Department of Soil Erosion and Riverbed Processes, Faculty of Geography, Lomonosov Moscow State University, based on the adapted and modified USLE natural setting of Central Russia. Based on archival and literary data, we have reconstructed changes in the spatial position of arable land boundaries, farming systems, crop composition, and other erosion factors over the course of three and a half centuries of agricultural development in the watershed. The obtained values were used as input parameters for the model. A comparison of the simulated results and actual soil losses on plowed slopes showed good agreement. When calculating with the Cell variant of the SERSAL model, using an indelible soil standard of 85 cm to determine total soil losses at well points, the simulated volume of washout was 1.2% lower than the actual losses. This confirms the importance of quantifying the contribution of mechanical erosion to total soil loss on arable slopes.. It has been revealed that it is important to take into account changes in the micro-relief of arable land during the study period due to erosion-accumulation processes and mechanical erosion.