Home – Home – Jornals – Atmospheric and Oceanic Optics 2025 number 11

It is quite difficult to determine the coordinates and magnification of reconstructed holographic image of a particle due to the lack of a clear geometrical-optical model describing the digital holographic process. To obtain magnified images in traditional optics and microscopy, lenses are usually used. In digital holography, such images can be formed without mechanical focusing and the use of optical components, for example, by controlling the divergence of illumination beams. This paper considers the issues related to the optimization of the optical scheme of digital holography that ensures lensless magnification of reconstructed images, justifies the feasibility of using a geometric optics apparatus in the design of such digital holographic systems, and describes their limitations. The results of the work can be used in the design and development of digital holographic microscopy systems, for high-precision reconstruction and analysis of holographic images of particles.

In the modern concept of forest science, forest vegetation zoning is recognized as the natural-historical basis of forestry zoning, and its purpose is to reflect the natural conditions and specific features of forests that are important for their complex multi-purpose use and increased productivity. The purpose of this article is to present the concept and map of forest vegetation zoning, created over more than 60 years by a team of researchers of the Institute of Forest Siberian Branch of the Russian Academy of Sciences. The stages of work on the map and the change of concepts and notions are noted - from a natural-territorial complex to an ecosystem and geosystem, from phytogeography and geobotany to the ecological-geographical direction in forestry. The map is based on forest fund inventory data from 1973-1990; the legend indicates the percentage of coniferous and deciduous formations (larch, pine, spruce, fir, birch, aspen, dwarf pine forests, stone birch, birch sparse forests, dwarf birch brakes and other formations) within each forest growth zone and subzone. In Siberia, as a part of the entire country, three longitudinal-climatic sectors are distinguished: West Siberian, Central Siberian and East Siberian, each with its own characteristics of forest growth zones and subzones, specific typological composition and productivity of stands. The region of the Mountains of Southern Siberia is distinguished separately, in which, according to the same criteria adopted for the plains and plateaus, 4 sectors of moisture-continentality are distinguished. The internal differentiation of this mountain region on a small scale cannot be shown on the map due to its small contours, but the principle of altitudinal zonal division is observed, published and briefly discussed. The methods and new approaches to compiling the published version of the map, which is part of the zoning map of the entire territory of the forest fund of the USSR, developed at the Institute of Forestry, are described. The published map can serve as a source of information as a starting point for monitoring the forest cover of Siberia, which has been conducted since the early 2000s on a new basis, using the state forest inventory of the country and remote sensing data. This is its historical, scientific and reference value.

For the first time, the phytopathogenic fungus Heterobasidion abietinum Niemelä & Коrhonena has been detected on coniferous trees Siberian pine ( Pinus sibirica Du Tour), Siberian fir ( Abies sibirica Ledeb.), and Siberian larch ( Larix sibirica Ledeb.) in southern Siberia, far from its previously established range. It is possible that its spread to the arboretum occurred due to the movement of planting material from European botanical gardens. Among other Heterobasidion species, H. parviporum Niemelä & Коrhonena is common in the dark coniferous forests of Siberia on Siberian spruce ( Picea obovata Ledeb.), Siberian pine and Siberian fir. In terms of phytopathogenicity and ability to colonize wood with well-developed resin ducts (especially Siberian spruce), H. abietinum is significantly inferior to H. parviporum . It has been established that the Siberian strains of H. abietinum and H. parviporum are closely related. A stable difference (with the formation of separate clades) only in the glyceraldehyde 3-phosphate dehydrogenase (GPD) gene. The vast areas of Siberian fir forests (about 13 million hectares), as well as regular outbreaks of mass insect infestations: (Siberian moth ( Dendrolimus sibiricus Tschetverikov), four-eyed fir bark beetle ( Polygraphus proximus Blandford), which lead to mass weakening and drying of Siberian fir, provide optimal conditions for the development of the low-pathogenic species H. abietinum . Forests that are not subjected to various types of stress are resistant to H. abietinum . Areas of forest dieback as a result of the phytopathogenic effect of H. abietinum has been established only in the conditions of an arboretum on soils after long-term agricultural use. Global climate change, accompanied by an increase in extreme weather events (droughts, storm winds, etc.), as well as an increase in anthropogenic impact (various types of logging and industrial pollution), creates conditions for a further increase in the aggressiveness of root pathogens, particularly H. abietinum .

The effect of mycocompost (the bioadditive) - pine sawdust partially destructured by a wood-destroying fungus culture - on the forest grey soil microbiocoenosis (Krasnoyarsk forest-steppe) was studied. Mycocompost variant was compared with the two ones: soil without bioadditives (control) and soil with addition of intact sawdust. In the trial areas (1 m²), a layer of turf was removed, bioadditives were applied in the amount of 1 % by weight to the top soil layer (10 cm), then the cut turf was returned to its place. During the first year an increase of the total number of soil microorganisms by 5-10 times was observed in all variants of the experiment including the control that was mainly related to the products of degradation of dead turf. Microbial processing of the both sawdust and mycocompost began in the second year of the experiment and was accompanied by a temporary decrease in soil pH, changes in the structure of soil microbocoenosis, a rise in the proportion of fungi and oligotrophic microorganisms, as well increase of availably nitrogen deficiency. The analysis of the data on soil microorganism number, structure of microbocoenosis, microbial respiration and biomass, mineralization velocity of organic matter, enzymatic activity, etc. showed that during two years in the variants with mycocompost and intact sawdust microbial utilization of bioadditives occurred gradually and did not cause imbalance of biological processes in grey forest soil. The mycocompost variant exceeded the control and sawdust ones in terms of the total number of soil microorganisms and biomass on average 2-3 times, did not cause stable soil acidification and provided better preservation of the introduced culture of Trichoderma harzianum Rifai. In combination with additional nitrogen supplementation, mycocompost can be used as a biofertilizer for poor forest soils.

The influence of spruce ( Picea obovata Ledeb.) stands on the change in morphological characteristics, physicochemical properties, state of organic matter, as well as the qualitative and quantitative composition of the microbiocenoses of cryogenic meadow-chernozem soil formed under meadow-steppe vegetation in Central Yakutia was studied. By means of the complex application of soil, microbiological, statistical research methods, all changes that occurred in the original cryogenic soil were identified and assessed. Thus, over a 45-year period of forest vegetation influence, the morphological profile of the original meadow-chernozem soil (Luvic Chernozems Sodic), which had the form: Аv, ca-Aca-ABca-Bcа-BCca-Cca, was transformed into the profile of cryogenic humus-carbonate soil (Calcic Cryosols Eutric), which was already characterized by the following structure: O-А0-A-ABca-Bса-BC-Cca. Over the noted period, a forb-green moss vegetation cover was formed on the surface of the forest soil, as a result of which the depth of seasonal thawing decreased. The physical-chemical properties, humus composition and the state of microbiocenoses of the studied cryogenic soils also changed significantly. Thus, in the meter-thick layer of these soils, the weighted average pH_H2O value decreased from 9.0 to 8.6, and the content of organic C and total N, respectively, increased from 0.79 to 1.72 % and from 0.03 to 0.13 %. At the same time, more mobile humus was formed in the humus profile of the cryogenic humus-carbonate soil, when the total amount of humic acids increased to 65.6-86.0 %, and the proportion of non-hydrolyzable residue decreased to 14.0-34.4 %. Also, this soil turned out to be the richest in microorganisms, where their total number was 2.4 ± 1.3×10⁶ CFU/g, while in the original soil it was only 5.8 ± 3.1×10⁵ CFU/g. Moreover, if actinomycetes (34 %) and micromycetes (29 %) were relatively predominant in the first soil, then oligonitrophilic bacteria (37 %) and ammonifiers (27 %) were predominant in the second.

The article presents the results of a sowing experiment (2016-2024) to assess the safety, growth and condition of seedlings/saplings of forest-swamp and forest-steppe ecotypes (origins) of Siberian larch ( Larix sibirica Ledeb.) planted in a forest area of Akademgorodok in Krasnoyarsk, and to assess the prospects for their use in urban greening. After transplantation from the sowing department in 2022, 6-year-old seedlings showed absolute survival. In the year of transplantation, during the initial examination, some of the young Siberian larch seedlings were found to be affected by hermes ( Adelges laricis Vall.) and larch bud midge ( Dasyneura laricis F. Low.), early yellowing, wilting and needle fall, which did not have a noticeable effect on survival. During the repeated examination, taking into account the degree of preservation of the needles, most of the seedlings of both forest-swamp and forest-steppe origin were characterized by satisfactory and good condition. The absolute growth of seedlings/saplings of the forest-steppe ecotype of Siberian larch was higher than that of the forest-swamp in the year of sowing seeds (2016) and in the year of transplanting young trees (2022). Statistically significant differences in growth between seedlings of forest-swamp and forest-steppe origin appeared when transplanting plants. In other years, greater growth was recorded in seedlings/saplings of the forest-swamp ecotype, compared to the forest-steppe. In 2024, seedlings of the forest-swamp ecotype of Siberian larch had a greater average height compared to the forest-steppe ecotype. Saplings of forest-swamp origin were distinguished by a wider range of height variability, while trees of forest-steppe origin had more even values of variation of this trait.

Environmental conditions of lava fields (moisture accumulation in porous basalts, and complex mesorelief) promote the naturalization of spruce ( Picea A. Dietr.), which forms stable phytocenoses here and acts as an edificator of plant communities. In contrast, larch ( Larix Mill.) occurs sporadically, which is due to its attachment to well-drained soils, making it less competitive in the conditions of lava fields. Dendroclimatic analysis of tree-ring chronologies of spruce and larch confirms the key role of atmospheric precipitation in the dynamics of wood vegetation. Trees, primarily spruce, in these conditions act as an edificator, modifying initial ecological niches and promoting their more active development by moss-grass vegetation. In the unusual ecological conditions of lava fields, hydrophilic and thermophilic spruce, compared to larch, shows greater dependence of radial increment on temperature conditions than on moisture availability.

The dynamics of quantitative and qualitative parameters of fir undergrowth in the indigenous South taiga fir forests of the Tomsk region, damaged by an invasive four-eyed fir bark beetle (Polygraphus proximus Blandford), has been studied. The observations were carried out twice - during the period of mass reproduction of the pest (2012-2016) and 10 years after the outbreak of reproduction (2023), on 8 test areas in phytocenoses, differing in the composition of stands, living ground cover, taxation indicators of the fir element of the mother canopy and the degree of damage. In 2012, the total number of live fir undergrowth in different phytocenoses was 500-6300 trees/ha, including the largest, most valuable, pre-renewal undergrowth of 325-1100 trees/ha. By 2023, the number of undergrowth Siberian fir ( Abies sibirica Ledeb . ) decreased by 1.5-8.5 times, mainly due to a decrease in the number of small undergrowth, and amounted to 167-4000 trees/ha, including large undergrowth 154-2500 trees/ha. The negative dynamics of the number of undergrowth is due to a complex of factors of a biogeocenotic, pathological and mechanical nature, as well as the transition of large undergrowth into a stand. The average height of small and medium-sized undergrowth changed slightly, in large undergrowth in most stands it increased by 1.2-1.7 times by 2023 and reached 4.5 m, the age of large undergrowth ranged from 14 to 36 years. A positive trend was noted in the vital condition of the undergrowth, due to the condition of large undergrowth, partially weakened during the period of mass reproduction of the beetle due to pest attacks and healthy in the post-outbreak period. The comprehensive characterization of fir undergrowth according to the studied parameters allowed us to assess the varying degrees of its success in restoring damaged stands.

Forms of Siberian stone pine ( Pinus sibirica Du Tour) (Siberian pine) with an annual reproductive cycle are unique natural models for studying reproductive processes, speciation and evolution of gymnosperms, as well as potential for genetic selection work aimed at obtaining high-yielding Siberian stone pine plantations. The study of the yield structure and seed productivity of Siberian stone pine trees with an annual cycle of female cone development showed that all growth characteristics of cones (linear dimensions, cone and seed weight) are significantly lower than in typical individuals, and morphogenetic characteristics (the number of seed scales) and the level of variability of yield structure characteristics are comparable to variability in Siberian stone pine populations as a whole. At the same time, for individual specimens with one-year development of reproductive structures, high seed productivity of female cones is characteristic (76.7 %). Selection and fixation in the offspring of traits that ensure stable yields of Siberian stone pine seeds are recognized as promising areas of breeding of Siberian stone pine. Species with one-year development of female cones are unique genotypes with the potential to obtain new varieties and forms.

The studies were carried out in two types of spruce forests: moist bilberry spruce and bilberry-sphagnum spruce forests. They cover the quantitative characteristics of precipitation in summer period and moisture consumption through transpiration by tree canopy of the studied stands. In moist bilberry spruce forest, trees evaporate about 304 mm of water against an average rainfall of 237 mm. In bilberry-sphagnum spruce forest, the values are 305 and 181 mm, respectively. According to the data of the meteorological station situated close to the area where the research was conducted, the air temperature has increased and precipitation has decreased, compared to the long-term annual average data, since 2003. The average sum of air temperatures for these years is by 3.7 °С above the norm, but precipitation is by 30 mm under the norm, which indicates climate warming in the study area. The soils of green moss spruce forests of the middle taiga subzone are characterized by a favorable moisture regime for plants. The moisture reserves in the root zone of the soil are 60-200 mm, so the trees do not experience a lack of moisture. Due to the fact that transpiration is a physiological process and is regulated not only by external factors, but also by the plant organism itself, it can exceed the amount of precipitation that falls in the form of rain. Water consumption for transpiration in each type of forest also depends on the composition of the forest stand, in particular on the admixture of deciduous species. Thus, the ratio of deciduous and coniferous species in the wet blueberry spruce forest was 97 : 3, in the blueberry-sphagnum spruce forest 99 : 1.

The experience of using terrestrial laser scanning LiDAR to assess the biometric characteristics of trees during the inventory of the artificial tree plantings in the «Bul’var Pobedy» (Boulevard of Victory) in the city of Petrozavodsk, Republic of Karelia, is discussed in the paper. The aim of the work was to conduct a comprehensive statistical analysis of LiDAR data in comparison with in-kind measurements of dendroparameters - tree height, crown and stem diameters at a height of 1.3 m, taking into account the species of trees. The results of the study showed the high efficiency of LiDAR technology for establishing the main dendroparameters. The best results were obtained for measuring stem diameter at a height of 1.3 m (91.5 % of reliable species), crown diameter (85.7 %) and tree height (92.9 %). The average relative error ranged from 5.0 % for stem diameter at a height of 1.3 m to 10.02 % for tree height. The most accurate measurement results are shown for a blue spruce ( Picea pungens Engelm.) and common ash ( Fraxinus excelsior L.), where all parameters were measured with high accuracy ( p > 0.05 in all cases). The stem diameter at 1.3 m turned out to be the most stable parameter with the lowest average error (4.99 %). This is explained by the relative simplicity of its measurement and lesser dependence on external factors. Measuring the crown diameter showed a higher average error (8.28 %). The obtained results of the study indicate the need to take into account tree species characteristics and crown density in the stand when scanning LiDAR and processing data.

The aim of the work was to study the pyrolysis of Siberian larch bark ( Larix sibirica Ledeb.) as a potential raw material for the production of torrefects and biochar. Based on the results of thermogravimetry and differential thermogravimetry (DTG), the kinetics of the pyrolysis process were analysed and its thermodynamic parameters were determined. The basic measurement data were analysed: stages of mass loss during heating, temperature intervals corresponding to them and mass loss rate. Taking into account the complexity of the structure and chemical composition of bark and the related appearance of the DTG peak in the thermogravimetric test, the ‘microstages’ of bark thermal decomposition were visualized by forth derivative of the DTG contour using the Savitsky-Golei differentiating filter. The dependence of the activation energy and the pre-exponential multiplier on the degree of conversion was calculated, using the isoconversion kinetic method of Ozawa-Flynn-Wall. The average value of activation energy is 283.7 kJ/mol when the degree of thermal conversion of bark (α) changes from 0.1 to 0.8. The obtained dependence E _a = f (α) was used to calculate thermodynamic parameters (Δ H , Δ G and Δ S ) and to determine the mechanism of reactions according to the Criado method characterising the bark pyrolysis process. The compensatory effect of thermodestruction was established. The mean values of Δ H , Δ G and Δ S are 294.7, 157.3, kJ/mol and 215.0 J/(mol × К), respectively. The conclusions formulate an integral evaluation of the obtained results, point out the area of their use and the subject of further research: analysis of physicochemical properties of torrefects and biochar obtained from larch bark.

The article presents the results of experiments conducted in order to establish the potential possibility of ignition of peat with 10 % moisture content from cigarette butts. The results showed that peat did not ignite from cigarette butts in the absence of wind. Wind velocity was the key factor that influenced the possibility of peat ignition from a cigarette butt. Ignition probability of cigarette butts was 10 % when the wind velocity was 1 m/s. As the wind velocity increased, ignition probability grew accordingly: 27 % of all experiments ended with peat ignition when the wind velocity was 1.5 m/s, and 50 % of experiments ended with peat ignition when the wind velocity was 2.5 m/s. During the process of peat ignition the cigarette filters burned completely, which prevents using filters as the evidence in order to investigate the cause of peat fires. The results showed that the arenation of the peat surface at the rate of 2.5 kg/m² prevented peat ignition from cigarette butts. Thus, the arenation of those drained peatlands sites where popular camping and smoking areas as well as hunting, fishing, mushroom and berries foraging routes are located can significantly reduce peatlands fire hazard and therefore can be used to develop fire prevention measures.

Greenhouse gas emissions have significantly changed the global climate. An increase in the frequency, duration, and severity of drought and heat stress associated with climate change can fundamentally alter the composition, structure, and biogeography of forests in many regions. Of particular concern is the potential increase in tree shrinkage associated with the physiological stress caused by climate change and interaction with other related processes such as insect infestations and forest fires. Despite the noted risks, existing forecasts of tree shrinkage and forest death are based on models that lack functionally realistic physiological mechanisms. It has become obvious that the current understanding of the physiological responses of trees to drought remains very insufficient, and additional basic knowledge is needed to make realistic forecasts of forest loss in the face of rapid climate change. A hydraulic concept has been applied to quantify the mechanisms of tree death, and based on it, different responses to drought of isohydric and anisohydric species have been shown. The presented analysis of the global vulnerability of world forests to hot droughts in the Anthropocene has shown that it is greatly underestimated, including forests in regions with sufficient moisture. In general, despite the ongoing discussions and research regarding many specific mechanisms of forest death, the enormous efforts that the research community has made to clarify these mechanisms have allowed us to obtain significant physiological data indicating an increased vulnerability of forests to death during hot droughts.

The results of a study of the intraseasonal radial growth of Gmelin larch ( Larix gmelinii (Rupr.) Rupr.) trees growing in a cryogenic larch forest on an anthropogenically modified site (the edge of a seasonal road) and on a natural forest site without anthropogenic disturbances are presented. Continuous measurements of radial growth during the season were conducted on experimental trees using DR-26A point dendrometers during the 2017-2019 seasons, which differed significantly in terms of weather conditions. The dynamics of intra-seasonal growth of the annual ring of an individual tree was characterized by a set of maximum daily values. Using the Pearl-Reed approximating logistic equation ( R ² = 68-99 %), the main phenological characteristics of tree ring seasonal growth for each tree were determined: the dates of the start and end of the growth season, duration of three stages of the growth season (in days), and the maximum growth intensity (mm/day) during the second stage. It was found that the tree ring width of the annual ring (TRW) is determined by the maximum intensity during the second stage of seasonal growth ( R = 78-97 %). In the anthropogenically modified site, the TRW is significantly wider than in the control area, regardless of the weather conditions during the season. The tree rings formed in the trees on the control site in 2019 was narrower than those in 2018, while they were wider in the anthropogenically modified site. The opposite trends are interpreted based on previously obtained relationships between radial increments and climatic factors (Benkova et al., 2024). The maximum intensity of tree ring growth during the season and TRW in the experimental sites are determined by weather conditions at different stages of xylogenesis. In the anthropogenically altered site, this is the period preceding the growth season (early May), when the weather conditions pre-determine the value of maximum intensity of tree ring growth associated with the stage of formation of new tracheids. In the control site, this is the later period (late May to middle June), when the weather conditions directly affect the process of new tracheid formation.

Trees are an important component of the urban landscape, a source of biodiversity and an important element in creating a comfortable environment. In urban conditions, trees are exposed to a wide range of stress factors that negatively affect their vital state and appearance. Regular observations are necessary to promptly assess the condition of the trees and their care. This is especially true for Arctic cities, where the range of tree stands is lower and their condition is more depressed. Combining visual and instrumental examination of a tree increases the accuracy of assessments, allows you to identify the volume of wood with varying degrees of destruction, assess the accident rate and make an informed decision on the appointment of support measures or removal. In 2024, the condition of tree stands in the Akademgorodok Park in Apatity, Murmansk Oblast was assessed using Siberian fir ( Abies sibirica Ledeb.). The categories of tree condition were determined using visual and instrumental methods using the Resistograph model R650-EA device, a number of health measures were recommended.

In recent decades, climate change has had a marked impact on ecosystems around the world. One of the most obvious effects of climate change is the marked transformations in stands of the upper forest limit. Studies show that climatic changes, particularly increases in mean annual temperatures and changes in precipitation regimes, are leading to significant shifts in vegetation zones. This paper is the first to analyze the dynamics of forest stands in the forest reserve Yenganepe on the western macro-slope of the Polar Urals. The variability of average morphometric indices of forest stands depending on altitude is shown. Despite the fact that individual trees of Siberian spruce ( Picea obovata Ledeb.), within the studied ecotone appeared in the early XIX century, the greatest changes in stand density occurred in the 30-60s of the XX century. The density of stands since the beginning of the XX century increased 12 times at the limit of individual trees distribution in tundra and up to 35-30 times in sparse forests and dense spruce forest. The dynamics of the studied stands differs significantly from the previously shown changes in the upper forest limit in the Subarctic.

A study of Scots pine ( Pinus sylvestris L.), Siberian spruce ( Picea obovata Ledeb.), and blue spruce ( Picea pungens Engelm.) tree samples in the parks of the city of Krasnoyarsk was conducted to select the most urban-tolerant forms. Morphological parameters of the stem and crown, as well as crown condition, were measured. Water-holding capacity of needles was used to assess tree drought tolerance. The most informative traits characterizing tree resilience to urban conditions, habit, and gas-cleaning capacity were selected for correlation analysis. Significant differences in the nature of multiple correlations between traits were found in the compared species within each park, as well as between samples of the same species from different parks across the city. A comparative analysis of correlation coefficients showed that the magnitude and direction of the relationship can serve as an additional significant criterion for selecting trees not only based on direct but also indirect traits. The results of correlation and discriminant analyses showed that tree breeding approaches should differ across the city, including due to the varying ages of tree stands. It is likely that, given increased air pollution and negative correlations between resistance traits and tree growth, a compromise between resistance and productivity is needed for urban tree breeding. Three evergreen coniferous species with the best traits were selected for further selection and use in urban landscaping.

This article identifies key distinguishing characteristics of the Canadian forest sector organization and compares the Canadian and Russian approaches to forest relations. It also focuses on current challenges facing forest sector authorities in these countries. The key distinguishing feature of the Canadian approach to forest sector organization is its high level of federalization. Each province has its own forest legislation, but a flexible system of leasing relations is a common feature. An analysis of Canadian forest legislation is conducted using the province of British Columbia as an example. This province is Canada’s leading forest region, accounting for more than a third of Canada’s total logging volume. Compared to the Russian forest sector, the Canadian sector demonstrates greater stability in both legislative changes and economic indicators. From 2002 to 2017, logging volume in Russia was significantly lower than in Canada, but since 2018, the countries have become comparable in this indicator. Indicators such as the area of forest damaged by fires and the volume of reforestation over the same period in both countries are subject to sharp fluctuations. Leasehold arrangements, adopted as the primary instrument for forest sector development, are one of the reasons for the limited interest of private capital. Lessees have insufficient incentive to voluntarily invest in forest areas beyond the minimum required by the lease terms. This problem is common to both the Canadian and Russian forestry sectors.

The intensity and duration of vegetative growth of plants determines their biological productivity, which in turn depends on various environmental factors and the climatic conditions of the growing region. Therefore, identifying patterns of seasonal growth in coniferous trees is essential for determining the type and timing of measures aimed at increasing the productivity of forest stands, especially in regions of introduction. Since research data are scarce in the south of Western Siberia and are of interest for generalizing the results of introduction, the aim of this study was to identify patterns of seasonal growth of two- and five-needle pine species of the genus pines ( Pinus L.) within the residential area of the city of Omsk. This article examines the climatic conditions of Omsk during the seasonal shoot growth period of model trees and constructs a climatic diagram of the G. Walter modification according to Bagnoul-Gossen for April-June 2024 and 2025. A study based on data from the Omsk Hydrometeorological Center examined the dynamics of seasonal shoot growth in two-needle pine trees: mountain pine ( Pinus mugo Turra), Scots pine ( Pinus sylvestris L.) and jack pine ( Pinus banksiana Lamb.), and five-needle pine trees: white pine ( Pinus strobus L.) and Siberian stone pine ( Pinus sibirica Du Tour).

Systematic scientific and technical support is an integral part of engineering surveys, design, and construction of various objects in the permafrost zone. Geotechnical monitoring is a continuation of the scientific and technical support provided to construction projects during the operational period. In this study, we examine the systematic scientific and technical support at all stages of project implementation and argue that the methods of scientific and technical support require refinement. Problematic issues and potential ways to improve scientific and technical support for projects under complex geocryological conditions are considered.

This study aimed to establish patterns of heat flow changes under the impact of snow tamping. To achieve this goal, a criterion for the efficiency of snow tamping has been introduced as the ratio of heat fluxes from the ground to the air before and after tamping the snow cover. If the convective component in the heat transfer coefficient is not taken into account, then the criterion is a simple quadratic dependence on the snow cover compaction coefficient. A quantitative and qualitative assessment of the accepted assumption has been performed and demonstrated that the error in determining the efficiency criterion does not exceed the values allowed in engineering practice. Thus, it has been found that the increase in the initial heat flux during snow tamping is proportional to the square of the degree of snow cover compaction and does not depend on its thermophysical properties. The formulated provisions are presented in the form of 3D graphs, which makes it possible to visually verify the validity of the assumptions made and the conclusions drawn.

Further deepening of the Yubileinaya kimberlite pipe open-pit mine and bringing its upper part to the maximum surface contour required a series of studies aimed at improving the stability of the pit’s upper slopes. This necessitated an investigation of local mining-geological and cryohydrogeological conditions, such as the presence of substantial talik zones beneath Protochnoye and Travyanistoye lakes, which affect not only the deposit’s water inflow but also slope stability, particularly in areas of talik water discharge. It was found that the talik zones had undergone changes during the deposit development expanding from their original dimensions both in plan and in section. Calculations were performed to assess potential shifts in the position of the 0 °C isotherm in the cross-section due to thawing caused by convective water flow. This flow intensified due to increased movement of groundwater and surface water from upland ditches through the talik body toward discharge points on the pit slopes. The predicted thawing extent generally aligns with the actual recorded changes in the depth of talik zones. The hydrogeological modeling helped determine the optimum operating regime for drainage wells with elimination of water discharge areas from talik zones after implementing the proposed solutions.

The prospects and relevance of the application of an all-season soil thermal stabilization system and the principles of its operation are considered. Data on soil temperature changes under the impact of the all-season thermal stabilization system and seasonal cooling devices on a test polygon and their comparative analysis are presented. The results obtained attest to a higher efficiency of the all-season soil thermal stabilization system for cooling and freezing soils in comparison with seasonal cooling devices.

The problem of the development of bypass filtration and static stability of waterworks in the permafrost zone continues to be relevant, especially in the current period of climate change on Earth. In conditions of western Yakutia, the main reason for the loss of filtration stability of hydraulic structures has been identified: the presence of ancient aeration zones in their base; these zones formed during the Holocene optimum and then were frozen under conditions of incomplete water saturation with the formation of ice jams and air cavities. Geophysical methods have been applied to study filtration processes. As a result, we have identified geocryological conditions favoring the development of bypass filtration processes and suggested a set of methods to detect and control them, which is an important challenge of permafrost engineering.

On August 23, 2025, Mikhail Nikolaevich Grigoriev, Deputy Director for Science at the Melnikov Permafrost Institute, Doctor of Geographical Sciences, Honored Scientist of the Republic of Sakha (Yakutia), celebrated his 70th birthday. This article presents his key scientific achievements and biographical information.

The article presents an analysis of the spatiotemporal differentiation of temperature characteristics in the Primorsky Range landscapes, obtained during 15 years of microclimatic observations. The work is based on data from automatic monitoring of air temperature and relative humidity at a height of 2 m from the surface, soil surface temperature, and soil temperature at a depth of 40 cm. The analysis of the microclimatic monitoring data showed that the close relationship between soil and air temperature regimes depends on landscape conditions. Within the study area, the main climate-forming factors at the local level are vegetation, orography, and distance from Lake Baikal. Open areas, compared to forested ones, are characterized by greater amplitudes of air and soil temperatures in both diurnal and annual cycles. The warming and cooling effects of Lake Baikal on the temperature regime of the adjacent territory are manifested no higher than 1000 m along the slope of the Primorsky Range. This study statistically confirms the relationships between air temperature series at study sites in similar landscapes. Several groups of sites can be identified, each differing in temperature regime; the number and composition of these groups vary throughout the year, depending on limiting factors. The results of the study, which identified patterns in the distribution of air and soil temperatures, will be useful for restoring missing data in shorter series and can subsequently be applied to reconstruct temperature regimes in areas not covered by the microclimate observation network. Furthermore, the identified patterns will serve as a basis for creating parametrization of processes in mountainous regions and scaling the results of global climate model calculations at the local and regional levels.

The species composition and isotopic characteristics of bone and dental tissues from zooarchaeological collections of Xiongnu sites (Early Iron Age) in Western Transbaikalia were studied. The presence of bones of small ruminants, cattle and horses among the sacred-burial utensils indicates a high proportion of the nomadic way of life in the life of the Xiongnu. At the same time, the remains of domestic pigs, wild animals and fish bear evidence of elements of a sedentary lifestyle, hunting and fishing. It has been revealed that the difference in the isotopic composition of carbon and nitrogen of the bones and teeth of the remains of small ruminants and cattle from the composition of the remains of horses suggests a differentiation in the conditions of their breeding. It has been found that cattle were grazed in dry steppe conditions, while horse pastures covered steppe and forest-steppe/forest landscapes. The heavier carbon isotope composition of the remains of pigs and dogs indicates the presence of C4-type plants (probably millet) in their diet. Based on a comparison of the values of the isotopic ratios of carbon and nitrogen in the bones and teeth of fossil ungulates and modern ecosystems, it was concluded that during the Xiongnu era, dry steppes dominated in the intermountain depressions of the southern part of Western Transbaikalia, and open landscapes were somewhat more widespread than at present. The Xiongnu sites in Western Transbaikalia (4^th century BC - 1^st century AD) date to the decline of the Xiongnu nomadic empire and are associated with the time of the climatic shift in Northern Mongolia and Transbaikalia towards aridity, which occurred at the beginning of the Subatlantic period 2500-1900 years ago.

The article examines current issues related to the development of the chemical industry in Irkutsk oblast as an integral part of the chemical complex of the Russian Federation. It was found that the chemical industry entered a consolidation stage in the 2000s. New economic ties were formed, new product markets were entered, and a transition to a qualitatively new technical and technological level was achieved. Interregional chemical clusters are actively being formed. All this has ensured the competitiveness of the region’s chemical complex in the Russian and foreign markets. It has been established that the main problems of the region’s chemical complex are: insufficient supply of domestic raw materials, high prices for raw materials and transportation costs, high level of production facilities depreciation, insufficient capacity of the domestic market, and a number of others. It is concluded that the chemical industry in Irkutsk oblast, although not playing a system-forming role in the region’s economy, occupies a significant share of industrial production and has a significant impact on the development of other industries. It is shown that chemical complex enterprises are city-forming for some areas of the region and ensure social stability. It has been revealed that the prospects for the development of deep processing of chemical products are constrained by low profitability and a limited product market. The pharmaceutical industry is an exception, where prospects are linked to the production of medicines based on regional scientific developments. It has been determined that there are opportunities in Irkutsk oblast to create innovative low-tonnage chemical production facilities at the former site of Usolyekhimprom LLC with the establishment of a Federal Chemistry Center. The prospects for the development of the industry are also linked to the implementation of new projects in the field of gas chemistry in the north of the region, the production of potash fertilizers, and the development of import substitution in the production of high value-added polymer-based products. It is also shown that the need to take into account the ESG-agenda will play an increasingly important role in the development of chemical production. The feasibility of developing comprehensive programs for the development of the chemical complex at both the federal and regional levels is substantiated.

The article identifies trends and features of the spatial development of the Trans-Siberian Economic Corridor within the Siberian Federal District (the territories of Omsk, Novosibirsk, and Kemerovo oblasts, Krasnoyarsk krai, and Irkutsk oblast). The economic corridor is considered as a set of municipalities at the levels of an urban district and a municipal area, formed along the Trans-Siberian multimodal transport route, the core of which is the railway. The study was conducted using statistical, cartographic, and comparative-geographical methods. Based on statistical and cartographic sources, several types of municipalities were identified in the Trans-Siberian Corridor, namely: regional centers, suburban municipalities (within urban agglomerations), and peripheral municipalities. Rural settlement zones and main urbanized areas in places of maximum population concentration were identified. Thus, the demographic potential of the Trans-Siberian Economic Corridor constitutes more than half of the population of the corresponding regions. By the industrial output, the region’s municipalities were ranked, and industrial specialization was revealed. The mutual influence of the development level, industrial specialization, the distribution of productive forces and the demographic situation and the transformation of settlement patterns were assessed. The geographical aspects of spatial development are expressed in the strengthening of two partially overlapping gradients of population and production concentration, namely: trunk-peripheral and central-peripheral ones. Agglomeration effects were found to predominate over trunk effects. The agglomeration effects are particularly pronounced in the example of the concentration of housing construction in regional centers and their suburban areas. This study, limited to the territories of the Siberian Federal District, provides an understanding of the spatial development of the most populated, economically diversified part of the Trans-Siberian Economic Corridor. Territorial expansion of the research will make it possible to update the geographical picture of the spatial development of the entire Trans-Siberian Economic Corridor.

The article reveals the sectoral and geographical structures of foreign trade turnover of Siberian regions with its bordering countries: China, Kazakhstan, and Mongolia. It highlights the place of Siberia in the structure of the Russian economy, and the problem of distortion of its statistical indicators. The role of Siberia’s foreign trade on a national and global scale, as well as the dynamics of its share and value indicators since 2017 are analyzed. The geographical structure of Siberia’s trade turnover is revealed. The issues of the Russia’s role in its trade with China, Kazakhstan, and Mongolia are touched upon. The share and value indicators of trade turnover, and commodity groups of exports and imports of each Siberian region with countries adjacent to Siberia, are calculated. A more detailed attention is paid to the leading regions in the structures of export and import. The features of the foreign trade structures of various Siberian regions are identified. The importance of foreign trade with China, Kazakhstan, and Mongolia for the regions of Siberia is revealed. The article touches upon the issue of the emerging competition between Siberia and Mongolia in the export of similar commodity groups to foreign markets, primarily coal, copper ores and concentrates. The routes of commodity flows between Siberia and neighboring countries are explained. The main border crossings in the trade turnover with the countries under consideration are identified. The issues related to China’s “One Belt, One Road” initiative are briefly touched upon. The article also considers issues of the future foreign trade turnover of Siberia with neighboring countries, such as the predicted increase in the role of China and Kazakhstan in Siberia’s foreign trade in the near term, and the instability of the prospects for trade between Mongolia and Siberia due to the narrow range of goods they supply. An analysis is made of the transformation of the geographical directions of the foreign trade structure on a national scale in the early 2020s using the example of the export of coal as the main cargo of Siberian railways. Specific cases of prospects for the development of Siberian foreign trade relations are predicted. The article concludes by examining the emerging need to diversify the geographical structure of Russia’s foreign trade.

The article systematizes the national-territorial units of state and municipal structure and other ethnic entities of Eastern Siberia, the hierarchy of which is presented as follows: republics - administrative-territorial units with a special status (former autonomous okrugs) - places of traditional residence of indigenous small-numbered peoples. An analysis of changes in the ethnic composition of the population of Eastern Siberia between the 2010 and 2021 censuses is provided at three territorial levels - macroregional, regional and municipal. Of the 10 groups of peoples identified by geographical location, an increase in the number and a rise in their share are observed only among the indigenous large and small-numbered peoples and the peoples of Central Asia. Russians and indigenous peoples predominate in the total population, the increase in the total share of which reflects the ongoing trend toward decreasing ethnic diversity. Based on the share of the Russian population in municipalities in 2021, the ethnic space of Eastern Siberia was divided into zones, identifying the Russian ethnic core, the contact zone of the Russian mega-core, and its internal and external periphery. It has been established that the dominant trend in the period 1989-2010 toward increasing polarization of the ethnic space into opposite components - the Russian ethnic core and its external polyethnic periphery, i.e. into “Russian” and “ethnic” districts and cities - has weakened significantly and has mostly exhausted itself in the period 2010-2021. This is largely due to the slowdown in growth (Yakuts) or even a decrease in the number (Buryats and especially Khakass) of indigenous large peoples. Therefore, a certain stabilization of the process of monoethnicization in the republics of the macroregion (with the exception of Tuva and partly Yakutia) can be expected.

The article is concerned with the research of land market development at the regional and municipal levels. Regional features of increasing polarization of space between densely populated regional centers and remote peripheral areas are shown. Land turnover characteristics, as well as demographic and migration indicators of municipalities, are selected as a tool reflecting the regional features of agglomeration growth. The article reveals the role of land redistribution, which shows a connection that may not always be apparent with the processes of population migration, but is closely related to the factor of distance between the center and the periphery. As a consequence of these processes, the spatial and social fabric of rural communities is being transformed. A territorial and functional transformation of large cities and their suburban areas is observed (an expansion of suburban areas, the transformation of country dwelling into urban areas, the reproduction of an urban lifestyle by the rural population in the suburbs, the professional transformation of the rural population, etc.). The example of the region demonstrates how agricultural lands, following the all-Russian trend, are acquiring an increasingly important role in the formation of suburbs. The trend toward the exclusion of agricultural lands from the turnover is increasing. Abandoned agricultural lands are used for residential development. The features of the intraregional population migration flow and the spatial distortion of the direction of its vector due to the presence of the region’s largest recreational site, namely, Lake Baikal, as well as border areas, are highlighted. The article uses cartographic material of the processed Rosreestr data from 2011 to 2022, as well as materials of the field studies in rural communities of the Baikal region.

The work was conducted within the framework of creation of a fundamental geographical work, namely: the Atlas of Territorial Development of the Regions of North and Northeast Asia. The study, carried out at a scale of 1:8,000,000, covers the territory located in the sector of the Arctic Ocean drainage basin, extending from the world watershed, located in the center of Mongolia, to the oceanic subarctic of the Russian Federation. The aim of the research was to study and map landscapes to address complex problems of spatial development of the macroregion. The process of map creation associated with classification constructions and geoecological interpretations was carried out within the framework of the geosystem concept of Academician V.B. Sochava. The principles of mapping are formulated, the organization and structure of maps, the forms and content of cartographic information, indicator features and criteria for assessing the state of geosystems in the field of security, and the system of methods and techniques used for the integration approach are defined. Based on previously published larger-scale landscape maps, a unified basic information cartographic framework for producing derivative conjugated maps of geosystems of various content has been created using geoinformation methods and MapInfo Professional GIS software. An idea has been formed about the stability of geosystems of regional rank as an important environmental factor stimulating or constraining the territorial development of the region. The main groups of classification features-indicators and criteria for assessing the stability of geosystems to anthropogenic impacts have been identified. The possibility of creating legends for estimated-predictive, predictive-advisory overview landscape maps and maps of multifunctional geoecological zoning of the territory using various combinations of classification geosystem features is considered. Within the unified atlas system, specially structured geographical information from the landscape map block will serve as a knowledge base on the natural environment, meeting the needs of complex problems of territorial development of the macroregion.

Soil depth plays an important role in plant growth. Evaluation of soil depth using digital terrain analysis is able to be conducted not only with less time and labors, but also without solum destruction, compared to conventional field observation. This research aims to improve the accuracy of soil depth prediction in digital terrain analysis using parent material dataset and non-linear partial least squares regression. Modeling of soil depth was performed and compared using simple partial least squares regression (SPLSR), PLSR with parent materials (PLSRP), and non-linear PLSR with parent materials (NPLSRP), simultaneously. While using the PLSRP and NPLSRP, different models were built, corresponding to parent materials within the study area. Models fit was evaluated with coefficient of determination of calibration (R2cal), coefficient of determination of validation (R2val), root mean square error of calibration (RMSEC), and root mean square error of prediction (RMSEP). The use of the PLSRP improved the performance of the prediction by 0,08 for the R2val and by 6,2 for the RMSEP, compared to the SPLSR. The NPLSRP increased the R2val by 0,31 and decreased the RMSEP by 17,1, compared to the PLSRP. The results indicated that the use of the NPLSRP would be able to improve accuracy of soil depth prediction, significantly.

The most significant economic and geographical conditions for the formation of the entrepreneurial environment in Kyrgyzstan have been identified. Some socioeconomic features of entrepreneurship in the Kyrgyz Republic are shown, taking into account the specifics of the transition period. The institutional problems that hinder the successful development of entrepreneurship in Kyrgyzstan have been clarified. The main institutional trends of recent years are characterized. The strategically significant task of successfully forming an entrepreneurial environment is considered in relation to the general state of the country’s national economy. The conclusion that the development of entrepreneurship is vital for the sustainable development of the state economy is substantiated. Socioeconomic processes in Kyrgyzstan that are significant from the viewpoint of ensuring the continuity of economic policy for the development of entrepreneurship in the region have been identified and analyzed. It has been revealed that historical and economic trends in the formation of the entrepreneurial environment in the Kyrgyz Republic influence the current state of entrepreneurship. The article has clarified the main chronological milestones in the development of entrepreneurship in Kyrgyzstan, which together help to understand the current contours of the entrepreneurial environment and determine the nature of the region’s prospective development. Due to the socio-political upheavals in the Republic, largely caused by the systemic socio-economic crisis, incompetence and corruption in all branches of government, and the strengthening of the shadow economy, issues of ensuring the country’s economic security are becoming acutely relevant. It is concluded that the most intense centers of destabilization require the priority implementation of adequate measures to eliminate them. It has been established that the country’s external debt has become a source of threat not only to the economic security of Kyrgyzstan, but also to the country’s political independence. It has been revealed that poverty of the population and income inequality continue to be the most pressing social factors, negatively impacting the quality of human capital, which is an important element in the context of formation of the “middle class” in society. It is concluded that sustainable development of entrepreneurship is of particular importance in Kyrgyzstan, since the success of the market economic system is associated with the development of entrepreneurship in the country.

The issue of optimal formation of transport corridors in Mongolia was examined on the basis of a comprehensive assessment of social, economic and infrastructural factors of domestic and international nature. The analysis used options of ten meridional and seven latitudinal transport corridors proposed by the State Great Khural, international organizations, and domestic researchers. The assessment of these options was carried out based on the multi-criteria analysis method for the following five groups of factors: basic conditions of the transport network, the possibility of servicing large cities and populations, border ports conditions, the possibility of connecting to the international transport network, and the possibility of supporting industrial development. Ten criteria and 25 variables were used within the framework of the aforementioned groups of factors, and the relative weights of the criteria were determined. Unlike previous studies, this research takes into account additional criteria, including the transport routes of neighboring countries, the location of cities and border ports, and others. It has been found that such indicators as the presence of cities along the corridors, the population size within their influence zones, and territories suitable for industrial development are of relatively high importance. The assessment identified Mongolia ’ s highest-rated transport corridors: three meridional corridors (Tsagaannuur - Khovd - Bulgan in the western part of the country, Altanbulag - Darkhan - Ulaanbaatar - Dalanzadgad - Gashuunsukhait and Altanbulag - Darkhan - Ulaanbaatar - Zamyn-Uude in the central part) and two latitudinal corridors (Tsagaannuur - Khovd - Bayankhongor - Ulaanbaatar - Choibalsan - Sumber and Tsagaannuur - Khovd - Bayankhongor - Ulaanbaatar - Bichigt). The resulting optimal transport corridor options are important both for supporting national socio-economic development and creating favorable conditions for population settlement, and for connecting Mongolia with neighboring countries, their major transport and logistics hubs, and seaports.

The article provides an assessment of the scientific legacy of the outstanding Siberian economic geographer and economist V.A. Krotov from the standpoint of modern problems of territorial development and management. During the period of industrial development of Eastern Siberia, V.A. Krotov worked on issues of optimal distribution of productive forces and on the development of the theory of territorial production complexes (TPCs), based on the geographical features of the regions of new development. In the context of the prevalence of sectoral planning, he insisted on the need to develop schemes for the distribution of territorial productive forces, and his approach to planning was based on economic zoning. It is shown that, with the cessation of state control of production, the main complexes created during that period remain the foundation of the economic structure of resource regions with integrating intra-corporate planning. In the economic zoning scheme, V.A. Krotov insisted on the integration of Irkutsk oblast with Krasnoyarsk krai within the Angara-Yenisei region, rather than with Transbaikalia. The scientist’s views are compared with modern approaches to solving this problem (the Baikal region, identified in the 2000s as part of the federal planning system, was again replaced by the Angara-Yenisei region in the 2019 Spatial Development Strategy of the Russian Federation, and Transbaikalia was annexed to the Far East). In his work on the territorial management system based on the TPCs, V.A. Krotov attempted to apply foreign experience, including elements of mutual attraction between producer and consumer in polarized development theories, as well as interregional agreements using the example of the Tennessee Valley Authority. With the elimination of institutional barriers of the socialist economic system, this issue began to be widely developed in modern regional science, including comparisons of the TPCs with poles of growth and clusters. The V.A. Krotov’s contribution to the methodological coordination and integration of research on key problems of distribution within the framework of economic geography and regional economics is noted.

The article considers the life and creative work of Honorary Member of the V.V. Dokuchaev Soil Science Society, Doctor of Biological Sciences V.A. Kuzmin, a leading specialist in soil geography, who headed the Irkutsk Branch of the V.V. Dokuchaev Soil Science Society for over 30 years and worked at the V.B. Sochava Institute of Geography of the Siberian Branch of the Russian Academy of Sciences (Institute of Geography of Siberia and the Far East of the USSR Academy of Sciences) for over 50 years. The main results of his research on the soils of Central and Eastern Siberia are presented from the very beginning of his scientific career at the Faculty of Biology and Soil Science (formerly the Faculty of Geology, Soil Science, and Geography) of Irkutsk State University and in the Soil Science Laboratory of the East Siberian Branch of the USSR Academy of Sciences. The article examines a wide range of issues of his scientific work: the history of soil development, the features of their development on various rocks, soil-geographical mapping, humus composition, soil cryogenesis, the features of mountain soil formation, water and temperature regimes, ecological functions and chemical composition of soils, as well as other landscape components. It presents the scientist’s first field soil studies in remote, almost inaccessible mountain areas of the Baikal region and Northern Mongolia, as well as the results of 50 years of soil-geographical and soil-geochemical research in various regions of Siberia, summarized in personal monographs. The main scientific achievements of V.A. Kuzmin are outlined, including the results of the study of the evolution of natural conditions and soils within these territories during the Holocene. The article lists his many soil maps of individual regions of southern Eastern Siberia (Irkutsk oblast, Western and Northern Pribaikalie, the Irkutsk-Cheremkhovo Plain, the Goloustnaya River basin, the Lake Baikal basin within the Russian Federation, and others), in the compilation of which he was one of the first to use space data, improving soil mapping techniques. The central motivation behind V.A. Kuzmin’s work is revealed, i.e. his concern for the rational use of Eastern Siberia’s land resources, the protection of its unique beauty, and the careful management of the Lake Baikal basin’s resources.

The article considers the role of Boris Filippovich Lut (1930-2021) in the study of the relief of the bottom and shores of Lake Baikal and the formation of the Baikal depression. The chronological framework of the article is defined by the second half of the 20^th century and covers the period of scientific and scientific-organizational activity of B.F. Lut, a famous Soviet and Russian scientist-geomorphologist, Baikal scholar, candidate of geographical sciences, and author of more than 200 scientific papers. His major geomorphological works include dozens of maps, diagrams, profiles, graphs, and photographs, which provide excellent illustrations of natural processes on the shores of Lake Baikal. The article provides an overview of his expeditionary fieldwork on deep surveys of Lake Baikal, geomorphological study of the bottom and shores of the lake, processes of relief formation, formation and geodynamics of the Baikal depression, and practical application of geomorphological knowledge. During the construction of the Baikal-Amur Mainline (BAM) on Northern Baikal, based on the work of B.F. Lut and his colleagues, the tunnel railway option was chosen as more economically and environmentally efficient than the “coastal” route, which would degrade the natural environment. B.F. Lut’s research into the Baikal depression, and particularly its underwater part, is a significant contribution to the geomorphology of the Baikal mountain region and is still in demand today, as evidenced by references in Baikal studies publications.