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The expediency of developing new methods for assessing the response of woody plants to environmental factors with an emphasis on the variability of the structure of the annual ring pool of wood is substantiated. Diagnostics and interpretation of the distributed pool of rings are considered in the context of forest society in connection with different intervals of their variability in signs of annual increments. The need for special attention to hydromorphic habitats, which differ in comparison with drylands by a more complex set of environmental factors determining the growth and development of trees in swamps of various types of water and mineral nutrition, is updated. Traditional domestic approaches to assessing the biological and technical maturity of wood, historically consonant with this study, are discussed, allowing the identification of rare and most valuable assortments in swamp forests. In the context of the implementation of the set tasks, the expediency of studying the pine forests of the forest-swamp complexes of the northern part of the Ob and Tom interfluve, which differ significantly in origin and localization in the relief, age structure, conditions of water-mineral nutrition, typological specificity and productivity of ground vegetation, is substantiated. Bioecological features of this region are characterized, where homogeneous in composition monospecific stands of excessively wet and dry pine forests represented by Scots pine ( Pinus sylvestris L.) were found and studied by targeted search. The main emphasis is placed on the ecological series of habitats and the typological characteristics of pine forests. The information presented in this report precedes the essential presentation of the research results in the second part of this article: «Communication II. Experimental and analytical aspects», reflecting their representativeness and extrapolation potential.

Using the example of excessively wet and dry pine forests represented by Scots pine ( Pinus sylvestris L.) growing on the northern boundary of the Ob’ and Tom’ interfluve, the experimental application of a new original technique for recognizing and assessing the chronological mosaic of rows of the width of annual rings in the form of individual alternations and group-fused (vector) sets is substantiated. The basic volume of the discussed material is formed by 13 sample plots with a sample of 1493 trees in the age range of 22-367 years. They contain 244702 annual rings, the total width of which in linear terms is 151788 mm. their indicative potential is described by total and unevenly distributed arrays of annual rings in large and small samples of trees from 11 to 280 pcs. The diagnostics and interpretation of the distributed pool of rings are considered in the context of the forest society in connection with different intervals of their variability in the signs of annual increments. The necessary distinction is made by the difference between the width of each subsequent ring and the width of the previous one. It is shown that the method of sliding-step comparison of rings-years not only reliably records, but also mutually separates the variants of the coincidence of years with an increase, decrease and duplication of trends in annual increments in the rows of the width of the rings. The concepts of conditionally starting and ordinary rings are introduced, of which the latter are numerically and in total width much larger than the former. The expediency of their involvement in the calculations of general and ecotope-divided trial areas of the lines of age differences is argued. In a comparative key, the separated signs of especially informative arrays of annual rings of swamp pine forests of post-fire genesis are assessed for the first time. It has been shown that in cases of spontaneous and anthropogenic elimination of forest stands, the species is capable of forming age generations and types of native maternal pine forests not only on former but also on derivative ecotopes.

Synchronous observations of the dynamics of wood and needle increment in young 22-year-old pine stands on former agricultural lands in Krasnoyarsk forest-steppe were conducted. It was found that overcrowded stands (the initial density of which was 40.7 thousand pcs./ha) reach the maximum wood increment at the age of 15 years, after which a steady decrease is observed. Stands with an initial density of 10.8 thousand trees/ha, as well as stands, the density of which as a result of thinning at the age of 8 years was reduced to 2.9 thousand trees/ha, demonstrate a continuing increase in wood increment throughout the observation period. At the same time, in the variant with thinning, stabilization and some decrease in the increment of needle mass are observed at the age of 18 years, while stands that have not undergone thinning, regardless of the initial density, retain a tendency to increase the increment of needle mass. The apparent paradox of a decrease in wood increment at a certain age with simultaneous preservation of the tendency to increase needle increment in densely densified young growth and a decrease in needle increment with simultaneous preservation of the tendency to increase wood increment in a stand undergoing thinning is explained by an increase in the efficiency of the assimilation apparatus under conditions of low competition for environmental resources. This fact is confirmed by special studies of the efficiency of needle photosynthesis in densely densified pine forests and tree stands where trees produce under conditions close to free growth. The results obtained may be useful in growing stands for various purposes.

The effect of anthropogenic impact (cutting of a «winter road» in 1984, in effect until 2002) on the radial growth dynamics of Gmelin larch trees ( Larix gmelinii (Rupr.) Rupr.), growing in permafrost larch forest has been analyzed. It has been established, that after the construction of the winter road the tree ring widths of the trees within the anthropogenically disturbed area increased sharply and after several years reached the peak values (0.971-1.601) mm, while in the natural stand it remained at the level of 0.121 ± 0.003 mm. Measurements showed that at the end of August (2017) the seasonally thawing layers on the abandoned road site and on the forest edge site (119.1 ± 18.4 and 71.9 ± 6.8 cm) were significantly larger than that in the natural stand (54.8 ± 5.8 cm). I.e., in the latter the temperature of the seasonally thawing layer increased faster and took on higher values. Using sliding climatic response functions of the radial increment indices, we revealed that anthropogenic impact modified the response of the trees to the influence of climatic factors. They manifested an earlier, in comparison with the natural stand, reaction of trees to spring-early summer air temperatures that show an earlier start of growth of the annual ring. We revealed also longer (end of May - end of June) dependence of the trees growing on the forest edge to precipitation compared to the native forest (end of May - beginning of June). We concluded that the modifications of the climatic response and a sharp increase of radial increment were due to the improvement of hydrothermal growth conditions in the anthropogenically disturbed area. Using extrapolation of the radial growth curves to future period of time, we can come to recognize that after finishing exploitation of the road in 2002, hydrothermal soil conditions and tree ring values in the anthropogenically modified forest sites will «return» to the background state in about 30 years, which is similar to post-pyrogenic restoration. Taking into account post-anthropogenic long-term effect manifested in improving the hydrothermal growth conditions, reducing the thickness of the organic layer and the formation of larger radial growth increments, the estimations of carbon balance in boreal forests growing on permafrost soils will make a significant improvement.

Forest fires occur annually on the territory of the Central Siberian subtaiga-forest-steppe region. During the five-year period from 2018 to 2022, 1303 fires were registered. The areas covered by forest fires during this period amounted to 87.5 thousand hectares. The article presents calculations of greenhouse gas emissions from fires in forest area plantations for the period under review. The volume of emissions from forest fires is determined by the intensity of burning and weather conditions. Using the data obtained on the amount of combustible forest materials burned in a fire, the mass of greenhouse gases (CO₂, CH₄, N₂O) released during combustion was calculated, depending on the type of planting and weather conditions affecting the drying of combustible materials using generally accepted methods. It was revealed that greenhouse gas emissions range from 13.5 thousand tons to 804 thousand tons annually during fires in plantations of the Central Siberian subtaiga-forest-steppe region. Over the five-year period under review, according to estimates, more than 1.2 million tons were released during forest fires. greenhouse gases, with a predominance of CO - CO₂. The largest share of emissions from fires (more than 95 %) falls on the spring fire season. The variability of the self-purification coefficient of the atmosphere varies significantly by periods of the fire season. It was revealed that favorable conditions for the dispersion of emissions from forest fires in the territory of the Central Siberian subtaiga-forest-steppe region develop in the spring period, when the largest number of windy days is recorded.

The article highlights the results of a paleobotanical study of peat deposits in the basin of the middle reaches of the river Kotuy (Northern Evenkia). The macro-remains of fossil plants became the basic material for the study. Based on the change in the species composition of fossil objects and radiocarbon dating by ¹⁴C, the dynamics of the phytocenotic structure of changes in the structure of forest formations from 6000 years ago to the present is reconstructed. A quantitative assessment of their climatic conditionality is given. At the beginning of the period under consideration, because of warming and increasing humidity, the biodiversity of the vegetation cover increases and the formation of mixed forests (Siberian spruce ( Picea obovata Ledeb.), Scots pine ( Pinus sylvestris L.)) is formed. With an increase in the continentality of the climate and cooling, biodiversity decreases, and the sparse larch (Gmelin larch ( Larix gmelinii (Rupr.) Rupr.))becomes the dominant formation. The dynamics of the boundaries of the ranges of Siberian larch ( Larix sibirica Ledeb.), Gmelin larch, Siberian dwarf pine ( Pinus pumila (Pall.) Regel.) at the boundary of the climatic optimum and in the late Holocene was established.

Siberian stone pine ( Pinus sibirica Du Tour) has three ecological forms, determined by the conditions of renewal and formation of forest stands: renewal of fresh burnt areas, renewal under the canopy of deciduous trees and the formation of the Siberian stone pine undergrowth under the canopy of light coniferous species, but not reaching the top canopy. The first two forms of renewal are observed in ecotopes corresponding to the growing conditions of the Siberian stone pine, but the scenarios for the formation of the forests are different. The study was carried out in two types of forest conditions: the Western Sayan district of mountain-taiga and subgoltsy-taiga Siberian stone pine forests Abaza forestry district) and the South Khakass district of mountain-taiga dark coniferous forests (Maturskoe and Kop’evskoe forestry district). In Abaza forestry, the average periodicity of fruiting of the Siberian stone pine stands was 5 years, and in the Kuznetsk Alatau - 3 years. Fruiting of the Siberian stone pine is a predictable phenomenon, but the spread and germination of the Siberian stone pine seeds are complex processes associated with zoochoric distribution and the powerful influence of the trophic factor of nut consumers. According to the radial growth of trees, determined from stumps in cutting areas (forest health felling) of the Abaza forestry, Siberian stone pine forests are of pyrogenic origin, have good growth throughout life and dry out without loss of growth. In the modern history of forestry, outbreak activity of root pathogens occurs for the first time. The forecast for the regeneration of drying Siberian stone pine forests in the mid-mountain part of the Western Sayan is positive. In Kuznetsk Alatau, the Siberian stone pine regrowth is insufficient and reforestation in large grass forest types is possible only with a change in species. The cutting of the tree stand, as well as its drying out with the subsequent growth of the grass stand, contributes to an increase in the population density of consumers of the Siberian stone pine nuts and, accordingly, excludes the regeneration of the trees. Preservation of undergrowth in clearings 30 years ago has yielded positive results in the formation of fruit-bearing Siberian stone pine forests. The organization of nut fishing zones with a ban on Siberian stone pine logging and its subsequent drying out led to economic losses of valuable wood and a by-product resource during the lifetime use of the Siberian stone pine stands.

Emerald ash borer ( Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)) is an aggressive East Asian invader that has destroyed millions of ash ( Fraxinus L.) trees in North America and Eastern Europe. Researches and practitioners are concerned about ongoing westward distribution of the species into Central Europe. In addition to that, the invasion of this buprestid to Siberia is also not ruled out bearing in mind suitable climatic conditions, particularly on the south, and the presence its favorable host plant, the green ash ( Fraxinus pennsylvanica Marshall). In 2024, the pest has been detected in Barnaul, the administrative center of Altai Krai. By August, the beetle destroyed almost 30 % of ash trees in the city and only 8 % of trees looked healthy. Based on the ratio of larval instars, the pest develops two years per generation in Barnaul. No parasitized larvae of A. planipennis was documented in Barnaul suggesting that the parasitoid, the braconid Spathius polonicus Niezabitowski, which controls this buprestid in Europe, either has not yet appeared in Siberia or remains at a low, undetectable, density. The prospects of introduction of the East Asian parasitoid Spahius galinae Belokobylskij et Strazanac (the most effective biocontrol agent of A. planipennis at its primary range) and the Manchurian ash ( F. mandshurica Rupr.) (the resistant host) to the secondary pest range are emphasized.

Rational forest management, which ensures the stability of the post-harvest state of stands and the direction of forest formation processes in the formation of forest phytocenoses of a new generation, largely depends on the methods of exploitation of forest stands. For each section of the forest fund allocated for logging, it is necessary to select the optimal combination of logging method, the complex of logging machines and the technological scheme of their application. The main criteria determining the choice of optimal logging techniques and logging equipment are three groups of factors, characterizing both the stand as a whole and the conditions of its growth (natural geographical factors), as well as silvicultural and environmental indicators of the impact of logging operations on the forest and the forest environment (technical and technological factors) and, functional and regulatory restrictions and requirements for wood harvesting (regulatory factors). The first group of factors influencing the choice of logging methods and cutting technology includes: the purpose of forests, the age structure of stands, the completeness of planting, the presence of natural regeneration, the steepness of the slope, the logging season, humidity and soil freezing. The second group of factors characterizes the indicators of the impact of equipment and technology of logging operations on the safety of the main components of the forest - stand, undergrowth and soil. The third group of factors is the silvicultural restrictions imposed on timber harvesting, including the permissible effects of forest exploitation on all components of the stand and the forest environment. Therefore, the optimization of wood harvesting techniques directly depends on the correct choice of logging methods and cutting technology in relation to the main forest formations of the Far East.

To determine the current state of the permafrost in the Yamalo-Nenets Autonomous Okrug and assess its transformation in connection with modern climate changes, transient electromagnetic (TEM) sounding was performed at ten sites along the submeridional profile from the Siberian Uvaly Hills in the south to the Pur-Taz Lowland in the north with a step of about 50 km. An interpretation of geoelectric models was carried out and the results of drilling surveys of permafrost were compared with those provided by the Arctic Research Center from its archive. As a result of the interpretation of geoelectric sections, modern and relict permafrost strata and closed taliks were identified. It was found that the modern base of permafrost lies at depths from 50 to 130 m. A comparison of the results of modern TEM surveys with archival reference geocryological sections did not show significant differences in the position of geocryological boundaries. However, it is necessary to note the significant distance between the TEM sites, as well as, often, considerable distances between them and reference boreholes. The greatest differences between the modern and archival data are noted in the northern part of the profile, which is probably due to the increased salinity of the rocks at the TEM survey sites.