Shrub birch or Yernik (Betulafruticosa) grows along river valleys in excessively waterlogged areas. Scientific interest in this plant is due to the lack of information on taxation patterns of vegetation and growth of this plant in Siberia. Shrub birch growing in the Baikit region, the territory of the Central Siberian Plateau is the object of the study. Based on the taxation data of the forest inventory of the Baikitsky forestry, 95 sections with the growth of birch shrub were selected. All plots were characterized by a clean composition. The quality of the growing conditions is Vа bonitet class. A birch forest up to 10 years old was characterized by a meadowsweet-ledum forest type, a sedge-sphagnum type was observed in birch forests of 15–20 years old and a rosemary-sphagnum forest type is characteristic of 30 years old birch forests. Yerniki of meadowsweet-ledum forest type had a density of 0.4–0.5. The birch forest of the sedge- sphagnum type was characterized by a wide variety of density (0.5–1.0) with a predominance of high-density thickets. Shrub of rosemary-sphagnum type develops in fullness of 0.4–0.5. On the basis of empirical formulas, a tabular form of indicators of heights and diameters, as well as the values of growth by age of shrub birch in the conditions of the Central Siberian Plateau, was obtained. It can be stated that the conditions of the place of growth determine the longevity and dimensional parameters of Shrub birch. The maximum parameters of Shrub birch characterize the critical conditions for the existence of a woody plant: age – 30 years; height – 5 m; diameter – 4 cm: fullness – 1.0. The current growth of Shrub birch in height and diameter exceeds the average growth, which indicates a steady growth of shrub birch in the study area. The absence of older age groups of birch forests is due to the processes of changing climatic conditions (permafrost thawing), which causes the death of thickets.

The age, typological and size structure of shrub birch forests depends largely on the habitat conditions and climatic characteristics of the territory.

The article is devoted to the model analysis of changes in the above-ground mass of trees in the forest per one tree under changes in tree height and normalised difference vegetation index. It is shown that the above-ground mass of trees on average rises with increasing NDVI index value. However, there is a certain height of trees at which the aboveground mass of trees does not change according to NDVI. A model explanation of this phenomenon, called the effect of “stabilisation of tree mass of a certain height with increasing vegetation index”, is given.

The results of the features of reforestation after fires in the pine forests of the southern taiga within the boundaries of the forest areas of the Krasnoyarsk Territory are presented. The objects of research were the areas covered by fires of different types and strengths, in stands of pine of an ordinary mixed-grass group of forest types representing the forest fund of the region, and fire-free cenoses. A slight pre-fire renewal of pine under the canopy of the mother stand was noted. The reason for this is the blocking of the growing processes of pine seedlings and – strong competition for young plants for the resources of the environment with grass cover, as a powerful soil blackener and a consumer of water and nutrients in the future.

The impact of fires on the nature of pine plantations in the areas exposed to fire has been established. The influence of the type and strength of fires that determine the level of destructive impact of fire on the phytocenosis, on the density and biometric indicators of self-seeding and undergrowth of pine at the initial stage of post-pyrogenic succession was revealed.

The average strength of the grass-roots fire contributes to the plantations of young pine plants on the conflagration, but retains the negative impact of the herbage, which, after burning, quickly regains its position. A strong grass-roots fire destroys the lower tier of phytocenosis, subthreshold woody vegetation, damages mature trees and creates a more comfortable environment for young plants localized in the windows of the tree canopy. Here the prerequisites for the formation of a complex vertical structure of planting are created.

After a riding fire, the landscape loses its forest appearance, losing the main element of the plant community – the stand of trees. Pine restoration is progressing at a good pace near the sources of seeding, but this process fades away as you move away from the borders of the forest, which may lead to changes in the woody type of vegetation to grass, which has less forestry and ecological value.

The harsh natural and climatic conditions in most of the Yenisei Siberia are the reason that the main agricultural lands are concentrated in its central and southern parts. Agricultural nature management begins with the southern taiga and sub-taiga, due to harsh natural conditions. The most important role in agricultural environmental management is played by the forest-steppe and steppe landscapes of southern Siberia, where they occupy 42 % of the territory and 84 % of the population of these zones live there. This area is distinguished by a wide variety of natural conditions. An assessment of the venerable and climatic conditions of the territory is made. It is associated with the beginning of establishment and development of agriculture, it talks about the history of the settlement and exploration of the territory by Russians and their advancement along the valleys and floodplains of rivers, forming a group of fort settlements: Yenisei, Krasnoyarsk, Achinsk and others. The article talks about the role of the Decembrists and their influence on the culture of agriculture, and the acceleration of development because of the construction of the Trans-Siberian Railway.

Pinus sibirica Du Tour is one of the main forest-forming species in our country. The object of the study was the halfsiblings of Pinus sibirica Du Tour growing in the arboretum located on the territory of the Precinct Forestry “Karaulnoe” of the Educational and Experimental Forestry of the Reshetnev Siberian State University of Science and Technology. The variability of half-siblings of plus trees certified in the Orsko-Simansk forestry of the Kolyvan Forestry of the Novosibirsk region was compared. Data on mother trees are given from passports compiled during their certification in 1977. Cones from these trees were harvested in the fall of 1986. Sowing was carried out in the spring of 1987. Planting on a permanent place was in 2000. The number of shoots with microstrobiles on the tree was determined visually using binoculars. The data was processed mathematically. The maximum number of microstrobiles was noted on the half-siblings of the plus trees 110/74 and 92/56. There is a high level of variability in the number of microstrobiles on individual half-siblings, which made it possible to select individuals for further reproduction: 84-12, 84-9, 79-8, 79-10.

On a test plantation of 35-year-old intraspecific hybrids of Siberian cedar in the Voronezh region, the influence of plants location on the plantation, which determines the volume, density of the green part of the crown and soil moisture, on their growth and physiological state was established. It was especially noticeable in the forest-steppe in the extremely hot summer of 2021. Within 36 days at a temperature of 30–36 °C, as a result of intensive transpiration, increased respiration and a sharp decrease in photosynthesis, the cedars dried up from dehydration, growing on the edge of the plantation and inside it, in the “windows” of the canopy, on a large illuminated area, with low growth energy and with a large evaporating surface of the crown. The hybrids remained viable, vigorously growing in dense standing on constantly shaded, sufficiently moistened soil, with a relatively small length and density of the photosynthetic surface of the crown.

The crowns of trees were subjected to much less quantitative study than their stems, primarily because of their lower use value. However, the size of the crown, closely related to the photosynthetic ability of the tree, is an important parameter in the study of tree growth. In closed and thickened stands, measuring the diameter of the crown is less accurate and much more labor-consuming compared to other indicators. Therefore, the availability of allometric models for estimating the diameter of crowns reduces costs when obtaining new initial data. In literature, the ratio of crown diameter to stem diameter at breast height (relative crown diameter) was used to predict the size of the tree growth area and to develop thinning regimes, to predict the stand density at a given average stem diameter and to estimate the stem diameter by crown diameter measured using remote sensing methods. The purpose of our study is to calculate the generic allometric dependences of the relative diameter of the crown on the diameter of the tree stem for the main forest-forming species and genera of Eurasia. According to the actual measurement data of 5,497 model trees of 23 forest-forming species and genera (subgenera) of Eurasia, allometric models of the relationship between the relative diameter of the crown and the stem diameter at breast height were compiled for the first time. According to the ranking performed, species and genera are distributed according to the relative diameter of the crown in the following descending order: Juglans, Phellodendron, Maackia, Acer, Ulmus, Chosenia, Salix, Quercus, Carpinus, Tilia, Fraxinus, Robinia, Populus, Larix, Fagus, Betula, Haploxylon, Chamaecyparis, Abies, Picea, Alnus, Pinus, Cryptomeria. Models at the level of genera can be applied to those species for which data are not yet available within the genus.

A general characterization of willow species growing in the Norilsk Industrial Region (NPR) is given. Peculiarities of phenological development of 3 species – Salix lanata L. s. str., Salix hastata L., Salix viminalis L. in these growing conditions are revealed. The obtained results will allow further selection of the most promising species for cultivation of planting material using seed and cuttings.

The article presents the results of a comparative analysis of the properties of plywood products based on ureaformaldehyde resins using heat-treated birch shelled veneer. The conducted full–factor experiments have shown that high water resistance and strength indicators of plywood based on heat-treated veneer are provided at a processing temperature of 160 ºC and a duration of 240 minutes, for combined plywood with outer layers of heat-treated veneer – at a temperature of 200 ºC and a heating duration of 180 minutes. The use of recommended veneer heat treatment modes that do not lead to a decrease in the strength of plywood leads to a decrease in water absorption and swelling rates for combined plywood by up to 9 and 44 %, respectively. It has been established that plywood with outer layers of thermomodified veneer has higher strength characteristics in comparison with plywood based on thermomodified veneer and is slightly inferior to it in water resistance. The use of thermomodified veneer only for the outer layers of plywood products does not lead to a significant decrease in the strength indicators of plywood, however, it can significantly reduce its hygroscopicity and increase water resistance, which expands the scope of its application.

The problem of increasing the efficiency of forestry machinery by monitoring its technical condition and timely performance of necessary maintenance and repair is relevant, since maintaining the working condition of machines requires large time, material and financial expenses, with sudden machine failure leading to downtime and losses of the enterprise. This is particularly important for forestry machines that are located at the harvesting area, far away from the company's service base. In this case, it is important to constantly monitor the condition of the machines and control all activities related to quality and timely maintenance and repair, which can be carried out by the machine operator himself, by a visiting company team, a field service of a universal or dealership. The use of electronic systems that facilitate the operation of modern machines, as well as self-diagnostic systems, creates the prerequisites for the introduction of technology for the remote monitoring of their technical condition. At the same time, in order to effectively solve the problem of maintaining machine operability it is necessary to take into account a large number of various factors related both to operating conditions of the machine and its real technical condition, and availability of spare repair capacities, qualified repair personnel, spare parts and materials, capabilities of third-party service organizations. A successful solution to the problem of improving the efficiency of the maintenance and repair system is possible through the introduction of digital technologies for both monitoring the technical condition of machines, and for planning work and the purchase of necessary spare parts and materials, management of all production processes on the basis of a unified management information system of ERP class. The selection of a specific maintenance and repair management software should be based on an analysis of the capabilities of the specific software product, the needs of the company, and the possibility of integrating the purchased software into a unified management information system.

The article presents a study of the coefficients of heat transfer and heat transmission of an integrated heat exchanger (deflegmator) of a distillation column used in technological lines of chemical processing of wood biomass. Mathematical modeling was carried out on the effect of changes in one of the technological parameters (dimeter of the heat exchanger tubes, material of the heat exchanger and coolant) of the heat exchanger on the heat transfer coefficient.

Rectification is widely used in the following industries: in the technologies of complex wood processing; in the forestry industry in the production of consumer products; in the recovery of extraction solutions in the extraction of biologically active substances from plant raw materials; in the technology of chemical processing of wood in the production of ethanol; when processing increasing natural waste by gasification and using synthesis gas to produce a biopolymer at the stage of solvent regeneration (methylene chloride, sodium hypochlorite, hexane, etc.), where highly efficient and productive distillation columns are also in demand.

For the most part, multicomponent mixtures are subject to rectification, usually azeotropic, having a similar boiling point, which explains the use of multi-stage rectification columns for their separation. At the same time, various methods of rectification are used, such as azeotropic, extractive, molecular, fractional, partial.