Plant organs perform many different functions. The leaves provide the supply of assimilates, the stem and branches provide photosynthesis, transportation of water and nutrients, and the roots supply water and nutrients and contribute to physical stability. To achieve optimal performance at the plant level as a whole, there is a certain proportionality between these functions, which is mediated by the amount of biomass in the plant organs. The ratio of the biomass of one organ to that of another is known as the “biomass partitioning”, which is the cumulative result of the dynamic distribution of assimilates over time. Some implementations of the distribution of plant biomass fractions are non-Gaussian distributions, in particular, the Zipf-Pareto distribution. Using 6 coniferous genera of Eurasia as an example, it has been established that the regression coefficient of the Zipf-Pareto equation is not constant throughout the entire period of plant growth, but changes its sign at a certain age. The aim of this study has been to create a database on the biomass of the genus Salix L. and to determine the age of reversion of aboveground biomass fractions. The authors’ and attracted source materials have been used in the amount of 94 measurements of the aboveground biomass of willows aged from 1 to 79 ye ars in the territory of the European part of Russia. The initial data on the biomass fractions have been ranked in descending order: stem, branches, foliage (respectively, i is equal to 1, 2 and 3) and approximated by a model in double logarithmic coordinates, including as independent variables not only the rank i, but also the age of the tree, its height and a combined variable in the form of the product of age by rank i. The latter has turned out to be statistically significant at the probability level of P < 0.0001, and its negative value reflects that at a certain age the sequence of fractions of aboveground biomass in descending order: leaves, branches, stem – changes to the opposite descending sequence: stem, branches, leaves – and the age of the reverse is about 2 years. The established fact of age-related reversal of fractions of the aboveground willow biomass and the determination of the age of the tree in which the reversal occurs are a contribution to the development of the theory of assimilate distribution in plants.

In aiming to improve the standards and increase the accuracy of forest taxation works, modeling of the growth of pine stands in the cowberry type of forest in the zone of tundra forests of the Murmansk region was carried out. In the process of modeling the course of growth, methods of analytical alignment of taxation indicators and analysis of enumerative taxation materials were used. Trial areas were used to study the course of growth. In 2023, repeated recounts were carried out on permanent test areas in the Murmansk Region, laid down in 1962 and repeated recounts in 1967 and 1972. V.F. Tsvetkov research is taken into account, one of the founders of tundra forestry, on the division into types of formation of cranberry pine forests by density into moderately dense and overgrown. The values of empirical coefficients of the equation of stand height or diameter from age in overdrained and moderately dense lingonberry pine forests, characterising high closeness of relationship (R2 =0,86-0,97) the relationship between the signs is statistically significant (p < 0.05). The stands under study are significantly influenced by natural conditions at the extreme limit of growth, which primarily affects the dynamics of growth in height. The materials are grouped and aligned, according to the results of processing, dynamic series of taxational indicators of stands are obtained, which are presented in the form of equations. The obtained height values indicate that modal pine stands in the cowberry type of forest grow according to IV-V classes of bonitet.

Climate change has a negative impact on the environment, including forest ecosystems. However, forests are not only passive objects affected by climate change, but also, due to their ability to absorb and accumulate carbon, they themselves can significantly influence this process. Carbon sequestration by forest ecosystems plays an important role in mitigating the effects of climate change. Therefore, it is necessary to know about the amount of carbon stored in forest phytomass, and it is becoming increasingly important to accurately determine the phytomass of forest trees. Due to the absorption of carbon dioxide during plant growth and its release during wood burning, forests are a carbon-neutral energy source. The idea of using phytomass as an energy source to replace fossil fuels is most promising for fast-growing species. These include willows (genus Salix L.), native to Europe, Asia, America and Africa and found from the tundra to the tropics. Willow is successfully used as fuel in many countries, showing excellent growth and productivity even at juvenile stages and, under certain climatic conditions, having the highest capacity among woody plants to convert solar radiation into phytomass. Short-rotation willow plantations represent an ecologically promising energy resource for reducing greenhouse gas levels. Since the development of phytomass models is a laborious process, so-called “generic meta-models” are used. The aim of this study has been to construct generic models of both aboveground phytomass and phytomass fractions (foliage, branches, stem, roots) of willow trees based on meta-analysis of data. In the course of the work, the models have been constructed for assessing the aboveground phytomass of trees both in diameter at the stem base and in diameter at breast height, the information content of which is close to functional, and the biases are only about 2 %. Since each fraction of phytomass has a specific carbon-sequestering capacity and makes a different contribution to the carbon balance, generic models have been developed to estimate the mass of foliage, branches, stems and roots in relation to the aboveground phytomass of trees, explaining from 82 % (for foliage) to 99 % (for stems and roots) of the total variability of phytomass.

The historical methods of forests research at fixed sites continue to be the most reliable way of collecting information about the processes of tree stand formation, differentiation, and the onset of various age stages. The article presents the results of 70 years of observations at a permanent sample plot located in waterside buffer forests at Lake Karasye in the Yemtsovsky Training and Experimental Forestry District of the Obozersky Forest Management Unit (Plesetsky District, Arkhangelsk Region). Baseline surveys were carried out and the permanent sample plot was established in 1952 under the guidance of Associate Professor V. I. Kalinin. Subsequently, measurements were repeated by students under the guidance of professors of the Northern (Arctic) Federal University (previously Arkhangelsk Forest Technology Institute and Arkhangelsk State Technical University). Long-term monitoring shows that, despite the old age, the stand continues to be highly productive. The stand evolves through tree-fall dynamics, with shadetolerant spruce regenerating successfully in the gaps forming after the fall of old pine and larch tree. Studies show that a spruce forest with an admixture of larch, pine and birch is replacing the mature pine-larch tree stand. The forest register data show the area occupied by larch stands in the Arkhangelsk Region is gradually declining. This may be due to the tendency to underestimate of the larch share during valuation inventories. The conservation measures such as excluding stands comprising 30 or more percent of larch from logging plans have proved ineffective. Monitoring in permanent sample plots shows that the stand's growing stock composition will usually change from larch to spruce. To ensure larch restoration at the limit of its distribution range in the Arkhangelsk Region, actions to promote its regeneration and artificial planting are needed.

In the Sokolsky district of the Vologda region of Russian Federation, the influence of continuous harvesting of wood in drained pine forests on the taxation and macrostructural parameters of common pine trees (Pinus sylvestris L.) was determined. The objects of the study are represented by pine forests: the main species is Scots pine (P. sylvestris L.) with an admixture of common spruce (Picea abies (L.) H. KARST.) and birch (Betula pendula Roth). The drained forest objects were selected after the continuous harvesting of wood and a control stand (without logging), temporary test areas (runway) were delimited. Drainage measures in experimental forests were carried out in 1972. Continuous logging was carried out in 2005 when skidding technological drags were attached to the main corridor at an angle of 45 degrees. The distribution of the number of P. sylvestris L. trees by thickness steps within the boundaries of the runway in 83% (p < 0.05) of cases tends to normal. Average periodical growth of late wood P. sylvestris L. on the runway after drainage increased in the channel position by 30 % (tfact ≥ tst; 4.51 > 2.70; p < 0.01), and after intermittent logging increased by 19 % (tfact ≥ tst; 1.99 > 1.71; p < 0.1). Carrying out continuous complex harvesting of wood in drained pine forests has a positive effect on increasing the stock (by 38%), while in stands without logging – by 28 %.

The task of increasing forest productivity has been and remains one of the current interests of the European North of Russia, especially after the period of primary development of the forest areas. In the European Northeast, excessive humidity is observed at rather low average temperatures, which prevents active surface evaporation. In the twentieth century, the hydrotechnical reclamations were conducted on the large areas of swampy forests that increased the total productivity. The ecologists have an ambivalent attitude concerning forest draining. The supporters, who try to protect the undisturbed forest territories, counteract such activities. At the same time, the cultivation of highly productive forests of the right composition and quality requires measures for natural afforestation, or artificial forests must be created. Besides the total productivity of the stands, wood quality is an important factor in the hydroamelioration. It is mainly determined by density and the ratio between early and late wood. The influence of the landscape peculiarities of the drained forests on the quality of the wood was examined by the devotion of the areas according to the most typical groups of microrelief: flat areas, elevations, transitional areas. In cases of extensive humidity, the death of seedlings and artificial forest plantings was observed (soaking, frost extrusion, etc.). The creation of micro-elevations and the drainage of the excessive moisture guarantee the regeneration and establishment of the highly productive forests. The differences in the density of pine wood before and after the hydrotechnical reclamation were detected according to the landscape. The largest changes in the indicator were determined at the elevations and the flat areas, with the increase and the decrease, respectively. The trees that grow on the flat terrain after the reclamation show a relative excess of early wood over late wood, while at the elevations the presence of the late wood is predominant. For citation: Zagorodski M.A., Tretyakov S.V., Koptev S.V. Density of Scots Pine Wood in Drained Sphagnum Pine Forest. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 2, pp. 160–171. (In Russ.). https://doi.org/10.37482/0536-1036-2023-2-160-171

The study of the wood quality in the drained pine stand was carried out on the territory of the north taiga of Arkhangelsk Oblast, which belongs to the green zone of the city of Arkhangelsk and the Arctic zone of the Russian Federation. Repeated measurements of forest inventory parameters were carried out on 6 permanent sample plots affected by melioration since 1974 and reconstruction of the drainage network in 1990. Before drainage, a swampy pine stands of the Vb bonitet class grew on them. At present, medium-aged scots pine (Pinus sylvestris L.) stands of shrubby sphagnum forest type, IV bonitet class, grow on the drained area. For half of the plots, it is possible to recommend thinning according to the current Russian Rules of forest care (2020). Some of the trees meet the requirements for the aviation lumber wood quality. For a visual simultaneous analysis of the drainage network quality impact, the location of objects relative to the drainage network and the air temperature in abnormally hot years, diagrams of changes in the average indicators of the width of the annual increment and the wood density in the drained pine stands by year are constructed. Similar diagrams are constructed on the basis of measuring the model tree cores at different relative heights of the trunk. This analytical approach has been applied for the first time. It is suggested that in 10 years the inventory parameters of all facilities will meet the requirements for the thinning purpose, and the wood quality will increase on average, for which it is recommended to reconstruct the channels.

In order to organize, plan and conduct forest management on a scientific basis in stands with predominance and participation of gray alder (Alnus incana (L.) Moench), formed in the conditions of the taiga zone, reliable data on the structure, growth and productivity of stands are needed. At present, there is an urgent need to develop growth progress tables for gray alder stands, as the areas occupied by this species have significantly increased as a result of abandoned agricultural lands overgrowth. The development of a unified system of regulatory and reference materials for accounting the number, assessment of the condition and volume of use of stands of gray alder in the European North of Russia is an important and urgent task. Growth progress tables for normal gray alder stands located in the taiga zone of the north-east of the European part of Russia have not been developed by anyone before. The purpose of this research is to study the age dynamics of normal gray alder stands to compile growth progress tables. We used 193 model trees of gray alder, as well as data from 175 sample plots. As a research result for the growth progress tables with relative stands density of 1.0 we obtained the equations for determining the average height, diameter, and stands stock by bonity classes. On the basis of the obtained equations, the tables of growth progress of normal stands by bonity classes were developed. The proposed tables will contribute to improving the accuracy of forest inventory, will give the opportunity to objectively assess the forest resources of the most represented stands, to forecast their growth when performing a set of works on the protection, conservation, and reproduction of forest resources, improving the ecological functions of the forest, as well as to control management in stands. For citation: Tretyakov S.V., Koptev S.V., Karaban A.A., Paramonov A.A., Davydov A.V. Age Dynamics of Normal Gray Alder Stands in the Taiga Zone of the North-East of the European Part of Russia. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 6, pp. 70–80. (In Russ.). https://doi.org/10.37482/0536-1036-2023-6-70-80

В связи с высокой экологической ценностью естественных сосновых древостоев, ограниченных Белым морем, авторами было проведено исследование роста сосны (Pinus sylvestris L.), произрастающей по береговой линии на территории Архангельской области.Остается открытым вопрос о том, применимы ли таксационные нормативы для таких древостоев.Особенности приморских сосен связаны с повышенной ветровой нагрузкой, а также специфичными условиями роста на песках.Полевые исследования проведены летом 2022 г. на территории острова Ягры (Приморский район, г.Северодвинск), а также в районе г.Онега (Онежский район).Всего произведены измерения на 18 пробных площадях в разных типах леса.В большинстве случаев доминантным видом напочвенного покрова выступает черника (Vaccinium myrtillus L.).Сравнение того, как соотносятся средние диаметры и высоты со средними возрастами, позволило отметить существенное влияние ветровой нагрузки и освещенности на динамику роста приморских насаждений сосны.Выявленные особенности роста отличаются от показателей таблиц хода роста как для северотаежных и притундровых сосновых древостоев Архангельской области, так и для притундровых сосен

In Russia, the intensive growth of areas naturally overgrown with such species as willow (Salix L.), alder (Alnus Mill.), pine (Pinus L.), etc., increases the biodiversity of entire regions, but the contribution of these areas to the carbon balance and climate stabilization is mostly unknown. Especially critical in this regard is the situation with willow plantations, which was not included in the system of State accounting of the forest fund. Since the energy generated from willow plantations is CO2 neutral, the use of this renewable and sustainable energy source has the potential to reduce global CO2 emissions from fossil fuels. Willow phytomass can be used for the production of fuel in the form of chips, briquettes and pellets, and in some cases – for the production of bioethanol or wood gas. In addition to economic aspects, willow cultivation has a number of environmental advantages, such as the ability to accumulate toxins from polluted areas, improve landscaping and serve as hedges. To plan and manage forestry in willow plantations in the conditions of the North taiga subzone of Arkhangelsk Oblast and assess its contribution to the carbon balance, data on the biological productivity of willow trees and standards for assessing their phytomass are needed. The purpose of the study is to develop models and tables for assessing the structure and dynamics of the aboveground phytomass of the willow stands in the conditions of Arkhangelsk Oblast. To achieve it, the following tasks have been implemented: 52 sample plots have been established to assess aboveground phytomass of willows; regression models of the dependence of willow phytomass on the volume-forming inventory indicators of trees are constructed; the models obtained are combined with the yield table of willow stands and the table of age dynamics of willow phytomass is constructed according to site indices for the conditions of Arkhangelsk Oblast. A comparative analysis of the results obtained with data on the productivity of willows in Sweden showed that at the same age of stands, the stocks of aboveground phytomass of Swedish willow correspond to the stocks of phytomass of willows of Arkhangelsk Oblast at an average level between the I and II site productivity classes.

ОЦЕНКА ТОЧНОСТИ ОПРЕДЕЛЕНИЯ ЗАПАСА В МОЛОДНЯКАХ И СРЕДНЕВОЗРАСТНЫХ ДРЕВОСТОЯХ ПО

Для организации, планирования и ведения лесного хозяйства на научной основе в насаждениях с преобладанием и участием ольхи серой (Alnus incana (L.) Moench), сформировавшихся в условиях таежной зоны, необходимы достоверные данные о строении, росте и продуктивности древостоев. В настоящее время ощущается острая необходимость в разработке таблиц хода роста для насаждений ольхи серой, так как площади, занятые этой породой, значительно увеличились в результате зарастания заброшенных сельскохозяйственных угодий. Разработка единой системы нормативных и справочных материалов для учета количества, оценки состояния и объема использования насаждений ольхи серой на Европейском Севере России является важной и актуальной задачей. Таблицы хода роста для нормальных древостоев ольхи серой в таежной зоне северо-востока европейской части России ранее не разрабатывались. Цель данного исследования – изучение возрастной динамики нормальных древостоев ольхи серой и составление таблиц хода роста. Использованы 193 модельных дерева ольхи серой, а также данные 175 пробных площадей. Полнота – 1,0. Получены уравнения для определения средней высоты, диаметра и запаса насаждений по классам бонитета. На основе уравнений разработаны таблицы хода роста нормальных древостоев по классам бонитета. Предложенные таблицы будут способствовать повышению точности таксации лесов, дадут возможность объективно оценить лесосырьевые ресурсы наиболее представленных древостоев, прогнозировать их рост при выполнении комплекса работ по охране, защите и воспроизводству лесных ресурсов, повышению экологических функций леса, а также контролировать ведение хозяйства в древостоях. Для цитирования: Третьяков С.В., Коптев С.В., Карабан А.А., Парамонов А.А., Давыдов А.В. Возрастная динамика нормальных древостоев ольхи серой в таежной зоне северо-востока европейской части России // Изв. вузов. Лесн. журн. 2023. № 6. С. 70–80. https://doi.org/10.37482/0536-1036-2023-6-70-80

An experimental open-type tapping was carried out in pine stands located in the Sokolsky district of the Vologda region. The objects of study are represented by plantations located on the sites, passed in 1972 by hydrotechnical reclamation, as well as similar forests after continuous thinning. The dominant species in the tree layer is pine, the share of spruce and birch does not reach 10%. The release of turpentine was studied in pine forests on a mesotrophic peat deposit. The tapping was carried out using the ascending method of applying the substrates. The main attention was paid to improving the method for determining the resin productivity of Scots pine. In the course of the study, the following tasks were solved: 1) four permanent test plots were laid in drained pine plantations, in addition, continuous thinning was performed on two sites; 2) for research purposes, an experimental double-sided harvesting of pine turpentine was carried out on each trial plot; 3) the influence of hydrotechnical reclamation and thinning on the amount of released pine turpentine has been determined; 4) specifying coefficients have been developed for the mathematical calculation (forecast) of turpentine yield with a 50% trunk load with tapping cuts. Based on the results of the study, a number of correction factors have been proposed to determine the resin productivity of pines, taking into account their taxation diameter, since the mathematical calculation of the turpentine yield under a trunk load with tapping cuts of 50% carr is often overestimated. The positive effect of hydrotechnical reclamation on the increase in the breast height diameter of pine was confirmed. The average yield of pine resin is about 22% higher, relative to the stand without silvicultural care, in a drained pine forest after silvicultural maintenance

The relationship between the absolutely dry aboveground phytomass of fractions of gray alder (Alnus incana (L.) Moench) trees and a diameter at a height of 1.3 m was researched in tall grass gray alder stands in the Arkhangelsk forestry, which belongs to the North-taiga forest region of the Arkhangelsk region and to the land territory of the Arctic. In the field season of 2020, 4 trial areas were laid, and 5-6 model trees were selected and measured on them, falling on 2- centimeter thick steps. A total of 21 model trees were studied. The weight of freshly cut and absolutely dry phytomass of 4 fractions of trunk wood, trunk bark, branches and foliage was determined from model trees. Based on the collected data, graphically obtained allometric equations of bonds by fractions for each sample area. Allometric equations are chosen for this purpose in both Russian and foreign studies. Based on the fact that the obtained determination coefficients in most cases exceed 0.8 and in two cases are in the range from 0.7 to 0.8, general allometric equations were derived using all model trees. Comparison of the results of the calculation of photometric indicators in t/ha by general equations with the equations obtained separately for each forest stand shows that the general allometric equations mostly underestimate the phytometric indicators. The best calculation results were obtained for wood and trunk bark fractions. These fractions are of the greatest importance when harvesting wood. Based on general equations, for the first time for the Arkhangelsk region, a table has been created that characterizes the wood fractions of gray alder by weight on each of the 2-centimeter steps of thickness from 4 to 16 cm. The equations are practically applicable for predicting the average absolutely dry phytomass of various fractions at various harvesting operations.

The sulphate soap separation from black liquor is influenced by a large number of factors: wood species composition, physical properties and composition of liquor components. The bases of the process are widely researched, but the influence of some factors requires additional research. Meanwhile, due to the diversity of the processed wood species composition and different cooking conditions, the composition and properties of the liquor may differ significantly, and the soap separation at different mills does not always follow the patterns established in previous studies. The purpose of this research is to determine the optimal parameters for the sulphate soap separation from semi-steamed black liquor from the mixed wood cooking, as well as the consumption of additives to increase the sulphate soap yield. The research is based on the principles of mathematical modeling of processes and was carried out in laboratory conditions. We used the method of a planned experiment in the form of a second-order rotatable compositional uniform plan in order to obtain a mathematical model of the soap skimming process, depending on the chosen variables and to determine the optimal values of the process parameters. In the experiment, the following factors were varied: temperature, soap settling time and liquor density. The optimal values of these factors for sulphate soap separation from black liquor were determined, a mathematical model of the process was developed, and the optimal parameters for the effective sulphate soap settling were determined as results of the experiment. Adjusting the soap skimming production conditions to the optimal can increase soap skimming from semi-steamed liquors by 20 %. As a result of evaluating the effect of adding surfactants of different nature to black liquor of different density on the completeness of sulphate soap separation, we have found their optimal dosages, which give the maximum positive effect – an increase in soap yield by 15 %. For citation: Starzhinskaya E.V., Kryazhev A.M., Tret’yakov S.I., Gluhanov A.A. Sulphate Soap Separation from Wood Mixture Cooking Black Liquor. Lesnoy Zhurnal = Russian Forestry Journal, 2022, no. 6, pp. 178–192. (In Russ.). https://doi.org/10.37482/0536-1036-2022-6-178-192

The purpose of the research is to analyse the successful creation of an artificial pine forest by seeding and develop recommendations for the guaranteed reproduction of pine stands in Northern European Russia. In recent decades, there has been a steady decline in the share of pine stands and their replacement with low-value and low-yielding tree species. We surveyed 12 permanent sample plots that were laid out in various variants of forest crops. The taxation parameters were obtained by a standard analysis of the experimental data. The evaluation parameters of the stands vary within the following limits: the average diameter of the pine trees varied from 21.9 to 30.9 cm; the total basal area of the pine varied from 19.1 to 38.8 m(2).ha(-1); the average height of the pine varied from 20.1 to 26.8 m; the number of growing trees varied from 754 to 1 952 ha(-1); the pines varied from 382 to 762 ha(-1); the growing stocks of stands varied from 416 to 608 m(3).ha(-1). The distribution of pine trees by thickness steps showed that all the studied samples were close to the normal distribution curve. The results of the correlation and multidimensional analyses showed that the creation method of the forest crops had a significant impact on the value of the taxation parameters. It was found that the best options for growing pure pine stands that can be recommended for practical production are plots with a large share of soil cultivation and the size of the seedbed.

Willow trees occupy an important place in the dendroflora of the middle zone of the European part of Russia due to their extensive species diversity and large intrapopulation variability. In the Arkhangelsk Region and other regions in the North-East of Russia, abandoned agricultural land (post-agrogenic land) can serve as places for the creation of willow plantations. Currently, such lands are actively overgrown with various tree species, usually of low quality and not of significant commercial interest. The creation of plantations will allows by a short logging turnover to obtain stable wood yields and organize a highly profitable economy on unused land. There is no any information on the willow cultivation in Russia. Willows of the Salix genus grow everywhere and there are more than 130 species. About 30 of these species are found in the Arkhangelsk region. Based on the data of the State forest register of the North Taiga forest region, the tree willow occupies an area of 5.3 thousand hectares. Land with strong moisture is widespread in the Arkhangelsk region. Willow grows well in these areas. Due to this, as well as the good strength of the pulpwillow wood can be widely used in pulp and paper production.

Current scenarios of the consequences of global warming stimulate research on the carbon-depositing capacity of vegetation cover. The stem is the main part of the tree biomass, and the accuracy of its volume assessment determines the possibility of correct monitoring and forecasting of forest resources. In the Russian forest management system, willow was not among the main forest-forming species, and therefore there was no need to develop valuation standards for it. However, due to the increased relevance of assessing the carbon-deposing function of Russian forests and the requirement to take into account the contribution to the carbon balance of all types of vegetation, there is a necessity to develop such standards. The solution can be found in the development of a generic model (or table) that takes into account the morphology of willows within the Salix L. genus and is based on data published in different regions and countries. The object of our research is data on the volume of willow stems, which is published and freely available in Russia, Kazakhstan, Bulgaria, and Norway in the form of tables or regression models. However, the extent to which each local model is applicable in other regions is unknown. To resolve this uncertainty, we used meta-analysis as a statistical procedure that combines the results of several independent studies in order to find a common pattern. As a result, we obtained a generic model of stem volume for the Salix genus, which is characterized by a high coefficient of determination and can be applied to estimate the stem volume of any species of this genus with minimum deviations from the calculated values. The results of the work are aimed at improving the accuracy of accounting deciduous stands during forest management and monitoring activities, valuation of stands on permanent and temporary trial plots. The implementation of unified standards for the use, reproduction, conservation and protection of willow stands with all the diversity of its species will solve a number of practical issues. For citation: Usoltsev V.А., Paramonov А.А., Tretyakov S.V., Koptev S.V., Tsepordey I.S. Generic Model of Willow Stem Volume: A Meta-Analysis. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 3, pp. 49–58. DOI: 10.37482/0536-1036-2021-3-49-58