Home – Home – Jornals – Siberian Journal of Forest Science 2023 number 2

When considering not only raw materials, but ecosystem functions of forests, the dynamics of forest stand indicators at all stages of growth is important. To regulate a high degree of fulfillment of ecosystem functions, the priority tasks are to increase the stability of stands and their productivity. The aim of the research is to study dynamics of growth and productivity of pine tree stands according to long-term observations data. The materials for the study were data of long-term observations due to the pine forest stands and plantations on permanent plots of the Forest Experimental Station of the Russian State Agrarian University - Moscow Timiryazev Agricultural Academy. Four main characteristics of the stock dynamics of pine stands have been identified, which requires the development of new approaches to its modeling. At the same time, the life cycle of a stand is not a monotonous process, as is customary, but a wave-like process of the dynamics of all main stand indicators, due to the different dependence of the influence of both internal (manifestations of self-regulation in stands and feedback loops) and external factors. The presence of several stages of dynamics can be reflected by empirical models, which include the sum of simple growth functions or nonmonotonic functions with one detection of the maximum or multiplicative-additive models of growth and correction functions. Generalized models of the dynamics of the stand basal areas and stocks of measurements that in late ages overcrowded stands have an advantage over rare ones. The nonmonotonic dynamics of stand yield and productivity indicators needs to be taken into account when substantiating the age of maturity and when designing thinning.

The results of long-term observations in pine tree stands of bilberry and sphagnum forest types are presented. The studies were carried out in the northern subzone taiga conditions of the European North-East of Russia. The method of observation on permanent sample plots was used (the period from 1967 to 2016). Pine tree stands develop on old logging areas (about 70 years ago) and after fire sites. Based on the results of observations carried out significant changes in the morphometric parameters of pine ( Pinus L.) trees and stands were established. In pine forests formed on logging areas, high values of the coefficients of variation of trees in terms of density and stock of stem wood (from 30 to 130 %) were revealed. Such high variation coefficients indicate their active formation. In post-pyrogenic naturally developing pine forests, the coefficients of variation of indicators vary from small (10 %) to high (40 %) values. In bilberry pine forests formed after logging, there is a tendency to reduce the density of trees, mainly caused by the loss of birch ( Betula L.) and aspen ( Populus tremula L.). Whereas, in sphagnum types pine forests, an active replenishment of forest stands with small pine trees from undergrowth was noted. It has been established that with an increase in the proportion of young generation of pine in the composition of forest stands, both a decrease in the average and current growth in stock, as well as a weakening of the vital state and an increase in damage to pine trees occur. During the observation period, the vital state of the most pine forest stands is characterized as «healthy status». In sphagnum types pine forests, the vital state of forest stands is somewhat weaker than in bilberry pine forests. This is due to the unfavorable conditions of their growth on waterlogged soils.

Studies were carried out in pine-birch stands with a second storey of spruce in the north-taiga forest region of Arkhangelsk Oblast (Obozerskoe forestry district), which are formed under the influence of thinning. It’s specified, that thinning at the age of 40 years for taiga zone is unreasonably late stage of formation in such stands. The best option is the formation of forest stands by thinning in three steps. Then, at the age of 40, carry out a second thinning operation, leaving 1000 trees per ha of pine and birch in the first storey, and 2000 trees per ha of spruce in the second storey. At the age of 60, carry out the third stage of thinning, leaving 500-600 pine trees per ha in the upper storey, and 1000 spruce trees in the lower storey. Numbering of pine in the structure is regulating within 90 %. Based on the results obtained in the course of the study, the silvicultural effect of thinning on permanent trial plots is the formation of a spruce storey, which in the future can replace the forest stand after the final felling of the first storey. When thinning in mixed pine forests completed, the attitude to undergrowth is important. Thinning can undoubtedly increase the productivity of forests. The results of the studies will serve as the basis for the subsequent development of recommendations for managing mixed pine-birch stands with a second storey of spruce.

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.

Urban green plantings have been recognized as an important component of the urban ecosystem. Inspecting the health of trees in settlements, in territories, near footpaths and highways is required regularly. In the city of Apatity, Murmansk Oblast, the state of the Siberian stone pine ( Pinus sibirica Du Tour) trees was studied, the presence of risk factors in the environment of the tree and damage that characterize the accident rate of the tree were determined. Visual inspection aims to identify symptoms of structural defects that may compromise the stability of the tree. Root zones, tree stems, crown base, skeletal branches, crown were assessed. The presence of hollows, cracks, signs of decomposition, fruiting bodies of fungi, damage and wounds, weak forks, dead branches were indicated. Among the examined trees, Siberian stone pine trees with a high risk of falling were not found. In trees in street row planting, a sparse crown is more often noted, damage to the butt zone, including mechanical damage. The root system of all examined trees functions in conditions of limited space. Trees in a linear planting along the road and pedestrian zones have more pronounced restrictions on the development of the root system. Stem damage occurs in all examined Siberian stone pine trees. Recommendations have been developed for regular monitoring, tree health pruning and other agrotechnical measures. The study carried out is of great practical importance. The results of the study can be used in the development of recommendations for the formation of a favorable ecological environment in the urbanized territories of the Arctic zone of Russia.

The features of the growth of spruce ( Picea A. Dietr.) trees of various state under the canopy of southern taiga oxalis birch forests ( Betuletum oxalidosum ) are considered. The studies were carried out at the North Forest Experimental Station of the Institute of Forest Science, Russian Academy of Sciences, where a system of permanent trial plots (PTP) was established to study the succession processes in birch forests. At one of the PTP, all spruce trees were cut down as models. Preliminary assessment of their condition (healthy, weakened) was carried out. The shape and foliation of the crown, its length along the height of the tree were taken as evaluation criteria. Growth analysis was performed for trees over 60 years old (40 healthy, 33 weakened). Tree growth was characterized by the dynamics of the following indicators: height, stem cross-sectional area at a height of 0.1 and 1.3 m, stem volume, form factor, shape factor. In the course of a retrospective analysis of the growth of trees, it was found that weakened trees, in terms of the value of the biometric characteristics of the stem, are significantly inferior to healthy ones already in the first 10 years of life. At the age of 60, the height and stem volume of healthy trees are 1.5 and 3.1, respectively, higher than the values of these indicators in weakened specimens. Regardless of the condition of the trees, the maximum average periodic growth in height is observed at 40 years, and the equality of the average and average periodic growths in weakened trees is observed 5 years earlier (55 years) than in healthy ones. The maximum average periodic growth in cross-sectional area and stem volume in weakened trees occurs 5-10 years earlier than in healthy ones. Weakened trees are characterized by more full-boled and less tapering stems. At the age of 60 years, the productivity of healthy trees under the canopy of birch forests corresponds to IV, and weakened ones - to V growth class. The prospects of spruce trees under the canopy of birch forests are best assessed when the spruce reaches the age of 40 years.

Forest area of the Far East reaches almost 50 % of the forest area of the Russian Federation. The share of the operational forest fund accounts for about 50 %, the rest are protective, protected, low-density, near-tundra and reserve forests. Most of the operational forests have been developed. The permissible volume of wood withdrawal is 92.0 million m³. Moreover, it is planned to harvest only 14 % by selective logging, the rest of the wood is planned to harvest by clear cuts. Care felling and forest health improving felling in the forests of the Far East are carried out in insignificant volumes. Timber harvesting during the creation of infrastructure facilities is organized mainly in subjects with a developed mining industry. The high diversity of forests and the differences in their growing conditions determined the need to allocate 12 special forest areas here, in 10 of which timber harvesting is carried out. Both continuous and selective logging methods are used. The main volume of logging take place on the Far Eastern taiga region and amounts 8.9 million m³, mainly by continuous logging. Selective logging of up to 3.5 million m³ of wood prevails in the Amur-Primorsky coniferous-deciduous area. In the Kamchatka taiga, Trans-Baikal forest-steppe and Altai-Sayan mountain-taiga forest areas, timber harvesting is carried out in insignificant volumes, only for the own needs of the population. Currently, due to the significant depletion of operational forests, the dynamics of timber harvesting in the Far Eastern Federal District tends to decrease.

Birch ( Betula L.) is a genus of approx. 60 species, subspecies or varieties with a wide distribution in the northern hemisphere. Understanding of systematics and evolution of this taxonomic group is of high practical importance, since most of the genus birch species are actively used in various industrial sectors and reforestation projects and are important forest tree species. The genus birch is considered to be one of the most complex among angiosperms. Taxonomy of birches has been revised several times, but systematic position of many representatives of the genus birch is being reconsidered today. Despite multiple comprehensive studies involving both morphological and molecular approaches a lot of unsolved issues remain in systematics and phylogeny of the genus birch. Main reasons for this include high variability of morphological characters, polyploidy, and intensive and widespread hybridization, which hampers identification of species. The purpose of the study is taxonomic analysis of the genus birch. Article discusses the features of birch introgressive hybridization, the origin of some species, summarizes the results of several molecular phylogenies based on various chloroplast and nuclear markers, and also lists birch representatives, whose taxonomic position is not confirmed by molecular genetic studies and requires additional study of natural populations using molecular markers. Various methods are used to determine the relationship between birch species: classical morphology analysis, chromosome number analysis and molecular genetic methods. One group of methods is not enough to clearly determine systematic position of some representatives of the genus birch. Therefore, the approach to the taxonomy and phylogeny of birches should be complex, using various modern methods complementing each other.

Comparative study was carried out by morphological, anatomical features of needles of four variations of the common juniper ( Juniperus communis L.). The plants belong to three ecological groups in relation to moisture - mesopsychrophytes, xeromesophytes and mesoxerophytes. Juniper variations choose different strategies for experiencing a lack of moisture. Mesopsychrophytes (a drought tolerance coefficient of less than 2) include variations of J. communis var . saxatilis and J. communis var. depressa and distinguished by small, blunt and thin needles, but large resin channels, the life form is a creeping shrub. Mesoxerophytes (drought resistance coefficient greater than 2.1) include, first of all, J. communis var. oblonga plants, have long, thick, sharp needles with two stomatal stripes, a large number of lining cells, large conductive bundles, developed conductive needle tissue, but small resin passages. These are usually tall shrubs or trees. Juniper variations of J. communis var. communis can be attributed to the group of xeromesophytes and by many features it occupies an intermediate position between J. communis var. saxatilis and J. communis var. oblonga . These plants, on the one hand, represent columnar shrubs and trees and have long sharp needles, small resin passages and, on the other, there are thin needles with as a rule, one stomatal strip and a small number of lining cells.

The issues of studying biological diversity, including at the intraspecific level, are among the most important in biology. The form diversity of woody plants is far from fully revealed. Most often, new forms are identified by crown habit, size and shape of leaf blades and their pubescence, size and color of flowers. Much less attention is paid to the color of the leaves. In the course of fieldwork in 2021, on the Kurtushibinsky Ridge, which is part of the Western Sayan system, in the protected zone of the Sayano-Shushensky State Natural Biosphere Reserve near the village of Bazaga, the authors found a small population of spiraea flexuous ( Spiraea flexuosa Fisch ex Cambess.) with bright, carmine-red leaves. Previously, no forms were noted in spiraea flexuous. However, for the closely related species S. сhamaedryfolia , which some authors previously considered a synonym for spiraea flexuous, 3 forms were described: f. crataegifolia Zhl., f. transiens Zhl. and f. stenophylla Zhl. They differed only in the shape and size of the leaf blades. Forms with leaves other than typical green have not been described before. The found form, being introduced into the arboretum of the Central Siberian Botanical Garden of the Siberian Branch of the Russian Academy of Sciences, retained its characteristics. In accordance with the Code of Botanical Nomenclature, she was given the name - Spiraea flexuosa Fisch ex Cambess., f. atropurpurea Karakulov et Shaulo. The red-leaved form of spiraea flexuousis highly decorative and can be successfully used in landscaping settlements in Siberia.

The analysis of the species richness and landscape positioning of terrestrial vertebrate animal communities in the territory of the potential impact of the reservoir of the planned Nizhneboguchanskaya Hydro Electric Power station (HEP) was carried out. The studies were conducted in the main animal habitats according to standard methods, from 2021 to 2022. The vertebrate fauna in the flooding zone and the potential impact of the projected reservoir of the Nizhneboguchanskaya HEP includes 250 species, including 56 species of mammals, 187 species of birds, 3 species of reptiles and 4 species of amphibians. There are eight main types of biotopes was identified: dark coniferous, light coniferous, mixed and small-leaved forests, wetland complexes, meadows and rocky outcrops. A comparative analysis of faunal richness was performed for each biotope type. The study showed that the highest species diversity is observed in forest habitat: from 126 to 155 species. Of these, the highest faunal diversity is inherent in communities of mixed forests, which is post-fire and after cutting long-derivatives of coniferous forests. Also, in different forest biogeocenoses, there is a high similarity in the species composition of terrestrial vertebrates. The most specific fauna compositions have rocky outcrops, wetlands and meadows, when compared with each other and, especially, with forest biocenoses. As a rule, these habitats are critical for the survival of a number of species, some of which are protected. The preservation of these habitats during the construction and operation of the Nizhneboguchanskaya HEP reservoir will require special attention to maintain the natural level of species diversity of terrestrial vertebrates.

The review is written for the book of Sergei Mikhailovich Bebiya «Forests of Abkhazia». Monograph. Sukhum: Academy, 2022. 589 p. (in Russian with English title, summary and contents).