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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 problem of changing tree species in protective afforestation remains poorly covered. The dynamics of species’ change in poplar ( Populus L.) protective forest belt growing next to the forest crops of the Scotch pine ( Рinus sylvestris L.) is discussed in the article. A forest belt 450 m long and 10 m wide grows in the steppe zone near the village of Shigaikulbash, Buzdyaksky District of the Republic of Bashkortostan. Accounting plots are laid every 50 m. Reliable pine undergrowth in the forest belt, poplar undergrowth was not found on any of the accounting plots. Comparative characteristics of pine undergrowth (density, average age, stem height, and diameter) and the condition of poplar trees were compared for 2008 and 2020. It was revealed that there was a change in the design of the forest belt from openwork to dense, there is a partial shrinkage of poplar, in some areas there is an exit of pine undergrowth to the first tier. For both periods, the highest density of pine (over 1.5 thousand trees/ha) was detected at a distance of up to 200 meters from pine forest crops, the lowest density (no more than 0.4 thousand trees/ha) - in the center of the forest belt. In 2020, the category of small undergrowth was not found, most of it is large undergrowth, some of which have entered the reproductive phase. The drying of poplar trees is observed. This was facilitated by a complex of reasons: the complete absence of agrotechnical care in the forest belts, a drought that has been recurring for several years and the maximum age of trees in the conditions of the steppe. There is no poplar undergrowth along the entire length of the forest strip. A similar pattern is observed in neighboring forest belts, which allows to make a conclusions about the actual change of balsam poplar ( Populus balsamifera L.) to Scotch pine in protective forest belts, which should be accompanied by logging and agrotechnical tillage on the edges of forest belts, followed by the formation of a young pine tree stand of openwork design.

The results of the studies of the features of adaptation of triploid aspen regenerants obtained in vitro using a hydroponic system are discussed in the article. Triploid clones of aspen ( Populus tremula L.) are characterized by rapid growth, high wood quality and increased resistance to diseases and pests compared to diploid clones and can be used to create forest plantations. Use of clonal micropropagation is advisable to preserve the valuable gene pool of triploid forms of aspen, while the adaptation of plants to ex vitro conditions is the most difficult process. Growing plants using the hydroponic method has several advantages. Triploid aspen regenerants, in which the length of the green mass prevails over the root mass, have a normal development without signs of infection and a good turgor of the green mass when they are removed from the test tube during the adaptation. Triploid aspen regenerants with decapitation of the apical shoot have the ratio of the lengths of the green mass to the root mass is close to 1:1, while the predominance of roots with values above the average is observed. Aspen plants with a predominance of root mass over green are formed from regenerants with leaving of 2 internodes and have an average of 2 roots of the first order. Triploid aspen plants-regenerants with biometric parameters of roots 5-7 cm and green mass up to 5 cm had the highest survival rates (94.7-100 %). A gradual decrease in the leaf surface area contributes to a better survival of regenerants, while it is necessary to reduce the humidity level from 100 % at the initial stage of adaptation to 60 % within 5 days, then - on 20 % with an interval of 3 days. The period of adaptation of triploid aspen plants in a hydroponic system is 16 days.

The study of the small mammal communities state in the city’s forest parks and park and in the forest, depending on changes in phytocenoses under the influence of recreation, was carried out. These studies have shown that the lower layers of phytocenoses of the forest communities belonging to pine stand characteristic of the South taiga district of the Trans-Urals foothill forest province (Kolesnikov et al., 1973) have been noticeably changed of the urban area. First of all, we observed a low renewable capacity of the main forest-forming species of the sites and the appearance of new species in the undergrowth, which are not important for forest-forming processes, but are signs of transformation of the lower layers of phytocenosis. The degree of regression digression in all urban sites was medium or weak. In the control it was very weak or absent. In forest parks and park both the extension of the shrub species composition due to synanthropic species and the increase in their number are of greater importance. The undergrowth in them is represented by raspberries ( Rubus idaeus L.), tatarian honeysuckle ( Lonicera tatarica L.), three-lobed viburnum ( Viburnum opulus L.), mountain ash ( Sorbus aucuparia L.), bird cherry ( Prunus padus L.), goat willow ( Salix caprea L.), elderberry ( Sambucus racemosa L.), round-leaved irga ( Amelanchier ovalis Medik.), dogwood ( Cotoneaster Medik.), rosehip ( Rosa acicularis Lindl.), hawthorn ( Crataegus oxyacantha L.). The undergrowth species composition of the control is much poorer than in urban localities: it contains: bird cherry, goat willow, dog rose, green broom ( Chamaecytisus ruthenicus (Fisch. ex Wol.) Klask.), mountain ash. The development of undergrowth is an influence on the growing conditions of grass-shrub species and the development of moss cover with the creation of a regime of favorability for some vegetation groups and suppression of others. Although there is a high similarity in the floral composition of the lower tiers between the forest parks, they differ in the composition of the dominant species. Changes in the lower levels of phytocenoses naturally had an impact on other components of the ecosystem, in particular, on communities of small mammals. In the urban sites appreciable share in the communities is made up of species absent from the forest: Ural field mouse ( Apodemus uralensis Pallas, 1811) and striped field mouse ( A. agrarius Pallas, 1771), which (during the years of depression in the surrounding forests) make up 60 % to 98 % of the community in the forest parks and parks. Comparison of the degree of similarity of the characteristics of the lower layers of phytocenoses and the characteristics of micromammal communities showed their high correspondence.

Species of the genus Cypress trees ( Chamaecyparis Spach), family Cupressaceae - monoecious evergreen trees with a cone-shaped dense crown and aromatic resinous needles. In nature, they grow in East Asia (China, Japan, Taiwan) and North America; ornamental plants suitable for urban gardening and modern urban floristry. These plants look good in single, group and avenue plantings, especially in places with a suitable climate. They give valuable light, fine-grained, fragrant, hard and durable wood. The varietal wealth is so great - only 4 species have produced over 1500 modern cultivars. In culture, many varieties of Japanese selection are known, which have already proven themselves well in other countries. In most cases, cypress trees are suitable in areas with a maritime climate, mild winters and high humidity. Comparison with literature and archival data shows that in recent years and decades, against the background of climate warming, there has been a significant increase in the size of plants. Blunt cypress ( Chamaecyparis obtusa (Siebold et Zucc.) Endl.), in the Peter the Great Botanical Garden of V. L. Komarov Botanical Institute, Russian Academy of Sciences has been known since 1870, it grown in the collection in different periods -the first mention from 1870 to 1898, then in the period from 1949 to 1977. It has been included in the modern collection of the arboretum since 2009. At the age of 14, it is a double-trunked tree 1.94 m high, with a trunk of 0.20 m. In 2018, seed production was observed for the first time. In 2021, seed offspring were obtained. Given the ongoing warming of the climate in St. Petersburg and increasingly favorable wintering conditions, blunt cypress has prospects for wider cultivation in the North-West of Russia and introduction into the modern range of gardens and parks in St. Petersburg as a new ornamental plant. For planting blunt cypress, one should choose a place protected from cold winds, without stagnant moisture, near groundwater, but a slightly shaded place is possible. In the summer, plants should be watered, this is especially important for young plants, preventing their earthen coma from drying out. In winter, during heavy snowfalls, it is useful to shake off the plants to avoid snow breakage.

Article analyzes scientific achievements and heritage of Elena Grigor’evna Minina - famous Russian scientist, biologist, plant physiologist (24.04.1903 - 01.04.1989). Being an outstanding researcher in many fields of reproductive biology and plant physiology, E. G. Minina created the doctrine of sex determination and sexual reproduction in plants and the influence of phytohormones on the processes of sexualization. She considered the course of the processes of sexualization as a complex chain of chemical transformations, primarily the redox system and hormonal regulation. Elena Grigor’evna determined the directions of the studies under environmental stress, laid the foundations for studying the patterns of morphogenesis, sexual transformations in woody plants. She was the first to describe sexual transformations in the Siberian stone pine ( Pinus sibirica Du Tour) trees with acceleration of the reproductive cycle. These forms show signs of apomixis, characteristic of thriving angiosperms. Much attention in Elena Grigor’evna’s research was paid to elucidating the role of gravity in the processes of growth, formation and seed-bearing in coniferous plants. The criterion of the initial stage of atmospheric pollution, in her opinion, may be the direction of growth of lateral shoots. She is particularly interested in the problems of evolutionary physiology and reproductive biology of plants, provides schemes of phylogenetic relationships in the evolutionary development of angiosperms and gymnosperms. The level of evolutionary advancement of taxa and individuals within the species, in her opinion, is manifested in the intensity of photosynthesis, carbohydrate-nitrogen metabolism, biosynthesis of gibberellins and growth processes. According to Elena Grigor’evna’s teaching, a biotechnology of somatic embryogenesis of coniferous species is being developed, in which somatic cells in in vitro culture switch to the path of embryonic development, forming numerous embryos and plants with selectively significant traits. The list of the main scientific publications and the list of dissertations defended under his supervision is given.