Vol 29, No 5 (2025)

The article studies natural reforestation of conifers in the Arctic zone of the European North. It has been established that the regeneration capability of coniferous species varies depending on different forest conditions. The largest amount of pine undergrowth is observed in shrubby-sphagnum pine forests (4,0 ± 0,6 thousand units/ha). Pine regeneration is also successful in lichen and blueberry pine forests. The largest amount of spruce undergrowth is observed in the blueberry spruce forest (3,4 thousand units/ha). Spruce regeneration is also successful in fern-acid pine and sedge-sphagnum spruce forests. The amount of spruce undergrowth tends to increase in overgrown blueberry spruce forests (about 200 years old) from the west to the east. It was revealed that in the shrubby-sphagnum pine forests, the coniferous undergrowth increases with an increased age of the stand. The maximum amount of coniferous undergrowth in blueberry pine is observed in the stand of the 4th age class. It is shown that the reproduction of coniferous undergrowth under the canopy of blueberry pine is influenced by age, height, relative completeness of the stand, and the presence of hardwood undergrowth. The maximum coniferous undergrowth is noted in the blueberry spruce forest of the 5th grade of age. The success of coniferous undergrowth regeneration under the canopy of blueberry spruce is influenced by age, height, relative completeness of the stand, and the presence of aspen undergrowth. We have revealed the dependence of the undergrowth height on its age has been revealed, which can be described by a linear equation. The allometric patterns of spruce undergrowth formation in blueberry pine and blueberry spruce forest are similar. It is recommended that the data obtained be used as an informative base for improving the methods and techniques of rational forestry management.

The article studies the trophogenic potential of soil-forming rocks and soils of watershed and outwash plain terrains in Voronezh upland oak forest as an integral component of the urban forested area. It was established that the original soil-forming rocks of the studied types of the terrain are composed of 96 % sand, mostly of medium grain. The share of siltstone is 64,2 kg, and silt-and-clay — 2,7 kg. As a result, forest soil formation in the sand habitat, which lasted 70 years, the amount of clay in the rooting depth layer (2 m) increased from 2,7 to 36,7 kg/m². In the heavy fraction of the fluvioglacial sands of the watershed and outwash plain terrains, minerals that are resistant to physico-chemical weathering are predominant. The total mineral content of heavy fractions is 0,11 %, or 1,1 kg per ton of rock. Pinus silvestris L. stands created on middle-quaternary fluvio-glacial sands synthesized 91,6 t/ha of organic matter over 70 years, which corresponds to 962 106 kJ/ha of energy. An artificially created landscape ecosystem, accumulating potentially active energy and biochemical elements in living and dead organic matter, is gradually creating a humus accumulation horizon of soil cover. Carbon deposition in the rooting depth layer is 28,3 t/ha. The artificially created forest landscapes of watershed and outwash plain terrains of forest- steppe have very low forest potential and are close to destruction, however they have fulfilled their tasks and require further research, monitoring and increasing the biomass, including increasing the undergrowth.

The growth dynamics and the seed productivity of 10-year-old Shore pines (Pinus contorta var. latifolia) of various ecotypes, which were grown in the period 2014–2024 in the Ozersky forestry of the Altai Territory (forest-steppe of Western Siberia), were assessed. The preliminary results show that the studied introduced species grown from seeds harvested on Swedish plantations of lodgepole pine of various geographical origins can successfully grow in the forest-steppe zone of the Altai Territory. The Larslund, Rumhult and Österby ecotypes of more southern origin turned out to be the best in terms of growth at the initial stage of ontogenesis. At the same time, they still lag behind the local Scots pines grown from improved seeds, but in recent years they have had annual height increments at the level of the highest quality classes. The lodgepole pine enters the fruiting period earlier than the local pine and has normally developed generative organs. But the yield of seeds from cones, which are moderately damaged by conobiont insects, is small due to the young age of the cultures.

The article presents data on the distribution of birch plantations in the Republic of Kazakhstan, as well as their representation in the forest fund of the Republic of Belarus and the Russian Federation. It has been determined that of the 83 birch species currently identified in the Republic of Kazakhstan, two species of birch, namely European white birch (Betula pendula Roth) and Pubescent birch (B. pubedcens Ehrh.), grow naturally and form plantations. These species do not only form natural plantations, but are also actively used in landscaping, agroforestry, reforestation and afforestation. The prospects and taxation indicators for 11 taxas of the Birch genus (Betula L.) growing in the arboretum of the A.N. Bukeikhan Kazakh Research Institute of Forestry and Agroforestry (KazRIFA) have been investigated. It has been established that in the territory of Northern Kazakhstan the most promising species for introduction are Karelian birch (B. pendula Roth vor. carelica (Mercklin) Hämet Ahti) and Asian white birch (B. platyphylla Sukaczev.), which surpass other taxa, including local ones, in height and trunk diameter. Despite some lag in height, Pubescent birch (black-barked form of (B. pendula Roth) and Manchurian birch (B. mandshurica (Regel.) Nakai) are best suitable for artificial afforestation and reforestation. Keller’s birch (B. Kelleriana Sukacz.), Daurian’s birch (B. dahurica Pall.) and Erman’s birch (B. ermanii Cham.) can be recommended for landscaping.

The results of a study of spruce ecotypes in the Senezhsky district of the Klin forestry branch of the Mosoblles State Autonomous Institution in the Moscow Region, located within the Klinsko-Dmitrov low ridge of the Smolensk-Moscow Upland, are presented. The presented range of tested provenance is quite wide and in the meridian direction covers the range of the genus Picea from the Kaliningrad region (Russia) and the Baltic States (Lithuania, Latvia, Estonia) to the Novosibirsk and Tomsk regions (Western Siberia, Russia). The trunks height range of the Yonishka (26,4 m), Strugo-Krasnensky (26,2 m), Sharangsky (25,9 m), Yaunelgavsky (25,7 m), Vygodsky (25,6 m) and Kumensky (25,5 m) ecotypes growing according to the Ib class of bonity has been established. Ecotypes from the Grodno, Brest and Minsk regions of Belarus, the Pskov region of Russia and the Lviv region of Ukraine have a high stock of stem wood. A high average increase in stock was recorded for the leading provenances in terms of stem wood productivity. An assessment of the forestry effect is given based on a complex indicator of the expediency of introducing specific spruce varieties. Vital ecotypes of spruce have been identified both in Russia and abroad.

Photosynthesis is the process that provides a plant cell with energy, therefore, the preservation of photosynthetic activity under conditions of physiological stress largely determines the plant’s resistance to adverse environmental factors. The improvement of methods that make it possible to monitor changes in the state of the photosynthetic apparatus is of both theoretical and practical importance. Photosynthetic processes were studied by pulse-amplitude fluorimetry using the WALZ JUNIOR-PAM instrument in coniferous trees (spruce and fir) of different health categories growing in the Perm region of Russia. The measurements carried out using the PAM fluorimeter consist of three components: measuring light, actinic light and saturation pulses. Photosynthetic activity is induced by actinic light, and saturation pulses are used to determine the maximum fluorescence output. The third component, modulated measuring light, does not cause photosynthesis by itself, but measures/observes changes in (fluorescent) output. The fluorometer registers only the fluorescence reaction caused by modulated light. The study assessed the effective quantum yield of Y(II), the electron transport density along the electron transport chain of thylakoid membranes (ETR), the non-photochemical quenching of chlorophyll fluorescence (NPQ), and the coefficient of photochemical quenching of chlorophyll fluorescence (qP). It was found that the ETR, Y(II), NPQ, and qP indices in trees reflect their individual condition. In trees of the 4th category of sanitary condition, these indices are significantly lower than in trees of higher categories, and the qP index is zero or close to zero.

Significant changes in the state of representatives of the poplar genus in urban urban ecosystems of the Irkutsk region related to global warming phenomena are considered. It was found that the climate has undergone significant changes over the period 2021 to 2024, with an increase in average annual temperatures from 1,30 to 1,50 °C. Since 2023, balsamic poplar (Populus balsamifera L.) and (Populus alba L.) plantings have begun to be affected by fungal diseases, which had not previously been widespread. Leaf blades of balsamic poplar, white poplar and, partially, aspen leaves were studied during 2023–2024, as well as a percentage of diseased plants from the total number of trees examined. It was found that after epiphytosis with poplar leaf rust (LRT), the leaves of 50…60 % of the trees were affected by brown spotting. The response to diseases of the leaves of Populus balsamifera L was abundant fruiting and increased growth. A minor lesion of LRT was noted on the leaves of Populus alba L. in 2024. The study of poplar growth in height, diameter and lateral linear growth was carried out. It was found that the increase depends on the degree of shaping of the trees, the direction of the cardinal directions. There is a direct dependence of the increase on the annual temperature course. The warmest year in 2024 saw the largest increase. There is a high growth capacity of Populus balsamifera L., which allows us to pay attention to this species as an invasive one. As a result of the research, it was revealed that the white poplar was the most resistant to changing natural conditions and fungal diseases. Also, white poplar (Populus alba L.) practically does not form shoots in the Irkutsk region and produces fewer catkins and, accordingly, fluff.