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The influence of spruce ( Picea obovata Ledeb.) stands on the change in morphological characteristics, physicochemical properties, state of organic matter, as well as the qualitative and quantitative composition of the microbiocenoses of cryogenic meadow-chernozem soil formed under meadow-steppe vegetation in Central Yakutia was studied. By means of the complex application of soil, microbiological, statistical research methods, all changes that occurred in the original cryogenic soil were identified and assessed. Thus, over a 45-year period of forest vegetation influence, the morphological profile of the original meadow-chernozem soil (Luvic Chernozems Sodic), which had the form: Аv, ca-Aca-ABca-Bcа-BCca-Cca, was transformed into the profile of cryogenic humus-carbonate soil (Calcic Cryosols Eutric), which was already characterized by the following structure: O-А0-A-ABca-Bса-BC-Cca. Over the noted period, a forb-green moss vegetation cover was formed on the surface of the forest soil, as a result of which the depth of seasonal thawing decreased. The physical-chemical properties, humus composition and the state of microbiocenoses of the studied cryogenic soils also changed significantly. Thus, in the meter-thick layer of these soils, the weighted average pH_H2O value decreased from 9.0 to 8.6, and the content of organic C and total N, respectively, increased from 0.79 to 1.72 % and from 0.03 to 0.13 %. At the same time, more mobile humus was formed in the humus profile of the cryogenic humus-carbonate soil, when the total amount of humic acids increased to 65.6-86.0 %, and the proportion of non-hydrolyzable residue decreased to 14.0-34.4 %. Also, this soil turned out to be the richest in microorganisms, where their total number was 2.4 ± 1.3×10⁶ CFU/g, while in the original soil it was only 5.8 ± 3.1×10⁵ CFU/g. Moreover, if actinomycetes (34 %) and micromycetes (29 %) were relatively predominant in the first soil, then oligonitrophilic bacteria (37 %) and ammonifiers (27 %) were predominant in the second.

The article presents the results of a sowing experiment (2016-2024) to assess the safety, growth and condition of seedlings/saplings of forest-swamp and forest-steppe ecotypes (origins) of Siberian larch ( Larix sibirica Ledeb.) planted in a forest area of Akademgorodok in Krasnoyarsk, and to assess the prospects for their use in urban greening. After transplantation from the sowing department in 2022, 6-year-old seedlings showed absolute survival. In the year of transplantation, during the initial examination, some of the young Siberian larch seedlings were found to be affected by hermes ( Adelges laricis Vall.) and larch bud midge ( Dasyneura laricis F. Low.), early yellowing, wilting and needle fall, which did not have a noticeable effect on survival. During the repeated examination, taking into account the degree of preservation of the needles, most of the seedlings of both forest-swamp and forest-steppe origin were characterized by satisfactory and good condition. The absolute growth of seedlings/saplings of the forest-steppe ecotype of Siberian larch was higher than that of the forest-swamp in the year of sowing seeds (2016) and in the year of transplanting young trees (2022). Statistically significant differences in growth between seedlings of forest-swamp and forest-steppe origin appeared when transplanting plants. In other years, greater growth was recorded in seedlings/saplings of the forest-swamp ecotype, compared to the forest-steppe. In 2024, seedlings of the forest-swamp ecotype of Siberian larch had a greater average height compared to the forest-steppe ecotype. Saplings of forest-swamp origin were distinguished by a wider range of height variability, while trees of forest-steppe origin had more even values of variation of this trait.

Environmental conditions of lava fields (moisture accumulation in porous basalts, and complex mesorelief) promote the naturalization of spruce ( Picea A. Dietr.), which forms stable phytocenoses here and acts as an edificator of plant communities. In contrast, larch ( Larix Mill.) occurs sporadically, which is due to its attachment to well-drained soils, making it less competitive in the conditions of lava fields. Dendroclimatic analysis of tree-ring chronologies of spruce and larch confirms the key role of atmospheric precipitation in the dynamics of wood vegetation. Trees, primarily spruce, in these conditions act as an edificator, modifying initial ecological niches and promoting their more active development by moss-grass vegetation. In the unusual ecological conditions of lava fields, hydrophilic and thermophilic spruce, compared to larch, shows greater dependence of radial increment on temperature conditions than on moisture availability.

The dynamics of quantitative and qualitative parameters of fir undergrowth in the indigenous South taiga fir forests of the Tomsk region, damaged by an invasive four-eyed fir bark beetle (Polygraphus proximus Blandford), has been studied. The observations were carried out twice - during the period of mass reproduction of the pest (2012-2016) and 10 years after the outbreak of reproduction (2023), on 8 test areas in phytocenoses, differing in the composition of stands, living ground cover, taxation indicators of the fir element of the mother canopy and the degree of damage. In 2012, the total number of live fir undergrowth in different phytocenoses was 500-6300 trees/ha, including the largest, most valuable, pre-renewal undergrowth of 325-1100 trees/ha. By 2023, the number of undergrowth Siberian fir ( Abies sibirica Ledeb . ) decreased by 1.5-8.5 times, mainly due to a decrease in the number of small undergrowth, and amounted to 167-4000 trees/ha, including large undergrowth 154-2500 trees/ha. The negative dynamics of the number of undergrowth is due to a complex of factors of a biogeocenotic, pathological and mechanical nature, as well as the transition of large undergrowth into a stand. The average height of small and medium-sized undergrowth changed slightly, in large undergrowth in most stands it increased by 1.2-1.7 times by 2023 and reached 4.5 m, the age of large undergrowth ranged from 14 to 36 years. A positive trend was noted in the vital condition of the undergrowth, due to the condition of large undergrowth, partially weakened during the period of mass reproduction of the beetle due to pest attacks and healthy in the post-outbreak period. The comprehensive characterization of fir undergrowth according to the studied parameters allowed us to assess the varying degrees of its success in restoring damaged stands.

Forms of Siberian stone pine ( Pinus sibirica Du Tour) (Siberian pine) with an annual reproductive cycle are unique natural models for studying reproductive processes, speciation and evolution of gymnosperms, as well as potential for genetic selection work aimed at obtaining high-yielding Siberian stone pine plantations. The study of the yield structure and seed productivity of Siberian stone pine trees with an annual cycle of female cone development showed that all growth characteristics of cones (linear dimensions, cone and seed weight) are significantly lower than in typical individuals, and morphogenetic characteristics (the number of seed scales) and the level of variability of yield structure characteristics are comparable to variability in Siberian stone pine populations as a whole. At the same time, for individual specimens with one-year development of reproductive structures, high seed productivity of female cones is characteristic (76.7 %). Selection and fixation in the offspring of traits that ensure stable yields of Siberian stone pine seeds are recognized as promising areas of breeding of Siberian stone pine. Species with one-year development of female cones are unique genotypes with the potential to obtain new varieties and forms.

The experience of using terrestrial laser scanning LiDAR to assess the biometric characteristics of trees during the inventory of the artificial tree plantings in the «Bul’var Pobedy» (Boulevard of Victory) in the city of Petrozavodsk, Republic of Karelia, is discussed in the paper. The aim of the work was to conduct a comprehensive statistical analysis of LiDAR data in comparison with in-kind measurements of dendroparameters - tree height, crown and stem diameters at a height of 1.3 m, taking into account the species of trees. The results of the study showed the high efficiency of LiDAR technology for establishing the main dendroparameters. The best results were obtained for measuring stem diameter at a height of 1.3 m (91.5 % of reliable species), crown diameter (85.7 %) and tree height (92.9 %). The average relative error ranged from 5.0 % for stem diameter at a height of 1.3 m to 10.02 % for tree height. The most accurate measurement results are shown for a blue spruce ( Picea pungens Engelm.) and common ash ( Fraxinus excelsior L.), where all parameters were measured with high accuracy ( p > 0.05 in all cases). The stem diameter at 1.3 m turned out to be the most stable parameter with the lowest average error (4.99 %). This is explained by the relative simplicity of its measurement and lesser dependence on external factors. Measuring the crown diameter showed a higher average error (8.28 %). The obtained results of the study indicate the need to take into account tree species characteristics and crown density in the stand when scanning LiDAR and processing data.

The aim of the work was to study the pyrolysis of Siberian larch bark ( Larix sibirica Ledeb.) as a potential raw material for the production of torrefects and biochar. Based on the results of thermogravimetry and differential thermogravimetry (DTG), the kinetics of the pyrolysis process were analysed and its thermodynamic parameters were determined. The basic measurement data were analysed: stages of mass loss during heating, temperature intervals corresponding to them and mass loss rate. Taking into account the complexity of the structure and chemical composition of bark and the related appearance of the DTG peak in the thermogravimetric test, the ‘microstages’ of bark thermal decomposition were visualized by forth derivative of the DTG contour using the Savitsky-Golei differentiating filter. The dependence of the activation energy and the pre-exponential multiplier on the degree of conversion was calculated, using the isoconversion kinetic method of Ozawa-Flynn-Wall. The average value of activation energy is 283.7 kJ/mol when the degree of thermal conversion of bark (α) changes from 0.1 to 0.8. The obtained dependence E _a = f (α) was used to calculate thermodynamic parameters (Δ H , Δ G and Δ S ) and to determine the mechanism of reactions according to the Criado method characterising the bark pyrolysis process. The compensatory effect of thermodestruction was established. The mean values of Δ H , Δ G and Δ S are 294.7, 157.3, kJ/mol and 215.0 J/(mol × К), respectively. The conclusions formulate an integral evaluation of the obtained results, point out the area of their use and the subject of further research: analysis of physicochemical properties of torrefects and biochar obtained from larch bark.

The article presents the results of experiments conducted in order to establish the potential possibility of ignition of peat with 10 % moisture content from cigarette butts. The results showed that peat did not ignite from cigarette butts in the absence of wind. Wind velocity was the key factor that influenced the possibility of peat ignition from a cigarette butt. Ignition probability of cigarette butts was 10 % when the wind velocity was 1 m/s. As the wind velocity increased, ignition probability grew accordingly: 27 % of all experiments ended with peat ignition when the wind velocity was 1.5 m/s, and 50 % of experiments ended with peat ignition when the wind velocity was 2.5 m/s. During the process of peat ignition the cigarette filters burned completely, which prevents using filters as the evidence in order to investigate the cause of peat fires. The results showed that the arenation of the peat surface at the rate of 2.5 kg/m² prevented peat ignition from cigarette butts. Thus, the arenation of those drained peatlands sites where popular camping and smoking areas as well as hunting, fishing, mushroom and berries foraging routes are located can significantly reduce peatlands fire hazard and therefore can be used to develop fire prevention measures.

Greenhouse gas emissions have significantly changed the global climate. An increase in the frequency, duration, and severity of drought and heat stress associated with climate change can fundamentally alter the composition, structure, and biogeography of forests in many regions. Of particular concern is the potential increase in tree shrinkage associated with the physiological stress caused by climate change and interaction with other related processes such as insect infestations and forest fires. Despite the noted risks, existing forecasts of tree shrinkage and forest death are based on models that lack functionally realistic physiological mechanisms. It has become obvious that the current understanding of the physiological responses of trees to drought remains very insufficient, and additional basic knowledge is needed to make realistic forecasts of forest loss in the face of rapid climate change. A hydraulic concept has been applied to quantify the mechanisms of tree death, and based on it, different responses to drought of isohydric and anisohydric species have been shown. The presented analysis of the global vulnerability of world forests to hot droughts in the Anthropocene has shown that it is greatly underestimated, including forests in regions with sufficient moisture. In general, despite the ongoing discussions and research regarding many specific mechanisms of forest death, the enormous efforts that the research community has made to clarify these mechanisms have allowed us to obtain significant physiological data indicating an increased vulnerability of forests to death during hot droughts.

This article identifies key distinguishing characteristics of the Canadian forest sector organization and compares the Canadian and Russian approaches to forest relations. It also focuses on current challenges facing forest sector authorities in these countries. The key distinguishing feature of the Canadian approach to forest sector organization is its high level of federalization. Each province has its own forest legislation, but a flexible system of leasing relations is a common feature. An analysis of Canadian forest legislation is conducted using the province of British Columbia as an example. This province is Canada’s leading forest region, accounting for more than a third of Canada’s total logging volume. Compared to the Russian forest sector, the Canadian sector demonstrates greater stability in both legislative changes and economic indicators. From 2002 to 2017, logging volume in Russia was significantly lower than in Canada, but since 2018, the countries have become comparable in this indicator. Indicators such as the area of forest damaged by fires and the volume of reforestation over the same period in both countries are subject to sharp fluctuations. Leasehold arrangements, adopted as the primary instrument for forest sector development, are one of the reasons for the limited interest of private capital. Lessees have insufficient incentive to voluntarily invest in forest areas beyond the minimum required by the lease terms. This problem is common to both the Canadian and Russian forestry sectors.