Photosynthesis is one of the processes most sensitive to changes in environmental factors. Woody plants cultivated outside their natural ranges experience introduction stress. The acclimatization of introduced species is associated with structural, physiological and biochemical changes that ensure the possibility of photosynthesis under abnormal environmental conditions. The primary photoreceptors are chlorophylls and carotenoids, and their quantitative and qualitative compositions serve as a reliable diagnostic marker of the state of introduced species in a new environment. The study aims at detecting changes in the pigment complex of the photosynthetic apparatus of coniferous trees native to North America following their introduction into the boreal zone of Northern Europe. The study focused on populations of the introduced species Picea pungens Engelm., Pinus contorta Douglas ex Loudon, and Thuja occidentalis L. growing in the arboretum of the Vologda State Dairy Farming Academy named after V.N. Vereshchagin. The arboretum is located in a region with a typical moderate continental climate, with unstable weather patterns. The research results have shown that the levels of both chlorophylls and carotenoids fall within the optimal range. Introduced species were found to have lower levels of photosynthetic pigments compared to native species. The pigment content ranges from 1.35 to 1.81 mg/g of fresh weight. The ratio of photosynthetic pigments in introduced plants tends toward a conventional physiological norm. The values for Picea pungens and Thuja occidentalis are the closest to optimal. Among the other plant species studied, the deviation does not exceed 6 %, which contributes to their successful adaptation to new environmental conditions. The chlorophyll ratio for all the analyzed species does not exceed optimal values, which indicates adaptation occurrence and minimal introduction stress. The results confirm the adaptability of the photosynthetic apparatus of North American tree species and their ability to adapt to the ecological conditions of the boreal zone, making it possible to grow these species in the European North.
Identification and assessment of quantitative parameters of forest stands are initial requirements for planning strategies and options for forestry measures. These parameters include structural diversity, which can be determined by modeling the density of distribution probability of tree diameters at breast height of 1.3 m (dbh). The study aimed at describing the tree stand structure and selecting the most appropriate finite mixture model (FMM) of the empirical diameter distribution of natural mixed-age small-leaved linden (Tilia cordata Mill.) stands in the central-eastern part of the Republic of Bashkortostan. We carried out a hierarchical cluster analysis using Ward’s method on tree parameters obtained from 19 sample plots, and determined the suitability of two-component finite mixture methods based on the gamma distribution, Weibull distribution, log-normal distribution, and skew-normal distribution. In order to fit the FMM to the diameter data, we used an expectation-maximization algorithm implemented in the ForestFit package, which was developed for the R environment. All the stands studied were classified as unimodal; the diameter distribution curves were described as skewed, complex, and irregular; no bimodal distributions of the M-shaped type with two peaks or downward-sloping inverted J-shaped distributions were observed. It was found that the mixture of the skew-normal model consistently demonstrated the best performance in terms of the Kolmogorov–Smirnov and Anderson–Darling goodness-of-fit statistics, as well as the Akaike and Bayes information criteria, for all sample plots. An assessment of the relative quality ranks of the correspondence allowed the finite mixtures to be ranked as follows: Weibull (3.5 – worst correspondence), log-normal distribution (3.2), gamma (2.9), and skew-normal distribution (1.0). Thus, an FMM based on a skew-normal distribution can reliably approximate the diameter distribution probabilities of small-leaved linden stands of mixed ages; it is highly flexible and offers an effective balance between accuracy and complexity. FMM allow the simultaneous estimation of the proportion and age distribution of trees and can serve as a key tool for converting field measurement data into dynamic models that predict forest development.
The lack of maintenance in post-agrogenic lands leads to the deterioration of plantations with fruit-bearing plants and accelerates the processes of reforestation, transformation into meadow, and ruderalization of plant communities in fallow fields and wastelands. The research aims at examining the vegetation cover of the Lukashov Nursery Nature Park (a specially protected natural area) and analyzing changes in the vital state of tree stands in orchard plantations and forest communities following the area’s agricultural use, thereby developing effective measures to mitigate anthropogenic risks. The vitality of plantations was determined using the relative vitality index. The coordinates of the trees and shrubs in the nature park were mapped using a Global Navigation Satellite Systems (GNSS) receiver. The tree stands have been shown to be primarily in a weakened state. The biological diversity of the tree population increases due to the introduction of native and invasive tree species. The park covers a total area of 163.943 ha, out of which vegetation occupies 153.785 ha. A comparative analysis revealed that the area of orchards had decreased by 1.6 times compared to 1993, while the area of shrub plantations had decreased by 3.2 times. The area of forest strips and secondary forests has increased by 1.6 times. The landscape area is classified as orchard and park-like, with natural and anthropogenic (modified) landscapes accounting for 70 % of the total area, and semi-natural (slightly modified) landscapes accounting for 23.8 %. Areas affected by human activity and industrial development are located on the edges of the park and account for 6.2 %. Most of the park’s area is covered by a forest, dominated by tree and shrub vegetation (60.7 %), while meadow and shrub communities account for 33.0 %. Fruit-bearing plantations and natural vegetation are in a weakened state, with a vitality index ranging from 59.57 to 78.09 %, except for secondary aspen forests (81.39 %) and sparse forest plantations among meadow and shrub vegetation (82.46 %). Weakened willow sparse woods (32.14 %) have formed within the meadow and shrub vegetation. The research results are applicable for regional management and planning.
This study investigates the influence of slope and agro-ecological regions on the growth and timber volume of Pinus plantations in the wet and intermediate zones of Sri Lanka. Annually, the Forest Department of Sri Lanka releases approximately 1,000 hectares of Pinus plantations for thinning and clear felling to the State Timber Corporation, which estimates timber yield using enumeration data. Notable discrepancies between estimated and actual timber volumes prompted a detailed analysis of the physical and environmental factors affecting plantation growth. The study covered 48 coupes from 11 plantations across three districts Nuwara Eliya, Matara, and Ratnapura selected based on regional representation. Data collected included actual timber volumes extracted in 2020 and 2021, slope measurements, standing tree counts, and agro-ecological region classifications. Statistical analysis focused on identifying correlations between slope, agro-ecological regions, and recorded timber volume. Results indicated a predominantly negative correlation between slope and timber volume, with volumes decreasing progressively from up-country to low-country regions. Steeper slopes were consistently associated with reduced timber yields, while agro-ecological zone significantly influenced overall plantation productivity across all sampled sites. These findings highlight the importance of incorporating topographical and ecological factors into timber yield forecasting models. Improved integration of such variables would reduce estimation discrepancies, support more accurate harvest planning, and contribute to the long-term sustainable management of forest plantation resources across Sri Lanka.
Soil disturbances caused by harvesting and logging machinery and equipment at cutting areas are one of the negative environmental impacts that affect subsequent natural reforestation. The research aimed at identifying the most important soil factors for Norway spruce recovery in areas disturbed by harvesting and logging. The study was carried out at the 7-year-old clear-cutting area in a blueberry forest in the Vilegodsky Forestry District of the Arkhangelsk Region. Basic biometric parameters were recorded for 40 spruce young trees at the cutting strip; for 20 trees on a skid trail with shallow disturbances (depth less than 15 cm); and for 20 trees on a skid trail with deep disturbances (depth 15–30 cm). Soil samples were collected from the root zone near each plant, and their water-physical and agrophysical properties were tested in the laboratory. Multivariate statistical methods were used to analyze the data. It has been found that the traits most responsive to variations in growing conditions are height, as defined by increment, and the length of lateral roots. The study showed that, in terms of the soil’s water-physical and agrophysical properties, the spruce trees at the cutting strip are more similar to those growing on soil with shallow disturbances. Differences in soil properties between areas with shallow and deep disturbances are related to soil compaction caused by the passage of harvesting and logging machinery and equipment. These conditions led to better growth of young trees at the cutting strip compared to the disturbed areas. High density of the soil solid phase, as well as bulk density, total porosity, and aeration porosity – which are closely related to this parameter – have been found to be key factors in ensuring spruce growth parameters throughout the first few years of life. The depth of disturbance is one of the factors limiting spruce growth in areas where the soil cover has been disturbed. The organic carbon and total nitrogen content are significant parameters of the soil’s agrochemical properties. Thus, excessive rutting degrades soil properties and can hinder successful reforestation. It is necessary to limit the formation of deep ruts during harvesting and logging operations.
We compared photosynthesis and transpiration in pine and spruce trees growing in natural conditions with optimal soil moisture at the beginning of the growing season. The research was carried out at the Serebryanoborsk Forest District of the Institute of Forest Science of the Russian Academy of Sciences in the Moscow Region. The research relevance stems from the significant amount of dead spruce stands and the need for pine reforestation in these areas. There are few comparative studies of photosynthesis and transpiration in pine and spruce trees growing under similar conditions. Leaky open chambers were used to measure photosynthesis and transpiration. The rates of photosynthesis and transpiration in the needle shoots were measured based on the difference in the CO2 and H2O concentrations, respectively, between the air outside the chamber and the air exiting the chamber, the airflow velocity, and the horizontal surface area of the needles in the exposure chamber. The CO2 and H2O concentrations were measured using a LI-840 portable infrared gas analyzer (Li-Cor, USA). The air depletion by CO2 in the chamber was, on average, 2 % lower than in the ambient air. The air flow was driven by diaphragm microcompressors (Sonic-388, China). The data showed that, on a mostly sunny day, the rate of photosynthesis in pine trees was more than 88 % higher than in spruce trees. On a cloudy day, the differences were significantly lower (20 %). On a mostly sunny and overcast days, the differences in transpiration rates between the two species were smaller; 18.5 and 20 %, respectively. The relationship between CO2 exchange in pine and spruce and solar radiation and air temperature is similar; differences are observed only in terms of intensity, although in conditions of water stress, pine shows higher photosynthesis rates. The CO2 gas exchange intensity in pine trees under optimal forest growing conditions is nearly twice as high as that in spruce trees. The calculated data on photosynthesis and transpiration were close to the experimental values. The nature of the relationship between transpiration and other factors differs significantly more between pine and spruce. In pine, the differences are mainly due to solar radiation, whereas in spruce, they occur due to air temperature.
Attractiveness is one of the most important properties of recreational complexes. The ornamental features of plants have a positive impact on their attractiveness. The research aimed at exploring the bioecological properties of exotic plant species rarely used in urban landscaping in the Middle Urals and assessing their potential for use. Among the studied exotic species were Juglans cinerea L., J. nigra L., J. regia L., Corylus colurna L., Aesculus hippocastanum L., A. × carnea Zeyh., A. glabra Willd., Catalpa bignonioides Walter, C. × erubescens Carr., Acer pseudosieboldianum (Pax.) Kom., Robinia pseudoacacia L., R. viscosa Vent. The paper describes the ornamental features of the studied species. Their winter hardiness was assessed using the 7-point scale of the Main Botanical Garden of the Russian Academy of Sciences for the period between 2016 and 2024. This paper provides data of phenological observations carried out over the period 2021–2024. We used the methodology developed by the Main Botanical Garden of the Russian Academy of Sciences to provide an overall assessment of the species introduction feasibility. Species of the genus Aesculus L. are the most resistant to winter conditions. J. cinerea, J. nigra, J. regia, Corylus colurna, and Acer pseudosieboldianum have close to high winter hardiness. Specimens of the genus Catalpa Scop. rank third in terms of winter hardiness. The genus Robinia L. shows the lowest winter hardiness. Tree species with the earliest onset of the growing season (Corylus colurna, Aesculus hippocastanum, A. × carnea, A. glabra, Acer pseudosieboldianum) and those with a later onset (Juglans, Catalpa, and Robinia) have been observed. The research revealed two groups of crops based on the number of colored leaves by the end of the growing season: those with 100 % colored leaves and those with some green leaves remaining. In terms of the prospects for introduction, only Robinia viscosa is classified as unpromising due to its low winter hardiness. The other exotic species studied, owing to their good winter hardiness and unusual appearance for the Middle Urals region, together with their ornamental features, show potential for landscaping and could enhance the attractiveness of public recreation areas in urban settings.
Terrain of the Arkhangelsk region is part of the introgressive hybridization zone of Siberian spruce (Picea obovata Ledeb.) and European spruce (Picea abies (L.) Karst.) on the East European Plain. In many species of the Pinaceae family, the shape of the seed scales contains a wealth of genetic information specific to both the species and its varieties. The research aimed at determining the seasonal dynamics of the photosynthetic pigment complex in Siberian spruce and hybrid spruce with a predominance of Siberian spruce traits in the northern taiga of the Arkhangelsk Region. The field studies were carried out in blueberry spruce forests on low-podzolic loamy soils overlying morainic loams, typical in the northern taiga near the mouth of the Northern Dvina River (64°30ʹ N, 41°00ʹ E). We have labelled 10 Siberian spruce trees and 10 hybrid spruce trees with a predominance of Siberian spruce traits, determined by the seed scale shape at the permanent trial plots. Samples of annual (shadow) needles were harvested from the lower part of the crown at various times of the year in 2023. Spectroscopic methods allowed us to determine the chlorophyll and carotenoid content in pine needles and to calculate the proportion of chlorophylls in the light-harvesting complex. The results revealed similarities in the dynamics of relative parameters of the photosynthetic pigment complex in annual needles of Siberian spruce and hybrid spruce with a predominance of Siberian spruce traits. Meanwhile, the research shows that during the summer and fall seasons, right up until the end of the growing season and as they prepare for winter dormancy, the spruce trees studied accumulate green pigments, with the hybrid form exhibiting this process more actively. This increases the protective role of carotenoids. The range of variation in the proportion of chlorophylls in the light-harvesting complex of Siberian spruce and hybrid spruce with a predominance of Siberian spruce traits from May to November averages 55–62 % per month, which is due to the adaptation of their photosynthetic apparatus to the ecological conditions of high latitudes.
The research covered age-related changes in the proportion of trees belonging to different Kraft classes in the structure of Norway spruce (Picea abies (L.) Karst.) forest plantations growing in the central Russian Plain under the site conditions of the wood sorrel spruce forest (Piceetum oxalidosum). The classification of an artificial stand into Kraft classes reflects the functional hierarchy of a single-species tree community and its temporal dynamics. The study relevance stems from the lack of similar research on artificial tree communities. The Kraft classes’ rank structure dynamics were observed in pure stands of European spruce over a 15–90-year age range. It has been found that the distribution of trees (up to 40 years old) by Kraft classes follows a normal distribution curve. Subsequently, the trend in the proportion of each class follows a wave-like pattern, shifting toward the higher ranks (Classes I and II). This is due to a decline at the ages of 30–35, 50, and 80. At the ages of 40, 60, and 90, the proportion of the IV–V class trees decreases sharply, while the proportion of the I and II class trees reaches its peak. It has also been found that the reduction rates for both height and the average periodic current increment in trunk volume are strictly differentiated according to Kraft classes. The intensive growth processes result in the high reduction rates observed in the I and II class trees compared to trees of other classes over the entire 90-year development of stands. This makes the I and II Kraft class trees promising throughout the entire course of artificial forest growing. They are particularly valuable in plantation forestry.
The forests of the north of European Russia have been well studied in many respects; however, the impact of wildfires on wood quality remains insufficiently understood. In response to pyrogenic stress, higher plants develop specific reactions similar to those triggered by various types of climatic stressors. The research aimed at examining the chemical composition, properties, and structural features of post-pyrogenic wood of northern taiga pine, as well as assessing the potential for using such wood in biorefining technologies. The Scots pine is a good target species for research as a typical representative of light coniferous forests, which are most susceptible to wildfires. A set of physicochemical methods was used to assess changes in the wood tissue main components. We observed thermal degradation of wood components (cellulose and lignin) due to pyrogenic stress (by 10–13 % in average), as well as a decrease in carbon and hydrogen content (by 16 and 17 %, respectively) in wood tissues in the most fire-damaged butt end of viable trees, along with a 16 % increase in oxygen content. Thermal exposure to the tissues of Scots pine trunks during a ground fire has been found to cause changes not only in the tissue composition but also in the tissue structure. A decrease, followed by a sharp increase in radial growth, was observed in damaged but viable trees several years after the fire. It has been shown that wood of trees damaged by a moderate-intensity ground fire, harvested at a height of 1.3 m and above, does not differ in its chemical composition and physicochemical properties from reference samples of wood that were not exposed to fire stress. Such wood can be used as raw material in the pulp and paper industry.
The research is aimed at improving the mechanical properties of plywood produced at a pressing temperature of 105 °C using phenol-formaldehyde resin modified with copper-containing additives or resorcin. The 5-layer waterproof plywood is made of 1.5 mm thick birch veneer and a phenol-formaldehyde resin binder. Copper acetate, resorcin, and copper resorcinate were used as modifiers (10 % aqueous solutions). We evaluated the strength of plywood under static bending and its strength when shearing along the adhesive layer after boiling. IR spectra of the binder and the plywood were obtained. The number of hydroxyl and hydroxymethyl groups decreases, and the hydrolytic stability of the binder increases due to the formation of coordinate bonds between the copper ion and the hydroxyl groups of the binder when the resin is modified with copper acetate and copper resorcinate. The number of hydroxyl groups remains virtually unchanged, but the number of –CH2 groups increases when the resin is modified with resorcin. Modification of the resin with copper resorcinate during low-temperature pressing resulted in a 52.2 % increase in shearing strength along the adhesive layer, with resorcin – a 70.0 % increase, and with copper acetate – a 78.8 % increase, compared to the values for samples made with phenol-formaldehyde resin. The static bending strength of plywood is the highest for the samples containing copper acetate and resorcin; it is higher than that of the samples produced at 120 °C. The use of copper acetate and resorcin for modification at 105 °C provides comparable mechanical properties of plywood. Since copper acetate is less expensive than resorcin, the use of a copper acetate-modified phenol-formaldehyde resin is recommended for industrial applications requiring low-temperature pressing. Lowering the pressing temperature will reduce the costs associated with the production of water-resistant plywood.
Mathematical models describing energy dissipation during oscillations of structures made of isotropic materials are approximate and empirical. The issue of accurately describing the energy dissipation of oscillations becomes even more acute when the oscillations occur in an anisotropic body containing inhomogeneities. This paper is devoted to a computational and experimental study of the dissipative properties of wood. In the majority of cases, these wood properties are determined by a single parameter: the decrement of mechanical oscillations. This is insufficient for accurately modeling the dynamic behavior of wood structures. It is known that the decrement of mechanical oscillations is not constant across the frequency range and depends on the orientation of the wood fibers relative to the direction of the driving force. These features have to be taken into account when developing appropriate mathematical models of wood structures. Therefore, development of new methods and determination of the energy dissipation fundamental patterns (both throughout the object volume and across various areas of the frequency range) appear to be of current relevance. This paper applies an original experimental method for assessing the elastic and dissipative properties of spruce and birch wood samples. Elastic moduli and mechanical oscillation decrements are determined for these samples. We studied the influence of anisotropy and the scale factor on these. A correlation has been found between the elastic and dissipative properties of wood. As the modulus of elasticity in the longitudinal direction of the sample increases, its dissipative properties decrease: the logarithmic decrement of the oscillations decreases. A hypothesis has been proposed concerning the relationship between the elastic and dissipative properties of wood. This means that an accurate description of the energy dissipation properties of a given type of wood should include not one damping constant, but nine (number of elastic constants for an orthotropic body). The validity of the results obtained was tested using a finite-element model of a wood sample. The computed ratios for wood are derived based on the orthotropic body model. Shear deformations are treated according to S.P. Timoshenko’s hypothesis. The results of the numerical studies are confirmed by their high correspondence with the data from field experiments.
The production of torrefied biomass is a strategically important area for diversifying the Russian forestry sector’s product range. Torrefied biomass is produced by the thermochemical biomass conversion in an oxygen-limited environment. High energy density, hydrophobicity, and resistance to biological degradation are among the advantages of torrefied biomass over raw biomass. The research is aimed at carrying out a comprehensive thermal analysis of the energy potential and thermal degradation parameters of torrefied biofuel produced from larch wood. The paper presents the characteristics of torrefied biomass, its elemental and compositional structure, and its metal oxide content. Pyrolysis gas chromatography-mass spectrometry determined the main organic compounds present in pyrolysis vapors at five different temperature settings (ranging from 200 to 600 °C with a 100 °C step) during processing. The temperature ranges for moisture loss and the combustion of fuel and coke residue were determined using thermogravimetry and differential thermogravimetry in an inert (argon) and air atmosphere at a heating rate of 10 °C/min. The release of high-calorie components and the greatest heat release occur in the 400–500 °C temperature range. It has been found that torrefaction produces a fuel with higher energy efficiency and improved fuel properties compared to solid wood. The results have practical significance for assessing the potential of torrefied biomass as a high-calorific-value solid biofuel for energy recovery at biofuel boiler plants in the Arctic region and provide a basis for further research in this area.
Mineral deposits are one of the main causes of unplanned shutdowns of Kamyr digesters. Currently, the use of inhibitors is one of the most effective and expensive methods for dealing with salt deposits. Therefore, the correct selection of an inhibitor and its dosage is essential for ensuring the smooth and cost-effective operation of the equipment. This requires determining the nature of mineral deposits and the concentration of the substances that cause their formation. We analyzed the mineral deposit samples from the continuously working Kamur digesters selected at two different production lines of an operating pulp and paper mill in the Russian Federation during forced shutdowns. The analysis results confirmed that calcium carbonate is the main component of the deposits. The predominant process leading to the formation of calcium carbonate deposits during the pulp cooking process is the interaction of calcium ions and carbonate ions. White liquor is an unavoidable source of carbonate ions. Calcium cations are introduced in large quantities with wood (up to 1.6 kg/t of dry matter), in smaller quantities with white liquor (due to the prolonged causticization), and in even smaller quantities with weak black liquor, which is used to maintain the digester’s water level. The paper presents the variation in sodium carbonate and calcium cation content in the raw materials used, their hourly intake considering the actual performance of digesters, and a consolidated calcium balance for the examined continuously working Kamur digesters at the production of hardwood and softwood sulfate pulp.
Due to sanctions, forestry enterprises have faced a number of challenges. The need to upgrade and repair logging equipment is among them. Leading international logging equipment manufacturers are constantly improving their equipment by implementing innovative technologies. The use of the Intelligent Boom Control (IBC) system for partially automated hydraulic manipulator control on forestry machines is one of the solutions. Therefore, it became necessary to evaluate the performance of logging machines with regard to new technical specifications (implementation of innovative hydraulic manipulator control systems), particularly in comparison with alternative logging machines. The research aims to analyze the performance of wheeled and tracked harvesters, considering the impact of modern hydraulic manipulator control systems. Objectives: 1. Creating a database and evaluate the actual performance metrics of harvesters based on the Sany SY245F excavator, the John Deere 1270G 6WD harvester, and the John Deere 1270G 8WD harvester equipped with the IBC system. 2. Developing a statistical model using regression analysis to describe the performance of harvesters under the studied natural and operating conditions. 3. Justifying the conclusions and drawing up recommendations on the use of wheeled and tracked harvesters. We have carried out a comparative assessment of the actual performance metrics of the studied harvesters. The analysis showed that the John Deere 1270G 8WD harvester with the IBC system had a higher daily output compared to the John Deere 1270G 6WD model (1.32 times higher) and the harvester based on the Sany SY245F crawler excavator (1.54 times higher). A regression model has been developed to predict changes in daily power generation under the studied natural and operating conditions. The assessment results are consistent with other studies and confirm the steady improvement in the efficiency of logging machines with the adoption of innovative technologies. However, it should be considered that the increased complexity of the manipulator control system leads to higher equipment costs and operating expenses.
Portable fillable supports for fastening timber rafting structures meet the requirements for devices that facilitate the implementation of a concept for the efficient and environmentally friendly transportation of timber along small and medium-sized rivers. Reliable operation of such supports is assumed when the vertical elements of the ground lugs are completely immersed into soil. In order to achieve this level of immersion, we need information about the effort required in this particular case. The research aims to ensure the reliable operation of portable fillable supports with ground lugs. We have used the theoretical and experimental research method. The results include analytical dependencies for the penetration forces of the ground lugs’ sections. These factors allowed us to identify the variables that determine the output values, as well as the nature and extent of the factors’ influence. Performing calculations based on these dependencies does not provide reliable results, since the ground stresses occurring beneath the lower edges and on the lateral surfaces of the ground lugs at the considered depths are unknown. We have found that the force required to drive the ground lug section into the soil depends on the same soil parameters as the number of blows required by the dynamic densimeter to drive its tip to the required depth and the specific penetration resistance measured by the penetrometer. Laboratory experiments, based on prior theoretical studies, confirmed that there is a clear relationship between the three parameters mentioned. In view of this relationship, experimental studies were carried out under field conditions. Approximate dependencies of the forces required to drive in the recommended sections of ground lugs were obtained based on the average number of blows from a dynamic densimeter and the specific penetration resistance. The values of the considered forces for a number of soil types are given, based on the maximum values recorded during experiments. The approximate dependencies and force values provided here will enable the most effective resolution of issues related to ensuring the penetration of ground lugs into soil and will contribute to the reliable operation of the studied supports.
Significant areas of the forest fund are occupied by mixed stands of different origins due to unseasonable tending and its low quality. In order to form coniferous stands with a slight admixture of deciduous trees, it is necessary to change their species composition and density. Carrying out thinning (release cuttings and forest clearings) requires significant costs and labor intensity. The most promising option for eliminating competition between deciduous trees in mixed stands is the herbicide injection into the trunks of undesirable deciduous trees. This technology combines high silvicultural and commercial efficiency with environmental safety. Guidelines for herbicide injection have not been updated for more than three decades and require significant adjustments. The research aimed at the regulation improvement of the forest stands composition and density by injecting herbicides and their mixtures into the trunks of deciduous trees while reducing the chemical and toxic load on forest ecosystems. Research objects were individual trees of grey alder (Alnus incana (L.) Moench) and aspen (Populus tremula L.) of vegetative origin in the pole stage in mixed plantations. The studies revealed the effective action of the Tornado herbicide preparation and its mixture with the Arbonal herbicide in low doses on grey alder and aspen with complete suppression of their vegetative capacity. The Arbonal alone acted somewhat slower than the Tornado, but showed high efficiency in the vegetation season following the treatment. The data obtained indicate the prospects of the recommended options for the herbicides application to suppress deciduous species common for the taiga zone. Costeffectiveness analysis of the proposed technology showed that the total financial costs are 16-21 times lower compared to the basic technology using mechanical means of eliminating undesirable vegetation.
Nondestructive testing is widely used for determining the technical quality, structure and internal condition of wood-based materials and wood in growing trees and elements of wood structures. The elastic rebound and impact pulse method belong to the most promising methods for evaluation of the physical and mechanical properties of construction materials. The paper aims at testing the application of these methods for indirect determination of wood density, static hardness and dynamic modulus of elasticity. The study used 67 non-defective specimens of Scots pine (Pinus sylvestris L.) wood with a normalized moisture content and dimensions of 50 & times;50 & times;50 mm3 with the use of applied portative devices such as Oniks 2.6 (Interpribor, Chelyabinsk, Russia) and Silver Schmidt (Proceq SA, Schwerzenbach, Switzerland). We assessed variability of the measured parameters and obtained regression models of the relationship between the parameters of elastic rebound/impact pulse and the mechanical and physical properties of wood. The highest variation coefficients were obtained for the impact pulse on the radial and tangential surfaces of the specimens as well as for the static hardness of the radial surface of the specimens. A moderate correlation was found between the density (R2 = 0.49) / dynamic modulus of elasticity along the fibers (R2 = 0.39) and the elastic rebound from the radial surface of the specimens. The low determination coefficients of the models for predicting the mechanical and physical properties of pine wood are due to the limited range of variation in the specimen density, as well as the local nature of the property evaluation with these methods. All this limits their application for the operational assessment of the properties of standing trees, lumber, and wooden construction elements. These methods are useful for estimating the wood quality or identifying areas affected by rot. The improved quality of models for predicting the mechanical and physical properties of wood by means of the impact pulse and elastic rebound methods may be achieved by using indenters with a larger contact area, as well as by expanding the range of variability in specimen properties for one or more wood species. This will be the focus of our further research.
The development of the forestry sector involves the use of heavy vehicles, which exert a significant impact on the road surface comparable to the impact of temporary traffic loads АК and НК of class 14. This requires the construction of appropriate engineering structures to support forest roads. The wooden bridges previously used in road construction do not meet modern requirements for load-bearing capacity, durability, and safety. The most appropriate designs for forest roads are those that combine glued laminated beams with a cast-in-place concrete deck. Composite bridges, including timber- reinforced concrete bridges, have a 50-year service life, which proves the high protective properties of the reinforced concrete slab and the durability of the glued laminated beams throughout their life cycle. However, in our country, they are not widely used in road construction due to the preference for prefabricated reinforced concrete. Meanwhile, international experience demonstrates the effectiveness of using glued laminated timber in road construction. The development and implementation of timber-concrete bridge superstructures are ongoing in Russia as well as in other countries. This research focuses on the design of composite bridge superstructures based on the interaction between a cast-in-place concrete deck and glued laminated beams, considering the impact of A14 and H14 road loads. The load calculations for the elements of the considered structure have been performed. The results show that the structure’s load-bearing capacity meets the requirements for logging bridges. The proposed bridge design can be used in both civil bridge construction and for forest roads, as a replacement for expensive and difficult-to- install reinforced concrete bridge superstructures.
The paper presents a comprehensive analysis of the effectiveness of sodium carboxymethylcellulose (Na-CMC) in the production of wet-strength paper. Na-CMC is a water-soluble anionic cellulose derivative produced by the esterification of cellulose with sodium chloroacetate in an alkaline solution. The resulting polymer is highly hydrophilic due to the presence of carboxyl (-COO-) and hydroxyl (-OH-) functional groups, which ensures the compound's high solubility in water and the formation of stable colloidal solutions. This study investigated the effect of Na-CMC on the paper pulp preparation process and the performance properties of the final product. The use of NA-CMC has been shown to have a comprehensive positive effect on the physical and mechanical, optical, and barrier properties of paper. NA-CMC reacts with paper pulp components such as wood and synthetic fibers, fillers, and binders, thereby enhancing the paper's adhesive properties and improving its overall structure. Na-CMC is effective in multi-component systems; it enhances the activity and performance of other chemical substances, such as moisture-resistant resins and pigments. The study revealed quantitative relationships that explain how paper quality depends on the amount of NA-CMC consumed. The results are applicable to the production of high-performance white papers, particularly in terms of reducing the environmental impact of wastewater discharges. The method can be adapted to existing production lines at pulp and paper mills.
