Felling Areas Research Articles

Влияние лесозаготовительной техники на динамику естественного возобновления леса после рубки хвойно-лиственного насаждения средней тайги

The work presents the results of experimental studies on assessment of preliminary and subsequent reforestation depending on the disturbance of the soil cover by logging equipment. The initial survey of the reforestation in the clearing showed the uneven settlement of the territory by woody plants in most parts and individual technological elements. According to morphological characteristics and a set of soil genetic horizons, the soil can be classified as typical Albic Retisols, which develop on loamy soil-forming rocks in well-drained landscapes. We found that the soil of the skidding trail is morphologically close to the original soil. The drag soils have undergone both morphological and chemical changes. The key difference is the change in the composition of the organic horizon following the arrival of a large amount of felling residues and changes in the composition of the ground cover plants. The morphometric parameters of the trees in the mixed stand and undergrowth are of high lability. The stand was dominated by small trees and small undergrowth. The stand and undergrowth are characterized as “healthy”. Relatively good uniformity of its settlement by woody plants was revealed only on portages in ruts with a predominant regeneration of small-leaved species. When the trails are heavily littered, there is no appearance of woody plants. There is no regeneration in the reclaimed felling areas in the first and second years. There is no resumption in sections with aligned tracks in the first and second year.

Особенности роста и структуры древесины сосны на вырубке и под пологом древостоя в условиях Республики Карелии

The intraspecific variability of the anatomical and hydraulic characteristics of xylem in the undergrowth in Scots pine (Pinus sylvestris L.) has been assessed during natural regeneration in the felling areas and under the canopy of a middle taiga blueberry pine forest in the conditions of the European North (Republic of Karelia). The influence of habitat conditions on the formation of structural elements of wood cells has been revealed. In felling areas under conditions of higher illumination, air and soil temperatures, the transition of pine undergrowth to the category of large with a height of more than 1.5 m occurs at the age of 6 years, whereas under the canopy of a mature stand the undergrowth reaches this category no earlier than 15 years. At the same time, in the 1st decade of growth under felling conditions, the growth of pine in diameter has been 4 times higher than that of pine under the canopy of a mature stand due to the formation of a larger number of rows of tracheids in the early and late zones. In addition, the pine undergrowth in the felling area has the highest potential hydraulic conductivity of the xylem, and, on the contrary, the lowest specific density of tracheids, the basic wood density and late wood content relative to the pine undergrowth under the canopy of the stand. The latter exhibited a significant decrease in the structural and functional characteristics of wood, with the exception of the thickness of the cell membranes of late tracheids. In the interanual dynamics, more stringent linear regression dependencies between the indices of early and late tracheids have been observed in pine undergrowth under the forest canopy. The results obtained indicate a greater correspondence of the environmental conditions in the felling area to the optimum for the growth and formation of wood of young pine trees relative to the conditions under the canopy of a mature blueberry pine forest. Inhibition of the growth activity of undergrowth under the canopy occurs due to high intraspecific competition from the dominant pine stand for light, moisture and soil nutrition.

Using Cut-to-Length (CTL) Harvester Production Data in Forest Inventories

Determining forest stand characteristics after thinning, in order to assess the quality of the work and update the inventory data of the thinned stand, is one of the few forest management tasks for which an efficient and accurate automation solution has not yet been developed. Currently, forest stand characteristics are determined by a certified inventory expert using manual instruments such as a range finder, digital or manual calliper, and a Bitterlich gauge. Manual measurements add a significant cost to forest management, and automating this process could increase the competitiveness of forest owners in the global timber market, helping reduce human error and providing more detailed information on the condition of stands and the distribution of trees of different dimensions in a stand.The aim of the study is to adapt a method developed in Sweden for the automated estimation of forest stand characteristics after thinning using the HprGallring software to Latvian conditions and to determine accuracy of the modelling-based prediction of stand characteristics.In the study, the height, number, diameter, and species of individual trees after thinning were determined using the sample plot method (according to methods applied in forest resources monitoring) and using photogrammetry as reference data for the study. In some felling areas, the diameters of all trees were measured before and after felling. The data obtained using different methods were compared with updated stand characteristics in the Forest resource database updated by certified inventory experts using plot measurement method.According to the results of the study, HprGallring can provide the data necessary for updating the forest inventory database after thinning, but the accuracy of the modelled projections, as compared to manual measurements, are not yet within the uncertainty range as required by the forest inventory regulations. The average tree height, as indicated in the State Forest Register, matches the HprGallring estimates within the regulatory uncertainty limits in 67% of Scots pine (Pinus sylvestris L.) stands, 65% of Norway spruce (Picea abies (L.) H.Karst.) stands, and 48% of Birch (Betula sp.) stands. The diameter of an average tree after thinning estimated by the HprGallring is larger than that according to the manual measurement. The average diameter estimated using HprGallring in pine stands matches the data in State Forest Register in 40% of the assessed areas, in 47% for spruce stands, and 35% of birch stands. The accuracy of the predictions needs to be improved to make HprGallring usable in forest inventory, but even now it provides valuable spatial information about the distribution of trees of different dimensions and species within stands, enabling more accurate planning of management methods and spatial redesigning of the forest compartments.

Soil disturbance caused by timber harvesting in a natural forest, West Sumatera Indonesia

Logging operations in natural forests generally use bulldozers. Bulldozers skid logs from the stump site to the landing site. The bulldozer maneuvers in the felling area cause skid trails and soil compaction. Soil compaction is one of the negative impacts of logging operations. The research aim is to analyze the level of soil compaction in various bulldozer skidding intensities after logging operations. The research occurred at a natural forest area in Siberut West Sumatera, Indonesia. The results of the study showed that there was a relationship between skidding intensity and the level of soil bulk density. The more a bulldozer moves at the same skid trail, the higher the soil bulk density. The range of soil bulk density is from 0.82 g cm−3 to 1.31 g cm−3. The bulk density increases markedly after the bulldozer’s first, second, and third passes. After the fourth pass, the bulk density is relatively constant. The porosity of the soil decreases with the increase of the bulk density. On skid trails where the soil is very compact, seeds that fall on skid trails will have difficulty growing well. Requires planting on primary skid trails. Soil damage in the form of soil compaction by bulldozers needs serious attention in the Reduce Impact Logging technique.

Использование многофакторного анализа данных в оценке состояния предварительного и последующего возобновления сосняков после выборочных рубок

A research of qualitative and quantitative characteristics of regeneration after the first selective felling with an intensity of 20 to 50 % in pine forests of the northern part of the Krasnoyarsk forest-steppe has been carried out. Some of the plantations were covered by a ground fire 5 to 10 years before the felling. The aim of this research is a generalized analysis of the regeneration state in view of the forest type, the density of forest stand and exposure to fire before felling, as well as the disturbance of soil cover, the state of forest live cover and the microclimatic conditions in the felling areas. The methods of principal component analysis as well as correlation analysis and variance analysis for individual characteristics have been used. The advantages of multivariate data analysis using the method of principal component analysis for obtaining more information on the contribution and combined effects of various environmental factors on pine regeneration in felling areas are shown. The share of explained variance of the considered factors has equaled 87 %. The most significant factors for pine regeneration have turned out to be the type of forest (felling area) and exposure to fire. The second place in terms of importance has been taken by the density of forest stand before felling and the intensity of felling. Of the factors mediated by them, illumination intensity and soil moisture have turned out to be important. Based on the characteristics of the 4 main components, 2 options for combining the main factors for better regeneration of plantations have been established: 1) the large initial density of mature forest stands, as well as the moderate development of mosses and grasses in forest live cover make it possible to choose any felling intensity (within the studied limits), preferably in combination with preliminary burning of a part of the litter (or partial soil mineralization) 5 years before moderately-high or high intensity felling, 2) in case of lower initial density of the forest stand in forest types with significant development of forest live cover, preliminary burning of part of the litter or mineralization of the soil and the choice of a lower intensity of the the first felling (up to 20 %) are required. Analysis of the variability of linear increases in height-and-age groups of undergrowth confirmed the conclusions drawn from the analysis of the quantity and quality of regeneration, showed differences in the response of different groups of undergrowth to changes in microclimatic conditions in felling areas. The similarity of the northern forest-steppe with the southern taiga in terms of pine regeneration conditions has been noted. The results of the study can be used to clarify the requirements for felling and achieve better regeneration of pine forests.

Современная практика искусственного лесовосстановления в таежной зоне европейской части России

The article presents an analysis of technologies and techniques for creating forest plantations used in the Arkhangelsk and Kirov Regions, as well as the Komi Republic, based on the materials of reforestation projects for 2020. The territories under consideration belong to 6 forest areas: the Northern taiga, the Dvina-Vychegda taiga, the Southern taiga, the coniferous- broad-leafed (mixed) forests, the Western Ural taiga and the area of tundra forests and sparse taiga. The database created on the basis of the data from reforestation projects includes 13 indicators: categories of reforestation areas, forest vegetation conditions (terrain, soil type, soil moisture, group of forest types, degree of turfing), as well as tillage methods, mechanisms and aggregates used for tillage and planting seedlings and saplings and planting stock type. It has been established that in the studied regions, reforestation is more often carried out in fresh (1–2-year-old) felling areas in place of spruce plantations of blueberry forests, with podzolic drained and poorly drained soils. When cultivating soil for forest plantations, excavators are widely used (44 %), replacing traditional tractors with ploughs (usually PL-1). In most areas, furrow tillage is prevalent (52 %), but strips, mounds and patch scarification are also common (40 %). Containerized spruce and pine planting stocks have become more widely used (more than 50 % of the area), though seedlings are extremely rare (7 % in the Kirov Region). The data obtained allow us to asses the real picture of the use of reforestation technologies in the taiga zone on the example of three subjects of the Russian Federation, which will help the subjects of the Russian Federation in making management decisions for exercising their powers in the reforestation field.

The impact of extra long-term storage of logging residues on fuel quality in Estonian conditions – a case study

Abstract The reduction of greenhouse gas (GHG) emissions demands a significant increase in the use of wood as a renewable energy source. However, environmental restrictions determine limits on the further growth of harvesting volume. Therefore, a viable solution to enhance the share of energy wood in Estonia’s energy balance involves focusing on less exploited assortments of raw material and implementing precise logistics planning. In recent years, mild winters have posed challenges to the extraction of residues and local transport of wood fuels, taking place on soft and unfrozen soils. In such conditions, ensuring a reliable supply of wood fuels becomes rather complicated. When piles of logging residues on unfrozen soils are inaccessible, there is a need to process older piles. The quality of wood chips from such piles is lower compared to the norm. To investigate the impact of extra long-term storage of residues in piles, a study was conducted at the Järvselja Training and Experimental Forest Centre. In 2010, sample piles were created in birch and spruce final felling areas. Over an eight-year period, samples were regularly taken from the piles to analyse the properties of woody biomass during storage. The study results indicate that the quality of fuel from covered piles changes slowly during the first two years of storage. Subsequently, the degradation speed equalizes in both uncovered and covered piles. Despite extensive degradation and loss of dry matter during long-term storage (approximately 29% for Norway spruce and 55% for silver birch after eight years), the quality of dry fuels still meets standard requirements and remains acceptable for boiler houses.

Влияние экологических факторов на генетический полиморфизм в природных популяциях Fragaria vesca

Genetic polymorphism of natural cenopopulations of wild strawberry (Fragaria vesca) from the Republic of Mari El was measured by randomly amplified polymorphic DNA (RAPD). The method of molecular genome marking based on RAPD-PCR makes it possible to determine the genetic status of populations and establish interpopulation relationships. The cenopopulations that we selected for the analysis were confined to different stages of the forest phytocenosis succession: the climatic phytocenosis and the area of the forest felling. These F. vesca cenopopulations differed in the ratio of sexual and vegetative reproduction during the maintenance of the cenopopulation size. In a felling area in conditions of greater illumination the intensity of sexual and vegetative reproduction increases. However, specimens of seed origin were not found in the felling area, since in conditions of high competition with ruderal and meadow plants, slowly developing strawberry seedlings died. The germination of seeds and plants of seed origin was noted under conditions of climatic phytocenosis. For the cenopopulation confined to the climax forest, Shannon’s diversity index and Nei’s genetic distance were 0.5179 and 0.3613 respectively. In a felling area vegetative reproduction processes predominate, so Shannon’s diversity index and Nei’s genetic distance were lower, 0.4573 and 0.3132 respectively. In a felling area revealed the loss of certain genetic clusters present in the climax forest. This indicates the loss of a strawberry genetic diversity in the transition to vegetative reproduction due to anthropogenic impact. Our data confirm the idea that climax communities with their more stable conditions can act as regenerative niches of the species.

Carbon Dioxide Emission from the Soil Surface of the 10-Year Felled Area of the Pine Forest in the European North-East of Russia

Experimental data on soil respiration are need for estimating role of industrial logging on carbon cycle of forest ecosystems. Investigations were carried out during snowless periods 2019–2021 years on felled area of pine forest 10 years after clear cutting (Komi Republic, Russia). The soil type is a Gleyic Folic Albic Podzol (Arenic). Emission CO2 was measured by LI COR 8100. The characteristic of weather conditions and soil temperature dynamic at 10 cm depth were given. The weather conditions were strongly influenced on soil respiration rate. More intensive CO2 flux from soil surface was observed in warm summer with insufficient precipitation. The mean month CO2 emission was less by 1.3–1.9 times in apiaries, parts of felled area with low soil cover damages, comparing to skidding tracks where logged trees were extracted. The significant positive correlation (R2 = 0.12–0.86) was detected between soil temperature at 10 cm depth and soil respiration investigated technological elements. A reliable interrelation between CO2 flux and moisture of forest floor was observed in skidding tracks in a year with abundant precipitation while in a dryer year it wasn’t. It is differ from apiaries where found reverse dependencies. Apiaries emitted in atmosphere 303–379 g С m–2 with soil respiration during snowless period, skidding tracks – 419–573 g С m–2 which is 60–75 tons of CO2 in terms of the area of the entire felled area (5 ha). The growing season formed most part (86–90%) of carbon efflux from May to October and input of summertime was 56–65%. The data obtained will serve to determine the role of timber harvesting in the carbon cycle of taiga forests.

Age Structure of Polygonatum Multiflorum (L.) All. Cenopulations in the Precarpatian Region

For population studies, the determination of age status is more important than the determination of calendar age. The research conducted in the biotopes of Precarpathian region indicates that according to the age structure the populations of Polygonatum multiflorum (L.) All. belong to the normal type. Self-maintenance of coenopopulations occurs in a combined way as a result of generative and vegetative reproduction, the intensity of which depends on local edaphic and coenotic conditions. The spectra of their age states and reproductive potential are determined by a set of biotope conditions and have species specificity. The nature of the spectrum of age conditions and the value of the recovery index are the most informative indicative markers. Left-sided spectra in combination with high recovery indices indicate the presence of favorable conditions and a high reproduction potential of cenopopulations. The biotopes of felling areas are the most favorable for the realization of the reproduction potential of most cenopopulations of the studied species; the least favorable are the mainline biotopes.

Decade-long soil changes after the clear felling in forests of the North-Western Caucasus mountains

<p class="71">Clear-fell harvesting significantly alters ecosystem attributes at multiple spatial scales. The results of a study of the dynamics of changes in Rendzik Leptosol and Greyic Phaeozem Vertic forests in the middle mountains of the North-Western Caucasus after clear-cutting in 2010-2020 are presented. Immediately after clearing the forest, areas with varying degrees of disturbance of the soil and vegetation cover were identified in the clearings, from maximum disturbance in the central part of the clearing to slight disturbance on their periphery at different elevations of 540-1600 meters above sea level (masl). The soil covering is represented with Rendzik Leptosol and Greyic Phaeozem Vertic. Among used metrics were temperature, humidity, texture density, penetration resistance, structural and aggregate composition, and other soil parameters. On felling areas, increased temperatures and decreased soil humidity were recorded. The temperature of Rendzik Leptosol at a depth of 10-30 cm changes within the range of 1-15°С in the period 2018-2020. The terrain elevation affects the soil due to the temperature gradient significantly. Rendzik Leptosol is much colder at an elevation 1640 meters above sea level than at 1200 meters above sea level. The temperature of Phaeozem (540 meters above sea level) reaches 20°С during the summer months at a depth of 10 cm. Soils in felling have differences in structural and aggregate composition and water resistance of aggregates. The study results can be used in assessing damage to ecosystems after deforestation and developing methods for accelerating the restoration of soil properties after deforestation. The result of the study can be applied to assess the change in the state of ecosystems after forest degradation. The most informative diagnostic indicators for assessing the state of ecosystems after forest degradation are discussed in the article.</p>

Seasonal Changes in the Sorption Activity of Water-soluble Polysaccharides in Scotch Pine Cones (<i>Pinus sylvestris</i> L.)

Introduction. Currently, there is much tension around the issue of increasing the efficiency of use of forest resources. One of these resources are scotch pine cones, which remain at the felling areas. Polysaccharides of scotch pine cones have a significant sorption activity; however, it remains unclear does the month, when raw materials were collected, affect the sorption activity.Aim. The research of the content, sorption activity and molecular weight of water-soluble polysaccharides of scotch pine cones in different seasons of the year.Materials and methods. Water-soluble polysaccharide complex (WSPC) of scotch pine cones was obtained with a method based on the well-known scheme for the carbohydrates separation according to Bailey et al. WSPC was obtained from the samples of scotch pine cones collected from July till March. Determination of the content of scots pine cones WSPC was spectrophotometrically carried out, with the modified Draywood anthrone-sulfurous method. The sorption activity of polysaccharides was determined by the methylene blue. The molecular weight of polysaccharides was identified by the viscosimetric method.Results and discussion. The content of WSPC in scotch pine cones from July till March was identified. The highest yield of WSPC was registered in winter (3.24 ± 0.31 %), and the lowest in summer (0.46 ± 0.01 %). The sorption activity of scotch pine cones WSPC in terms of methylene blue from July till March was researched in vitro. It was found that WSPC has the highest sorption activity in October (230.69 ± 4.18 %) and November (243.30 ± 9.43 %). The WSPC sorption activity is above the activity of standard medications: absorbent carbon (230.9 ± 2.34 mg/g) and colloidal silicon dioxide ("Рolisorb MP") (211.5 ± 1.87 mg/g). The average molecular weight of scotch pine cones WSPC from July till March was determined. The average molecular weight of WSPC is in the range from 6 872,27 to 21 598,06. The dependence of the scotch pine cones WSPC sorption activity on the molecular weight was registered.Conclusion. The water-soluble polysaccharide complex of scotch pine cones, obtained at different seasons, has different sorption activity, which depends on a polysaccharide molecular weight. The highest content and sorption activity of scotch pine cones WSPC matches with the period of wood production, which stipulates a practical use of cones and directions for future research.

CHARACTERISTICS OF NATURAL OAK FORESTS AND NATURAL RENEWAL IN THE CONDITIONS OF SE «TULCHINSKE LMG»

It was established that the territory of the farm belongs to the following forest categories: forests of nature protection, scientific, historical and cultural purposes – 1322.4 ha; recreational and health forests – 718 ha; protective forests – 3837.9 ha; exploitation forests – 17,407.7 ha. As a result of conducted field research within the forest fund of the enterprise, it was established that plantations over 100 years old are characterized by the predominance of common oak with the participation of common ash in the composition. It has been established that within the boundaries of the forest and hunting economy, among the areas where it is planned to carry out felling for the main use, plantations that are classified as exploitation forests predominate. The total area of such plantations is 152.3 hectares, and the number of plots is 47. It was determined that the number of areas of oak forests over 100 years old that will be felled in the next audit period during felling of the main use in protective and recreational forests is 6 and 5, respectively. According to the above results, out of the total number of main-use felling plots – 58 forest stands of fresh hornbeam forest – 55. Only 3 plots are located in wet hornbeam forest. Accordingly, the largest areas of main felling areas – 179.9 hectares – are concentrated in fresh hornbeam forest. It was investigated that the territory of the farm belongs to high credit standings (credit rating 1-1a-2). The largest number and area of plots is characterized by the 1st rating (42 plots with an area of 114.0 ha). There are almost 2-3 times less plots of 2 rating (15 plots, with an area of 68.3 hectares). In the process of conducting research, we discovered a significant number of stands with possible natural regeneration. The total share of such stands in relation to the total number is 3.75 %, and from the total area – 4.88 %. Accordingly, the maximum area of a separate plot is 10.5 hectares, and the minimum is 2.5 hectares. According to the conducted research, out of 80 plots, 37 lack any natural regeneration in sufficient quantity.It was determined that the average age of natural renewal is 11 years. The height is 3.6 m, the density of natural regeneration is 7.7 thousand pieces/ha, the average age is 23.6 years.

Changes in Soil and Vegetation with Different Number of Passes of Wheeled Forestry Equipment (Middle Taiga, Komi Republic)

—Changes in podzolic soils (Albic Retisols) and vegetation after felling blueberry spruce forest in the middle taiga of the Komi Republic are discussed. Changes in the morphological and physicochemical properties of soils after three and ten passes of the forwarder, as well as after ten passes with subsequent leveling of the ruts are characterized. It is shown that the number of forwarder passes is the decisive factor in soil changes. At the site with three passes, the formation of ruts with a depth of 11 ± 3 cm is observed, while at the site with ten passes, the depth of the ruts can reach 66 cm with an average value of 27 ± 4 cm. Leveling of forwarding trails to remove the ruts leads to the greatest transformation of the natural composition of the upper soil horizons over a larger area. A significant increase in the bulk density of the upper mineral horizon of the soil of the trail takes place after three passes. After ten passes, the bulk density of the upper mineral horizon decreases because of its mixing and loosening by wheeled vehicles. At the same time, an increase in the bulk density of the underlying middle-profile mineral horizon retaining its natural composition is observed. The upper horizons of the soil of the trail leveled with the use of an excavator are characterized by a significant increase in the bulk density compared to the initial soil. It was found that the regrowth of the main tree species in the first year after felling is extremely uneven. In the case of a strong clutter on the trails, there is no regrowth, which requires additional measures to improve tree growing these technological elements of felling area. On the leveled areas of the trails, the absence of regrowth in the first year after felling was observed. However, it can be assumed that in the future these areas will be fairly quickly populated with regrowth of tree species.

Productivity and Fuel Consumption in Skidding Roundwood on Flat Terrains by a Zetor Farm Tractor in Group Shelterwood Cutting of Mixed Oak Forests

Productivity assessment studies are essential in forest operations, mainly because their results enable operational planning and rate setting, the development of equitable payment systems, the assessment of environmental performance, the assessment of improvements brought by technology development, and the optimization of larger forest-based systems. This study examines productive performance and fuel consumption in farm-tractor based skidding operations implemented in flat terrain oak harvesting by developing detailed statistics and predictive models on skidding performance. Two felling areas were selected to monitor the operations, and detailed statistics and predictive models were developed at two resolutions by an end-to-end assessment. Based on 56 observed work cycles, and for average values of the number of logs, payload volume, winching distance and extraction distance of 4.96, 1.81 m3, 14.43 m, 177.3 m, respectively, the net efficiency and productivity rates of skidding operations were estimated at 0.125 h/m3 and 8.03 m3/h, respectively. At the resolution of piece-by-piece winching, winching time depended only on the winching distance. At the resolution of overall skidding operations, the skidding time depended on the number of logs in a payload and average winching and extraction distances. The same predictors were relevant in explaining the fuel consumption in skidding operations, which accounted for 3.72 L/h or 0.46 L/m3, while there was a variation in fuel consumption induced by the type of operation. Both efficiency and productivity were found to be highly sensitive to the operational distances, as the main factors affecting them. Nevertheless, significant improvements in efficiency, productivity, and fuel consumption may be achieved when dealing with fewer logs per turn and higher volumes per piece, since the models indicated no effects brought in fuel and time consumption by the log size, and the technical limits of the used winched reached 8.5 tons.

Delineation and description of soil horizons using ground-penetrating radar for soils under boreal forest in Central Karelia (Russia)

This article focused on studying the landscape-scale spatial variation of boreal forest soils in data-scarce areas using ground-penetrating radar (GPR). An important goal of the research was to discuss correlations between attributes of the soil profile under boreal forest and GPR data. We detected the soil horizons of Entic Podzols and determined their attributes based on a GPR transect with a 400 MHz antenna unit. GPR cross-section showed the soil thickness variation over the transect being 18.8 cm to 44.7 cm. The mean depth for the soil's lower boundary from sounding was 23.1 cm versus the probing of 24 cm. The fieldwork research has revealed GPR patterns for different ecological settings: typical forest, paludified forest, and felling area. We investigated the GPR applicability for delineating organic layers in soils and considered quantifying soil organic carbon content (SOC) relying on GPR attributes. To achieve this purpose, we have surveyed Albic Podzols with a 1,700 MHz antenna unit considering vegetation cover. The resolution of GPR was ±1 cm, which made to determine relatively thin horizons. GPR reflected signal amplitudes demonstrated sensitivity to SOC variations in the organic layers. The obtained relationship between SOC and GPR attributes indicates the possibility of determining the carbon storage variations in situ. However, the problem is to substantiate the mechanism of the SOC influence on the signature of the GPR traces. The findings prove that GPR is a tool for predicting the state and scope of the transformation of sandy forest soils. GPR cross-sections can be the basement for a novel approach for forest soil mapping on a landscape scale. In prospect, digital soil mapping can include a sequence of methods: remote sensing – GPR – manual probing. Admittedly, alignments between soil characteristics and GPR attributes are needed to identify the capabilities and limitations of the method.

Dynamic impact of wheeled skidders on forest soil in felling areas

Soil compaction from wheeled vehicles poses a huge challenge for the forest ecosystems. Modeling the impact of skidding machines on the soil could help solve the problem. The present work seeks to construct a mathematical model of soil compaction under the cyclic dynamic loading of wheeled skidding machines using the vibration analysis method for elastic dynamic systems. The study found that 4 × 4, 6 × 6 and 8 × 8 forestry vehicles have similar amplitude-frequency characteristics regardless of driving speed and load. The analysis of soil compaction from dynamic loading revealed that loaded and unloaded skidder passes cause the least damage (21–31%) to forest roads compared to skid trails. As regards skid trails, 4 × 4 and 6 × 6 tractors were found to compact the soil by 23–50% in the first four passes. The subsequent passes will lead to 60–66% of compaction. Finally, 8 × 8 trucks cause 98–99% of soil compaction. The difference between the experimental and theoretical values of soil density does not exceed 12%. The unevenness coefficient of the soil compaction and the confidence interval fall within the acceptable range. The mathematical models are in good agreement with the experimental data and can be used to calculate the operating modes of wheeled forestry equipment.

АНАЛИЗ КОНСТРУКЦИЙ И РЕЖИМОВ РАБОТЫ ДИСКОВЫХ РУБИТЕЛЬНЫХ МАШИН

Recently, timber harvesting has increased significantly. As a result of which the volume of felling residues in felling areas and waste in the woodworking industry has also increased. The rapid growth of waste necessitated the processing of large volumes of wood pulp and the creation of new high-performance machines capable of shredding it into chips. Chips are usually used as fuel pellets, as well as for the manufacture of chipboard panels. The operation of chipping wood can be carried out during harvesting or a few days after the trees have been cut down. This article has examined the various types of disc chippers. They were distributed according to distinctive design features. The distinctive features of machines in terms of productivity, power, rotation speed, the number of cutting knives, dimensions and weight of the machine itself, as well as the type and size of the processed wood, the ways of feeding it into the machine and removing chips from it are described. It is shown that disk chippers are widely used in the manufacture of technological chips in the pulp and paper, woodworking, forestry and other industries. The review is based on the study of domestic and foreign material, analysis of the operation of existing machines of various types, as well as on numerous experimental and theoretical studies carried out by various authors. Our review of disc chippers will contribute to a more rational use and modernization of the existing chippers and the creation of new cost-effective equipment for chipping wood into chips, which meets the current level of development of technology and production

Algorithms for calculating schemes of transport routes in a felling area

The study considers the problem of constructing routes for the export of timber. The task reduced to building a rooted tree. The study presents two approximate algorithms for solving the problem of covering polygons with rooted trees. To simplify the task, the polygon is covered with a square grid. A greedy algorithm is described that should give an approximate solution. The article also describes the branch and bound method with a reduced number of iteration options. We have reduced the number of iterations by using a special way of building links.

SPATIAL-TEMPORAL ASPECTS OF THE HYDROLOGICAL REGIME IN CATCHMENTS AFTER CLEARCUTTING

This article discusses the spatial and temporal aspects of hydrological processes in catchments after logging for different landscape conditions of Central Siberia. For this discussion, the results of our own research in the Sayan Mountains, the Yenisei Ridge, the Angara River basin, the Khamar-Daban ridge and literature data were involved. It analyzed the impact of felling area to change the river flow and development of the erosion at the catchment area. The annual runoff, its seasonal structure and sediment discharge change significantly in dependence on as area of clearcutting so area of river basin. The authors analyzed the results of observations of the restoration of the water balance in the experimental logging sites of small catchments and the dynamics of runoff in large rivers. Research has shown the vegetation cover structure changes continuously on logged sites during post-logging forest regeneration and future post-cutting hydrologic regime scenarios are determined both by further climatic changes and by vegetation succession trajectories. The role of the time as a factor to decrease erosion at watershed after logging depends of many regional and local features of landscapes and of initial soil mineralized by logging. For the forests of Khamar-Daban mountainous in Baikal basin the model of soil erosion at watersheds after logging was developed.