Том 20, № 3 (2023)
Articles
Biodegradable Composites with Polyvinyl Chloride Polymer Phase and Lignocellulose Fillers
Аннотация
The way to solve the problem of waste disposal from the timber industry and agrarian complexes, as well as plastic waste from the production and consumption of marketable products is to develop compositions of new composite materials and to improve technologies for their processing. Therefore, biodegradable composites with polymer phases of synthetic and natural polymers and various lignocellulosic fillers are of great interest. In the present work, the issues of biodegradation of composites with polymeric phases of primary and recycled polyvinyl chloride (PVC) were considered. Wood flour, beech sawdust, oat husks, biomass of fallen leaves, hay from natural haylands were used as fillers. Samples of composites were obtained by rolling and hot pressing. The degree of the resulting composites biodegradation was determined by the amount of weight loss after seasoning in active (nondormant) soil. The maximum exposure time of the samples in the soil was 120 days. As a result of the study, it was The authors found that the use of a plasticizer (dibutyl phthalate) allows increasing the mass loss rate of unfilled polyvinyl chloride during its 120-day seasoning in the soil by more than three times. Introduction of lignocellulose fillers into the composition of PVC significantly increased its degree of decomposition in the soil. The highest degree of biodegradation in activated soil was demonstrated by samples of composites with fillers of non-wood origin. For samples of composites with a polymer phase of primary PVC and oat husk, the weight loss after seasoning in activated soil was 10.1 wt. %, with meadow grass hay – 14.5 wt. %; for a sample with a polymer phase of recycled PVC (waste from phased-out ceiling boards) – 24.6 wt. %. For the fillers used in the work, the contents of lignin, cellulose, hemicelluloses, and minerals were determined. Using the method of multivariate regression analysis, regularities were established for the influence of the component composition of lignocellulose filler on the degree of biodegradation of the component in the soil. It is shown that the content of hemicelluloses in the filler had the greatest effect on the biodegradation of composites with a polymer phase of primary PVC. At the same time, an increase in the content of lignin and cellulose in the filler resulted in a decrease in the degree of composite biodegradation. The influence of mineral substances in the composition of the composite on its degree of biodegradation was not revealed. For samples with a polymer phase of recycled PVC, the main factor determining the degree of biodegradation in the soil was the content of hemicelluloses in the filler. No statistically significant effect of lignin and cellulose content was found.
1-14
Geotechnical substantiation of the operability of skidding drags and technological corridors on the slopes of thawing soils during the operation of forest machines with wheeled and semi-tracked propulsion
Аннотация
In the Russian Federation a significant part of the forest fund is located on permafrost. Many regions of Russia have large reserves of ripe and over-mature operational forests, and a significant part of these reserves is located in hard-to-reach places. Currently, the overwhelming volume of wood harvesting in Russia is performed by using modern machine complexes mainly including wheeled forestry machines of various configuration and purposes. At the same time the problem of the negative impact of wheeled forest machines and skidding systems based on them becomes even more acute since the ecosystems of mountain forests and forests on the slopes of hills are among the most vulnerable ones due to water and wind erosion. To reduce the negative impact of forest machinery propellers on soils semi-tracked vehicles are often used because of their significantly larger contact surface and a greater traction force in difficult conditions. The article shows that each slope as a unique geotechnical object that features its own geometric parameters and actual data including the capacity of the thawing soil bearing surface and permafrost zone edge should be classified taking into account the variety of skidder movement parameters, the technological properties of soils and the criterion of the extraction road operability. The development of such a classification should be based on up-to-date hydrogeological and geomechanical data on the state of the soils composing the slope area. The presented studies expand the understanding of the technological requirements for ensuring the extraction road operability on the slopes with thawing soils, thus contributing to more efficient use of logging technology in difficult seasonal and climatic conditions.
15-31
Optimal planning of a forest road network: from methods to solutions
Аннотация
The article presents the methods of optimal planning of forest road networks, which allow automating the planning processes of road transport infrastructure development for logging enterprises by taking into account the characteristics of forest road construction under present day conditions. The methodology is described and the the optimal density of forest roads has been found for the natural and industrial conditions of the North-Western Federal District. The authors propose decision-making models for choosing the forest roadbed and road topping designs. They also propose a model for evaluating alternative sections of forest roads, a model for selecting key points of the forest resource base and a final optimization model for making decisions on logging roads network design. The developed computer system allows the user to display information in a user-friendly and layer-by-layer form on the required road construction volumes and to obtain a wide list of indicators characterizing both individual sections and all roads as a whole. This system application demonstrated a reasonably good compliance with actual conditions and the ability to adapt to the user's tasks. The proposed solutions make it possible to achieve a significant economic effect for a planning horizon of 5—10 years or more.
32-47
Longevity of common pine needle (Pinus sylvestris L.)
Аннотация
Identification of the standard period of tree needle retention characteristic for a particular region is necessary to use the pine needle longevity as criteria for assessing coniferous woody plants state and productive growing conditions. Information about the pine needle longevity and various affecting factors is contradictory. The aim of the work was to estimate the pine needle longevity in various growing conditions. The studies were conducted in lichen, cranberry, blueberry, shrub-sphagnum drained pine forests and in sedge-sphagnum, pitch pine forests in the north and south taiga forest areas. The authors assessed 15 model trees selected proportionally by the thickness steps on 3 model branches in the middle part of the crown. The influence of forest type, age, stand density, drainage, raised water table, and recreation on pine needle longevity was considered. The stability of the average pine needle longevity in various forest types and forest-growing zones determined the optimal value of this indicator for a specific age group. In the young plantation the average needle longevity was 3.2 years; in the middle-aged and maturing stand it was 4.3—4.8 years. In case of a pitch pine tree or in pines in a depressed state resulting from anthropogenic flooding, the needle longevity decreased. The needle longevity increased in pines growing near drainage ditches but in pines growing in the interditch space it remained at the level characteristic for a natural forest. The effect of recreation on the duration of needles retention in the crown depended on the stage of digression. A decrease the needle longevity was noted at the III stage of digression. Needle longevity is conditioned by the tree ability to withstand a stressful factor. Consequently, longer needle longevity is associated with the mechanism of tree adaptation to external influences. The needles mortality in trees of older ages is due to their inability to adapt to the negative environmental effects.
48-59
The use of unmanned aerial vehicles to assess young trees formation in clean cutting areas
Аннотация
The article presents information on the use of an unmanned aerial vehicle to assess young trees state in seed blocks. An unmanned aircraft complex of an airplane type was used to obtain aerial photographs. Aerial photography was carried out in the visible range (RGB) and the visible and near infrared ranges (RED, REG, GRE, NIR). The spatial resolution in the visible range was less than 5 cm, in the visible and near infrared – 19 cm. The use of an unmanned aerial vehicle and multispectral images allowed assessing the condition and structure of young trees at the cutting of 8 years ago with the created forest crops of scots pine. On the orthophotoplane, rows of forest crops and admixtures of coniferous and deciduous species of natural origin are clearly visible both in the rows and in the inter-row spacing. The compositions of the young trees formed on the experimental plots and that of the stands in the seed blocks were determined. The Scotch pine was deciphered by the rounded shape and relatively uniform, fine-grained texture of the crown projection, as well as the shadow in the form of a crescent or half-ring, which is due to the spherical or paraboloid shape of the crown with a rounded top. Spruce was deciphered by a star-shaped crown projection pattern and a shadow in the form of a semicircle and a triangle, which is due to the cone-shaped shape of the crown. Multispectral image analysis allowed identifying the European spruce by its greenish-blue color. Deciduous trees in multispectral images had yellow-green, yellow-orange, reddish shade of crown projections. The image of the warty birch was characterized by the rounded shape of the crown projection with an uneven edge, medium-grained or lumpy texture due to the distribution of shaded and illuminated areas in the crown of the tree. Due to the high spatial resolution of images from an unmanned aerial vehicle on inclined projections of trees in the visible range, the birch was noticeable by the white color of the trunk. Using special programs, the number of trees by species was determined, and even so the biometric characteristics of individual plants. It is advisable to use the obtained materials in the development of regulatory documents and planning of forestry work.
60-75
Investigation and justification of the layout and parameters of the hydraulic drive of the lifting mechanism of the forest manipulator
Аннотация
The paper describes ways of reducing the dynamic loads on a forest manipulator construction according to the layout of the hydraulic cylinders of the boom lifting mechanism. A mathematical model of the manipulator boom lifting process has been generated. The parameters of the boom lifting hydraulic drive have been optimized. It is established that the optimization of the hydraulic cylinders layout for lifting the forest manipulator boom by taking into account the inertia forces and the hydraulic drive flexibility will reduce working fluid pressure surge during transient modes of forest freight lifting. A new design and technological scheme of the boom lifting mechanism of the manipulator has been developed to provide automatic optimal positioning of the hydraulic boom lifting cylinder and working fluid vibration damping. It is found that with a decrease in the nominal feed the angular velocity tends to stabilize and peak pressures increase from 16 MPa to 40 MPa. It has been verified that with twofold increases of the flexibility coefficient of elastic hydraulic drive elements and of the leakage factor the pressure of the working fluid increases and decreases by 2 times respectively. The optimal value of the parameter b1, that is the point of the hydraulic cylinder attachment to the boom should be equal to 0.6 m. Dynamic loads are reduced by 41 % due to optimizing the layout of the hydraulic boom lifting cylinder and increasing the flexibility coefficient of the elastic elements of the hydraulic drive. However, the time of damped pressure fluctuations during transients is increased by 32 %. Therefore, the manipulator repair downtime due to hydraulic equipment breakdowns will be reduced to compensate for a slight increase in the time of transient modes.
76-93
Analysis of forest legislation violations using the Republic of Karelia as an example
Аннотация
The paper presents an analysis of forest legislation violations in the Republic of Karelia. The purpose and the objectives of the study were formulated based on the preliminary assessment. The purpose of the study was to assess forest legislation violations on the territory of the Republic of Karelia. Research tasks included the following: 1. Collection of information on forest legislation violations on the territory of Olonetskiy, Muezerskiy, Medvezhyegorskiy, Kondopozhskiy, Suoyarvskiy, Pudozhskiy central forest ranger stations; 2. Analysis of forest legislation violations in the studied areas; 3. Development of recommendations and forecasting possible forest legislation violations. The sample included forest districts from six central forest ranger stations of the Republic of Karelia. The time period for the analysis of forest legislation violations was 5 years (from 2017 to 2021). The analysis revealed that the main types of forest legislation violations were illegal logging, failing to forward logs by the deadline, incomplete felling and unsatisfactory cleaning of cutting areas from logging residues. In the study area some types of forest legislation violations followed a downward trend (failing to forward logs by the deadline and illegal logging). At the same time, a number of forest legislation violations after a decline in 2018-2019 tended to increase (leaving undercuts and unsatisfactory cleaning of cutting areas). The volume of timber that was not forwarded by the deadline decreased approximately by half over the period from 2017 to 2021. The volume of illegal logging fell 3.5 times. At the beginning of 2017, the volume of violations associated with the incomplete felling decreased by 4 times, however, it has increased by 2.5 times since 2019. No obvious regularities have been revealed by the analysis of the data on the violation connected with unsatisfactory cleaning of cutting areas. The authors note that penalties for incomplete felling should be removed from the legislation and from lease agreements, since leaving the growing forest does not do any harm or damage especially in the cutting areas left for natural reforestation. It is important that the solution of the main problems of control and detection of forest legislation violations will make it possible to radically improve the situation with the prevention of forest legislation violations and will positively affect the functioning of the forest ecosystem.
94-108