Wood Quality along the Trunk Height of Birch and Aspen Growing in the Restoring Forests of Central Russia
Abstract: The structure of forests has changed with an increase in soft-wooded broadleaved species over the past decade. The demand for hard-wooded broadleaved species can be met by replacing them with compressed wood of soft-wooded broadleaved species. Existing compressed wood technologies do not fully take into account the density variations that exist along the height of a tree trunk. In this study, we examined the variability of birch and aspen microstructures along the height of the trunk, including vessels per squ… Show more
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Cited by 3 publications
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Investigation of the moisture conductivity of pine wood by trunk height
The hydrothermal treatment process is one of the most energy-intensive in wood processing technology, including dewatering and moistening of wood. The hydrothermal treatment process is one of the most energy-intensive in wood processing technology, including dewatering and moistening of wood. The hydrothermal treatment process is one of the most energy-intensive in wood processing technology, including dewatering and moistening of wood. The processes of dewatering or drying of wood are carried out in natural conditions, in drying or steaming chambers. Obtaining a high-quality dried material with minimal internal stresses is possible based on information about the value of the moisture current in the wood, expressed in terms of the moisture conductivity coefficient. The moisture content coefficient depends on the density and humidity of the wood, the direction of moisture flow, temperature, etc. As the temperature rises and the humidity of the wood decreases, the intensity of the moisture current also increases. With a decrease in the moisture content of wood, the value of the diffusion moisture current in it increases. The available information on the moisture content of wood does not take into account the variability of the density of wood in the height of the tree trunk and is presented for the butt part of the trunk. The determination of the moisture conductivity coefficient was established in the radial and tangential directions for sound pine wood, taking into account the height of the trunk by the method of stationary moisture current. Experimentally, an increase in the value of the moisture conductivity coefficient of the pine wood along the trunk height in the radial and tangential directions in the middle part of the trunk by 1.6 times, and in the upper part by 2.05 times compared with the lump. In pine wood, the current intensity in the radial direction is higher than in the tangential direction in wood from the butt part of the trunk by an average of 14.0%, from the middle part of the trunk by 5.0%, and from the apex by 16.0%, regardless of the ambient temperature. The obtained patterns on the variability of the moisture conductivity coefficient of pine wood along the trunk height show the expediency of carrying out preliminary sorting of wood before hydrothermal treatment, taking into account its location in the tree trunk. This will make it possible to optimize the processes of drying and drying of wood, to justify rational modes of chamber and atmospheric drying.
Investigation of the moisture conductivity of pine wood by trunk height
The hydrothermal treatment process is one of the most energy-intensive in wood processing technology, including dewatering and moistening of wood. The hydrothermal treatment process is one of the most energy-intensive in wood processing technology, including dewatering and moistening of wood. The hydrothermal treatment process is one of the most energy-intensive in wood processing technology, including dewatering and moistening of wood. The processes of dewatering or drying of wood are carried out in natural conditions, in drying or steaming chambers. Obtaining a high-quality dried material with minimal internal stresses is possible based on information about the value of the moisture current in the wood, expressed in terms of the moisture conductivity coefficient. The moisture content coefficient depends on the density and humidity of the wood, the direction of moisture flow, temperature, etc. As the temperature rises and the humidity of the wood decreases, the intensity of the moisture current also increases. With a decrease in the moisture content of wood, the value of the diffusion moisture current in it increases. The available information on the moisture content of wood does not take into account the variability of the density of wood in the height of the tree trunk and is presented for the butt part of the trunk. The determination of the moisture conductivity coefficient was established in the radial and tangential directions for sound pine wood, taking into account the height of the trunk by the method of stationary moisture current. Experimentally, an increase in the value of the moisture conductivity coefficient of the pine wood along the trunk height in the radial and tangential directions in the middle part of the trunk by 1.6 times, and in the upper part by 2.05 times compared with the lump. In pine wood, the current intensity in the radial direction is higher than in the tangential direction in wood from the butt part of the trunk by an average of 14.0%, from the middle part of the trunk by 5.0%, and from the apex by 16.0%, regardless of the ambient temperature. The obtained patterns on the variability of the moisture conductivity coefficient of pine wood along the trunk height show the expediency of carrying out preliminary sorting of wood before hydrothermal treatment, taking into account its location in the tree trunk. This will make it possible to optimize the processes of drying and drying of wood, to justify rational modes of chamber and atmospheric drying.
The influence of the anatomical structure of birch wood on its permeability to liquids
Береза является одной из наиболее распространенных лиственных пород на территории России. Древесина березы обладает сравнительно высокими физико-механическими свойствами, но при этом имеет ряд недостатков. Отрицательные свойства березовой древесины могут быть нивелированы с помощью направленной модификации древесины за счет сквозной пропитки активными составами. По имеющимся данным, при сквозном пропитывании березовой древесины, не всегда наблюдается равномерная локализация пропиточного состава по ширине годичного слоя. Для выявления причин неравномерной локализации пропиточного раствора, были проведены исследования особенностей анатомического строения древесины березы по ширине годичного слоя. Для этого образцы размерами 20×20×100 мм (последний вдоль волокон) пропитывались кислотным красителем в автоклаве. После пропитки образцы выдерживались в течение суток при нормальных условиях для перераспределения красителя. Далее из центральной части окрашенных образцов выпиливались участки древесины размерами 20×20×20 мм. Из полученных образцов, имеющих неоднородное окрашивание по ширине годичного слоя, по стандартной методике изготавливались поперечные микросрезы древесины, на которых при помощи микроскопа и цифровой камеры производилось изучение особенностей распределения красителя в древесине. В целях изучения анатомических особенностей строения элементов древесины березы, локализованных в разных частях по ширине годичного слоя, осуществлялась мацерация древесной ткани, взятая из «ранней» и «поздней» зоны годичного слоя. Изучение микростроения полученных древесных волокон из различных частей годичного слоя проводилось в проходящем свете с помощью микроскопа и цифровой камеры. В ходе микроскопических исследований, с помощью программы ScopyFoto, были выполнены измерения параметров анатомических элементов, таких как длина, диаметр полостей, толщина клеточных стенок, а также количество и размеры пор. Полученные данные были обработаны с помощью инструментов Microsoft Excel и программы Statgraphics. В результате проведенных исследований установлено, что волокнистые трахеиды, располагающиеся в «поздней» зоне годичного слоя, в сравнении с трахеидами «ранней» зоны, имеют большие на 26% размеры полостей клеток, на 47% более толстые клеточные стенки, на 11,1% больше по ширине окаймленные поры, а также на 17% большее количество пор. Но по высоте поры волокнистых трахеид «ранней» зоны превышают высоту трахеид «поздней» зоны почти на 27,5%. По длине волокнистые трахеиды «ранней» и «поздней» зоны годичного слоя достоверных различий не имеют. Исходя из полученных данных, одной из причин неравномерного окрашивания годичного слоя березовой древесины по ширине, по-видимому, является разница показателей фильтрации пропиточного раствора, обусловленная различием ширины пор волокнистых трахеид в «ранней» и «поздней» зоне годичного слоя. Birch is one of the most common hardwood trees in Russia. In addition to relatively high physical and mechanical properties, birch wood has a number of disadvantages. Wood modification and active compounds to be used to impregnate birch wood can neutralise such negative properties. According to available information, these impregnation compounds are not always uniformly localised along the width of an annual ring when wood is impregnated. To identify the causes of nonuniform localisation, we studied the anatomical structure of birch wood along the width of the annual ring. To do so, samples of 20×20×100 mm (the latter along the fibres) were impregnated with an acid dye in an autoclave. After impregnation, the samples were kept for 24 hours under normal conditions to redistribute the dye. After that, wood sections of 20×20×20 mm were cut out of the central part of the dyed samples. Based on the resulted samples nonuniformly dyed along the width of the annual ring, we used our standard method to make transverse wood microcuts, on which the distribution of the dye was studied using a microscope and a digital camera. To study the structural anatomical characteristics of birch wood elements localised in different parts along the width of the annual ring, the wood tissue taken from the «early» and «late» zones of the ring was macerated. The microstructure of the wood fibres obtained from various parts of the annual ring was studied in transmitted light using a microscope and a digital camera. In the course of microscopic studies, the ScopyFoto software product was used to measure anatomical parameters, such as length, cavity diameter, cell wall thickness, pore number and size. The data obtained were processed using Microsoft Excel and Statgraphics. As a result of the studies, it was established that fibrous tracheids located in the «late» zone of the annual layer, in comparison with tracheids of the «early» zone, have 26% larger cell cavities, 47% thicker cell walls, 11.1% more width of bordered pores, as well as 17% more number of pores. But as for their height, the fibre tracheid pores of the «early» zone exceed those of the «late» zone by almost 27.5%. The fibre tracheids of the «early» and «late» zones of the annual ring have no significant differences in the length. Based on the obtained data, one of the reasons for the uneven coloring of the annual birch wood layer across the width seems to be the difference in the filtration parameters of the impregnation solution due to the difference in the pore width of fibrous tracheids in the «early» and «late» zone of the annual layer.
Heartwood moisture conductivity of standing pine damaged by running crown and strong surface wildfire
The forest fire has an effect on the tree trunk. Of the total number of fires in the forest-steppe zone of Russia, strong grass-roots fires prevail. As a result of this type of fire, the undergrowth burns out, which contributes to the most prolonged exposure to high temperature on the lumpy, economically valuable part of the trunk. The effect of high temperature affects the structure of the anatomical elements of wood, its integrity is violated. In the standing timber of the Scots pine (Pinus sylvestris L.) destructive processes occur after fire damage, which have a significant effect on its physico-mechanical properties and are accompanied by intensive tar formation. One of the primary processes in wood processing technology is its dehydration, as a result of which wood is transformed from a natural material into a technological raw material. Therefore, the application of existing technological drying modes to wood damaged by fire is impractical. It is impossible to carry out the processes of dehydration or humidification of wood without information about the value of its moisture conductivity. The moisture conductivity of wood is determined by the moisture conductivity coefficient. The value of the moisture conductivity coefficient of samples of fire-damaged and undamaged P. sylvestris heartwood extracted from the stemwood was determined by the method of stationary moisture flow in the radial and tangential directions. In comparison with the intact Scots pine wood, wood damaged by fire has an inverse dependence of the intensity of the moisture current – in the tangential direction it is higher than in the radial direction. There is a general decrease in the moisture conductivity coefficient of pine wood: in the radial direction – by 40.2 ± 1.58% (p < 0.05), in the tangential direction – by 14.5 ± 0.92% (p < 0.05) compared with intact wood. Patterns of changes in the value of the heartwood coefficient of moisture conductivity in standing pine, damaged by fire, will allow to adjust the existing drying modes and improve the quality of the dried wood and the efficiency of the softwood kiln drying technology.
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