Home – Home – Jornals – Siberian Journal of Forest Science 2019 number 3

In the last decades different methods have been developed for measuring piled wood, i.e. wood stacks. There are two main groups of measurements: the first one is manual methods and the second one is automatic measurements. Taking into consideration the amount and market value of stacked wood, the accuracy of applied measurement is of high importance, as the price is calculated according to the measured amount of wood. Manual measurements are mostly time consuming and dependent on individual performance. On the other hand, the automatic methods are fast and their accuracy has increased in the last years. They allow to obtain relevant results when calculating prices at different locations, independent of the measurement time. These methods range from simple manual measurements using a tape to photo-optical measurement systems. Also, other measurement methods (e. g. water immersion) are currently used in practice. The paper describes the individual manual and automatic measurement methods for industrial timber and their working principles. Furthermore, the advantages and disadvantages related with the requirements and accuracy of the individual procedures have been explained and their practical use discussed.

The study describes a ground contact test on natural durability of the Siberian larch heartwood timber. The test has been conducted in Finland according to the European norm EN 252 since the year 2006. The material is timber imported from natural larch stands in Ust-Ilimsk, Russia, and cultivated larch stand in Punkaharju, Finland. The Finnish stand is growing outside the natural range of distribution of Siberian larch. Untreated Scots pine heartwood and impregnated Scots pine sapwood were used as reference materials. The results after 11 years showed that there was remarkable variation in the durability between the larch heartwood samples. Nevertheless, the most durable timber lots on average were the Siberian larch heartwoods harvested from the Russian native stands and the Finnish cultivated stand. It is predicted that it will take another 10 years or more until the failure of the most durable larch stakes.

This overview presents the research fields of the Institute of Wood Science at the University of Sopron (Hungary) in the first two decades of the third millennium. The classic wood research topics such as physical, mechanical and anatomical examinations of untreated wood species are one of the major fields of the studies conducted. The other major part is the topic of this paper, i.e. the study of different wood modification processes. There are many possibilities in wood science to improve the properties of wood and, as a result, to improve its usability. Various heat treatments were performed in gaseous atmosphere for more than ten softwood and hardwood species, as well as heat treatment in different fluids. The latter includes the treatment in vegetable oils, paraffin and beeswax to improve the resistance and dimensional stability of wood. Within the mechanical wood modification the densification of poplar resulted in a great increase of its hardness to make this common wood available in more fields of wood industry. The longitudinal compression of hardwoods results in obtaining a flexible material that extends the usability of wood. As a chemical treatment, acetylation provides a good protection against wood-destroying organisms, a high increase in dimensional stability and a long life span. The impregnation of wood with different nanoparticles has successfully in improved its durability. In summary, this paper demonstrates several processes from mechanical wood modifications through heat treatments to chemical modification methods.

This paper deals with the hygroscopic properties of the wood of the Siberian tree species. We analyzed Siberian larch Larix sibirica Ledeb., Scotch pine Pinus sylvestris L., Siberian spruce Picea obovata Ledeb., Siberian fir Abies sibirica Ledeb., drooping birch Betula pendula Roth., and wood samples of aspen Populus tremula L. using sorption models including the Brunauer-Emmet-Teller (BET), Frenkel-Halsey-Hill (FHH), Zimm-Lundberg (ZL), and micropore volume filling (MVF) theories along with accurate methods, namely thermogravimetry (TG), differential thermogravimetry (DTG) and differential scanning calorimetry (DSC). The isotherms of moisture sorption by wood were used to quantify the most important hygroscopic characteristics. We used BET to calculate monolayer capacity ( u_m ), specific inner surface area ( S_sp ) and ZL equation to find water vapor content and relative pressure when water clusters start to form in the wood samples, FHH model and MVF theory to obtain fractal dimension of «sorption surface» and characteristic sorption energy ( Е_с ), respectively. Application of Ozawa-Flynn-Wall method to TG/DTG data allowed us to identify a dependence of water desorption activation energy on the stage of nonisothermal wood drying and to determine maximum moisture loss rate. Based on the measurement values obtained from DSC experiments, we found the energy spent for the removal of bound water when heating samples at a constant rate. The values of u_m , S_sp and Е_с indicated that moisture sorption differed considerably (8.8 % for u_m and S_sp and 31.4 % for Е_с ) among the woody species of interest. A kinetical analysis revealed that the wood of birch, aspen, and larch had higher values of moisture desorption activation energy as compared to pine, spruce and fir. These differences agreed well with the values for moisture evaporation heat determined by DSC method.

Due to the increase of the amount of unused waste, including that of plant origin, the prospects of its application to obtaining new products is becoming increasingly important. Unused (irreversible) soft wood waste from woodworking enterprises and spinning waste of flax and cotton are sent to landfill or incinerated, which adversely affects the environment. Plant waste can be used to obtain new products, which is a positive approach from the point of view of natural environment. Domestic and foreign studies have developed composites based on plant waste, including the use of chipboard technology (CB) and board materials produced by soft fiberboard technology, which has not been developed yet. Composite board materials with wood chip fillers and irreversible waste from the processing of flax and cotton based on a matrix of thermosetting binder can be used as a building material for thermal-insulation purposes. The paper is focused on physical and mechanical properties of composites manufactured using the CB technology and soft fiber board on a phenol-formaldehyde binder, and examines the effect of environmental temperature and humidity on the performance of composite board materials. The results of determining the dynamics of strength and thickness swelling of board materials after cyclic tests of «soaking - freezing - thawing - drying» are considered. The results of experimental studies have shown that heat-insulating composites of soft wood waste on a phenol-formaldehyde binder made according to the technology of CB have higher strength during static bending in comparison with boards made of spinning waste of plant fibers. However, wood composites have a higher thickness swelling after being water treatment and a more intensive decrease in strength and water resistance. Experimental data confirm long-term resistance of composites to changing temperature and humidity; this allowed us to recommend the materials as heat-insulating elements of building structures.

Black locust Robinia pseudoacacia L. is a fast growing tree, used in forest establishment. It is an economically important tree for tool production, obtaining timber and fuel as well as an important constituent element for landscapes. Though the tree is abundant, information on genetics, physiology, biology, wood quality and adaptability to different ecological conditions is limited and fragmented. The aim of this research was to study physiological and biochemical adaptation by comparing two black locust Clones that showed different responses to drought. The two Clones were exposed to different water regimes: Medium Stress and High Stress (50 and 25 % of water supplied to control). Physiological and biochemical measurements were made. Stress affected negatively the growth of both Clones. The effect of different stress intensity (MS and HS treatments) was observed on stem shape. When re-watered the stem showed partial recovery. Net photosynthesis rate in drought period did not show marked difference between the Clones. After soil rehydration both Clones recovered photosynthesis level. The Clones 1 did not show differences in osmotic potential when comparing Control and MS or HS trees. The Clone 2 showed increased osmotic potential in relation to stress intensity. The maximum potential in Clone 2 was comparable to the values for Clone 1. Amino acids, especially proline, increased in drought. The soluble sugars increased during the stress period in the stems of Clone 2. The increased absence of osmolytes increase in Clone 1 could be due to the absence of adaptive mechanism. Alternatively, osmolytes concentration was already too high to be increased more by drought. Different osmotic potential and changes during drought can be related to the growth during tree life. Selection of Clones according to osmolyte index could to select better trees for different climate zones.

The results of comparative analysis of adaptive features of bark and secondary xylem of the spirea of Bower Spiraea beauverdiana Schneid (Rosaceae Juss.) are presented in the extreme conditions of the Arctic and volcanic activity in the Kuril Islands. Structural analysis of the bark and wood parameters in ontogenesis under the conditions of post-volcanic activity is carried out. The identified features are of adaptive character and are aimed at optimizing the water supply system. It has been established that the combination of environmental factors in conditions of gas-hydrothermal outputs of the Golovnin volcano caldera on the Kunashir Island causes disruption in the activity of phellogen and cambia. Unstable operation of these meristems leads to the formation of tissues of abnormal structure, forming separate loci in the stem, as well as tissues with deviations from the normal structure. In terms of their structural and functional characteristics, the anomalies formed in the secondary phloem and xylem are similar to the anomalies caused by stem pitting syndrome. The commonality and specificity of structural reaction of the secondary xylem under these conditions is revealed. In these extreme conditions, spirea of Bower wood retains its juvenile features throughout the entire ontogenesis, with solitary and cluster vessels located within one year growth ring. More specialized vessels, cluster vessels are more narrow and larger rays are present, with the former being homogeneous (ray cells upright) and the latter being mixed heterogeneous and heterogeneous (rays with procumbent, square and upright cells).

Illegal timber harvesting and traffic is one of the most pressing environmental and economic problems worldwide. According to some estimates, between 15 to 30 % of the world’s timber market are of illegal origin. At present it is becoming increasingly important to conduct an independent examination to confirm the legality of the origin of forest products. One of the effective approaches that allow such verification is genetic analysis. This paper presents the results of genetic examination of 34 timber samples of Scots pine Pinus sylvestris L., collected in the framework of a model experiment from the logged area and from the timber storage site. Genetic analysis was performed on the basis of ten microsatellite loci of DNA. Electrophoretic separation of amplification products was carried out in a polyacrylamide gel. The images indicating the identity or difference in DNA of timber samples collected from the logged area and timber samples collected from timber storage site were obtained by gel electrophoresis. 26 combinations of multilocus genotypes were identified in the analysis. Four variants of the genotypes indicated the identity of timber samples collected from the logged area and timber samples collected from the timber storage site. Thus, within the framework of this experiment the efficiency of using the methods of molecular genetic analysis of timber samples to determine the degree of their identity is confirmed. It was revealed that the microsatellite loci of DNA (SSR-analysis) can reliably verify the place of origin of samples. The results of these works can be used to create a national system of harvested timber control and identification of forest products.

The problem of wood waste utilization is of great importance. In connection with the outbreaks of microorganisms resistant to most of the known antibiotics researchers are increasingly interested in natural objects that can serve as raw materials for producing medicines, including those with antimicrobial activity. Bark of conifers is a source of many biologically active substances. From the pharmacological and therapeutic points of view, phenolic compounds of bark are most interesting. The extraction of the bark of conifers with monoethanolamine provides a product with an increased proportion of phenolic compounds in comparison with other known methods. The antibacterial activity of the extracts and their solutions obtained by the abovementioned method from the bark of conifers of Siberian larch Larix sibirica L. , Scotch pine Pinus sylvestris L., and Siberian fir Abies sibirica L. was studied. We used the museum strains of sanitary-indicative opportunistic bacteria such as Klebsiella pneumoniae (Schroeter) Trevisan Т 904, Escherichia coli Migula ATCC 39/21141, Staphylococcus aureus Rosenbach АТСС 25922, Proteus vulgaris Hauser MX 19 и Micrococcus luteus (Schroeter) Cohn emend. Wieser et al. ATCC 9341 as test objects It was found that the extract of Scotch pine demonstrated greater inhibitory activity while fir bark extract had the lowest bacteriostatic properties. The diluted extracts of larch and Scotch pine bark were less effective against the tested bacteria, and the diluted extracts of fir bark had no antibacterial effect. The obtained data are promising for further research of the development of antibiotic / disinfecting substances based on conifer bark extracts.