Search

As a result of climate change, the species structure of forest stands is gradually changing when the growing share of core species of deciduous trees at the expense of conifers places demands on its future efficient processing into final products. This study evaluates the influence of the surface modification of the heartwood of oak (Quercus robur) with five selected chemical modifiers on the strength of the glued joint with the used one-component PUR adhesive for interior and exterior structural applications. Samples of test bodies produced according to the standards were exposed to the given environment and subsequently subjected to a test using the method of determining the longitudinal shear strength under tensile stress. By applying a chemical modification to the surface layers of the glued surfaces of oak wood, the tannins in the surface layers were neutralized, increasing the adhesion of the glued surface. The resulting values of the strength of the glued joints with the applied chemical modification of the heartwood surface also confirmed this.

Scots pine (Pinus sylvestris L.) represents one of the most important commercial coniferous tree species, providing valuable timber. Due to climate change, it is experiencing serious problems in some areas, therefore, finding a suitable substitute for its wood is currently a challenge. In this study, we compared the wood quality of three different non-native pine species and Scots pine growing at the same site to ensure identical growing conditions. Black pine (Pinus nigra J. F. Arnold), a pine species native to Southern Europe, lodgepole pine (Pinus contorta Douglas ex Loudon), and ponderosa pine (Pinus ponderosa Douglas ex C. Lawson) native to North America were compared to Scots pine for selected quantitative (productivity) and qualitative (physical and mechanical) properties. Significant differences between pine species were found in all quantitative dendrometric parameters, except average diameter at breast height. The stand volume ranged from 157 m3 ha−1 for lodgepole pine to 356 m3 ha−1 for Scots pine. For qualitative characteristics, wood density, shrinkage, and compressive strength were used to find differences among species in choosing the best alternative. The highest wood density was obtained for Scots pine (458 kg m−3), followed by black pine with 441 kg m−3. The density of the remaining pine species was significantly lower. Scots pine also exceeded the tested species in compressive strength (44.2 MPa). Lodgepole pine achieved the second highest value (39.3 MPa) but was statistically similar to black pine (36.5 MPa). The tested pine species exhibited similar values in shrinkage, which were statistically insignificant, ranging from 14.3% for lodgepole pine to 15.1% for Scots pine. Based on applications and preferred characteristics, black pine or lodgepole pine could serve as the Scots pine substitute in some areas. And vice versa, ponderosa pine did not attain the Scots pine wood quality. [ABSTRACT FROM AUTHOR]

European forests are facing ongoing climate change, and certain tree species are being critically impacted. The Norway spruce (Picea abies (L.) Karst.) is one of the most sensitive species to climate fluctuations, a fact manifesting itself through massive dieback resulting in a lack of high-quality timber and timber market destabilization. Therefore, the possibility of wood substitution with non-native spruce species, namely, black spruce (Picea mariana (Mill.) Britt., Sterns, et Poggenburg), Serbian spruce (Picea omorika (Pančić) Purk.), and blue spruce (Picea pungens Engelm.), under the specific conditions of forest reclamations with great potential for future afforestation was tested. Wood density, modulus of rupture, and modulus of elasticity were used to evaluate wood quality in comparison with native Norway spruce. The results confirmed that only the Serbian spruce reached the quality of Norway spruce and even exceeded it in terms of wood density (P. omorika 525 kg·m−3 vs. P. abies 517 kg·m−3) and exhibited comparable parameters with regard to other properties. The density of the other species was significantly lower for blue spruce (476 kg·m−3) and black spruce (468 kg·m−3). A similar trend was found for other wood parameters, which confirmed that Norway spruce quality was nearly comparable with that of Serbian spruce. On the other hand, black spruce and blue spruce did not match the quality of Norway spruce. The within-stem variability of the properties tested was low for all the spruce species examined. In conclusion, the Serbian spruce showed great potential for future usage in forest management and is one of the possible methods of Norway spruce replacement in times of unprecedented forest disturbances under the effects of global climate change. [ABSTRACT FROM AUTHOR]

Joints are used to join furniture parts, and they represent a critical part of the structure of furniture. The quality of joints is greatly affected by the accuracy of their execution. When designing furniture, it is important to carefully consider the type of joint used so that it can hold all the joined elements together. Under loading of the joined structures, internal forces develop, which can lead to failure of the joints. This study investigated the elastic stiffness of spruce (Picea abies L.) dowel joints. The effects of selected factors such as the type of loading (compressive versus tensile), the size of the dowels (one-half versus one-third of the thickness of the joined elements), the type of adhesive used (polyvinyl acetate versus polyurethane), and annual ring deflection were examined. Spruce dowel joints exhibited the highest elastic stiffness values with a higher-diameter dowel glued with PUR adhesives and subjected to compressive loading. The impact of annual rings was not a significant factor. Finally, the reference type joints were compared with other commonly used types, such as three types of mortise and tenon joints (simple, haunched, and dovetail). [ABSTRACT FROM AUTHOR]

This study compares the quality of wood from two distinct sites in the Czech Republic—from former afforested agricultural land and forest land. We compared the properties of Norway spruce wood (Picea abies Karst.) and Scots pine wood (Pinus sylvestris L.), the most important domestic tree species, to Douglas fir (Pseudotsuga menziesii (Mirbel) Franco), a North American tree species and a potential substitute for the domestic spruce. Wood density, modulus of elasticity (MOE), modulus of rupture (MOR) and impact bending strength were the properties tested that were used for comparing tree species. Without taking into consideration the site, the highest density values from the tested tree species were obtained for Douglas fir (0.568 g·cm−3), followed by the pine (0.508 g·cm−3) and the spruce (0.463 g·cm−3). The Douglas fir also dominated in the remaining assessed properties, whilst the influence of site was not confirmed, with the exception of MOE and MOR, and only for the Douglas fir wood, wherein higher values were obtained for forest land. In terms assessed Douglas fir properties, it exceeds the domestic softwoods and represents a possible suitable replacement for them. The site only plays a role in terms of the Douglas fir, and only for certain properties. [ABSTRACT FROM AUTHOR]

Joints are one of the most important issues in the design of furniture structures. Joints in furniture structures made from wood and wood materials represent a critical area because furniture most often breaks at the joints of structural elements. This article discusses the analysis of the effect of selected factors: type of loading (compressive, tensile), wood species (Fagus sylvatica L., Picea abies L.), thickness of joint (one-third and half the thickness of the tenon), type of glue (polyvinyl acetate and polyurethane), and the annual ring deflection, on the elastic stiffness of joints. These results indicated significant effects for the wood species, thickness of joint, and type of glue used. The annual ring deflection was on the borderline of statistical significance, while its effect was more significant than the effect of the basic material characteristic, i.e., the wood density. The type of loading was not statistically significant. [ABSTRACT FROM AUTHOR]

The effect of thermal treatment temperatures on the dynamic and static modulus of elasticity (MOE) of Norway spruce wood (Picea abies (L.) H. Karst.) was evaluated. The dynamic MOE was measured using ultrasound and resonance methods in the longitudinal and transverse directions. The static MOE was determined by the three-point bending test. The dynamic MOE values determined by the ultrasound method were higher than the static MOE values in each case. As the temperature of the thermal treatment increased, the difference between the dynamic and static MOE values decreased. The MOE increased with increasing temperature, and it was more pronounced on a tangential surface. Increasing the sensor distance had a positive effect on the correlation between the static and dynamic MOE, and the effect from the increased temperature decreased. Measurement by the resonance method showed twice as high MOE values in the transverse direction than in the longitudinal direction. The thermal treatment caused a significant decrease in the MOE only in the transverse direction, and the differences were insignificant in the longitudinal direction. The dynamic MOE values measured by the resonance method were higher than the static MOE values but slightly lower than the values measured by the ultrasound method. [ABSTRACT FROM AUTHOR]

Strength properties were evaluated for Grand fir wood (Abies grandis /Douglas/ Lindl.), a North American species that is considered to be a promising species for the Central European forestry industry. The bending, compression, and impact strengths of wood from Grand fir trees grown in the Czech Republic area were tested, including their variability within a stem and correlation to wood density. The average values of the compression strength reached 39.577 MPa; the bending strength was 78.119 MPa, the impact strength was 4.186 J/cm², and the density was 410.267 kg/m³. The greatest dependence of the strength characteristics on the evaluated density was shown in the case of bending at the vertical bottom position (r = 0.95). Compression strength values were observed to highly correlate with the density at vertical positions (bottom and middle) in the first site (r = 0.98). The values of the correlations between density and impact strength were observed to be moderate or poor in the vertical position, where a good value was shown in the middle position (r = 0.87). The results of the study suggest that Grand fir is a satisfactory substitute for indigenous species of fir in the Czech Republic; with respect to bending strength and toughness, it can replace the most important commercial conifer, spruce. [ABSTRACT FROM AUTHOR]

Copyright of Wood Industry / Drvna Industrija is the property of Drvna Industrija and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)