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The purpose of this study was to determine variation in the density of wood from different provenances, growing under the same soil and climate conditions. Samples were obtained from an experimental site located at the Siemianice Forest Experimental Station. We analyzed larch wood samples from trees aged 48 years, collected from six different provenances in Poland. Diameter at breast height (DBH) and tree height were used to calculate the parameters for sample trees, from which a 70 cm segment was cut, from breast height upwards (up to 2 m of tree height). Samples with dimensions 20 × 20 × 30 mm were obtained from the material. Sample volume was determined by stereometry. Relative density was determined for 890 samples. The highest wood density was found in trees from Czerniejewo, and the lowest in trees from Rawa Mazowiecka. Analysis of variance, including the mean wood density values of trees, did not demonstrate significant differences between provenances in terms of this characteristic. Mean relative density was higher in larch wood samples from the heartwood zone. The density of samples cut closer to the bark was lower, as the value was affected by the large content of sapwood. A relation was found between the provenances from which the study material was sourced and the relative density of wood. [ABSTRACT FROM AUTHOR]

In this study, the effect of altitude difference on the physical and mechanical properties of Scots pine (Pinus sylvestris L.) wood was investigated. For this purpose, nine Scots pine trees were selected from three altitudes: 250 m (low altitude), 700 m (intermediate altitude), and 1200 m (high altitude) located in the forestry of Sinop province (Black Sea Region in Turkey). For the physical properties of wood: air and oven dry specific gravity were determined, and for the mechanical properties of wood: compression strength parallel to the grain, static bending strength and modulus of elasticity in static bending were determined. Moreover, the variation of all wood properties was determined related to the altitude difference. The results of statistical analyses showed that the altitude difference was an important factor influencing the physical and mechanical properties of Scots pine wood. The air and oven dry density, compression strength parallel to the grain, static bending strength and modulus of elasticity in static bending were higher at intermediate altitude than at other altitudes.

This work presents the findings of a study concerning variability in the basic density of silver birch (Betula pendula Roth) wood, depending on the geographical location of tree stands, the age and thickness of the trees, the forest habitat type, and interactions between some of these factors. The study was carried out on wood from trees aged approximately 30, 50 and 70 years in 12 forest districts located throughout Poland. In total 4777 wood samples, taken from 306 trees from 51 test plots, were measured. The location, the age of the trees, the thickness of the trees and the forest habitat type, as well as interactions between these factors, proved to have a significant influence on the basic density of silver birch wood. The highest mean values of the basic density of the birch wood were found in Sokołów forest district on the FBF habitat type (549 kg m–3) and in Giżycko forest district on the FMBF habitat type (548 kg m–3). For the entire set of examined material, the average values of the basic density of wood increase with tree age. For the examined material originating in FBF and FMBF habitats the average values of basic density showed no significant differences; however, in the cases of the forest districts of Giżycko, Łobez and Rudziniec, significant differences in the analysed property were observed.

This work presents the findings of a study concerning the variability in the density of oven-dry silver birch wood, depending on the geographical placement of tree stands, of the age and thickness of the trees, the influence of the forest habitat type and interactions occurring between chosen factors. The study was carried out on wood from trees aged approx. 30, 50 and 70 years old in 12 forest districts located throughout Poland. Altogether 4777 wood samples taken from 306 trees acquired on 51 test plots were measured. A significant influence of all the examined factors on the variability of the density of the oven-dry wood of the silver birch was proven. The highest mean values of the density of the birch wood in an oven-dry state were found in the Forest District of Giżycko in fresh mixed broadleaved forests - 669,85 kg/m3 and in the Forest District of Sokołów in fresh broadleaved forests - 662,04 kg/m3. For the entire examined material, mean values of the density of oven-dry wood are increasing along with age. In all three of the examined tree ages, the highest mean values were noted in the thinnest trees. [ABSTRACT FROM AUTHOR]

Investigators wanting to study aspects of wood machining face many challenges. The material under investigation is inherently different with respect to its three major axes, and it responds in various ways to local temperature, moisture, and many other variables. Researchers proposing future research projects in this area thus face a critically important task of selecting parameters to include either as variables or as quantities to hold constant. This editorial outlines key parameters and conditions of wood machining that can be considered, depending on the scope of a project.

Se estudió la densidad, contracción, higroscopicidad y punto de saturación de la pared celular en la madera de ejemplares jóvenes de tres especies importantes en la producción maderera española: Pinus pinaster, Pinus sylvestris y Pinus radiata. Se muestrearon 29 pinos procedentes de raleos efectuados en diferentes masas forestales de Galicia (noroeste de España). El material de ensayo fueron probetas de pequeñas dimensiones sin defectos. La madera de Pinus pinaster resultó semipesada y más inestable en dimensiones ante los cambios de humedad que las de Pinus radiata y Pinus sylvestris, que resultaron ligeras y relativamente estables, especialmente Pinus radiata. La densidad en Pinus pinaster fue similar a la obtenida en estudios anteriores sobre pies adultos. Pinus radiata y Pinus sylvestris presentaron madera más ligera que la de pies adultos. Las propiedades relativas a la estabilidad dimensional fueron similares en la madera joven analizada y en la madera de pies adultos, a excepción de la madera de Pinus radiata, que resultó más estable en la muestra que en la madera adulta. La variación entre zonas del fuste y entre individuos fue notable para las variables densidad y peso específico, aun en el caso de árboles muestreados en un mismo rodal y estaciónWood density, shrinkage, hygroscopicity and fibre saturation point were studied in young trees corresponding to three important species in the spanish timber production (Pinus pinaster, Pinus sylvestris and Pinus radiata). Twenty-nine thinned pines from different stands of Galicia (northwestern Spain) were sampled. The test material was small size defect-free specimens. The wood of Pinus pinaster exhibited intermediate density and more instability in dimensions, due to environmental moisture changes, than wood of Pinus radiata and Pinus sylvestris. These woods were light and relatively stable, especially Pinus radiata. The density in Pinus pinaster was similar to that obtained in previous studies on adult trees. Pinus radiata and Pinus sylvestris showed lower density than adult trees. The shrinkage properties were similar in the analyzed young wood and in the wood of adult trees, excepting the wood sampled for Pinus radiata, more stable than adult wood. Even with a sample of trees from the same stand in a specific site, there were significant differences in wood density among positions in each tree and among trees

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Se estudió la densidad, contracción, higroscopicidad y punto de saturación de la pared celular en la madera de ejemplares jóvenes de tres especies importantes en la producción maderera española: Pinus pinaster, Pinus sylvestris y Pinus radiata. Se muestrearon 29 pinos procedentes de raleos efectuados en diferentes masas forestales de Galicia (noroeste de España). El material de ensayo fueron probetas de pequeñas dimensiones sin defectos. La madera de Pinus pinaster resultó semipesada y más inestable en dimensiones ante los cambios de humedad que las de Pinus radiata y Pinus sylvestris, que resultaron ligeras y relativamente estables, especialmente Pinus radiata. La densidad en Pinus pinaster fue similar a la obtenida en estudios anteriores sobre pies adultos. Pinus radiata y Pinus sylvestris presentaron madera más ligera que la de pies adultos. Las propiedades relativas a la estabilidad dimensional fueron similares en la madera joven analizada y en la madera de pies adultos, a excepción de la madera de Pinus radiata, que resultó más estable en la muestra que en la madera adulta. La variación entre zonas del fuste y entre individuos fue notable para las variables densidad y peso específico, aun en el caso de árboles muestreados en un mismo rodal y estación. Abstract Wood density, shrinkage, hygroscopicity and fibre saturation point were studied in young trees corresponding to three important species in the spanish timber production (Pinus pinaster, Pinus sylvestris and Pinus radiata). Twenty-nine thinned pines from different stands of Galicia (northwestern Spain) were sampled. The test material was small size defect-free specimens. The wood of Pinus pinaster exhibited intermediate density and more instability in dimensions, due to environmental moisture changes, than wood of Pinus radiata and Pinus sylvestris. These woods were light and relatively stable, especially Pinus radiata. The density in Pinus pinaster was similar to that obtained in previous studies on adult trees. Pinus radiata and Pinus sylvestris showed lower density than adult trees. The shrinkage properties were similar in the analyzed young wood and in the wood of adult trees, excepting the wood sampled for Pinus radiata, more stable than adult wood. Even with a sample of trees from the same stand in a specific site, there were significant differences in wood density among positions in each tree and among trees.

The paper presents a comparison of the density of seven provenances of spruce trees, grown on an experimental plot located at Siemianice Forest Experimental Station. This plot is a unique research area on which observations concerning the growth of spruce trees of different provenances have been conducted for 41 years. The conditions in which the trees grow are very similar and it may be assumed that provenance is the element differentiating growth and wood properties. Trees growing on this plot have reached such large dimensions that it was possible to collect experimental material in the form of blocks, from which wood samples for further tests were obtained. Analyses were conducted on 651 samples collected from spruce trees of 7 provenances (Orawa, Międzygórze, Nowe Ramuki, Istebna Bukowiec, Kartuzy, Zwierzyniec 281B, Zwierzyniec Lubelski). The results indicated that wood of each individual provenance differed significantly in terms of the analysed trait. It was found that wood coming from Zwierzyniec Lubelski had the greatest values of basic density, while the lowest values were recorded for the Orawa provenance. Moreover, the examined provenances were divided into four groups, thus creating a ranking list of provenances in terms of the basic wood density of Norway spruce. [ABSTRACT FROM AUTHOR]

Investigators wanting to study aspects of wood machining face many challenges. The material under investigation is inherently different with respect to its three major axes, and it responds in various ways to local temperature, moisture, and many other variables. Researchers proposing future research projects in this area thus face a critically important task of selecting parameters to include either as variables or as quantities to hold constant. This editorial outlines key parameters and conditions of wood machining that can be considered, depending on the scope of a project. [ABSTRACT FROM AUTHOR]

Timber is normally dried by kiln drying, in the course of which moisture-induced stresses and fractures can occur. Cracks occur primarily in the radial direction due to tangential tensile strength (TSt) that exceeds the strength of the material. The present article reports on experiments and numerical simulations by finite element modeling (FEM) concerning the TSt and fracture behavior of Norway spruce under various climatic conditions. Thin log disc specimens were studied to simplify the description of the moisture flow in the samples. The specimens designed for TS were acclimatized to a moisture content (MC) of 18% before TSt tests at 20°C, 60°C, and 90°C were carried out. The maximum stress results of the disc simulations by FEM were compared with the experimental strength results at the same temperature levels. There is a rather good agreement between the results of modeling and experiments. The results also illustrate the strong decrease of TSt with increasing temperature at a constant MC level. [ABSTRACT FROM AUTHOR]

Wood density, shrinkage, hygroscopicity and fibre saturation point were studied in young trees corresponding to three important species in the spanish timber production (Pinus pinaster, Pinus sylvestris and Pinus radiata). Twenty-nine thinned pines from different stands of Galicia (northwestern Spain) were sampled. The test material was small size defect-free specimens. The wood of Pinus pinaster exhibited intermediate density and more instability in dimensions, due to environmental moisture changes, than wood of Pinus radiata and Pinus sylvestris. These woods were light and relatively stable, especially Pinus radiata. The density in Pinus pinaster was similar to that obtained in previous studies on adult trees. Pinus radiata and Pinus sylvestris showed lower density than adult trees. The shrinkage properties were similar in the analyzed young wood and in the wood of adult trees, excepting the wood sampled for Pinus radiata, more stable than adult wood. Even with a sample of trees from the same stand in a specific site, there were significant differences in wood density among positions in each tree and among trees. [ABSTRACT FROM AUTHOR]