Average Annual Ring Width Research Articles

WOOD DENSITY AND ANNUAL RING WIDTH OF PEDUNCULATE OAK FROM STANDS GROWN ON FORMER AGRICULTURAL LAND

The main aim of this study was to determine differences in basic density and average annual ring width of pendulate oak wood collected from trees grown on former agricultural land and on forestland, using a dimensional method. The experiment was carried out in thewestern part of Poland, near to Poznan, which is in the central part of the European range of pedunculate oak. In our study the average basic density was 0.528 g.cm-3, and the value for former agricultural land was lower by 0.026 g.cm-3 than that for forest land. Differences in basic density values between these two land types were statistically significant. The average annual ring width in samples collected from forest land in our study was 2.48 mm, samples from former agricultural land were characterized by wider average annual rings. The results suggest that there are significant differences in quality of wood from former agricultural land and from forest. However, from view of wood quality and applications the difference is not important.

Anatomical and Morphological Changes with Needle Removal Treatments on the Seedlings of Pinus nigra Arn. (Anatolian black pine)

The effect of needle removal treatments on the morphology, anatomy and wood density was less studied in the literature. Therefore, the aim this study was to investigate the effect of needle removal on the morphological, anatomical and wood density properties of the seedlings of Pinus nigra Arn. (Anatolian black pine). The needles of the seedlings were removed in four different amounts (0%, 25%, 50% and 75%) to determine whether there is a relationship between the properties of seedlings and the needle removal treatments. The morphological (stem diameter, node numbers, pith percentage, bark percentage, xylem percentage), anatomical properties (average annual ring width, tracheid number per mm2, tracheid height/width, tracheid lumen width, tracheid wall thickness, ray number per mm2, ray height/width) and wood densities were individually determined for each treatment. The morphological results showed that stem diameter was greatest in 0% and 25% needle removal treatments than that of two treatments. Bark% was also found to be higher in the 0% needle removal treatments than others. However, node numbers, pith% and xylem% did not differ significantly between four removal treatments. The density results showed that the seedlings of 0% and 25% needle treatments were denser than 50% and 75% needle removal treatments. The results of anatomical analysis also found surprising results between four treatments. Ray height/width, tracheid number per mm2and tracheid length were significantly greater in the 0% removal of needles than that of three treatments. 25% needle removal treatment also showed larger tracheid area and tracheid wall thickness than that of three needle removal treatments.

Deformations of boards from uneven-aged Norway spruce stands

This study focused on wood distortion of boards sawn from Norway spruce (Picea abies (L.) Karst.) trees grown in uneven-aged stands. The stands were multi-aged with tree ages up to 170 years. In total, 60 trees were harvested from six stands that had been managed by single-tree selection for decades. A butt log and a top log were sawn from each tree, both 2.5 m long. Wood deformations were measured from boards dried to an average moisture content of 7–10% from the 2.5 m long boards. A linear mixed model was constructed to describe the variation in twist deformations in the boards after drying. According to the model analysis, twist increased with greater grain angle, greater average annual ring width and relative ring width difference, greater knot size and count, and the interaction of grain angle with the vertical log position along the stem. Greater distance of the board from the pith was associated with lesser twist. Contrary to expectations, proportion of compression wood and tree position in the stand diameter distribution were not correlated with twist. Pin knots, although their occurrence and size was minimal, had a high degree of correlation with twist. The occurrence and severity of twist remained approximately at the same level as in even-aged Norway spruce as observed in other studies.

Effects of geo-ecological conditions on larch wood variations in the North European part of Russia (Arkhangelsk region)

The present study examines the macrostructure and density of larch wood and possible influences on the productivity of larch stands. The studies were conducted in the middle and sub-tundra taiga in the Arkhangelsk region. The selected trees were of the same age and diameter at breast height. In all sample plots the average annual ring width varied from 0.68 to 0.93 mm, the average content of latewood was about 29.7–35.1% and the average wood density of these old Siberian larch trees was 572 (500–698) kg·m<sup>–3</sup>. There were no significant differences between sample plots in terms of the latewood content, density and annual ring width of the growth rings. Wood macrostructure of larch wood has the same values in forests growing in the sub-tundra and middle taiga. A possible explanation for this is the location of these stands in the karst landscape, which possesses abundant mineral nutrition. Geological factors are surpassing the influence of climatic factors and contribute to the formation of productive larch stands in the sub-tundra taiga in the European part of Russia.

Variability of the compression properties of cork

The variability of the compression properties of cork was determined after field sampling covering the main production area in Portugal (10 sites) with samples taken from 20 trees per site at the time of cork stripping. In all cases, cork showed compressive stress–strain curves typical for cellular materials, which are characterized by an approximately “elastic” region up to a 5 % strain, followed by a large plateau up to 70 % strain caused by progressive buckling of cell walls, and a steep stress increase for higher strains corresponding to cell collapse. The radial direction of compression offered higher strength. The Young’s moduli averaged 10.4 and 9.2 MPa for radial and non-radial directions, respectively, spreading from 3.5 to 22.5 MPa for the non-radial and 4.2 to 21.5 MPa for the radial directions. The geographical location of cork production was the major factor of variability. Density, annual growth ring width and chemical composition influenced compression. Cork samples with higher density showed overall larger resistance to compression. The energy absorbed per unit volume to achieve the maximal deformation with full densification of cork is higher when the average annual ring width is smaller. Cork samples with relatively higher suberin content required less stress for deformation. The results encompass the natural variability of cork and are the most extensive to characterize cork. They allow a better insight into the differences that may explain the variation in cork properties and strengthen its use either in the known applications, i.e. as a sealant, or in novel applications.

Determination of dynamic elastic moduli and shear moduli of aged wood by means of ultrasonic devices

Due to ecological and environmental factors, re-using aged wood is becoming more and more important, also in applications where mechanical strength plays a central role. The aim of this study was to examine specific mechanical parameters of naturally aged and dried wood and to better understand the influence of aging on the elastic behaviour of wood. To this aim, measurements on boards and on small, clear wood specimens were carried out. Ultrasound velocities of longitudinal and, in some cases, of transversal waves were measured to determine dynamic elastic moduli and shear moduli. The measurements were performed on structural timber of aged Norway spruce (aged wood) and compared with specimens of recently cut and kiln dried timber of the same species (recent wood) as a reference with comparable density properties and average annual ring width. The measurements revealed higher values of dynamic elastic modulus for aged wood in the longitudinal and radial directions, but no significant difference was found in the tangential direction or in the shear moduli. It is supposed that the difference is more likely a consequence of variability in densities and the structure parameters (annual ring structure, microfibril angle, growth conditions) rather than a consequence of the wood age. The relation between the dynamic elastic modulus in the longitudinal direction and wood density was nearly the same for aged and recent wood specimens, so with increased prudence, grading methods developed for recent wood can also be applied for aged wood.

일본산속성수 찬친모도키재의 물리적 성질과 흡음성능 평가

To suggest the practical use of fast growing tree, we estimated the physical and sound absorption properties of Cherospondias axillaris which is one of the japanese fast growing species. The average annual ring width and air dry specific gravity were 8 mm and 0.55 respectively. The sound absorption coefficients of Cherospondias axillaris wood generally seemed to be a little higher than those of other construction materials such as 6 mm thick gypsum board and 18 mm thick fiberboard, and considered that it could be used as a constructing material owing to relatively good mechanical properties and sound absorption properties.

Growth rate and wood properties of Norway spruce cutting clones on different sites

The effect of growth rate on weight density and strength properties of three Norway spruce cutting clones growing on three different sites in different geographic locations was studied. The purpose was to follow variation in wood physical and mechanical properties and in quality between fast-growing clones grown in environments differing in nutritional and soil properties and climate within the boreal zone. The cloned trees had been selected on grounds of good growth, health and quality. The cuttings were collected from three-year-old seedlings and rooted. The rooted cuttings were planted in the 1970’s and they were on average 26 years old at a time of felling. The variation of weight density was studied within the annual ring and within the stem between the juvenile and mature wood from the pith to the bark with an X-ray densitometric method. The average annual ring width (and latewood proportion, %) varied between the clones from 2.92±1.36 mm (15.34%) to 3.30±1.25 mm (11.80%) and between the sites from 2.76±1.07 mm (14.71%) to 3.70±1.22 mm (13.29%). The mean weight density was 0.461±0.077 g cm–3 and latewood density 0.750±0.125 g cm–3 in this material. The mean modulus of elasticity was 9.88±1.43 GPa, modulus of rupture 67.51±11.50 MPa and weight density of the test samples (ρ12) 414±44 kg m–3 in mature wood. The parameters studied showed clearly that the environment had a large effect while the three clones differed from each other similarly in the different sites, e.g. the fastest growing clone was fastest on all sites.

DEPENDENCE OF PINUS SYLVESTRIS WOOD STRUCTURE AND PHYSICAL PROPERTIES ON GROWTH ENVIRONMENT CONDITIONS

The paper considers the variation o f annual ring parameters and physical properties of wood of the pine species prevailing in Latvia’s forests, depending on the forest type (bog-land, vacciniosa) and the growth region in Latvia (Vidzeme, Latgale). Wood samples were taken from the stem butt-end, the middle and 3 A o f the height, in its sapwood or core part. An average annual ring width, latewood and earlywood width in the year ring, the percentage of latewood in the annual ring, wood density in oven-dry state (0), tangential swelling (tg) and radial swelling (rad) o f wood, as well as volume swelling (v) and swelling anisotropy coefficient (k) o f wood were determined for the samples. A comparison of these data shows that, in the majority of cases, the indices for the wood of pines grown in vacciniose have higher values, which suggests the advantage of pine wood over the bog-land pine wood. In its turn, no unambiguous distinctions between the parameter values for pine wood o f Latgale and Vidzeme origin were found, although the pine wood of Vidzeme origin had a somewhat higher indices. It may be concluded that the greatest impact on the leading pine wood properties is caused by the forest types regarded herewith, and not the belonging o f the pine wood site to its different growth regions in Latvia.

Tree Properties and Yield of Picea abies Planted in Shelterwoods

Tree properties affecting timber quality and yield were examined in six stands of Norway spruce [Picea abies (L.) Karst.] planted in shelterwoods. For each stand a pairwise comparison was made with trees planted in the open. When compared 16 - 32 yrs after planting, the sheltered trees were generally shorter and had thinner trunks than the open - grown ones. Furthermore, sheltered Norway spruce had thinner branches, a lower average annual ring width and a lower frequency of defects such as spike knots, forked stems and sharp bends. The reduction in ring width was significant for ring numbers 1 - 5 and 6 - 10. No significant differences in basic density were detected between treatments. The yield of Norway spruce was lower for sheltered trees than for those growing in the open. Total volume yield, however, including shelter trees, was higher on the sheltered plots.