Physical and mechanical properties of the stem and branch wood of West African ebony (Diospyros mespiliformis)

ABSTRACTBranchwood is being exploited as a supplement to stemwood in wood products manufacturing, and the wood’s bending strength properties are vital for structural and non-structural applications. Non-destructive methods are being adopted in determining wood properties, and wood density and moisture content are two variables that could be useful. This study assessed the influence of density and moisture content (MC) on the Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) of branch and stem woods of Entandrophragma cylindricum (sapele) tested at two moisture levels (10 ± 4% MC and 17 ± 3% MC). Density was determined in accordance with ISO 3131. To determine bending strength properties, BS 373 was followed, using an INSTRON TCM Machine with a crosshead speed of 6.6 mm per minute. Results indicated that branchwood has higher density than its stemwood counterparts. MOE and MOR of both wood types were significantly higher at 10 ± 4% MC than their counterparts at 17 ± 3% MC. Differences in MOE and MOR between the wood types were not significant, although the branchwood had 87% and 93% respectively of the MOE and MOR of stemwood. From the two-way ANOVA, MC had a significant effect (P < 0.05) but wood type and the interactions of wood type and MC did not have a significant effect on MOE and MOR of stem and branch woods. The predictive powers of MC and density as a combined predictor for estimating bending strength properties were higher for branchwood than stemwood. Although density of E. cylindricum branchwood was significantly higher than its stemwood counterpart that did not translate into significant differences between MOE and MOR of branchwood and stemwood.

Branch wood is being promoted as supplement to stem wood but its natural durability is scarcely studied. This study compared the biological durability of branch wood of Entrandophragma cylindricum (sapele) to its stem wood for ground or other outdoor applications like garden furniture at two moisture levels (i.e., 9 ± 3 and 14 ± 2 % using kiln-drying and air-drying methods, respectively). The study followed a field test method according to EN 252-1989 in combination with percentage weight loss. Branch and stem wood samples were extracted from two natural forests in Ghana. Results indicated that branch wood of sapele was marginally denser than its stem wood. Percentage weight loss of branch wood compared to its stem wood was significantly higher by approximately 108 % at 14 ± 2 % moisture content (MC) but significantly lower by 53 % at 9 ± 3 % MC. The stem and branch woods at 14 ± 2 % MC were classified respectively as moderately durable and non-durable, but at 9 ± 3 % MC both were classified as moderately durable. Visual rating indicated that at 9 ± 3 % MC branch wood could have a better service life than stem wood. Density and MC correlated positively and negatively respectively with weight loss but the association was marginally stronger for stem wood (R2 = 0.86 %) than branch wood (R2 = 0.82 %). In conclusion, sapele branch wood material dried to 9 ± 3 % MC appeared more durable than branch wood at 14 ± 2 % MC or stem wood at either 9 ± 3 or 14 ± 2 % MC. Wood products manufacturers and users should consider using well dried branch wood of sapele to supplement stem wood for ground applications. Further research is encouraged to assess other properties of the branch wood in comparison with its stem wood for a firmer conclusion to be drawn on their utilization.

The physical and mechanical properties of branch wood from falcata [Falcataria molucanna (Miq.) Barneby &amp; J.W. Grimes] grown in Caraga Region, Philippines were determined to assess suitability for end-uses such as core veneer and as material for light construction and handles and boxes as the stem wood. Tests done to compare the properties with the stem wood showed significant differences in relative density (average values of 0.284 for the stem wood and 0.255 for the branch wood) and shrinkage properties in all directions. Axial position significantly influenced variation in moisture content (p = 0.0024) for stem and branch wood, as well as relative density (p = &lt; 0.0001) plus percent tangential (p = &lt; 0.0001) and radial (p = 0.0014) shrinkage. For the mechanical properties, the stem wood end hardness was significantly higher by 28.8% at green condition (p = 0.0003) and by 13.36% at 12% MC (p = 0.0133) than the branch wood. The compression perpendicular to the grain at 12% MC of the stem wood was also higher by 16.10% (p = 0.0166). However, for the other mechanical properties studied, the differences were not significant. The bottom portion of the stem and branch wood exhibited the highest mechanical properties, which can be attributed to the higher relative density at this portion (p = 0.0001). Based on the results that showed insignificant differences in most of the properties between the wood types of F. moluccana, the branch wood can possibly be used for similar applications as the stem wood such as for light construction, non-structural veneer, and plywood; for tool handles, boxes, and other household items; and for pulp and paper. The utilization of the branch wood of F. moluccana, therefore, can augment the raw materials supply for the local wood industry.

The objective of this study was to investigate density and some microscopic characteristics (fibre length, vessel lumen diameter, and vessel, fibre and parenchyma proportions) of stem and branch wood of Terminalia superba (ofram) and Pterygota macrocarpa (koto). Branch and stem wood samples were obtained from two natural forest reserves. Wood density was determined in accordance with ISO 3131, whereas the anatomical investigations followed the IAWA Committee 1989 recommendations. The results indicated that at 5 % level of significance, wood density was significantly higher (p 0.1) in the branch wood of koto than that of their respective stem wood counterparts. For both species, significant difference (p 0.1) was found in ray parenchyma proportion. Branch wood density correlated significantly and positively with only fibre (r = 0.216, p < 0.05) and axial parenchyma (r = 0.286, p < 0.05) proportions but stem wood density correlated significantly and positively with fibre length (r = 0.417, p < 0.01) and fibre proportion (r = 0.490, p < 0.01) but negatively with vessel proportion (r = −0.669, p < 0.01) and vessel lumen diameter (r = −0.291, p < 0.05). The results from the present study indicated that the position of wood in a tree (stem or branch) is a factor for consideration in processing and utilizing the two species as the fibre length, vessel lumen diameter, and vessel and fibre proportions affect the strength, porosity, leachability, natural durability and drying of the lumber.

As wood resources deplete, branchwood is being promoted to supplement stemwood in Ghana, but its natural durability, which indicates its service life and can influence its acceptance and use is scarcely studied. This study compares the natural durability and some anatomical properties of branchwood and stemwood of Entandrophragma cylindricum (sapele) and Khaya ivorensis (mahogany) using Ceiba pentandra stemwood as control. Natural durability test followed field test method according to European Standard EN 252 1989 in combination with percentage weight losses while the anatomical investigations followed IAWA Committee 1989 recommendations. For each species, two branch logs were cut from each of two sampled trees from two natural forests in Ghana. Stemwood was also obtained from the same forest reserves as the branches. All sample groups were tested at air-dried moisture content of 14 ± 2 % as specified in the standard. Branchwood of both species were denser than their stemwood, but in addition to mahogany stemwood they were rated “non-durable”, while sapele stemwood was rated moderately durable. Thus at 5 % significance level, natural durability of mahogany branchwood appeared comparable to that of its stemwood whereas sapele branchwood was significantly less durable than its stemwood but more durable than Ceiba stemwood. Branchwood and stemwood vessels diameter and proportion also were significantly different (p < 0.1). Expectedly, density correlated positively with natural durability, but the correlation among anatomical properties, natural durability and density were stronger in stemwood than in branchwood. In conclusion, stem and branchwood of mahogany are both non-durable but sapele stemwood appears better than its branchwood for ground applications. Anatomical properties of stemwood influenced natural durability more than those of branchwood. For better acceptance of branchwood of the species for wood products manufacturing, further research would be necessary for additional data on their toxic extractive levels, mechanical properties and durability at different sites or/and using other drying methods.

This study investigated density and some anatomical features, and also assessed the correlations among them in stem and branch woods of Entandrophragma cylindricum, Entandrophragma angolense and Khaya ivorensis. Branch and stem wood samples were sampled from two natural forest reserves. Wood density was determined in accordance with ISO 3131 whereas anatomical investigations followed IAWA committee’s recommendations-1989. Results indicated that at 5% level of significance, wood density was significantly higher in branchwood than stemwood for all three species. Generally for all the three species, significant differences were found in fibre length and vessel diameter between branchwood and stemwood of same species but no significant differences were found in both ray and axial parenchyma quantities. Stemwood density correlated significantly and positively with fibre (r = 0.408, p < 0.01) and ray parenchyma (r = 0.280, p < 0.05) proportions but negatively with fibre length (r = −0.528, p < 0.01), vessel lumen diameter (r = −0.304, p < 0.05) and axial parenchyma proportion (r = −0.679, p < 0.01). However, branchwood density correlated significantly and positively with fibre (r = 0.505; p < 0.01) and axial parenchyma (r = 0.385; p < 0.01) proportions but negatively with fibre length (r = −0.316, p < 0.05), vessel proportion (r = −0.486, p < 0.01) and ray parenchyma proportion (r = −0.357, p < 0.01). The study suggests that wood type (stem or branch) is an important factor to consider in terms of their effect on some properties of products produced from them, since differences in fibre length, vessel lumen diameter and vessel proportion could affect strength, porosity, leachability, natural durability and drying properties of wood.

In order to determine the possibility of whole-tree wood utilization of a native tree species in Northeast China (P. ussuriensis), this study investigated the air-dried wood density and fiber dimensions for each ring in the branch, stem, and root wood of the tree species. The results showed significant differences in wood densities and fiber dimensions among tree positions (p &lt;0.05). The root had the highest average density (0.596 g/cm3), and branch had the lowest average density (0.506 g/cm3). The root and branch wood exhibited larger fibers than that of the stem wood. The root wood had the highest average fiber wall (6.038 µm). The fiber wall of branch wood appeared thinner than the stem wood, although the difference was not statistically significant. The radial pattern of wood density and fiber dimensions indicated that branches and roots did not have juvenile wood such as was found in the stems. The study concludes that the use of branch or root wood of P. ussuriensis would be favorable for papermaking or wood-based panels.

&lt;p&gt;The quantitative anatomical differences between the stem and branch wood of Ficus carica L. subsp. carica (Moraceae) were investigated. In spite of the similarity in the qualitative traits, according to statistical analysis, tangential vessel diameter, radial vessel diameter, vessel frequency, vessel wall thickness, multiseriate ray width, fibre length, fibre diameter, and fibre wall thickness showed statistically significant differences in the stem and branch wood of taxon examined. Fibre length and vessel element length in branch wood is about 16% and 3% shorter respectively. In addition, vessel frequency in the branch wood is about 52% higher. Whilst the number of rays per mm is not different in branch wood and stem wood, ray width is about 18% narrower in branch wood.&lt;/p&gt;

In this study, the chemical composition, fiber morphology, pulp, and paper properties of the pomegranate tree (Punica granatum L.) were determined. Stem and branch wood were analyzed separately. Kraft and kraft- anthraquinone (AQ) methods were used for the pulping processes. Stem wood showed superiority to branch wood with longer, wider, thicker-walled fibers. The holocellulose, $\\alpha$-cellulose, and lignin contents of branch and stem wood were 72.98%-73.50%, 38.37%-39.92%, and 21.04%-25.29%, respectively. In addition, the yield of kraft pulp made from stem wood was higher than that of branch wood. However, branch wood handsheets had higher strength properties and brightness than those of stem wood handsheets.

The growing need for wood in construction and furniture production has led to a gradual increase for interest in other tree components, such as the use of root wood. However, to evaluate the quality of wood, one must consider its mechanical, anatomical, and physical characteristics. African mahogany (Khaya ivorensis) is a hard and durable wood that has been over-exploited. However, its other tree components, such as root wood, are available and considered waste left to rot. This study investigated the physical and mechanical properties of mahogany root wood and known properties of other wood species as an alternative base for wood resources. Root samples were extracted from three trees with three roots each, with average diameters of 54.3 cm, 23.3 cm, and 20.6 cm for trees 1, 2, and 3, respectively, and prepared according to BS 373 standard. All tests were investigated at the Kumasi CSRI (FORIG) laboratory. The results indicated that the root wood of the species dried at 17 - 20 % MC proved to be as good a material as its stem wood and branch wood counterparts in terms of physical and mechanical properties. Basic density values averaged 508 kg/m3, 531 kg/m3, and 569 kg/m3 across the roots. The green moisture content was 80 %, 76 % and 70 % for tree 1, 2, and 3, respectively. Average shrinkage was 0.84 %, 4.58 %, and 6.28 %, respectively, in longitudinal, tangential, and radial direction. MOE recorded 6724.4 MPa, 9276.0 MPa and 10010.0 MPa, MOR was 54.3 MPa, 76.1 MPa, and 78.5 MPa, compressive strength parallel to the grain was 41.8 MPa, 54.4 MPa, and 59.2 MPa, shear strength values ranged from 14.3 MPa, 15.4 MPa, to 17.2 and Janka hardness from 3.81 kN to 4.01 kN for tree 1, 2, and 3. Most of the recorded root wood results weresimilar to those of the stem and branch wood, indicating that it was equally fit for structural purposes.

Calycophyllum spruceanum Benth. is an important tree for timber and energy in the western Amazon, with expanding national and international markets for its wood. There is relatively little information, however, about geographic variation in tree growth and wood properties, and correlations among these traits. The first provenance trial was established with farming communities in the Peruvian Amazon. Seven provenances, sampled from regions near the equator, were tested in three planting zones located in one watershed. Variation and correlations were investigated in stem growth at 30 and 42 months, wood density (in the lower and upper parts of the stem) and mean heat content of stem wood at 32 months. Stem height varied significantly among provenances and planting zones, but zones accounted for much more variation than provenances. Stem wood traits did not vary significantly among provenances. Wood density was greater in the lower than in the upper stem. Wood density in the upper stem and the difference in density between the lower and upper stem varied significantly among planting zones: density in the upper stem was lowest, and the difference in density between the lower and upper stem was largest in the zone where trees grew most rapidly. Phenotypic correlations between stem growth and wood density differed in sign among planting zones, suggesting that selecting fastgrowing trees could indirectly reduce wood density in environments where trees grow slowly, and increase the difference in wood density between the lower and upper stem in environments where trees grow very rapidly. Correlations between stem growth and wood heat content were stable across zones, and indicated that larger trees tended to have wood with higher heat content. Stem-wood heat content varied with provenance latitude/ longitude in the sample region, but none of the other traits varied clinally. Results indicate that there is potential to select faster-growing provenances at an early age, but this could affect wood density in certain environments.

This study aims at investigating the effect of three altitude levels (below 1800 m, 1800-2000 m and above 2000 m) on the physical and biometric properties of stem-wood and branch-wood of hawthorn species. Moreover, the relationship between wood dry density and volumetric swelling, fiber length, fiber diameter, cell wall thickness were studied. Results indicated that altitude had significant effects on the dry density, volumetric swelling and fiber length of stem wood while did not significant effects on the density of branch wood. Additionally, some physical and biometric properties had relatively greater correlation coefficients in branch wood than in stem wood whereas others had higher coefficients in stem wood compared to branch wood. Deep understanding of properties this wood species will provide a fresh insight into the relationship between wood properties and environmental factors.

Wood density is strongly related to key aspects of tree physiological performance. While many studies have examined wood density in different parts of trees for a variety of reasons, there are very few studies that have compared within-tree density variation across many trees, of many species, drawn from a large geographic area. Here, a large data set representing trees of 78 species/genera in the Eastern United States was compiled and analyzed to explore branch to main stem wood basic density relationships. The expectation was that differences in stem versus branch wood density among trees would be due to both genetic constraints and plastic responses in wood properties, due to tree growth responses to external environments. The results show a wide tree-to-tree variation in average branch density, relative to main stem density. However, there was a general pattern for overstory tree species to have high tree branch density relative to stem density, at lower stem densities, and a declining branch to stem wood density ratio as stem density increased. Evergreen gymnosperms showed the strongest change in branch to stem wood density ratios over the range of stem wood densities and deciduous angiosperms the least; deciduous gymnosperms showed an intermediate pattern, but with generally higher branch- than stem- wood densities. More cold-hearty, shade-tolerant / drought-intolerant, evergreen gymnosperms, growing at higher latitudes, showed higher branch to stem density ratios than more shade-intolerant / drought tolerant evergreen gymnosperms growing at lower latitudes. Across all trees, canopy position had a significant influence on branch to stem density relationships, with higher branch to stem density ratios for canopy dominant trees and successively lower branch to stem density ratios for trees in successively inferior canopy positions (in terms of light availability). Understory tree species, which remain in the forest understory at maximum height, showed generally lower branch than stem densities over a wide range of stem densities. The results suggested that tradeoffs between mechanical safety and whole-tree hydraulic conductance are driving within-tree differences in wood density and highlighted the need for more detailed examinations of within-tree density variation at the whole-tree level.

ContextForest harvest removal may cause nutrient depletion of soils, when removal of essential nutrients, including nitrogen (N), phosphorus (P), sulphur (S), calcium (Ca), potassium (K) and magnesium (Mg) exceeds their net input by deposition and weImpacts of acid atmospheric deposition on woodland athering minus leaching. Nutrient removal by harvest depends on tree species and the harvesting method, i.e. whole-tree harvesting (removal of stems and branches) versus stem wood removal only.AimThe aim of this study was to assess the impacts of these two harvesting methods on nutrient removal in Dutch forests exposed to high-nitrogen deposition.MethodsTo assess those impacts, we measured nutrient concentrations in stem wood and branch wood of seven major tree species in the Netherlands, i.e. Japanese larch (Larix kaempferi Lamb.), Norway spruce (Picea abies L. Karst.), Douglas fir (Pseudotsuga menziesii Mirb.), Scots pine (Pinus sylvestris L.), silver birch (Betula pendula Roth), beech (Fagus sylvatica L.) and common oak (Quercus robur L.). Average nutrient concentrations in stems were based on measured concentrations in heartwood, sapwood and bark and estimated volumes and densities of these compartments. Similarly, average nutrient concentrations in branches were based on measured concentrations in coarse branches, fine branches and the bark of coarse branches and estimated volumes and densities of these compartments. Removal was assessed by using the average growth rates of these tree species on nutrient poor sandy soils in the Netherlands.ResultsCompared to other countries, N concentrations in the Netherlands were higher in stems, while phosphorus, Ca, K and Mg concentrations in both stems and branches were nearly always lower. The elevated long-term N deposition levels in the Netherlands most likely contribute to this finding, since N deposition causes soil acidification reducing the availability of Ca, K, Mg and P, that could become limiting to growth. Limits for sustainable harvest, above which outputs exceed inputs of nutrients, depend on nutrient, soil type and tree species and are mostly determined by K and P and sometimes Ca, which may already be depleted at relatively low harvest levels on poor sandy soils, in particular for broadleaved species, while depletion of Mg is not likely. Nevertheless, the average growth of forests in the Netherlands appears to be slightly higher than in most other countries in Europe.ConclusionOverall, we thus conclude that limited P, Ca, Mg and K availability in response to elevated N deposition is reflected in reduced contents of these nutrients in stem wood and branch wood but not in growth.Key messageNutrient concentrations in tree compartments were assessed for seven major tree species in the Netherlands. Concentrations of phosphorus, calcium, potassium and magnesium (base cations) in stems and branches are mostly lower compared to those in other countries, while nitrogen concentrations are higher. A long-term nitrogen deposition has likely contributed to these differences. The average growth has not declined, despite the low availability of phosphorus and base cations. Limiting the harvest of branch wood is suggested on nutrient poor soils to avoid depletion of phosphorus and base cations.

Effects of tree selection on strength properties and distribution of structural roots of clonal Sitka spruce