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Variations in intrinsic wood properties [growth ring width (GRW), specific gravity (SG), fiber length (FL), and microfibril angle (MFA)] of 17–19-year-old Melia azedarach trees grown in two sites in northern Vietnam were investigated for effective utilization of the wood. Five discs were collected at 0.3-, 1.3-, 3.3-, 5.3-, and 7.3-m heights above the ground. The estimated mean GRW, SG, FL, and MFA were 7.44 mm, 0.548, 1.07 mm, and 14.65°, respectively. There were significant (P

Indole acetic acid (IAA) was believed to be an important regulator in xylem formation in conifers. However, few studies have been done on the endogenous amount of IAA in cambial region tissues in sugi (Cryptomeria japonica) trees. In this study, we report the IAA amounts in the lower and upper trunk of mature sugi cultivars (Kumotoshi, Yaichi and Obiaka) in September, and the effects of growth traits on the IAA amounts. The effect of height position (lower or upper trunk) on IAA amounts was found to be larger than that of genetic variation (Kumotoshi, Yaichi or Obiaka) by two-way ANOVA. There was no significant interaction effect (genetic variation × height position). The IAA amounts of all trees varied from 3 to 42 ng/cm2 at the lower trunk and 9 to 47 ng/cm2 at the upper trunk. Crown length and distance from crown base had significant positive and negative effects on IAA amounts in the trunk of sugi cultivars, respectively. Distance from crown base had a larger effect on IAA amounts than crown length. In Yaichi, taller trees had larger IAA amounts at both the lower and upper trunk.

Recently, breeding programs have attempted to produce high growth rates for shorter rotation cycles in plantation trees. In these trees, the ratio of juvenile wood increases; thus, the juvenile wood properties should be improved for structural use. To this end, it is important to understand the influences on juvenile wood properties precisely. In this study, we report on the indole acetic acid (IAA) amounts of juvenile sugi (Cryptomeria japonica) trees in September and compare the IAA amounts to those in mature trees. The IAA amounts at the lower trunks in juvenile trees were significantly larger than those in mature trees and the IAA amounts decreased with tree height. In each stand, except a mature tree stand, there is no significant effect of IAA amounts on latewood width and MFA. However, put together all samples, the latewood width and MFA increased with IAA amounts in samples with IAA

To clarify the mechanical behaviour differences between earlywood and latewood, separated the early- wood and the latewood specimens loaded to the rupture with tensile load parallel to the grain. The separated test specimens for tensile test were prepared from douglas fir (Pseudotsuga menziesii) and stress-strain relation was evaluated by optical measurement system using the Digital Image Correlation (DIC), which can visualize strain during the tensile test. The results are summarized as follows: The estimated strain data by universal testing machine show good accordance with that estimated by DIC. There was a difference in the fracture pattern of the earlywood and the latewood of douglas fir that the surface of ruptured earlywood typically simple while that of was somewhat complicate. The longitudinal tensile strength of earlywood specimens of douglas fir at wood height from ground 12.8 m, 9.8 m, 6.7 m and 0.9 m were 51 MPa, 69 MPa, 110 MPa and 114 MPa, while those of latewood were 208 MPa, 234 MPa, 247 MPa and 198 MPa. Elastic modulus in the longitudinal tensile of earlywood speci- mens of douglas fir at wood height from ground 12.8 m, 9.8 m, 6.7 m and 0.9 m were 5458 MPa, 7202 MPa, 9705 MPa and 8761 MPa, while those of latewood were 13747 MPa, 19405 MPa, 17365 MPa and 14044 MPa.

Pinus patula is one of the major exotic species grown in Malawi mainly for saw-timber production. It is native to Mexico. Little has been reported about the mechanical properties of the wood. The objective of this study was to investigate the mechanical properties of Pinus patula in more detail, in order to provide a basis for utilizing this resource. The mechanical properties of small clear wood specimens of Pinus patula were evaluated using 40 cm logs from 1, 3, 5, 7 and 9 m above the ground. Small clear wood specimens were selected and subjected to a bending test in accordance with Japan Industrial Standards (JIS) air-dry conditions. The growth rate did not affect the mechanical properties measured. There were significant correlations at 1% level between air-dry density and Modulus Of Elasticity (MOE) (R = 0.85) and between air-dry density and Modulus Of Rupture (MOR) (R = 0.83). There was also a significant correlation between MOE and MOR at 1% level (R = 0.90). At about 12% moisture content, the tested five Pinus patula families have average MOR and MOE of 105.17 MPa and 10.93 GPa, respectively.

Growth ring structure and wood density were compared among five families of Pinus patula planted in Malawi, Africa. The vertical and radial variations of wood density and growth characteristics were investigated in stems of 30-year-old Pinus patula planted at a spacing of 2.74 × 2.74 m. The pattern of ring width with cambial aging was broadly similar at all stem heights: wide to the 4th growth ring, decreasing gradually up to the 10th ring and then very narrow towards the bark. In all the families, the first complete growth ring was the widest, ranging from 20 to 50 mm across the families. This trend was different from other similar studies carried out in Zimbabwe and South Africa where the growth ring width increased from the 1st to the 3rd ring with the highest ring width of 19 mm. Specific gravity varied with height above the ground for all the trees. The average specific gravity was 0.56. Weak to medium correlations between latewood percentage and specific gravity were observed. The study shows that selection for density in Pinus patula could be made at least by the age of 10 years.

Successful development of an appropriate tree breeding strategy and wood utilization requires information on wood properties. This study was therefore conducted to assess wood density and mechanical properties of Pinus kesiya Royle ex Gordon grown in Malawi. Wood samples from six families of P. kesiya at the age of 30 years were used for the study. The estimated mean wood density, Modulus of Elasticity (MoE), Modulus of Rupture (MoR) and moisture content were 0.593 ± 0.001 g/cm3, 13.46 ± 0.07 GPa, 113.67 ± 0.57 MPa and 12.08% ± 0.03%, respectively. There were statistically significant (p < 0.001) differences in wood density and mechanical properties along the radial direction and stem height. Wood density and mechanical properties increased from pith to bark and decreased from the butt upwards. There were no significant (p > 0.05) differences in wood density and mechanical properties among the families. This is an indication that any tree among the families can be selected for tree improvement programs if density is considered as a variable. Wood density had a strong positive significant linear relationship with both MoE (r = 0.790; p < 0.001) and MoR (r = 0.793; p < 0.001). This suggests that it has the potential to simultaneously improve the wood density and mechanical properties of this species. Therefore, controlling wood density for the tree improvement program of P. kesiya in Malawi would have a positive impact on mechanical properties.

Hinoki (Chamaecyparis obtusa) wood has been used as a structural material in Japan because of its superior mechanical properties, its excellent durability and the beautiful color of its heartwood. Variations of termite resistance and compositions of extractives among hinoki trees have been reported. However, genetic variation of termite resistance and the effect of heartwood color on termite resistance remain unknown. In this study, we report the characteristics of termite resistance and color indexes (L*, a* and b*) of heartwood of hinoki half-sib families in a progeny test stand. The survival days of termites and the mass loss of samples of hinoki heartwood differed significantly among hinoki families. Families with red-color heartwood had larger termite resistance than families with yellow-color heartwood. The termite resistances of individual samples from two families with yellow-color heartwood were as small as that of Pinus densiflora. Larger a* and smaller b* induced larger termite resistance of heartwood. The effect of DBH (diameter at breast height) of hinoki trees on termite resistance of hinoki families was small.

We investigated clonal and site variations in wood fiber length, microfibril angle, and specific gravity of seven natural hybrid clones of Acacia (Acacia mangium × Acacia auriculiformis) grown in northern and southern Vietnam. Fiber length did not differ between clones or between sites. The microfibril angle of the S2 layer did not significantly differ between clones but significantly differed between sites. Clone and site significantly affected specific gravity. The significant effects of genetic × environmental interactions on wood properties indicated the difference in the response of clones to different growing conditions. The trends of changes in fiber length, microfibril angle, and specific gravity from the vicinity of the pith to near the bark were similar for all clones at each site; however, variations in fiber length, microfibril angle, and specific gravity were more visible in northern Vietnam than in southern Vietnam, with a significant effect of genetic factors. This difference may be attributable to winter, which is experienced in northern Vietnam but not in southern Vietnam. For clone selection for plantation in the northern region, combining growth rate with wood properties was recommended. On the other hand, for plantation in the southern region, clone selection depends mainly on the growth rate, taking into consideration the specific gravity.

Wood is widely used as a housing material because of its environmental superiority, good mechanical properties, fine appearance, and high thermal insulation properties. However, wood is a sound reflecting material with a relatively low sound absorption capability. It is recognized that the sound absorption capability of wood is influenced by air permeability that varies by the sound incident surface structure. Wood is a porous material which has numerous cylindrical pores in the fiber direction. However, the permeability of wood is relatively low because there are very few continuous pores in wood. The pores in wood are classified into three types: through, blind, and closed. Among these pores, only the through pore has continuous vessel elements that readily permit fluid flow. Furthermore, the formation of pit–aspirations in softwoods or tylosis in hardwoods restricts the air or liquid flow in wood. Improving the permeability of wood has been an interest of many wood researchers because highly permeable solid wood can be treated easily by a functional treatment that allows the good dimensional stability, fire proofing, and other traits. It is generally recognized that wood treatability increases with permeability. Several treatments, such as steaming, extraction with solvents, and degradation with enzymes or microorganisms, have been attempted to increase the permeability of wood. However these treatments did not have a sufficient effect on increasing permeability, and a useful method has not yet been developed. In a previous paper, Kang et al. (2008 a) reported that the delignification treatment by Wise’s method improved wood permeability in the fiber direction, and that the sound absorption capability on the cross sectional surface of Larix kaemferi increased, as compared with the control wood. Also, it was found that the sound absorption capability of a mushroom bed log of Mongolian oak degraded by fungus over four years was 2–3 times higher than that of control wood (Kang et al., 2008 b). On the other hand, steam explosion is used in the field of pulp and fiberboard manufacturing or the wood– based biomass industry and is exposure to violent pressure and temperature changes via steam. For this treatment, the target material is mounted in a closed chamber, and then superheated steam is introduced from a boiler. The superheated steam heats the chamber and target material to a high temperature and pressure, which is maintained for a moment and then discharged abruptly by a blasting device. By this process, high–pressure Changes in Permeability and Sound Absorption Capability of Yellow Poplar Wood by Steam Explosion Treatment

A dye injection method was used to elucidate the xylem water-conducting pathways of 34 broadleaved evergreen trees growing in southern Japan: two semi-ring-porous, 26 diffuse-porous, five radial-porous and one non-vessel species. The large earlywood vessels in semi-ring-porous species have a water transport function in only the outermost annual ring, as in deciduous ring-porous species. On the other hand, the small vessels in semi-ring-porous species maintain the water transport function in many outer annual rings. For the other xylem-type species, the many vessels in many outer annual rings have a water transport function. In diffuse-porous species, we categorized the water-conducting pattern within the annual rings into two types: d1 type, where water travels through vessels in the whole region; and d2 type, where water travels mainly through the earlywood vessels. The pattern in radial-porous species is similar to that in the d1 type; the pattern in non-vessels species is similar to that in the d2 type. The vessel diameter in radial-porous species is similar to that of the earlywood vessels of semi-ring-porous species. These results suggest that the conduit diameter size is only one of many factors determining the water-conducting pathways of broadleaved evergreen species.

Growth, specific gravity, and wood fiber length of Acacia mangium, Acacia auriculiformis, artificial acacia hybrid clones, and combinations, which were planted in a trial forest in Bavi, Vietnam, in July 2001, were examined. The radial variations from pith to bark were investigated to clarify the effect of genetic factors on these traits. Superiority of hybrids over their parents ranged from 36.3% to 41.6% for diameter, from 20.0% to 25.3% for height, from 6.9% to 20.7% for specific gravity, and from 6.1% to 12.8% for wood fiber length. The hybrid possessed heterosis in diameter, height, specific gravity, and wood fiber length regardless of whether the female parent was A. mangium or A. auriculiformis. The profiles of wood fiber length and specific gravity in the radial direction were similar for all the trees investigated. Wood fiber length was initially 0.5–0.6 mm near the pith and then increased slowly, finally reaching 1.0–1.2 mm near the bark. The specific gravity of acacia increased from 0.49–0.58 near the pith to 0.63–0.74 near the bark. From a relative distance of 30% from the pith, the specific gravity increased slightly and seemed to be stable. The relations among tree diameter, specific gravity, and wood fiber length were fair and could be represented by positive linear regression formulas. Hybrids for which A. auriculiformis was the female parent and A. mangium was the male parent had a faster growth rate and longer wood fibers than the inverse hybrids.

Wood properties of six 8-year-old natural acacia hybrid clones between Acacia mangium and Acacia auriculiformis, planted in Bavi, Vietnam, were studied. The hybrid clones possessed obvious heterosis in growth and in some wood properties. The characteristics of growth, air-dry specific gravity, lengths of fibers and vessel elements, S2 microfibril angle, green moisture content, and shrinkage were examined to clarify the variation among clones. From the results, the differences among the clones in growth and in some wood properties were significant. The pattern of distribution of specific gravity showed that there were low and high specific gravity zones in the stem. Specific gravity at stump height or at 3.0 m was useful for prediction of specific gravity in the whole tree stem. Moreover, clones with high specific gravity can be predicted at a young age. There was no significant correlation between diameter growth and specific gravity. Of the six clones studied, clone BV5 was selected as the best based on its growth ability and specific gravity.

The interspecific variation of dye ascent in the stems of 44 broadleaved deciduous species growing in Japan was studied using freeze-dried samples after dye injection. The dye ascending pattern differed both within and between ring-porous and diffuse-porous species. In large earlywood vessels of all ring-porous species, the dye ascended only in the outermost annual ring, and the inner annual rings had lost their water transport function. The dye ascending pattern within the inner annual rings in the ring-porous species was categorized into three types: i) the dye ascended both in the many latewood vessels throughout the latewood and small earlywood vessels; ii) the dye ascended in the many vessels throughout the latewood; and iii) the dye ascended mainly in the late latewood vessels. In diffuse-porous species, the dye ascending pattern within the annual rings also was categorized into three types: i) the dye ascended throughout the annual rings; ii) the dye ascended mainly in the earlywood vessels; and iii) the dye ascended mainly in the latewood vessels. Xylem water distribution was also examined by cryo-SEM in three ring-porous and three diffuse-porous species that had different dye ascending patterns. The water distribution pattern within annual rings was correlated with the dye ascending pattern except for one diffuseporous species (Salix gracilistyla). In this case, water was distributed in the whole region of the annual rings although dye was mainly distributed in the earlywood. These results showed that the functional area of water transport within annual rings differed among ring-porous species and diffuse-porous species.

Confocal laser scanning microscopy (CLSM) was applied as a new method of visualizing the shrinkage of wood and its anisotropy. Control of relative humidity and temperature in a specialized environment chamber made it possible to acquire transverse images of tracheids of Akamatsu (Pinus densiflora) from the saturated condition to the dried condition. The shrinkage of tracheid cells was also determined by measuring the tangential diameter of tracheid and lumen, the radial diameter of tracheid and lumen, and the thickness of tangential and radial walls. Moreover, this technique makes it possible to discuss the relationship between moisture content and tracheid cell shape. We found the CLSM technique to be an effective method for visualizing shrinkage of tracheid cells with desorption.

This is the first report to ascertain potassium location in black heartwood of sugi (Cryptomeria japonica). The objective of this study was to understand the distribution of potassium in sugi black heartwood in connection with anatomical morphology. Scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDXA) was used to investigate the distribution of inorganic elements, especially potassium. In black heartwood, potassium was detected in all tissues (tracheids, ray parenchyma, and axial parenchyma), but its concentrations were different in each xylem tissue. Potassium was particularly accumulated in the droplets in axial parenchyma cells. In addition, calcium was also detected in all tissues. Phosphorus sometimes existed in the granules in ray parenchyma cells. From optical microscopy, the axial parenchyma cells were observed to be arranged in a tangential direction on transverse section and the droplets in these cells were distributed in areas of high ash and green moisture content. For red heartwood, potassium detected by SEM-EDXA was far lower in all tissues than in the black heartwood, while the trend for calcium was the converse. Potassium in axial parenchyma cells was more abundant in black heartwood than in typical pale red heartwood.

Nine trees of Cryptomeria japonica from six elite tree clones with a broad range of heartwood colors were selected. The profiles of pit aspiration percentage (ASP) of earlywood and latewood from pith to bark for green and air-dry conditions were determined to study the relationship between heartwood color and pit aspiration. Confocal laser scanning microscopy (CLSM) observations showed that the ASP of earlywood was low in sapwood and high in heartwood in the green condition. Pit aspiration increased in intermediate wood when compared with sapwood. On the other hand, latewood pits did not aspirate during heartwood formation. Comparing the air-dry condition with the green condition, sapwood pits aspirated during drying in both earlywood and latewood; however, there was no significant difference in pit aspiration of heartwood. There was no significant difference between samples with red and black heartwoods for ASP. The difference in ASP between individual trees was larger than that by heartwood color. The general advantage of CLSM over light microscopy is that serial optical sections along the Z axis can be obtained for any moisture condition, without the need for thin sectioning or embedding.

ヒノキ根材と幹材において, 晩材仮道管二次壁中層のミクロフィブリル傾角 (MFA) の放射方向変動と樹高方向および根端方向の変動を調べた。胸高部位では20年輪目前後でMFAは安定した。地上高が高くなるとMFAの安定時期は早まり, 8m部位では10年輪目前後で安定した。しかし, MFAの安定値には地上高による差異がなかった。根材では10年輪目前後でMFAは安定し, 基部からの距離や径の大きさに関わらず, 安定値や安定時期に大差は見られなかった。採取が容易な基部から根端側へ20cm部位の根材を使って, 幹の成熟材部の予測可能性を検討した結果, 根材の安定値と幹材の安定値との間に1%レベルで有意な相関関係が認められた。順位相関もまた1%レベルで有意であった。根材の18～20年輪目のMFAと幹の安定値との間には0.1%レベルで有意な相関関係が認められたが, 若い年輪では有意な相関関係は認められず, 早期予測は困難であった。一方, 直径が40mm以上の根材の最外部から幹の成熟材部MFAが予測可能であることが示唆された。

銅系水溶性防腐剤の固着性を木材組織ごとに明らかにするための基礎的知見を得ることを目的に,スギ心材から得られた薄切片にCuAz水溶液を滴下し,銅元素の濃度分布をSEM-EDXA法で調べた。薄切片の使用は,木材中の銅元素の分布について,より詳細な分析を可能にした。仮道管細胞壁では早・晩材ともに二次壁に比べて複合細胞間層で銅元素が多く検出された。辺材では有縁壁孔対の壁孔膜のトールスに銅元素が早・晩材ともに集中するのに対して,心材のトールスにおける銅元素の相対濃度は辺材と比べて低かった。また半縁壁孔対の壁孔膜,軸方向柔細胞の内容物に多量の銅元素が存在した。一方,アルコール・ベンゼン抽出処理した心材における銅元素の相対濃度は,全ての部位で無処理の心材と比べて低かった。木材組織によって銅元素の濃度分布が異なった理由として,各部位を構成する木材化学成分とアミンー銅錯体との固着性の違いが考えられた。

Microfibril angles of the S2 layer and tracheid lengths were measured in the root wood of Pinus nigra, and the root and stem wood of Pinus radiata. Within 10 mm (the first 2–3 growth rings) from the root centre, microfibril angles were large in the wood of both species, ranging from 25° to 40°. Beyond 10 mm (the fourth growth ring and beyond) from the root centre, microfibril angles were small. This pattern of microfibril angle change in root wood differs from those normally found in stems where angles are large until the 10–15th rings. Root wood tracheid length also showed a different pattern in radial direction from that normally observed in stem wood. Tracheids of Pinus radiata root wood were long in the first ring, decreasing to the third ring and then increased to the seventh ring. Beyond the seventh ring tracheid length was stable at around 3 to 3.5 mm. It was noted that microfibril angles were not influenced by tracheid length in root wood.

Radiata pine sapwood and heartwood were dried with or without presteaming and then impregnated by vacuum treatment with water, toluidine blue and fluorescein. Sapwood uptake was 0.571 g/cm3 and was not affected by pre-steaming. As expected, the uptake by heartwood that had not been pre-steamed was very low. Pre-steaming increased liquid uptake from 0.113 g/cm3 to 0.438 g/cm3. When the uptake by pre-steamed heartwood from radial, tangential and transverse surfaces was compared, the greatest increase was from the radial surfaces, suggesting that pre-steaming of heartwood resulted in changes to the tangential liquid flow pathways. The liquid flow pathways in sapwood consisted ofaxial and radial resin canals, ray parenchyma cells in both fusiform and uniseriate rays. Penetration into tracheids was also observed. Without pre-steaming, there was limited liquid flow into heartwood, and this was generally confined to resin canals and ray parenchyma. Pre-steaming of heartwood increased penetration of dye into the resin canal network, presumably due to removal or redistribution of resin. Fluorescein was also evident in bordered pits between tracheids, suggesting that one of the ways that pre-steaming increased heartwood treatability was by altering the condition ofbordered pits to allow greater conduction. The combination of fluorescein dye and confocal microscopy was found to be a particularly effective way of visualising flow patterns, as it was possible to examine thick sections, which avoided microtome damage at the section surface. Examination of dry wood also minimised the possibility of dye redistribution.

Accurate prediction of genetic potential and response to selection in breeding requires knowledge of genetic parameters for important selection traits. In this study, we estimated genetic parameters for wood properties in Khasi pine (Pinus kesiya Royle ex Gordon) grown in Malawi. Data on wood properties and growth traits were collected from six families of Pinus kesiya at the age of 30. The results show that wood density had a higher genetic control (h2 = 0.595 ± 0.055) than wood stiffness (h2 = 0.559 ± 0.038) and wood strength (h2 = 0.542 ± 0.091). The genetic correlation among wood quality traits was significantly moderate (0.464 ± 0.061) to high (0.735 ± 0.025). The predicted genetic response indicated that selection for wood density at 10% selection intensity would increase stiffness and strength by 12.6% and 8.85%, respectively. The genetic correlations between growth and wood quality traits were moderately unfavourable. However, sufficient variation exists within the breeding population to select individuals with both good growth rate and high wood quality traits. It is therefore suggested that all trees with both diameter at breast height (DBH) greater than 32.0 cm and density greater than 0.593 g/cm3 must be selected in order to increase the efficiency of the breeding programme. However, in the long term, it is recommended that the best selection strategy would be to develop a multiple-trait selection index. The selection index should be developed using optimal index weights for the advanced Pinus kesiya breeding programme in Malawi.