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1.
Summary Relationships between various anatomical parameters and selected physico-mechanical properties of wood were examined statistically in East-Liaoning Oak. Path analysis revealed that the key anatomical factors influencing wood shrinkage vary with the type of shrinkage: both radial and tangential shrinkage are mainly controlled by fiber diameter, differential shrinkage mainly by microfibrillar angle and volumetric shrinkage by tissue proportions; specific gravity is determined directly by percentage of cell wall material, while the percentage, in turn, is closely related to tissue proportions, among which vessel proportion is the most important; tensile strength is closely related to microfibrillar angle and specific gravity is not always a good estimator of strength.We to express our sincere thanks to Prof. B. F. Ke and Prof. Dr. P. Baas for their support and help. The paper is based mainly on the presentation at the Timber Engineering Meeting, Saint John, Canada, July 30–August 4, 1990. 相似文献
2.
Differences in wood properties between juvenile wood and mature wood in 10 species grown in China 总被引：3，自引：0，他引：3
F. C. Bao Z. H. Jiang X. M. Jiang X. X. Lu X. Q. Luo S. Y. Zhang 《Wood Science and Technology》2001,35(4):363-375
This study examined the intrinsic differences in various wood properties between juvenile wood and mature wood in 10 major
reforestation species in China. Comparisons between juvenile wood and mature wood were made in both plantation- and naturally-grown
trees. Considerable differences in most wood properties were found both between plantation-grown juvenile wood and mature
wood, and between naturally-grown juvenile wood and mature wood. This suggests that wood properties of plantation-grown trees,
to a large extent, depends on their juvenile wood contents, and can thus be manipulated effectively through rotation age.
In general, the longer the rotation age, the lower the juvenile wood content, and the stronger the mechanical properties of
the plantation-grown woods. However, the differences between juvenile wood and mature wood vary with wood properties and species.
In general, juvenile wood and mature wood have less difference in chemical composition than in anatomical and physico-mechanical
properties. Compared to the softwoods studied, the hardwoods appear to have less difference between juvenile wood and mature
wood.
Received 25 June 1999 相似文献
3.
随着天然林保护工程的实施 ,我国木材资源结构正在进行由主要利用天然林木材到利用人工林木材的转变 .由于人工林木材所含幼龄材比例相当高 ,木材资源结构的变化反过来必将对我国的木材加工工业及林产品工业带来一系列影响 .该文综述了我国木材资源的现状 ,比较了人工林幼龄材与天然林成熟材的木材基本特性 ,探讨了人工林木材性质特征与营林培育的关系 ,阐述了木材质量与不同最终用途之间的关系 ,并对加强开展人工林木材性质的研究提出了几点建议 相似文献
4.
Variations of certain anatomical and mechanical indices within tree stems of aged sugi (Cryptomeria japonica) trees planted in Akita prefecture were studied. The determination of the juvenile/mature wood boundary was also discussed, and the effects of wood structure on mechanical properties were investigated. On the basis of radial and vertical variation of the anatomical and mechanical indices, modulus of elasticity (MOE)/ shear modulus (G) was chosen as the index for determining the juvenile/mature wood boundary. The increase rates of MOE/G at the points of 1%, 2%, and 3% were discussed. It was found that for aged trees, all three points were thought to be effective for dividing juvenile and mature wood. However, for younger trees, the point of 2% was recommended, which was mostly consistent with the result obtained by the increase rate of 1% for tracheid length (TL). Among mechanical properties, the MOE showed more significant juvenile/mature wood differences than did modulus of rupture (MOR) and . By correlation analysis, it was suggested that microfibril angle largely contributed to the indices of MOE and G, and specific gravity largely contributed to the indices of MOR and .Part of this report was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, March 2003 相似文献
5.
Log Characteristics and Sawn Timber Recovery of Home-Garden Teak from Wet and Dry Localities of Kerala, India 总被引：1，自引：1，他引：0
There is a widely held view among smallholders that teak timber produced from small-scale agroforestry systems, especially
home-garden forestry, fetches a lower price than that from conventional plantation forestry. To examine the veracity of this
view, the wood quality attributes of teak from two home gardens in the district of Ernakulam (wet site) and Palakkad (dry
site) in India were compared to those of forest plantation in Nilambur. The logs were graded using standard timber trade practices
into high, medium and low quality as determined by the potential sawn timber grade-yield recovery pattern. Of 96 home garden
teak logs (aged 35 years) from wet and dry sites, 59% belonged to timber Grade II–IV and the rest were classified as poles.
Grade I logs (export quality) with a girth above 150 cm were not available from either of the homesteads. Faster-grown teak
in the wet site produced large diameter logs (dbh 1.37 m) with average diameter of 39.6 cm, which is comparable to that of
best site quality in India. In contrast, the average dbh for teak grown in the dry site was 24 cm as compared to the average
dbh of 31 cm recorded from the same aged forest plantation in Nilambur. It was found that only 10% of logs belonged to Grade
II timber and the rest fell under grades III and IV with more frequent visual defects. The sawn timber recovery percentage
was lower for the dry site (66.8%), whereas there was no significant difference in grade from the wet and forest plantation
sites, with recovery rates of 76.5% and 78.8%, respectively. The general notion that home garden teak has a large proportion
of sapwood seems to be baseless, no significant difference being found between the heartwood-sapwood ratio of home-garden
and forest plantation teak. Lack of appropriate silvicultural practices in home-garden forestry caused the production of more
defective logs, adversely affecting the market price of timber.
相似文献
| Puthenpurayil Kumaran ThulasidasEmail: |
6.
Inter-clonal, intra-clonal and within tree variations in specific gravity and wood anatomical properties of 8-year-old grown
ramets of Dalbergia sissoo Roxb. have been investigated. Radial and location-wise intra-clonal variations were non-significant for anatomical properties
and specific gravity for all six clones at all three sites. However, inter-clonal variations in wood anatomical properties
and specific gravity were significantly different. Inter-clonal variations in anatomical properties and specific gravity were
also significant due to sites, which indicated that site-characteristics overshadowed the genetic priority of different clones
for wood anatomical properties. Average fiber-characteristics of all clones showed the best performance at Lalkuan, Haldwani
(site III), while average specific gravity performed well at Brandis Road, Dehradun (site I) followed by site III (Lalkuan,
Haldwani) and site II (Lachchiwala, Dehradun). Within tree variations in anatomical properties like fiber length, fiber diameter,
wall thickness, vessel member length and vessel member diameter due to vertical or radial direction and location (pith to
periphery) are non-significant. Radial direction, location and height showed no impact on wood element variation. It indicated
that there is no impact of juvenile wood, sapwood and heartwood ratio, and reaction wood on wood anatomical properties of
8-year-old ramet of D. sissoo. It further indicated that clone raised ramet of 8-year-old D. sissoo showed the characteristics of mature wood. Within tree variations in specific gravity were significant due to height, which
may be related to differential sapwood and heartwood ratio in the vertical direction. Different wood elements viz. fiber length,
fiber diameter, wall thickness, vessel member length and vessel member diameter showed significant correlations with each
other and with specific gravity. 相似文献
7.
R. V. Rao S. Shashikala P. Sreevani V. Kothiyal C. R. Sarma P. Lal 《Wood Science and Technology》2002,36(3):271-285
Within tree variation in anatomical properties of four and half year old grown Eucalyptus tereticornis Sm. clones have been investigated and correlated with specific gravity. Vessel frequency, vessel diameter and fiber length
were found to vary significantly from bottom to top with no definite trend. Significant variation exists in all the clones
of different parameters. Fiber length was positively correlated with fiber diameter and double wall thickness. Tissue proportions
did not show any significant variation from bottom to top. However, highly significant differences have been found between
clones among four cell types except fibers. Specific gravity is positively correlated with ray percentage, fiber percentage
– vessel percentage ratio and negatively correlated with vessel percentage, while all other anatomical parameters including
height and girth have no effect.
Received 25 August 1998 相似文献
8.
9.
The wood quality from 50- to 70-year-old Tectona grandis trees from an unmanaged forest in East Timor was assessed. The aim was to evaluate teak in mature stands that had undergone
uncontrolled disturbances, e.g., fire and local community usage. Heartwood represented 91% of the tree radius at a height
of 1.7 m, and sapwood contained on average nine rings. The mean ring width showed within-tree and between-tree variability.
The chemical compositions of heartwood and sapwood were similar. Within-tree chemical variation occurred only in terms of
extractives, which increased from the pith (8.3%) to the heartwood-sapwood transition (12.7%) and decreased in the sapwood
(9.2%). Overall, the wood properties of teak from a unmanaged forest in East Timor were comparable to those reported for plantation
teaks of other origin: 607 kg/m3 basic density, 3.5% and 5.2% radial and tangential shrinkage, 141 N/mm2 modulus of rupture, 10684 N/mm2 modulus of elasticity, and 50 N/mm2 maximum crushing strength in compression parallel to the grain. Disturbances on individual tree growth arising from the unmanaged
status of the stand were evidenced by higher within-tree variability of ring width. However, the longitudinal and radial variations
of wood density and mechanical properties were of low magnitude and in a degree that did not negatively impact on timber quality. 相似文献
10.
Growth, wood quality parameters and productivity estimations of 12-year-old teak (Tectona grandis L.f.) grown under three agroforestry systems, namely unmanaged block (Bum), unmanaged line on the farm boundary (Lum) and intensively managed block (Bim) plantations are studied. Mean annual increment (MAI) of 0.020, 0.006 and 0.016 m3 tree?1 year?1 was recorded in Lum, Bum and Bim, respectively. Overall growth performance of teak raised in Lum, plantation appears to be better than two block plantations (Bum and Bim). For evaluating various wood quality parameters, tree logs from each plantation were tested for different physical and mechanical properties according to the standard procedures. The wood quality of Bum was found to be comparatively superior to Bim and much better than those of Lum. The 12-year-old farm teak trees from three systems exhibited lower average values of different wood quality parameters compared to mature forest teak. Since physical and strength properties of Bum were inferior compared to Lum and Bim, its exploitation is not advisable at this stage. Line plantation, however, releases land for cultivation of arable crops and does not demand any special silvicultural management as required by Bim. Although, total extractable volume of teak wood available after 12-years of age from Bum was much smaller compared to Bim or Lum, its commercial exploitation at an early age may be preferred over other two practices due to better wood quality and lower management cost. For optimum economic utilization and mechanical maturity of wood, harvesting of block plantation may be delayed for about 10-15 years because growth volume and strength properties are expected to improve with age of tree. 相似文献
11.
Nakai Takashi 《中国林业科技(英文版)》2003,(2)
A comprehensive analysis on the variation pattern of early- and latewood tracheid morphological parameters along tree (Cunninghamia lanceolata Hook.) height, including length and width, wall thickness, tissue proportion, cell wall percentage, width of growth rings, and on the relationship among them are conducted. The results indicate an initially rapid and then gentle increase of tracheid length and width, thickness of the radial wall and tangential wall of tracheid, area percentage of tracheid from pith to outward, while S2 microfibril angle (Mfa) of tracheid, and rays percentage gradually decrease and then tend to be stable. The variation of all anatomical parameters but earlywood cell wall thickness shows no significance along tree height. The radial variation pattern of width of growth rings is characterized with initially slight decrease followed immediately by a rapid and then much more gentle increase from pith to outward. The delimitation age between juvenile and mature wood is 14-16 years. Com 相似文献
12.
Widyanto Dwi Nugroho Sri Nugroho Marsoem Koh Yasue Takeshi Fujiwara Toshiko Nakajima Masanori Hayakawa Satoshi Nakaba Yusuke Yamagishi Hyun-O Jin Takafumi Kubo Ryo Funada 《Journal of Wood Science》2012,58(3):185-194
The anatomical characteristics and density of wood were examined in 23-year-old Acacia mangium trees that had been planted in Yogyakarta, Indonesia. The seeds had been collected from trees of five different provenances. The distance from the pith of the boundary between juvenile and mature wood was also examined to clarify the maturity of the wood. Lengths of wood fibers near the pith and the distance from the pith of the boundary between juvenile and mature wood differed significantly among provenances. By contrast, other anatomical characteristics of the wood such as fiber wall area, fiber wall thickness, fiber diameter, vessel lumen area, vessel diameter, vessel frequency and wood density did not differ significantly among provenances. Wood density was strongly correlated with the area of fiber walls. Our observations suggest that Sidei and Daintree might be more appropriate provenances among those examined for the Acacia mangium tree-breeding programs in Indonesia that are aimed at improving wood quality, because these provenances are associated with longer initial wood fibers and narrower juvenile areas than the other provenances studied. 相似文献
13.
14.
S. Pramod 《Journal of Sustainable Forestry》2013,32(7):661-673
The anatomical changes occurring during transition from juvenile to mature wood were studied in the branch and main trunk of Leucaena leucocephala. To confirm the wood maturity in the 5-yr-old tree, the anatomical features were compared with the adult wood collected from the main trunk of a 15-yr-old tree. In both the branch and wood of the trunk, most of the anatomical features—such as increase in dimensions of fibers and vessel elements, and decrease in frequency of vessel elements and rays—were gradual during radial growth from pith to periphery. A noticeable anatomical change is observed in the transition of triseriate rays to multiseriate rays in the region of wood which is about 5.5 cm away from the pith. The ray dimensions and anatomical features of other elements from the periphery of the branch and 5-yr-old trunk xylem match with that of 15-yr-old main trunk wood. This indicates that in both the branches and main trunk of Leucaena, transition from juvenile to adult or mature wood occurs after the trees have attained 14 cm radial growth. 相似文献
15.
Marko Peura Klaas Kölln Ingo Grotkopp Pekka Saranpää Martin Müller Ritva Serimaa 《Wood Science and Technology》2007,41(7):565-583
The effect of strain on dry, clear Norway spruce (Picea abies [L.] Karst.) wood was studied by tensile testing along the cell axis and by in situ X-ray diffraction measurements. The mean
microfibril angle (MFA) was initially 3–12 degrees and did not decrease due to strain. Based on the positions of the reflections
200 and 004 of crystalline cellulose, cellulose chains elongated and the distance between the hydrogen bonded sheets of chains decreased
due to the strain. The elongation of the unit cell parallel to the cellulose chains was twice as high in juvenile wood as
in mature wood. The (X-ray) Poisson ratio ν
ca
for crystalline cellulose in Norway spruce was calculated from the deformation of the unit cell. The average ν
ca
of earlywood was 0.28 ± 0.10 in juvenile wood and 0.38 ± 0.23 in mature wood. In latewood, the average ν
ca
was 0.48 ± 0.10 in juvenile wood and 0.82 ± 0.11 in mature wood. The average ν
ca
values were not directly correlated to the crystallite dimensions or to the mean MFA in juvenile and mature earlywood and
latewood. The results show that the amorphous matrix has a definite effect on the deformation of cellulose crystallites. 相似文献
16.
Daniel Keunecke Walter Sonderegger Karol Pereteanu Thomas Lüthi Peter Niemz 《Wood Science and Technology》2007,41(4):309-327
Despite the exceptional position of yew among the gymnosperms concerning its elastomechanical properties, no reference values
for its elastic constants apart from the longitudinal Young’s modulus have been available from literature so far. Hence, this
study’s objective was to determine the Young’s moduli E
L, E
R and E
T and the shear moduli G
LR, G
LT and G
RT of yew wood. For that purpose, we measured the ultrasound velocities of longitudinal and transversal waves applied to small
cubic specimens and derived the elastic constants from the results. The tests were carried out at varying wood moisture contents
and were applied to spruce specimens as well in order to put the results into perspective. Results indicate that E
L is in the same order of magnitude for both species, which means that a high-density wood species like yew does not inevitably
have to have a high longitudinal Young’s modulus. For the transverse Young’s moduli of yew, however, we obtained 1.5–2 times,
for the shear moduli even 3–6 times higher values compared to spruce. The variation of moisture content primarily revealed
differences between both species concerning the shear modulus of the RT plane. We concluded that anatomical features such
as the microfibril angle, the high ray percentage and presumably the large amount of extractives must fulfil important functions
for the extraordinary elastomechanical behaviour of yew wood which still has to be investigated in subsequent micromechanical
studies. 相似文献
17.
Futoshi Ishiguri Imam Wahyudi Masae Takeuchi Yuya Takashima Kazuya Iizuka Shinso Yokota Nobuo Yoshizawa 《Journal of Wood Science》2011,57(3):241-246
The relationships between growth characteristics and wood properties were investigated for a threatened species, Pericopsis mooniana, to promote the establishment of plantations of this species in the tropics. Growth characteristics (diameter and height)
and stress-wave velocity (SWV) of trees were measured for 22-year-old P. mooniana trees planted in Indonesia. The trees were categorized into three groups, fast-growing, middle-growing, and slow-growing
trees, to investigate the effect of growth rate on the wood properties. In addition, radial variation of anatomical characteristics
and wood properties were determined. No significant correlation was found between growth characteristics and SWV. The values
for the vessel diameter, cell wall thickness of wood fibers, wood fiber length, basic density, modulus of elasticity, and
modulus of rupture from wood at the bark side were higher than those at the pith side. On the other hand, vessel frequency
gradually decreased from pith to bark. These results suggested that low-quality wood, such as juvenile wood, existed near
the pith area. 相似文献
18.
Yoshio Kijidani Naoki Ohshiro Daisuke Iwata Masanori Nagamine Taiga Nishiyama Junji Matsumura Shinya Koga 《Journal of Wood Science》2014,60(3):177-185
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 <200 ng/cm2. The samples at lower trunk in juvenile trees had significantly larger IAA amounts, larger MFA and larger latewood width than the samples in mature trees (p < 0.01). The very large IAA amounts may have a certain relation with juvenile wood properties. 相似文献
19.
Shijun Wu Jianmin Xu Guangyou Li Vuokko Risto Zhihu Du Zhaohua Lu Baoqi Li Wei Wang 《New Forests》2011,42(1):35-50
Growth traits, wood properties and bark percentage were assessed for 19 hybrid eucalypt clones at three sites in southern
China sampled at age 51 months. Analysis of variance showed that there were significant differences in growth traits and wood
properties between clones and sites, and that the clone × site interactions were also significant except for basic density.
Coefficients of variation ranged from 8.4 to 27.9% for growth traits, 2.7–11.1% for wood properties and 14.0–23.3% for bark
percentage. Repeatability ranged from 0.73 to 0.96 for growth traits, 0.32–0.93 for wood properties and 0.77–0.88 for bark
percentage. Strong genotypic correlations between the same traits in clones at pairs of sites indicated that the traits were
rather stable across sites. The genotypic correlations between growth traits and basic density ranged from −0.67 to 0.43,
and generally favorable negative genotypic correlations between growth traits and bark percentage were also found. The correlations
between growth traits and Pilodyn pin penetration were positive, ranging from 0.28 to 0.65 and therefore unfavorable as lower
wood density will be associated with higher values of Pilodyn pin penetration and improved growth rate. The correlations between
traits assessed using non-destructive field methods and wood property assessment results indicated that Pilodyn and Fakopp
microsecond timer tools can be confidently used to indirectly select for fiber width and basic density. 相似文献
20.
Chih-Ming Chiu Song-Yung Wang Cheng-Jung Lin Te-Hsin Yang Ming-Chun Jane 《Journal of Wood Science》2006,52(1):9-14
The fractometer is a device that breaks a radial increment core along the fiber for the measurement of crushing strength,
which is a direct wood quality indicator for structural lumber. In this study, the crushing strength of Taiwania (Taiwania cryptomerioides Hay) trees using the fractometer was investigated and the data were used to determine the position of demarcation between
juvenile and mature wood. Segmented regression and variance component analysis were used to estimate the demarcation position.
With increasing cambium age, the core wood improves the crushing strength in the outer wood area. Within-tree variations in
wood properties were greater than between-tree variations. In this experiment, the position of demarcation between juvenile
and mature wood occurred at an approximate distance of 10.8cm to 13.2cm from the pith at about 18–20 years of cambium age. 相似文献