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1.
Interpretation of X-ray diffractograms of wood for assessments of microfibril angles in fibre cell walls 总被引：1，自引：0，他引：1
J. D. Boyd 《Wood Science and Technology》1977,11(2):93-114
Summary Graphical models have been developed to represent X-ray diffraction patterns for microfibril arrangements in each of the characteristic secondary wall layers of fibres in normal earlywood, latewood, compression wood, and tension wood. Models for usual combinations of typical layers S1, S2, and S3, and for complex tissues including more than one S2 layer class indicate a basis for a new analytical technique for diffractograms.Diffractograms of tissues from earlywood or latewood zones may involve effects of three to four S2 layer variations, possibly including tension wood or compression wood. The new technique enables assessment of the microfibril angle for each. Corresponding probable experimental errors are considered. Thus it is demonstrated that, even without direct calibration by other methods for measuring microfibril angle, realistic comparative values may be obtained for all S2 layer classes substantially represented. Such data constitute significantly more reliable indices of actual values than those provided by other techniques. Also, the data give qualitative information on other aspects of the variability of fibre types within each specimen. 相似文献
2.
T. E. Timell 《Wood Science and Technology》1973,7(2):79-91
Summary A study has been made of the histology and ultrastructure of opposite wood in Larix laricina, Picea rubens, and Pinus resinosa. The width of the growth rings varied considerably, in one case from 0.1–1.0 mm, with the wide rings containing a much higher proportion of latewood than the narrow ones. The earlywood tracheids were square in outline and more regularly arranged than in normal wood. In the latewood they were sometimes irregular and distorted. The S3 layer in the tracheids was 0.2 m thick in the earlywood and 0.4–0.8 m in the latewood, as compared to a thickness in normal wood of 0.1–0.2 m in both zones. The S3 was often buckled in the latewood and was terminated towards the lumen by a spiral thickening. The cell wall structure of the tracheid pit border was described. Normal coniferous wood might be regarded as an intermediate between opposite wood and compression wood.This paper is dedicated to Dean Edwin C. Jahn in honor of his 70th birthday. 相似文献
3.
Variability of selected wood characteristics in 40 half-sib families of black spruce (Picea mariana)
Summary Based on 15-year-old black spruce (Picea mariana) trees from 40 half-sib families sampled from 9 blocks of a family test in New Brunswick, this study examined intertree and intratree variation in various wood density and ring width characteristics. Of various variance components of the intertree variation, a remarkable variance component due to family was found in wood density characteristics (viz. average wood density, average earlywood density and latewood density of the tree), and these characteristics are thus under strong genetic control (h
i
2
ranging from 0.60 to 0.86, and h
f
2
from 0.56 to 0.68). It, to a lesser extent, applies to ring width characteristics at the tree level (viz. average ring width, and average earlywood width, latewood width and latewood percent of the tree) that show a lower heritability (h? from 0.18 to 0.28, and h
f
2
from 0.22 to 0.36). Both block and block × family interaction contribute little to the total intertree variation encountered in 40 families from 9 blocks, while tree-to-tree variation within the family accounts for most (over 3/4) of the total intertree variation.Compared to the intertree variation (tree-to-tree variation within the family), the intratree variation in various wood characteristics studied is considerably larger in this species. It appears that most intraring wood density characteristics show a relatively smaller intertree variation but a relatively larger intratree variation as compared to ring width characteristics (except latewood width and latewood percent). Latewood width and latewood percent show the smallest intertree variation and the largest intratree variation. Between the two sources of the radial intratree variation, cambial age explains much more variation in most intraring wood density characteristics, while ring width accounts for more variation in earlywood width, latewood width and intraring density variation. This indicates that wood density of growth rings in this species is dependent more on cambial age than ring width (growth rate). Among various wood density and ring width characteristics studies, maximum (latewood) density shows the strongest response to calendar year. This characteristics is thus a useful dendroclimatic parameter in this species.I would like to thank Dr. E.K. Morgenstern and Mr. D. Simpson for their involvement in the planning of this study. Thanks are also due to G. Chauret, T. Keenam, R. Ploure, V. Steel and C. Reitlingshoefer for their technical assistance 相似文献
4.
Genetic parameters for various wood density traits were estimated in 29-year-old trees of 18 full-sib families of hybrid larch
(Larix gmelinii var. japonica × Larix kaempferi) F1. Intra-ring density variation (IDV) was also evaluated using a model that expresses the pattern curve from earlywood to latewood
as a power function. A high IDV indicates an abrupt change in wood density from earlywood to latewood. The ring width and
wood density traits of individual rings were determined by X-ray densitometry. Overall wood density (RD) was shown to increase
with increasing ring number, ranging from 0.42–0.59 g/cm3, whereas IDV of individual rings decreased gradually from pith outwards. Estimates of individual tree narrow-sense heritability
of RD and IDV were 0.66 and 0.67, respectively. IDV showed negative genetic and phenotypic correlations with RD (r
g = −0.99, r
p = −0.72). The predicted genetic gains in latewood proportion and IDV were higher than that of RD. These results suggest that
the intra-ring density variation is under moderate genetic control equivalent to wood density. The trend of increasing wood
density from earlywood to latewood was associated with changes in both tracheid diameter and cell wall thickness. 相似文献
5.
Ultrastructural analysis of softwood fracture surfaces 总被引：2，自引：0，他引：2
Assistant Professor A. G. Zink Professor P. J. Pelikane Associate Professor C. E. Shuler 《Wood Science and Technology》1994,28(5):329-338
Summary The ultrastructural characteristics of fracture surfaces from southern pine and Douglas-fir specimens tested in tension at various angles to grain were examined. The fracture surace morphology was inspected using scanning electron microscopy. Three anatomical failure types were recognized: intercell failure, transwall failure, and intrawall failure. Certain failure characteristics were ascribed as a function of the magnitudes of paralleland perpendicular-tograin tension and parallel-to-grain shear present in the specimen. In specimens tested in paralleland perpendicular-to-grain tension, the thick-walled latewood cells were found to fail in a combination of transwall and intrawall failure. The intrawall failures were usually at the S1–S2 interface. The more thin-walled earlywood cells were more likely to exhibit abrupt, transwall failures. At intermediate angles of load to grain, surfaces indicative of the type found in pure shear tests were predominant. Perpendicularto-grain tension failures resulted in mostly intercell failures. Ray cells consistently exhibited transwall failures. The failure surface frequently changed planes in all loading modes. This path transfer was inevidably associated with material discontinuities in the wood. When the path did transfer, all three failure types were observed. No significant species effect was observed. 相似文献
6.
Variations and correlations of various ring width and ring density features in European oak: implications in dendroclimatology 总被引：1，自引：0，他引：1
S. Y. Zhang 《Wood Science and Technology》1997,31(1):63-72
Summary Variations and correlations of various ring width and ring density features were analyzed in 18 European oak (Quercus petraea andQuercus robur) trees from northeastern France. In light of these analyses, the goodness of various tree-ring features as a climatic parameter was discussed. In general, ring density features (viz. earlywood density, latewood density, average ring density, minimum density and maximum density) show a stronger response to calendar year, a comprehensive climatic variable, than ring width features (viz. earlywood width, latewood width, total ring width and latewood percent). The response of latewood features (viz. latewood width, latewood density and maximum latewood density) is stronger than that of earlywood features (viz. earlywood width, earlywood density and minimum earlywood density). Average ring density seems to be the most sensible tree-ring feature in European oak in terms of the response to calendar year. Moreover, total ring width as a climatic parameter is not as good as latewood width, and maximum (latewood) density and minimum (earlywood) density appears not to contain as much climatic information as (average) latewood density and (average) earlywood density, respectively.This project was supported by the institut National de la Recherche Agromonique (INRA). Thanks are due to Dr. G. Nepveu for his constant encouragement and assistance during this study 相似文献
7.
Genetic parameters for early wood and latewood densities and development with increasing age in Scots pine 总被引：1，自引：0，他引：1
8.
《Forest Ecology and Management》1986,17(4):253-259
Three oak species from East Tennessee were core-sampled to determine whether the density of wood produced in a pre-pollution period (1940–45) was different from that of a pollution period (1970–75) using gamma-densitometry. Component densities of average earlywood, average latewood, minimum earlywood, maximum latewood and average periodic density for Quercus alba L. and Quercus prinus L. were significantly greater for 1940–45 than for 1970–75. Differences between the two time periods for mean earlywood (P = 0.05), maximum latewood and mean periodic densities were found for Q. velutina. 相似文献
9.
T. C. Innes 《Wood Science and Technology》1996,30(6):373-383
Summary Tangential shrinkage was measured on longitudinal-tangential slices of separate earlywood and latewood from one board of Eucalyptus regnans F.Muell. at various temperatures. Large amounts of collapse shrinkage were measured in the latewood slices, and lesser amounts in the earlywood slices. Collapse shrinkage in the earlywood was found only when the slices were dried at temperatures above a minimum temperature (the collapse threshold temperature). End-coated board sections approximately 200 mm long were rapidly dried at dry-bulb temperatures below the collapse threshold temperature for earlywood. Incipient internal checks were found in the latewood of these boards. Board sections dried at higher temperatures showed internal checks starting in both early and latewood. A non-linear drying simulation model was modified to take the heterogeneous nature of wood into account. This model predicted that internal checks would form in this wood even if it were dried sufficiently slowly to avoid surface checking.Symbols D
Diffusion coefficient
- ec
Creep strain
- ei
Instantaneous strain
- em
Mechano-sorptive strain
- en
Net strain
- eu
Unconfined shrinkage strain
- EW
Earlywood
- FSP
Fibre saturation point
- LW
Latewood
- L-T
Longitudinal-tangential slice
- MC
Moisture content (kg water/kg dry wood)
- q
Moisture concentration
- R-T
Radial-tangential slice
- t
Time
- y
Depth in board
The author is pleased to acknowledge the assistance of Emeritus Professor A. R. Oliver, Associate Professor P. E. Doe, University of Tasmania, and the Australian Furniture Research and Development Institute 相似文献
10.
The fracture behaviour of single wood fibres is governed by geometrical constraints: in situ ESEM studies on three fibre types 总被引：1，自引：1，他引：0
In situ tensile tests were performed in an environmental scanning electron microscope (ESEM) on earlywood, transition wood
and latewood cells of Norway spruce (Picea abies [L.] Karst.). In order to examine the single wood fibres in a wet state, a specially designed tensile testing stage with
a cooling device was built. The fracture behaviour of the cell types was studied at high resolution while straining. Different
failure mechanisms were observed for the three tissue types. The thin-walled earlywood fibres showed tension buckling which
gave rise to crack initiation and resulted in low tensile strength, whereas thick-walled latewood fibres predominately failed
by transverse crack propagation without fibre folding. 相似文献
11.
In this study, the contact angles of four different reference liquids (including distilled water, diiodomethane, formadide
and glycerol) formed on the surfaces of wood, treated with chromated copper arsenate (CCA) and two other emerging copper-based
water-borne systems (commercial names: NW and NS) were measured with sessile drop method. Based on the contact angle data,
the surface energy was obtained from the acid-base approach. The total surface energy consisted of Lifshiz-van der Waals parameter
and acid-base parameter. Results showed that the NW and CCA treatments made the wood surface more hydrophobic while the NS
treatment had the reverse effect on the wood surface mainly owing to the increased penetration of earlywood. By using three
liquids, diiodomethane, formamide and distilled water, the total surface energy obtained for untreated earlywood, untreated
latewood, CCA-treated earlywood, CCA-treated latewood, NW-treated earlywood, NW-treated latewood, NS-treated earlywood and
NS-treated latewood were 43.1, 44.5, 43.4, 45.1, 49.4, 40.6, 46.0 and 40.9 mJ/m2, respectively. The surface energy of CCA-treated wood was almost the same as untreated wood. After NW and NS treatments,
the surface energy of both earlywood and latewood changed a little. However, the change was not so obvious as to draw any
further conclusion concerning the influence of NW and NS treatments on the surface energy of wood.
__________
Translated from Journal of Beijing Forestry University, 2006, 28(4): 1–4 [译自: 北京林业大学学报] 相似文献
12.
Hiroyuki Sugimoto Sakiko Kawabuchi Masatoshi Sugimori Joseph Gril 《Journal of Wood Science》2018,64(6):738-744
Transmittance and reflectance of visible light by sugi wood (Cryptomeria japonica) were investigated in the longitudinal (L) and tangential (T) directions. Transmittance was the highest in the L direction and reflectance was the highest in the T direction, suggesting that structural anisotropy influences transmittance and reflectance. Intra-ring variations observed with a microspectrometer indicated that T transmittance was higher for latewood than for earlywood, but there was no such trend in for L transmittance in which the highest levels occurred near the annual ring boundaries, on either the earlywood or latewood side, and the lowest at the transition from earlywood to latewood. Dependence of L transmittance on wavelength also showed variations according to the intra-ring position. The increasing of transmittance of earlywood at wavelengths?<?500 nm with increasing wavelength was observed, but this was not confirmed for latewood because of absorption by lignin. These observations supported a previously published finding, which was based on measurements in the radial direction, that the number of internal cell wall reflections, rather than density, determines wood lightness. Indeed, in the L direction, most of the incident light passes through lumens in earlywood and through cell walls in latewood, while it is subjected to numerous internal reflections at the interface between lumens and cell walls. This was further confirmed by the transmittance of earlywood being greatly decreased by radial compression. 相似文献
13.
The ring characteristics and screw withdrawal resistance (SWR) of naturally regenerated Taiwan yellow cypress (Chamaecyparis obtusa var. formosana) trees were explored. Significant differences in average ring width (RW), earlywood width, latewood width, ring density (RD),
earlywood density (ED), latewood density (LD), highest density (Dmax), lowest density (Dmin), latewood percentage (LWP), and SWR were observed between trees, rings (SWR excluded), and tree height positions. The RW
components in the radial direction increased from the pith outward to about the 3rd to 5th ring and then decreased to about
the 25th ring; it was almost constantly sustained toward the bark side. The RD in the radial direction slowly decreased from
the pith outward to the bark side. Average ring width and ring density were significantly affected by the various tree growth
rates, radial ring numbers, and tree height positions. ED, LD, Dmax, Dmin, and LWP were the most important factors determining the overall RD. RW did not correlate with tree RD. SWR is correlated
with ED, RD, Dmin, LWP, and intra-ring density variation (IDV). Thus, the SWR can be used to predict wood density and in nondestructive evaluation
of a living tree. 相似文献
14.
Trairat Neimsuwan Siqun Wang Adam M. Taylor Timothy G. Rials 《Wood Science and Technology》2008,42(6):493-506
A better understanding of the sorption behavior of different wood structures could be useful in protecting wood against wood
deterioration and fungal attack. The purpose of this study was to investigate the effect of differences among earlywood, latewood,
and tree ring location within the stem cross-section of loblolly pine (Pinus taeda) on the sorption kinetics and statics of water vapor under ambient conditions. The water vapor sorption of earlywood and
latewood in different tree rings was recorded using a dynamic contact angle analyzer under relative humidity changes from
11 to 89%, as provided by saturated salt solutions. Earlywood had higher sorption rates and diffusion coefficients than latewood,
while outer tree rings had higher sorption rates and diffusion coefficients than inner tree rings. The sorption isotherms
of earlywood, latewood, and different tree ring locations within the stem cross-section were fitted very well by a Hailwood–Horrobin
model. 相似文献
15.
对10个10年生日本落叶松无性系的早材和晚材微纤丝角进行了测定,结果表明:早、晚材微纤丝角无性系间差异极显著,同一年轮内早材微纤丝角大于晚材.日本落叶松微纤丝角的径向变异规律为:在髓心处最大,以后逐渐减小.早、晚材微纤丝角与树木年轮间的变异模式(径向变异)以对数和乘幂式方程拟合效果较好,R2(R为相关系数)均在0.8以上.早、晚材微纤丝角同树高、形率、树皮厚度、主枝粗、枝干比、主枝夹角、主枝长的相关关系不显著,早、晚材微纤丝角同胸径、冠幅的相关关系达到显著水平;早材与晚材的微纤丝角也相关显著.早材和晚材的微纤丝角受中到强度遗传控制,广义遗传力分别为0.767 4、0.804 3.按照20%的选择率,早材和晚材的微纤丝角的遗传增益分别为21.82%和29.75%. 相似文献
16.
Cornelia Krause Sergio Rossi Maxime Thibeault-Martel Pierre -Y. Plourde 《Annals of Forest Science》2010,67(4):402-402
17.
《Scandinavian Journal of Forest Research》2012,27(5):462-469
Abstract Wood properties, including tracheid cross-sectional dimensions, show a large degree of variation. To improve the properties of products made from wood, different methods to control variation have been developed. This study aims to determine the theoretical efficiency of three control strategies: the fractionation of pulped tracheids into earlywood and latewood, the separation of juvenile and mature wood, and sorting of logs according to tree size. The efficiency of each method was studied by first constructing virtual trees from measured tracheid cross-sectional dimensions, then simulating the efficiency of above-mentioned methods. The tracheid dimension data include Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.). The simulations show that separation into earlywood and latewood classes has the highest theoretical efficiency and yields the lowest variances in raw material. Classification into juvenile and mature wood groups is the second most efficient method, and the sorting of logs according to the size class of the tree is the least efficient method. It was also concluded that the variation in cell-wall thickness and radial diameter mainly originates from differences between earlywood and latewood, whereas the variation in tangential diameter mainly originates from differences between mature and juvenile wood. 相似文献
18.
Transverse swelling and its anisotropy in hinoki (Chamaecyparis obtusa) in several kinds of organic liquids and in water were investigated by means the replica method. There was more cross-sectional swelling of cell walls and cell wall thickness in earlywood than in latewood. Marked swelling toward cell lumens was observed in wood swollen in liquids that had higher swelling potentials than water. This suggests that the swelling of cell walls in these liquids is much greater than the external swelling. Feret's diameters of the cell lumens were reduced by swelling in all the observed cases except in the tangential direction of earlywood, suggesting that cell walls swell to a much less extent in width than in thickness. Deformation of cell shapes caused by the tensile force from the latewood were observed in the earlywood and in the transitional region from earlywood to latewood. When swollen in water, transverse swelling anisotropy caused only by the swelling in cell wall thickness were calculated to be 1.2 for the whole region over an annual ring and 1.4 for the earlywood. These values could not account for the external swelling anisotropy of 2.1. Considering obvious deformations of cell shapes in the earlywood and in the transitional region, we conclude that the interaction between earlywood and latewood is one of the prime factors contributing to the transverse swelling anisotropy of coniferous wood.Part of this report was presented at the 48th Annual Meeting of the Japan Wood Research Society, Nagoya, April 1998 相似文献
19.
T. E. Timell 《Wood Science and Technology》1973,7(3):163-172
Summary The distribution of lignin in opposite wood has been studied by removing the polysaccharides with hydrofluoric acid and examining the resulting lignin skeletons in the electron microscope. The thick S3 layer was more highly lignified than the S1 and S2 layers in Abies balsamea, Picea rubens, Pinus resinosa, and Tsuga canadensis. In Picea rubens, but not in the other species, there was, adjacent to the S3 layer, a transition zone in S2 with a high concentration of lignin. The S3 layer varied considerably in thickness and was often buckled, especially in the latewood. The structure of the bordered pits was that observed in the original wood. The margo, the torus, and the initial pit border were all highly lignified.This paper is dedicated to Dean Edwin C. Jahn in honor of his 70th birthday. 相似文献
20.
对10个10年生日本落叶松无性系的木材基本密度、管胞参数进行了测定.结果表明:木材基本密度,早、晚材管胞宽度和早材长宽比无性系间差异显著;木材基本密度,早、晚材管胞长度,早晚材管胞宽度和早晚材长宽比径向变异模式相似,即从髓心向外以曲线形式不断增加,有时亦有起伏;早材从髓心向外以近似直线的形式缓慢增加,晚材从髓心向外以曲线形式增加,初期增加幅度较大,到一定年龄后趋于水平变化并略有波动;材质性状与树木年轮间的关系以对数方程、幂函数方程、指数方程拟合效果较好;除了晚材壁腔比和早材壁厚外,其它木材性质的重复力均在0.5以上,受中度或中度以上的遗传制约,按照20%的选择率,长宽比和晚材管胞长能获得较高的遗传增益. 相似文献