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1.
Study of the transverse liquid flow paths in pine and spruce using scanning electron microscopy 总被引：4，自引：0，他引：4
Samples of pine (Pinus sylvestris) and spruce (Picea abies) were impregnated with a low-viscous epoxy resin using a vacuum process. The epoxy was cured in situ and the specimens sectioned. Deposits of the cured epoxy was then observed in the wood cavities using a scanning electron microscope. The investigation concentrated on tracing the transverse movements of a viscous liquid in the wood, and special attention was therefore given to the cross-field area between ray cells and longitudinal tracheids. A damage hypothesis is proposed based on the results obtained in the present investigation in combination with those from earlier studies on linseed oil-impregnated pine: In addition to the morphology of the bordered pits, viscous liquid flow in wood is dependent on damage that occurs during the impregnation procedure. For pine sapwood, liquid flow is enabled through disrupted window pit membranes, which divide the longitudinal tracheids and the ray parenchyma cells. A mechanism accounting for the reduced permeability of pine heartwood is believed to be deposits of higher-molecular-weight substances (extractives) in the ray parenchyma cells and on the cell walls. In spruce the thicker ray cells in combination with the smaller pits, which are connected to the longitudinal tracheids, reduce permeability considerably. 相似文献
2.
Summary The pit membranes of the bordered pits in about one hundred coniferous wood species were investigated in regard to their chemical composition, in particular to the aromatic compounds. In many species pit membranes, even in the sapwood, contain phenolic substances. In heartwood, normally lignification takes place besides the development of other polyphenols. The variability of these compounds, both in sapwood an in heartwood, may be considerable not only between species but also within the same species and even between neighbouring tracheids and pits respectively.We are thankful to Prof. Dr. W. Liese for his support and his frequent discussions. 相似文献
3.
Summary The effects of air-drying and solvent-drying on the sapwood of Abies grandis have been investigated by a new method for the determination of the size and number of conducting tracheid lumina and pit membrane pores which involves the measurement of gaseous permeability at various mean pressures. Both earlywood and latewood tracheids (83% of the total) were found to be conducting in solvent-dried wood, but in air-dried wood only latewood tracheids (32% of the total) were conducting. In solvent-dried wood there were on average 27,000 pit membrane pores per conducting tracheid compared with only 600 in air-dried wood. In both, the average pit membrane pore radius was about 0.1 m.Liquid permeabilities have been predicted from the calculated radii and numbers. The liquid permeability of solvent-dried wood was 31 times greater than that of air-dried wood in which the lumina were responsible for 13% of the total resistance to flow. The lumina were responsible for 39% of the resistance in solvent-dried wood and it is suggested that in first-formed earlywood the lumina may cause more than half the total resistance.A new method is described for the cleaning of direct carbon replicas of wood. In this the cellulose is removed by cellulase instead of sulphuric acid, and no wax backing is required. This provides much cleaner replicas. Electron micrographs have been obtained of both earlywood and latewood dried by the two methods.The authors wish to thank Mr. A. R. Sayers for preparing the computer programme used in this work, Dr. R. Ph. C. Johnson for his help and advice regarding the electron microscopy and Professors Matthews and Weatherley for their advice and encouragement. 相似文献
4.
Summary One of the problem areas in the kiln drying of western hemlock lumber is the wide variation in final moisture content of the
wood. This variation in moisture content is due to the presence of sinker or wetwood in the heartwood. The features of wetwood
which differentiate it from the normal heartwood include higher specific gravity, higher extractives content, and lower permeability.
The apparent higher specific gravity can be fully accounted for by the higher extractives content. The principial extractive is α-conidendrin.
The wetwood in western hemlock often occurs together with ring shake and under these circumstances the white deposit on the
shake surfaces is also α-conidendrin and not matairesinol, the substance usually associated with ring shake in western hemlock.
A viewpoint is presented on the origin of wetwood as the endproduct of a reaction by the tree to injury, i.e., ring shake,
in which additional extractives are deposited. The extractives result in a greatly lowered permeability, which prevents loss
of moisture during heartwood formation and thereby resulting in wetwood. Bacteria usually found in wetwood and responsible
for many of the symptoms associated with wetwood are a result of the high moisture content which favors bacterial growth in
wood. Presumably, the two primary sources of loss in kiln drying of western hemlock, shake and wetwood, are often intimately
associated.
The authors appreciate the assistance of Allen H. Doerksen and Louis W. Hamlin of the Forest Research Laboratory.
All samples collected for this study were donated by Willamette Industries, Inc., Dallas, Oregon, and a portion of the research
was supported by the Forest Research Laboratory, Oregon State University. 相似文献
5.
Lignans and norlignans constitute abundant classes of phenylpropanoids. Biosynthesis of these compounds has received widespread
interest, mainly because they have various clinically important biological activities. In addition, lignans and norlignans
are often biosynthesized and deposited in significant amounts in the heartwood region of trees as a metabolic event of heartwood
formation, probably preventing heart rot by heart-rot fungi. Furthermore, biosynthetic reactions of lignans and norlignans
involve unique stereochemical properties that are of great interest in terms of bioorganic chemistry and are expected to provide
a model for biomimetic chemistry and its application. We outline the recent advances in the study of lignan and norlignan
biosynthesis. 相似文献
6.
Summary An anatomical and chemical examination was made of living stumps of Douglas-fir. Changes in heartwood and extractives formation are not significant under the conditions of severe physiological stress that existed unless cell morphology was also altered. It is proposed that the factors controlling the amount and composition of heartwood extractives are incorporated in the ray cells during the early stages of their development.The authors are particularly grateful to Mr. J. Walters, Director of the Research Forest and to Professor J. A. F. Gardner, Dean of the Faculty of Forestry, of the University of British Columbia, Canada for their considerable help in the collection and transport of the samples of living stumps which formed the basis of this investigation. They are also grateful to Mr. A. Ceselli, Mrs. J. Juricskay and Miss D. Muston for assistance in the anatomical studies. 相似文献
7.
Summary The purpose of this study was to examine the influence of the moisture level on the cell-wall material in wood using pulsed proton nuclear magnetic resonance. The wood species used were western hemlock (Tsuga heterophylla (Raf.) Sarg.) and sitka spruce (Picea sitchensis (Bong.) Carr.), distinguishing between heartwood and sapwood regions. The moisture contents of the specimens were below the fibre saturation point and they were conditioned to equilibrium moisture contents based on initial desorption, adsorption and secondary desorption processes. From the FID experiments, the NMR-based moisture contents and the solid-wood lineshape second moments were determined. Average relative proton-spin densities, which were needed to calculate the NMR-based moisture contents, were determined from known moisture contents and they were: hemlock sapwood: 0.616; hemlock heartwood: 0.537; spruce sapwood: 0.679; and, spruce heartwood: 0.446. The average RSD value, considering both heartwood and sapwood, for western hemlock species was 0.577 and for sitka spruce was 0.563; these are close to published RSD values for other species. The condition as to how the equilibrium moisture content was attained did not influence the second moment for hemlock; however, for spruce sapwood, the second moments were sorption dependent. The hemlock M2 decreased from about 5.1 × 109 s-2 at low MNMR to 4.5 × 109 s-2 (heartwood) and 4.3 × 109 s-2 (sapwood) at higher mnmr. The adsorption and secondary desorption M2 for the spruce sapwood region decreased from about 5.0 × 109 s-2 at low mnmr to about 4.1 × 109 s-2 near the MF, whereas M2 for the spruce heartwood decreased from about 4.3 × 109 s-2 at low MNMR to about 3.5 × 109 s-2 near MF. Extractives may have a key role in obtaining the RSD and second moments.This project was financially supported by the Science Council of British Columbia, MacMillan Bloedel Research. The Natural Sciences and Engineering Research Council of Canada is acknowledged for their support of the NMR spectrometer measurements 相似文献
8.
Summary The cross-sectional view of pitting between various cell types inPinus banksiana Lamb. was studied at the ultrastructural level. Cell types inPinus banksiana include longitudinal tracheids, ray tracheids, ray parenchyma cells, buffer cells and epithelial cells. Two common characteristic features of bordered pit-pairs between longitudinal tracheids are an initial pit border and a thickened torus at the center of the pit membrane. The shape and size of the pit border and torus of bordered pit-pairs between two compression wood cells, and between the last-formed latewood longitudinal tracheid and first-formed earlywood longitudinal tracheid were different from those in the earlywood and latewood longitudinal tracheids. The pit border on the ray tracheid side varied in size and shape due to wall dentation. No initial pit border was found on the pit border of the ray tracheid side. The shape of bordered pit-pairs between two ray tracheids varied considerably due to irregularity of the dentate cell wall. The size of bordered pit-pairs in longitudinal tracheids was between 16 m to 20 m, which was twice the diameter of bordered pit-pairs in ray tracheids. Bordered pitpairs at the end wall of two ray tracheids appeared to be the smallest at 5 m, Pit aspiration occurred in the bordered pit-pairs with or without a torus. In the heartwood zone, some half-borders pit-pairs between tracheary and ray parenchyma cells showed an additional secondary wall on the ray parenchyma cell side. Plasmodesmata were found in the half-bordered pit-pairs as well in the simple pit-pairs. Blind pits were observed between a ray tracheid and a longitudinal tracheid. Bordered pit-pairs between two buffer cells were also observed. The possible functions of buffer cells were discussed.Use of transmission electron microscope provided by the Science Instrumentation Lab, Lakehead University and the technical assistance provided by Mr. A. MacKenzie, Director of Science Instrumentation Lab are gratefully appreciated 相似文献
9.
Peroxidase activity and isoenzymes of fresh wood samples of the third shoot of 12-year old trees and from the sapwood, transition
zone and heartwood of c. 60-year old stems of Scots pine (Pinus sylvestris L.) were investigated. Wood samples were ground at −30°C, extracted, and the extracts concentrated c. 20-fold for peroxidase
activity assays (guaiacol method) and for IEF-PAGE. At least 11 major isoenzymes could be found in the gels. Even the heartwood
contained some peroxidase isoenzymes. Isoenzyme patterns of the juvenile wood did not change with the season. However, juvenile
wood showed the highest peroxidase activity at the end of the growing season. Peroxidase activity decreased from the outer
sapwood towards the heartwood. Thin sections of different wood zones stained for peroxidase revealed activity in ray parenchyma
and resin canal epithelial cells. Intensive staining was localised in the bordered pits of vertical and ray tracheids, and
in the end walls of ray parenchyma cells. 相似文献
10.
Yoshinori Kobayashi Ikuho Iida Yuji Imamura Ugai Watanabe 《Journal of Wood Science》1998,44(6):482-485
The sap flow method of wood impregnation was conducted to aid the movement of bacteria through the living tree, thereby accelerating their distribution through wood within a short time. When log-pond water containing mixed species of bacteria were introduced in the living trees by butt-end dipping and then laid horizontally for 6 months, bacteria could be delivered by sap flow vertically through the sapwood tracheids up to the high portions from the butt-end of trees; they could be detected in the ray parenchymal cells. The sap-flow method was assumed to deliver the bacteria to sapwood and heartwood at high levels of standing sugi (Cryptomeria japonica D. Don) trees. Degradation of the pit membranes was observed even at more than 3 m upward from the butt-end after the treatment in sapwood, as well as around the butt-end of the trees. The uptake of the aqueous dye solutions in sapwood of the treated logs were about eight times more than those of control specimens after 8h.Part of this report was presented at the 40th annual meeting of the Japan Wood Research Society, Tsukuba, April 1990; the 41st annual meeting of Japan Wood Research Society, Matsue, April 1991; and the IUFRO 4th international conference on wood drying, Rotorua, New Zealand, August 1994 相似文献
11.
Naohiro Takaku Dr. Don-Ha Choi Keigo Mikame Tomoya Okunishi Shiro Suzuki Hideo Ohashi Toshiaki Umezawa Mikio Shimada 《Journal of Wood Science》2001,47(6):476-482
Heartwood ofChamaecyparis obtusa contains significant amounts of a dibenzylbutyrolactone lignan, hinokinin (8). This investigation demonstrated that the contents of 8 and a norlignan, hinokiresinol (12), were higher in the heartwood region than in the sapwood, indicating their nature of being heartwood extractives. Eleven lignans — xanthoxylol (1), 7-oxohinokinin (2), savinin (3), dihydrosesamin (4), isoactifolin (5), sesamin (6), piperitol (7), hinokinin (8), pluviatolide (9), haplomyrfolin (10), and rnatairesinol (11) — were isolated from young shoots ofChamaecyparis obtusa cv. Breviramea. Eight lignans (1, 2, 4, 5, 7, 9,10, and11) were isolated from this plant for the first time. Chiral high-performance liquid Chromatographie analysis showed that8, 9, 10, and11, were found to be levorotatory and optically pure (>99% e.e.). Based on the chemical structures of the isolated lignans, possible biosynthetic pathways of8 are discussed.Parts of this report were presented at the 44th annual meeting of the Japan Wood Research Society, Nara, April 1994; the 46th annual meeting of the Japan Wood Research Society, Kumamoto, April 1996; and the 44th Lignin Symposium, Gifu, October 1999 相似文献
12.
Summary Evidence of the detection by radiography of -conidendrin and hydroxymatairesinol, major lignans of western hemlock wood, is presented. Advantages of this new technique to wood chemists, as well as implications to wood technologists in terms of erroneous measurement of the specific gravity of unextracted wood by X-ray densitometry, are discussed.The authors thank R. M. Kellogg of the Western Forest Products Laboratory for his helpful discussions. This research was supported in part through grants to J.H.G. Smith, University of British Columbia, Faculty of Forestry, from the National Research Council of Canada (Grant No. A-2077) and the British Columbia Forest Service. 相似文献
13.
We investigated morphological changes in wood tissues of sugi (Cryptomeria japonica) resulting from treatment with the ionic liquid 1-ethyl-3-methylimidazolium chloride ([C2mim][Cl]), which dissolves cellulose. Treatment with [C2mim][Cl] caused dissociation and distortion of tracheids in latewood, but not in earlywood. This difference was due to the difference in swelling behavior of the cell wall between earlywood and latewood. Many pit membranes in bordered pits were broken by treatment with [C2mim][Cl]. In addition, some chemical changes in wood components, such as cellulose and lignin, occurred before significant disruption or destruction of the cell wall. Our results show that the reaction of wood liquefaction by [C2mim][Cl] treatment is not homogeneous, both from chemical and morphological viewpoints. 相似文献
14.
Junji Matsumura Yoko Yamasaki Kazuyuki Oda Yoshitake Fujisawa 《Journal of Wood Science》2005,51(4):328-333
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. 相似文献
15.
Summary The dissolution and dispersion of components from Norway spruce (Picea abies) wood were examined in laboratory experiments to determine the factors influencing variations in dissolved and colloidal substances in mechanical pulp suspensions. Finely ground, fresh spruce wood was suspended in water at 90 °C and was agitated intensively for up to 12 h, after which the concentrations of dissolved and dispersed lipophilic extractives, lignans, carbohydrates and lignins were determined. Sapwood and heartwood were studied separately. Effects of pH and added electrolytes on the dissolution and dispersion of wood components were also investigated.Higher amounts of lipophilic extractives, and especially of triglycerides, were dispersed from sapwood than from heartwood. The release of lipophilic extractives continued for up to 3 h, after which the concentrations in the suspensions leveled off. At this stage the composition of the dissolved and dispersed lipophilic extractives equaled that of the wood. The amount of lipophilic extractives in the suspensions increased with increased pH, in the range of 4.5–6.7, but was lower in the presence of electrolytes. The dissolution of carbohydrates continued even beyond 3 h of agitation. The high water temperature induced hydrolytic reactions, thereby releasing especially arabinose. The release of arabinose through the hydrolytic cleavage from polysaccharides was more extensive at pH 4.5 than at pH 5.5 and 6.7. More polysaccharides containing galacturonic acid units (pectins) were dissolved at a higher pH. Much more polysaccharides containing glucose, most probably starch, were present in the sapwood suspensions. The dissolution of lignins also continued throughout the 12 h experiment. The measured UV-absorption, after extraction of lignans, was roughly the same for sapwood and heartwood suspensions. Slightly less lignins were released in the presence of electrolytes. Lignans were released only from heartwood. 相似文献
16.
Summary The distribution of lignin in normal and compression wood of loblolly pine (Pinus taeda L.) has been studied by the technique of lignin skeletonizing. Hydrolysis of the wood carbohydrates with hydrofluoric acid left normal wood tracheids with a uniform distribution of lignin in the S1 and S2 cell wall layers. However, the S3 region of both earlywood and latewood tracheids consistently retained a dense network of unhydrolyzable material throughout, perhaps lignin.Lignin content in compression wood averaged about 7% more than in normal wood and appears to be concentrated in the outer zone of the S2 layer. The inner S2 region, despite helical checking, is also heavily lignified. The S1 layer, although thicker than normal in compression wood tracheids, contains relatively little lignin.Ray cells, at least in normal wood, appear to be lignified to the same extent, if not more so in certain cases, than the longitudinal tracheids. Other locations where lignin may be concentrated include initial pit border regions and the membranes of bordered pits.This report is a detailed excerpt from the Ph. D. dissertation of R. A. P. Financial support provided by the College of Forestry at Syracuse University and the National Defense Education Act is hereby gratefully acknowledged. 相似文献
17.
Ana Lourenço Isabel Baptista Jorge Gominho Helena Pereira 《Journal of Wood Science》2008,54(6):464-469
The pulping wood quality of Acacia melanoxylon was evaluated in relation to the presence of heartwood. The sapwood and heartwood from 20 trees from four sites in Portugal
were evaluated separately at 5% stem height level in terms of chemical composition and kraft pulping aptitude. Heartwood had
more extractives than sapwood ranging from 7.4% to 9.5% and from 4.0% to 4.2%, respectively, and with a heartwood-to-sapwood
ratio for extractives ranging from 1.9 to 2.3. The major component of heartwood extractives was made up of ethanol-soluble
compounds (70% of total extractives). Lignin content was similar in sapwood and heartwood (21.5% and 20.7%, respectively)
as well as the sugar composition. Site did not influence the chemical composition. Pulping heartwood differed from sapwood
in chemical and optical terms: lower values of pulp yield (53% vs 56% respectively), higher kappa number (11 vs. 7), and lower
brightness (28% vs 49%). Acacia melanoxylon wood showed an overall good pulping aptitude, but the presence of heartwood should be taken into account because it decreases
the raw-material quality for pulping. Heartwood content should therefore be considered as a quality variable when using A. melanoxylon wood in pulp industries 相似文献
18.
M. P. Coutts 《Forest Pathology》1977,7(1):6-12
Dry zones in conifer wood, characterised by gas filled tracheids, were induced by the injection of dilute solutions of various toxic chemicals followed by incubation at 10 or 20°C. The development of dry zones did not occur at lower temperatures nor with concentrated solutions and was prevented or retarded in an atmosphere of nitrogen. These results are discussed in relation to the development of dry zones in infections by Fomes annosus and other fungi and in the formation of heartwood. It is postulated that the gradual death of ray cells alters their metabolism in such a way that gas emboli are evolved in adjacent tracheids; this can occur at sites of infection or at a distance under the influence of transportable or diffusible toxins. 相似文献
19.
João Carvalho Óscar Cardoso Mário Costa Abel Rodrigues 《European Journal of Forest Research》2017,136(1):185-192
This work presents the results of a study on the variation of the chemical composition of Pyrenean oak (Quercus pyrenaica Willd.) heartwood among different sites and its relationship with the soil chemical characteristics. The chemical characteristics of the heartwood are quantified in terms of proximate and ultimate analysis, calorific value and ash composition. Subsequently, the relationship between the wood chemical characteristics and the soil characteristics was also examined. The results showed no significant differences between the wood chemical characteristics from different sites. There are, however, significant differences between trees from the same site regarding the wood ash content, the calorific value and the contents of nitrogen and hydrogen. Strong correlations were observed between the heartwood ash contents of BaO, MnO, CuO and TiO2 and the soil nitrogen, phosphorous and potassium and the soil exchangeable base contents. 相似文献
20.
Vladimír Račko František Kačík Oľga Mišíková Pavol Hlaváč Igor Čunderlík Jaroslav Ďurkovič 《Annals of Forest Science》2018,75(3):82