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1.
Heartwood extractives (nonstructural wood components) are believed to be formed from a combination of compounds present in the adjacent sapwood and materials imported from the phloem. The roles of local compounds and imported material in heartwood formation could have important implications for the wood quality of species having naturally durable wood. Stable isotope composition (delta(13)C) was analyzed to assess radial variation in sapwood extractives, and to estimate the relative importance of adjacent sapwood extractives and imported photosynthate in the formation of heartwood extractives. Cellulose and extractives from the outer 39 annual rings of six Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees were isolated and their delta(13)C composition determined. Although the extractives and the cellulose showed different absolute delta(13)C values, the patterns of change over time (as represented by the annual rings) were similar in most cases. Within an annual ring, carbon isotope ratios of extractives were correlated with the cellulose isotope ratio (R2 = 0.33 in sapwood, R2 = 0.34 in heartwood for aqueous acetone-soluble extractives; R2 = 0.41 in sapwood for hot-water-soluble extractives). These data suggest that some sapwood extractives are formed when the wood ring forms, and remain in place until they are converted to heartwood extractives many years later. Sapwood extractives appear to be important sources of materials for the biosynthesis of heartwood extractives in Douglas-fir.  相似文献   

2.
Abstract

Wood is susceptible to decay by rot fungi if it is exposed to high-moisture contents during long periods of time and it is therefore important to limit the duration of such periods. Critical points in outdoor wood structures are, for example, end grain surfaces in joints where water can get trapped after a rain. It is therefore of interest to study both absorption and redistribution of moisture in wood. This paper presents moisture content profiles during end grain water absorption and redistribution in Norway spruce (Picea abies (L.) Karst.) measured by computed tomography with the specimens in individual climate boxes. Heartwood and sapwood of two provenances (slow-grown and fast-grown wood) were included. No major differences were seen between the water uptake of the slow-grown and the fast-grown wood since the densities were similar despite of the large difference in growth ring width. However, for the sapwood specimens, the moisture content was higher further into the specimens than for the heartwood specimens in agreement with previous studies. For the slow-grown wood, the redistribution was also generally more rapid for the sapwood specimens than for the heartwood specimens.  相似文献   

3.
The variation in extractives content in sapwood and heartwood was investigated among 12 trees in each of four commercial plantations of Eucalyptus globulus in central Portugal. The study was carried out at the 15% height level and extractions used successively dichloromethane, ethanol and water. At all sites, heartwood had significantly more extractives than sapwood, on average 3.8 and 2.4%, respectively. Most extractives consisted of ethanol soluble material (on average 52% of total extractives). Among the sites, there was a statistically significant difference in the content of extractives but the most important source of variation was the within-tree variation between sapwood and heartwood. Differences in the content of extractives were also observed among trees. A strong relation between extractives content and heartwood proportion was found. The potential loss of pulp yield and problems associated with accumulation of extractives are directly related to the heartwood proportion in the eucalypt stems. Forest management should take into account heartwood development and selection for minimising heartwood extractives.  相似文献   

4.
Abstract

The objective of this study was to investigate the moisture content (MC), density, and amount of extractives along the height of a 32-year-old oil palm stem. The extractives were removed following TAPPI standards T-207 and T-280 for water solubility and acetone extractives. The results showed that the MC of the palm stem increased from the outer towards the inner section, while the density decreased. Along the tree height, the MC was found to increase from the bottom to the middle part, but slightly decreased towards the top. An inverse trend was obtained for the density distribution along the tree height. The results of the extractive separation showed that the middle and center sections of the oil palm stem contained the highest amount of extractives irrespective of the types of solvent. The highest amount of extractives was obtained from hot water extraction, followed by cold water and acetone extractions. The lowest amount of extractives was located at the bottom outer section of the oil palm stem which ranging from 2.0 to 9.2%, whereas the middle and center sections contained a greater amount of extractives ranged from 4.6 to 32.8% regardless of the type of solvent used.  相似文献   

5.
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   

6.
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   

7.
Summary In the future, wood will be used largely for the manufacture of fibre products and particle board. The quality of wood used to meet increasing world demand will vary considerably. One feature of quality that can affect utilisation is the amount and type of wood extractives present. The distribution and variation in composition of extractives in the tree, as well as their effect on pulp manufacture, durability and surface films, are summarized. Methods to reduce the effects of some extractives in existing trees are described. Extractives can be reduced in plantation material by minimizing heartwood formation and by using silvicultural methods which result in small amounts of extractives being formed in this tissue. Current knowledge on heartwood formation is summarized.Paper presented to the 3rd Plenary Meeting of the International Academy of Wood Science held at the N. C. State University, Raleigh, March 11, 1971.  相似文献   

8.
The effect of selective removal of extractives on termite or decay resistance was assessed with matched samples of Thuja plicata Donn ex D. Don and Chamaecyparis nootkatensis (D.Don) Spach heartwood. Samples were extracted using a variety of solvents and then exposed to the subterranean termite Coptotermes formosanus Shiraki in a no-choice feeding test or to the brown-rot fungus Postia placenta (Fr.) M. Larsen & Lombard in a soil bottle test. At the same time, the effect of naturally occurring variations in heartwood extractives on termite or decay resistance was evaluated by testing samples from the inner and outer heartwood of five trees of each species against C. formosanus and P. placenta and analyzing matched wood samples for their extractive content. The results suggest that the methanol-soluble extractives in T. plicata and C. nootkatensis play an important role in heartwood resistance to attack by C. formosanus and P. placenta. Total methanol-soluble extractive content of the heartwood was positively correlated with both termite and decay resistance; however, there was much unexplained variation and levels of individual extractive components were only weakly correlated with one another. Further studies are under way to develop a better understanding of the relationships between individual extractive levels and performance.  相似文献   

9.
Phenolic extractives in the trunk of Toxicodendron vernicifluum (syn. Rhus verniciflua) were investigated. Seventeen compounds, gallic acid, protocatechuic acid, (?)-fisetinidol-4β-ol, (?)-fisetinidol-4α-ol, 2-benzyl-2,6,3′,4′-tetrahydroxycoumaran-3-one, (?)-fustin, 1,2,3,6-Tetra-O-galloyl-β-d-glucose, (?)-epifustin, (+)-taxifolin, 1,2,3,4,6-penta-O-galloyl-β-d-glucose, (?)-garbanzol, (?)-fustin-3-O-gallate, (?)-epifustin-3-O-gallate, fisetin, sulfuretin, quercetin and butein, were identified from the heartwood extractives. It was found that only (+)-taxifolin which had 5,7-dihydroxy A-ring possessed a 3R configuration although other flavonoids which had 7-hydroxy A-ring possessed a 3S configuration. Quantitative analysis revealed that the total phenolic contents were much higher in the heartwood (5–7 wt%) than in the sapwood and bark (1–2 wt%), and (?)-fustin was the most abundant extractive in the heartwood (1.4–2.4 wt%). For the radial distribution of phenolic extractives, it was generally found that their content was lowest in the sapwood, increased to the highest in the outer heartwood, and then decreased in the inner heartwood.  相似文献   

10.
The objectives were to determine the content and composition of lipophilic extractives, particularly fatty and resin acids, in three Scots pine trees from each of two stands in northern Sweden, one that was due for thinning and one due for final cutting. Extractives content of branches, needles, barks, stem discs from branch whorls, and sapwood and heartwood samples from various heights was measured. Fractions had very different concentrations and distributions of extractives due to differences in the composition of tissues. The needles had the highest total extractive concentration (around 150?kg/ton d.w.), followed by the branches, bark, timber from the final cut stand, and then the pulpwood and timber from the thinning stand. The final cut stand generally provided higher yields of extractives in assortments per hectare than the thinning stand; the difference was five-fold for timber, three-fold for whole trees, two-fold for branches, needles and bark and similar for pulpwood. This information on the content and composition of extractives in different tissues, and the dependence of these quantities on tree age could be used together with information on conventional stand data such as tree numbers and dimensions to guide the selection and management of feedstocks for biorefineries.  相似文献   

11.
Summary Radial distribution of thujaplicins in western red cedar (Thuja plicata Donn) trees of varying ages was studied in order to assess relative decay resistance of their wood. Samples were extracted with ethanol: benzene (1: 2), and the extractives were analyzed for thujaplicin codtent by a new method utilizing capillary gas chromatography of their methylated derivatives. The combined concentration of thujic acid and methyl thujate was also determined for each sample. Distribution of extractives, thujaplicins and thujic acid, generally increased from pith to outside heartwood, then decreased in the sapwood. Maximum extractive and thujaplicin contents were also related to tree age. This suggests that products made from the wood of younger trees will be less resistant to decay than similar products made from the wood of old trees.  相似文献   

12.
The quantities of some extractives in the heartwood of 25 plus tree clones of Japanese cedar (Cryptomeria japonica) from two different sites were investigated to clarify the differences in antitermite properties in relation to clones and environmental factors. The measured compounds were cubebol, epicubebol, sandaracopimarinol, and ferruginol. The total amounts of extractives were calculated from gas chromatogram peak areas. The heartwoods from Tano (Tano Forest Research Station, Miyazaki University; 31° N, 131° E, 130 m asl) tended to contain more of the individual extractives and total extractives than those from Komenono (Komenono Forest Research Station, Ehime University; 33° N, 132° E, 700 m asl). There was a significant difference (calculated by analysis of variance) at the 1% level among clones at both sites in quantities of total and individual extractives. This result suggests that the qualities and quantities of heartwood extractives are largely affected by genetic factors. Spearman’s rank correlation with the average of the extractive quantities at the sites was investigated. The correlation coefficients of total extractives, cubebol, epicubebol, sandaracopimarinol, and ferruginol were 0.61, 0.85, 0.76, 0.67, and 0.74, respectively. This result means that the order of the amounts of these compounds among the cultivars could be maintained at different sites. It is apparent that both environmental and genetic factors affected the quantities of these extractives in the heartwoods of Japanese cedar.  相似文献   

13.
侧柏心材活性成分的提取及其抑菌性能   总被引：2，自引：0，他引：2  
研究侧柏心材不同部位及正己烷和二氯甲烷依次提取的心材活性成分对白腐菌、褐腐菌、黑曲霉菌的抑菌作用,并采用GC/MS联用技术对提取物中的活性成分进行鉴定和分析.结果表明:侧柏心材从髓心向边材根据年轮所划分的3个部位对3种真菌都具有较好的抑菌效果,并且靠近边材的2部分抑菌效果更明显些.气质联机技术对正己烷和二氯甲烷提取物分析鉴定表明:侧柏心材正己烷提取物中有14种化合物,大部分化合物属于萜烯类物质及其衍生物,最高含量化合物为罗汉柏烯(25.564%)和雪松醇(19.743%);侧柏心材二氯甲烷提取物中鉴定出24种化合物,最高含量化合物也为罗汉柏烯(15.429%).侧柏心材正己烷提取物对褐腐菌、白腐菌和黑曲霉菌第14 d时的抑菌圈直径分别为10.0,9.3和8.3 mm,大于二氯甲烷提取物抑菌圈直径(0,2.7和1.3mm),表明正己烷提取物对3种真菌的抑制生长作用明显优于二氯甲烷提取物的抑菌作用.  相似文献   

14.
The aim of this study is to characterise the properties of juvenile and mature heartwood of black locust (Robinia pseudoacacia L.). Content, composition and the subcellular distribution of heartwood extractives were studied in 14 old-growth trees from forest sites in Germany and Hungary as well as in 16 younger trees of four clone types. Heartwood extractives (methanol and acetone extraction) were analysed by HPLC-chromatography. UV microspectrophotometry was used to topochemically localise the extractives in the cell walls. The natural durability of the juvenile and mature heartwood was analysed according to the European standard EN 350-1. Growth as well as chemical analyses showed that, based on extractives content, the formation of juvenile wood in black locust is restricted to the first 10–20 years of cambial growth. In mature heartwood, high contents of phenolic compounds and flavonoids were present, localised in high concentrations in the cell walls and cell lumen of axial parenchyma and vessels. In juvenile wood, the content of these extractives is significantly lower. Juvenile wood had a correspondingly lower resistance to decay by Coniophora puteana (brown rot fungus) and Coriolus versicolor (white rot fungus) than mature heartwood.  相似文献   

15.
为探究国产柚木抽提物对心材和边材颜色差异的影响,采用3种沸程的石油醚溶液分别对国产柚木的心材与边材进行抽提处理,利用气相色谱-质谱法分析抽提液的成分和含量,并以差异较大的抽提物溶液处理柚木边材,通过色度学参数表征柚木边材的变色情况,从而验证影响柚木心材和边材颜色的主要抽提物成分。结果表明:在3种沸程的石油醚抽提液中,柚木心材抽提物在成分种类数量和含量上均显著高于边材;不同沸程的石油醚对柚木心、边材中抽提物成分有一定的影响,其中30~60℃(低沸程)和60~90℃(中沸程)石油醚抽提物成分和含量的差异较小,而90~120℃(高沸程)石油醚抽提物的含量较高,约为中、低沸程抽提物含量的2倍;柚木心材抽提液中酚类、醌类、烯烃类物质的含量较多,但这些物质在边材中含量极低;4-叔丁基-2-苯基苯酚、2-甲基蒽醌(柚木醌)、全反式三十碳六烯(角鲨烯)是柚木心、边材抽提物含量差异最明显的物质。经角鲨烯溶液处理后的柚木边材表面颜色变黄,更接近心材颜色,因此,角鲨烯是导致柚木心边材颜色差异的重要抽提物成分。  相似文献   

16.
长白落叶松提取物对木材防腐作用的研究   总被引：3，自引：0，他引：3  
以长白落叶松心材、边材及树皮为原料,分别用乙醚、氯仿、丙酮、甲醇和水5种溶剂对其进行提取,采用滤纸片法研究了不同溶剂提取物分别对白腐菌和褐腐菌的抑菌性能,发现心材的甲醇提取物和丙酮提取物对白腐菌有较好的抑制效果,树皮的水提取物对2种菌都有较好的抑制效果.并研究了这两种提取物在室内对木材的防腐性能,借助扫描电子显微镜(SEM)照片观察了木材腐朽后菌丝生长的情况,与常用木材防腐剂酸性铬酸铜(ACC)进行了对比,结果显示:心材的甲醇提取物对白腐菌的抑制效果较好;而树皮的水提取物对褐腐菌抑制效果较好.  相似文献   

17.
Dissolution and dispersion of spruce wood components into hot water   总被引：1，自引：0，他引：1  
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   

18.
The chemical components of dichloromethane extractives for Sawara Falsecypress heartwood were analyzed with GC/MS except for basic chemical composition analysis for heartwood with Chinese standard method. 14 kinds of compounds were idenfifjed according to the computer compounds library data. The major compounds in dichloromethane extractives comprised of terpene and naphthalene derivafives. The experiments of antifungal effects of the dichloromethane extractive on Aspergillus niger were also carded out. The result showed that the dichloromethane extractive from Sawara Falsecypress has no or weak antifungal capability.  相似文献   

19.
Forty-one E. bosistoana families were evaluated for the production of heartwood quantity and quality in two sites. High estimated heritabilities of heartwood diameter (HWD) were found in both sites (0.66 and 0.71). The estimated heritabilities of extractives content (EC) were lower with 0.16 and 0.25. Weak genetic correlations between HWD and EC were found in one site, but highly negative (??0.86) genetic correlations were observed in the other. The G?×?E interaction had no significant influence on growth traits but a small-level influence on the EC. Five families were selected for tree breeding as they produced both large HWD and high EC in both sites. It was suggested that genetic breeding selection could improve the heartwood quantity and quality of E. bosistoana plantations.  相似文献   

20.
Abstract

Uncoated Norway spruce specimens from different spatial positions within stems from two origins with different growth conditions were exposed to liquid water over a prolonged time, and apparent diffusion coefficients and rates of void filling were calculated from sorption curves. Both apparent diffusion and rate of void filling were significantly affected by origin and by the difference between inner and outer boards. The differences between inner and outer boards were explained by heartwood proportion and density, but some effects of origin remained when these properties were accounted for. The apparent diffusion coefficient was reduced by increasing density, and increased by increasing heartwood proportion. Void filling rate was reduced by both increasing density and increasing heartwood proportion. Since the effect of heartwood proportion was more pronounced in the material from the highly productive area, it may have been confounded with properties of juvenile wood.  相似文献   

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