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1.
Summary Morphological and chemical examinations of the extractives of the tissues and shake contents of eight Dacrydium and one Podocarpus species have been made. The whitish deposits in heart-shakes are without exception mainly podocarpic acid (PCA). This compound occurs also in the tissue of samples but only when shakes are found nearby. Accordingly PCA is regarded as an anomalous extractive, synthesized in response to those conditions resulting in shake formation. In samples with shakes PCA is present in very small amounts at the sapwood-heartwood boundary and in one sample there were traces even in the innermost sapwood. It was notable that shakes containing deposits can arise in those Dacrydium species with coloured heartwood and with a known tendency for wetwood formation. On the other hand Dacrydium franklinii does not develop coloured heartwood or wetwood or shakes, and the lack of these features may have taxonomic significance.The third author expresses his gratitude to the Division of Building Research, CSIRO, Highett, Vic., for a visiting Fellowship during 1974. 相似文献
2.
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
3.
Nobumasa Bito Ryogo Nakada Eitaro Fukatsu Yasuyuki Matsushita Kazuhiko Fukushima Takanori Imai 《Annals of Forest Science》2011,68(6):1049-1056
• Introduction
In Cryptomeria japonica, heartwood properties are considered to be affected by specific extractives. It remains unclear whether traits of specific heartwood compounds are under genetic control. 相似文献4.
M. Hubbes 《Forest Pathology》1973,3(3):163-168
The seasonal fluctuation in the production of coremia by Ceratocystis ulmi (Buis.) was studied on elm stem discs taken from trees felled in April, June, July, September, October and November 1971 at Valcartier, Quebec. More coremia formed on stem discs of trees felled during the growing season. Except for trees felled in October and November, more coremia formed on sapwood than on heartwood. Evidence obtained during the study showed that the compounds, which trigger coremia formation, are not uniformly distributed within and between trees or throughout the period from April to November. 相似文献
5.
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
6.
Gunthard Scholz Falk Liebner Gerald Koch Claus-Thomas Bues Björn Günther Ernst Bäucker 《Wood Science and Technology》2007,41(8):673-686
The very decorative heartwood of Brosimum guianense is internationally well known. Snakewood, as it is colloquially known, is represented in wood databases (e.g. the DELTA or
InsideWood) as well as in lists of commercial timbers of many timber trading companies. The very decorative heartwood is hardly
available and gains prices of up to 25 €/kg in form of half stems. In the present study, the chemical composition and especially
the subcellular cell structure was analysed by means of UV microspectrophotometry to explain the high natural durability and
some extraordinary physical properties in addition to the anatomical composition. The heartwood consists of approximately
39% lignin, 54% carbohydrates and 0.4% lipophilic compounds of unspecified origin. The fibres are very thick-walled. Numerous
sclerotic tyloses and organic deposits are present in the vessel. The extractives in high content are also components of parenchyma
cells as well as in tyloses, respectively. These detected phenolic extractives, partly of flavonoid character, are also part
of the cell wall. Calcium oxalate crystals are deposited in the upright and square cells of rays and sporadically in axial
parenchyma cells. These facts are reasons for the famous natural durability of Snakewood. The sapwood density ranges from
1.1 to 1.4 g/cm3 for heartwood (12% mc). The compression strength (119 N/mm2), the bending strength (241 N/mm2), the modulus of elasticity (23,200 N/mm2) and the hardness (196 N/mm2) indicate exceedingly high elastomechanical properties. 相似文献
7.
In this paper, we demonstrate that 140 mg/kg of essential oil from the wood of yellow‐cedar, incense cedar, Port‐Orford‐cedar or western juniper strongly inhibits zoospore germination and hyphal growth of Phytophthora ramorum in culture. Four individual compounds in yellow‐cedar heartwood were also tested. Zoospore germination was reduced to 0% with 10, 100 and 1000 mg/kg of nootkatin, carvacrol and valencene, respectively. Nootkatone was the least active compound, with 3.5% zoospore germination at 1000 mg/kg. Sporangia germination was 0% with 500 mg/kg of nootkatin or carvacrol. The disruption of the zoospore outer membrane and the loss of sporangial contents were often observed and indicative of sporicidal activity. Hyphal growth was inhibited by 99.9% with 50 mg/kg of nootkatin or 500 mg/kg of carvacrol, but growth resumed upon removing the inhibitors. The zoosporicidal activity of yellow‐cedar heartwood shavings stored dry for approximately 10 years was consistent with the quantity of extractable compounds they contained. Thus, spreading fresh shavings or chips of yellow‐cedar heartwood with appreciable higher concentrations of the active compounds, over areas in infection zones where spores might be difficult to control such as trails and parking lots used by hikers and bicyclists, might be useful as part of an integrated program to minimize P. ramorum spore distribution. 相似文献
8.
Karen M. Barry Rie Mihara Noel W. Davies Tohru Mitsunaga Caroline L. Mohammed 《Journal of Wood Science》2005,51(6):615-621
The heartwood of Acacia mangium is vulnerable to heart rot and this is the first study to investigate the role of heartwood extractives in its susceptibility.
Acacia auriculiformis was compared with A. mangium because it is rarely associated with heart rot. The heartwood extracts of both species were dominated by three flavonoids
(2,3-trans-3,4′,7,8-tetrahydroxyflavanone, teracacidin, and 4′,7,8,-trihydroxyflavanone), which were purified and identified by nuclear
magnetic resonance spectroscopy. The latter compound has not been previously reported in A. mangium and evidence for melacacidin is also newly reported. The mass spectrometric (MS) behavior of these compounds is given, for
example teracacidin does not form molecular ions by either electrospray ionization or atmospheric-pressure chemical ionization.
The nature of Acacia tannins was compared to quebracho tannin (composed of profisetinidins) using oxidative cleavage to enable MS detection but
a negative reaction was obtained for both, which suggests the Acacia tannins may also be of the 5-deoxy proanthocyanidin type. The concentration of flavanones was less when A. mangium heartwood was decayed but the amount of proanthocyanidins was only slightly reduced and therefore these compounds may be
more resistant to degradation by heart rot fungi. We found that the total phenol content of A. auriculiformis was about fivefold that of A. mangium, and, while preliminary, this provides evidence for a role played by phenolic extractives in heart rot resistance of these
Acacia species. 相似文献
9.
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
10.
Summary In the West African Ilomba wood (Pycnanthus angolensis Exell) discolourations frequently develop after felling, which lead to serious degradation with regard to utilization. Therefore, structure and chemical composition of normal and discoloured wood were investigated in order to characterize the original wood and give a detailed account of the reactions which lead to discolourations. According to the results Ilomba, in normal condition, is all sapwood, which explains its high reactivity. The species does not have the ability to develop heartwood; only false heartwood is formed, initiated by exogenous influences. Discolourations arising in the wood after felling are reddish-brown, due to the deposition of extraneous compounds in the lumina of the ray cells. Soluble sugars disappear and the permeability decreases as a result of tyloses development. From discoloured wood only 60% of extraneous compounds could be extracted as compared to the normal sapwood, thus indicating that polymerisation of extraneous compounds takes place. Discoloured wood appears even more susceptible to decay than the bright sapwood. The pH-value increases from about 5.5 to 7.5 during discolouration, and bacteria present within the reddish-brown zones are involved in that process.We are indebted to Mrs. R. Endeward for assistance in the experimental work, to Prof. N. Parameswaran for support in the REM work, to Fa. Bernhard, Wangen and to Mr. K.-G. Dahms, Hamburg, for the supply of Ilomba wood. Acknowledgement is given to Deutsche Forschungsgemeinschaft for financial support 相似文献
11.
Summary Western hemlock heartwood contains patches of tracheids with large amounts of cellular inclusions. Microscopic and chemical examination of the wood showed several types of deposits containing the lignans matairesinol, hydroxymatairesinol and conidendrin. The deposits, which were often relatively pure individual lignans, frequently assumed different physical forms and chemical composition. A check in the wood contained three distinct forms of deposits each of which was a different lignan. Rays contained deposits physically similar to those in adjacent tracheids but, while lignans were present in the tracheids, they were not detected in the rays. Lignans lined tracheid walls as surface films and often encrusted the bordered pits. The amount of lignans in the wood was not related to wet wood zones although surface films and pit encrustations should have an influence on physical properties. The location and physical nature of lignan deposits in western hemlock heartwood indicates their biosynthesis has probably taken place at the heartwood periphery in the vicinity of the half-bordered pit.Presented at the International Wood Chemistry Symposium, Seattle, U. S. A. September 1969.Requests for reprints should be sent to W. E. Hillis. We thank Miss J. Barratt for assistance with part of this work and Mr. C. J. Kozlik for collecting wood samples. 相似文献
12.
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
13.
J. Wilkes 《Wood Science and Technology》1991,25(2):85-90
Summary The rate of heartwood development was examined at four heights in stems of Pinus radiata D. Don from 18 mature stands in south-eastern Australia. While the diameter of heartwood tended to be greatest at stump and breast heights, formation commenced earlier (i.e. with fewer sapwood rings) and/or progressed more rapidly 10–20 m above ground level. Appreciable variation in heartwood development was detected between trees in the same and different stands, with both environmental and genetic factors apparently important. Regression analyses involving three parameters of heartwood development (number of rings, diameter and percentage area) and stem characteristics including height, diameter and ring width suggested that heartwood formation is affected little by tree vigour in the post-juvenile growth phase. Rather it seems that the rate at which annual increments are included in heartwood is largely fixed for any particular height level and stem. Thus the amount (but not necessarily the percentage) or heartwood in a stem is substantially dependent on diameter growth early in tree life.The expert technical assistance of Mr. R. Colley is gratefully acknowledged. Valuable assistance in the measurement of heartwood dimensions was also provided by Ms. V. Kurz and Mr. C. Slatyer. Dr. R. K. Bamber and Mr. A. P. Wilkins offered particularly helpful advice 相似文献
14.
The methanol extractives from western red cedar mechanical pulps were found to be radically different in composition to the
extractives obtained from the heartwood. The major heartwood extractive components, the tropolones and lignans, were not present
in the extractives from the pulps. However, the proportion of a brown polymer doubled. The low and high molecular weight methanol
extractives components from the pulps were separated using methyl tert-butyl ether. The low molecular fraction contained mostly
guaiacyl-based compounds with dihydroquercetin, thujic acid, 3-hydroxy-1-(4′-hydroxy-3′-methoxyphenyl)-2-oxopropane and 4-ethyl-2-methoxy-6-hydroxyphenol
being positively identified. The brown polymeric portion had molecular weights ranging from 1,000 to 10,000. Infrared analysis
indicated that the polymers were formed from lignans. Examination of the changes in diffuse reflectance UV-visible and infra
red spectra of the pulps on extraction with methanol, suggested that the colour resides in insoluble polymers formed from
plicatic acid/plicatin during refining.
Received 18 December 1998 相似文献
15.
The distribution of Phellinus tremulae in stems of Populus tremula was studied visually, macroscopically as well as microscopically, and by means of isolation of the fungus in pure culture. Evidence suggests that P. tremulae occurs alone in most of the tree. Microorganisms associated with P. tremulae in the wood are suggested to be independent invaders or secondary invaders. A dark reaction zone was formed in certain parts of the wood and consisted microscopically of melanized hyphes and brown material in the ray cells. An inner wood, formed as a result of the death of nearby brandies, is apparently the main part infected by P. tremulae, and its outer border may basically limit the spread of the fungus in the trunk. The formation of “heartwood” in aspen is discussed, and a suggested outline shown for the infection and decay processes caused by the fungus. 相似文献
16.
The amount and composition of sugar units comprising polysaccharides in sapwood and heartwood, or stemwood, of 11 industrially
important pulpwood species were analysed. The polysaccharide content was between 60 and 80% (w/w) for all species, with cellulose
as the predominant polysaccharide type and glucuronoxylans as the main non-cellulosic polysaccharides. The second most abundant
non-cellulosic polysaccharides were either pectins, i.e. polygalacturonic acids, or glucomannans. The amount of acidic sugar
units were 15–23% of the total amount of non-cellulosic sugar units in all samples, with the Acacia species in the high end. The amount and composition of water-soluble carbohydrates from ground wood samples were also analysed,
since these are important in mechanical and chemimechanical pulping, and as a possible source of bioactive polymers. Sapwood
released more carbohydrates than heartwood for most species. It is to be noted that the relative amount of dissolved acidic
sugar units was larger from the heartwood than from the sapwood for all species. Probably due to the mild treatment conditions,
the main dissolved polysaccharides were xylans only for a few samples, while easily soluble galactans, arabinogalactans, or
mannans dominated in most species. Pectins dominated in heartwood of Populus grandidentata. Generally, pectins and acidic xylans were the main acidic polysaccharides. 相似文献
17.
The content and composition of carbohydrates comprising polysaccharides in sapwood and heartwood of 12 industrially important pulpwood species were analysed. The polysaccharide content was between 60% and 80% (w/w) for all species, with cellulose as the predominant polysaccharide type. The carbohydrate composition suggested that the main non-cellulose polysaccharides were galactoglucomannans, except in Larix heartwood, where arabinogalactans were predominant, while the content of xylans were in the same range as the mannans in Pinus resinosa heartwood and Thuja occidentalis heartwood and sapwood. Pectins, i.e. polygalacturonic acids, were the main acidic polysaccharides in all species. The amount and composition of water-soluble carbohydrates from ground wood samples were also analysed, since these are important in mechanical pulping and as a possible source of bioactive polymers. The main polysaccharides released from the spruce species were mannans, together with starch from sapwood. Especially Abies balsamea stemwood, but also Abies sibirica heartwood, released considerable amounts of pectins, suggesting that fir species may release more troublesome anionic polysaccharides than spruce species. Heartwood of Larix lariciana, Larix decidua, Pinus banksiana, and Pinus resinosa released considerable amounts of acidic arabinogalactans. Thuja occidentalis released mainly arabinogalactans and pectins. Pseudotsuga menziesii heartwood released a large amount of arabinogalactans. 相似文献
18.
Norway spruce [Picea abies (L.) Karst.] heartwood and sapwood have differing wood properties, but are similar in appearance. An investigation was made
to see whether near-infrared spectroscopy (NIRS) could be used with multivariate statistics for separation between heartwood
and sapwood in dry state on tangential longitudinal surfaces. For classification of wood into sapwood and heartwood, partial
least square (PLS) regression was used. Orthogonal signal correction (OSC) filtering was used on the spectra. This study shows
that a separation of sapwood and heartwood of spruce is possible with NIR spectra measured in a laboratory environment. The
visible-wavelength spectra have significant influence on the predictive power of separation models between sapwood and heartwood
of spruce. All 44 specimens in the calibration set were correctly classified into heartwood and sapwood. Validation of the
model was done with a prediction set of 16 specimens, of which one was classified incorrectly. 相似文献
19.
Adam M. Taylor Barbara L. Gartner Jeffrey J. Morrell K. Tsunoda 《Journal of Wood Science》2006,52(2):147-153
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
20.
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