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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.
Dietrich Fengel 《Wood Science and Technology》1970,4(3):176-188
Although most of the wood cells which are produced in the cambium die after the deposition of secondary wall thickening and lignification, the parenchymous cells contain living substances throughout the sapwood and are used for transportation and storage of metabolic materials. In the electron microscope dark globular particles of different sizes were traced from cambium to heartwood border in the parenchymous cells of pine. In the sapwood-heartwood transition zone the dark particles loose their globular shape and the dark content is deposited upon the parenchymous cell wall and therewith upon the membranes of the window-like pits. In this state the membranes are darkly colored so that it is assumed that the dark materials diffuse into the membranes. Dark deposits were observed within the compound middle lamella, in the chambers of bordered pits, and within the fiber lumina. From these observations it is concluded that the dark substances migrate through the middle lamella into the pit chambers and from there into the cell lumina. There is evidence that the decomposition of the globular particles as well as the diffusion of the dark substances into the cell walls begin in a region which is macroscopically considered to be part of the sapwood. Subsequent reactions in the deposition places result in the formation of typical heartwood substances.Presented at the International Wood Chemistry Symposium held at the University of Washington, Seattle, Wash., Aug. 31 to Sept. 4, 1969. 相似文献
3.
Heartwood is a determining factor of wood quality and understanding the biology of heartwood may allow us to control its formation. Heartwood formation is a form of senescence that is accompanied by a variety of metabolic alterations in ray parenchyma cells at the sapwood-heartwood transition zone. Although senescence has been studied at the molecular level with respect to primary growth, the cell maturation and death events occurring during heartwood formation have been difficult to study because of their location and timing. Analysis of global gene expression patterns during the transition from sapwood to heartwood may offer a powerful means of identifying the mechanisms controlling heartwood formation. Previously, we developed cDNA microarrays carrying 2567 unigenes derived from the bark/cambium region, sapwood and transition zone of a mature black locust tree. Here, we describe the use of these microarrays to characterize seasonal changes in the expression patterns of 1873 genes from the transition zone of mature black locust trees. When samples collected in summer and fall were compared, 569 genes showed differential expression patterns: 293 genes were up-regulated (> twofold) in summer (July 5) and 276 genes were up-regulated in fall (November 27). More than 50% of the secondary and hormone metabolism-related genes on the microarrays were up-regulated in summer. Twenty-nine out of 55 genes involved in signal transduction were differentially regulated, suggesting that the ray parenchyma cells located in the innermost part of the trunk wood react to seasonal changes. We established the expression patterns of 349 novel genes (previously unknown or no-hit), of which 154 were up-regulated in summer and 195 were up-regulated in the fall. 相似文献
4.
Beritognolo I Magel E Abdel-Latif A Charpentier JP Jay-Allemand C Breton C 《Tree physiology》2002,22(5):291-300
5.
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
6.
《Scandinavian Journal of Forest Research》2012,27(1):41-53
Abstract This study focused on the amount of sapwood and its variation by means of computed tomographic (CT) imaging. Twenty-four trees were selected from four Norway spruce [Picea abies (L.) Karst.] stands in north-eastern France, varying in age, density and fertility. In each stand, sampled trees represented the dominant, co-dominant and suppressed strata. The heartwood/sapwood boundary was detected from the CT images, and the heartwood and sapwood amount and their variations were then evaluated. At the within-tree level sapwood width was relatively constant along the tree stem above the butt swelling and below the living crown. The between-tree sapwood width variations were partially explained by the total cross-sectional area of living branches. This result opens up the possibility of investigating within-tree allometric relationships. Sapwood width was found to be highly correlated with tree slendemess (tree height/breast height diameter) and with the relative height of the crown. This suggests that sapwood width could be readily predicted from conventional forest inventory measurements. The number of sapwood rings within the stem was largely dependent on cambial age, and could be determined dynamically using the concept of mean lifetime of sapwood rings. 相似文献
7.
综述了矿质元素在针叶树干内的径向、轴向和细胞壁内的分布特点;影响矿质元素在树干内分布的主要因素。评述了以树木中矿质元素的分布特征进行树木分类的可行性,以及树干年轮间元素的变化值作为评价环境年代变迁指标的有效性。并对今后的研究方向提出了建议。 相似文献
8.
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
9.
Eucalyptus globulus sapwood and heartwood were delignified at 130°, 150°, or 170°C by kraft pulping. Pulp yields of heartwood were lower than
those of sapwood (46.5% vs. 50.4% at 170°C). Delignification was modeled using consecutive and simultaneous kinetic models.
The modeling was similar for heartwood and sapwood, and either approach could be used, with both yielding good correlations
between experimental and model data. The consecutive model identified two delignification phases with similar reaction rates
and activation energies for heartwood and sapwood at 150° and 170°C. At 130°C only one phase was identified. Three reactive
types of lignin fractions were identified using the simultaneous model, without differences between heartwood and sapwood.
Their reaction rates were 0.152, 0.138, and 0.003 min−1 at 170°C, and the activation energies were 132, 119, and 102 kJ.mol−1. The presence of heartwood did not influence the kinetic development of delignification. The negative impact of heartwood
in pulping is related to the higher content of extractives (9.8% vs. 3.9% in heartwood and sapwood) and to their influence
on the process, namely in the heating-totemperature phase when a substantial mass loss occurs (30% vs. 20% for heartwood and
sapwood). 相似文献
10.
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
11.
W. E. Hillis 《Wood Science and Technology》1968,2(4):241-259
Summary A complete understanding of the processes underlying the transformation of sapwood into heartwood requires consideration of the chemical as well as other aspects of the change. A review of recent investigations into chemical topics is presented. There is a decrease in the storage materials from the outer and middle sapwood to the heartwood boundary, although there is one case where the reverse trend of sugar content was found and this may be a seasonal effect. The evidence presented shows that, in some species, some metabolic pathways operating at the sapwood-heartwood boundary differ from those in the sapwood. It is not known whether the reactions operating at the heartwood boundary include those previously operating in the sapwood or whether the new compounds are added to those already present. The composition of the heartwood extractives in a species is the same in different samles. Examples are given to show that the affected wood resulting from different forms of damage can be chemically different from normal heartwood. Consequently, the processes leading up to the death of the living cells can have a great influence on the composition of the extractives. Accordingly it is not only the constant composition of normal heartwood extractives that is under genetic control, but also the processes which initiate their formation. The intermediate zone and the factors which could initiate heartwood formation and control the amount of extractives formed, are considered. Evidence shows the extractives to be formed at the heartwood periphery from translocated carbohydrate, the amount of which is possibly under the control of growth-promoting hormones.
The paper was prepared for the Symposium Heartwood Formation and its Influence on Utilisation at the XIV. IUFRO Congress Section 41, Munich, September 1967. 相似文献
Zusammenfassung Zum Gesamtverständnis des Vorganges der Umwandlung von Splintholz in Kernholz müssen sowohl chemische als auch andere Gesichtspunkte in Betracht gezogen werden. Es wird zunächst ein Überblick über die neuesten Untersuchungen mit chemischen Zielsetzungen gegeben. Man findet vom äußeren und mittleren Splintholz gegen die Kernholzgrenze hin eine Abnahme der Inhaltsstoffe, obwohl es auch einen Fall gibt, wo es sich mit dem Zuckergehalt genau umgekehrt verhält, was auf eine jahreszeitliche Gegebenheit zurückzuführen sein dürfte. Die gewonnenen Erkenntnisse weisen darauf hin, daß bei einigen Holzarten die Art und Weise des Stoffwechsels in der Nähe der Splint-/Kernholzgrenze von demjenigen im reinen Splintholz wesentlich abweicht. Es ist bisher nicht bekannt, ob die Prozesse, die an der Kernholzgrenze ablaufen, auch diejenigen Prozesse einschließen, die zuvor im Splintholz stattfanden oder ob die neugebildeten Bestandteile einfach zu den schon vorhandenen hinzutreten. Die Zusammensetzung der Inhaltsstoffe des Kernholzes einer Holzart bleibt dieselbe innerhalb verschiedener Proben. Es werden Beispiele dafür aufgeführt, daß Holz mit Verletzungen, die das Ergebnis verschiedener Formen von Beschädigung sind, sich chemiseh vom normalen Kernholz unterscheidet. Infolgedessen kann der Vorgang, der schließlich zum Absterben lebender Zellen führt, einen beträchtlichen Einfluß auf die Zusammensetzung der Inhaltsstoffe haben. Es ist ferner nicht nur die konstante Zusammensetzung der normalen Kernholz-Inhaltsstoffe, die einer genetischen Steuerung unterliegt, sondern auch der Vorgang, durch welchen ihre Entstehung eingeleitet wird. Die Zwischenzone und jene Faktoren, welche die Kernholzbildung einleiten und die Menge der gebildeten Inhaltsstoffe steuern, werden erörtert. Das Ergebnis zeigt, daß die Inhaltsstoffe an der äußeren Hartholzgrenze aus umgelagerten Kohlenhydraten geformt werden. Ihre Menge wird möglicherweise von wuchsfördernden Hormonen gesteuert.
The paper was prepared for the Symposium Heartwood Formation and its Influence on Utilisation at the XIV. IUFRO Congress Section 41, Munich, September 1967. 相似文献
12.
《Wood material science & engineering》2013,8(4):242-244
Abstract This study assessed the decay resistance of Pinus leucodermis wood to the brown-rot fungus Coniophora puteana. Based upon the median weight losses of 30.65% for heartwood and of 34.68% for sapwood obtained in the biological tests, both the heartwood and sapwood material examined was classified as not durable (durability class 5) according to the CEN/TS 15083-1 classification. Total extractives were low, 3.93% in heartwood and 1.00% in sapwood, while lignin content was 22.60% and 25.41% in heartwood and sapwood, respectively. It is highly recommended to use protective treatments before using P. leucodermis wood in outdoor conditions. 相似文献
13.
Ethylene concentrations were determined in gas samples extracted from sealed holes made in the sapwood and heartwood of stems of 70-100-year-old Scots pine (Pinus sylvestris L). Gas could be collected from the heartwood holes by lowering the pressure by means of a large syringe. However, attempts to extract gas from air spaces in the sapwood with the same technique failed, presumably because of lack of an interconnected system of gas-filled canals. High ethylene concentrations, usually in excess of 1 ppm, accumulated in the sapwood holes within one day after sealing. Ethylene concentrations in the sapwood rose to 3-7 ppm during the growing season, and decreased to 0.1-0.3 ppm during the winter. In response to extreme drought, sapwood ethylene concentration increased to 30 ppm, followed by a rapid decrease after the onset of rain. Ethylene concentrations in gas samples from the heartwood were consistently lower than 1 ppm. The lowest values, about 0.1 ppm, were found during the autumn and early winter, whereas values around 0.5 ppm were typical from February to August. 相似文献
14.
Heartwood,its function and formation 总被引：3，自引：0，他引：3
R. K. Bamber 《Wood Science and Technology》1976,10(1):1-8
Summary Some of the changes which occur in wood during the transition from sapwood to heartwood have been reviewed. The nature of these changes suggest that heartwood formation is a regulatory process serving to keep the amount of sapwood at an optimum level. The pattern formed by the transition of cells from sapwood to heartwood suggests that heartwood development is controlled by a centripetally-translocated growth-active substance. The nature of the heartwood transformation is indicative of a developmental process rather than a deterioration of cell function with age so that death of the parenchyma cells is the result and not the cause of heartwood formation.The assistance of Jeanette Gregory, transmission electron microscopy; Dianne Higginbotham, scanning electron microscopy; N. Omar, statistical analysis; C. Taylor, photography; F. R. Humphreys, D. Edwards, D. Adamson, R. C. Foster, and F. V. Mercer, critical comments, is acknowledged. The scanning electron microscopy was undertaken at the Electron Microscopy Unit, Sydney University with the kind co-operation of C. Nockolds. The permission of Marcia Lambert to use unpublished data in Table 2 is also acknowledged. 相似文献
15.
At present, a carbon (C) content of 50% (w/w) in dry wood is widely accepted as a generic value; however, few wood C measurements have been reported. We used elemental analysis to investigate C content per unit of dry matter and observed that it varied both radially and vertically in boles of two old-growth tree species: sugar maple (Acer saccharum Marsh.) and giant sequoia (Sequoiadendron giganteum (Lindl.) Bucholz). In sugar maple there was considerable variation in tree ring widths among four radii for particular annual layers of xylem, revealing that the annual rate of C assimilation differs around the circumference and from the base of each tree to its top, but the observed variation in C content was unrelated to diameter growth rate and strongly related to the calendar year when the wood was formed. Carbon content in sugar maple wood increased in an approximately linear fashion, from < 50 to 51% from pith to cambium, at both the base and top of the boles. In giant sequoia, C was essentially constant at > 55% across many hundreds of years of heartwood, but it declined abruptly at the sapwood-heartwood boundary and remained lower in all sapwood samples, an indication that heartwood formation involves anabolic metabolism. Factors that may be responsible for the different C contents and trends with age between sugar maple and sequoia trees are considered. Tree-ring data from this study do not support some of the key assumptions made by dendrochronology. 相似文献
16.
There are indications that the drying process may have negative effects on the natural durability of wood. The impact of various
drying processes on the durability of Scots pine lumber has been evaluated with mass loss in a decay test with brown rot fungus,
Coniophora puteana, as measure of the decay resistance of sapwood and inner and outer heartwood. Drying with or without steam conditioning was
performed in six different series: air drying, kiln drying at temperature ranges commonly used in Swedish sawmills at 70°C
and 90°C with two different regulation principles, and one high-temperature drying at 110°C. Durability varied considerably
both between and within boards. Sapwood showed considerable less durability than heartwood. No difference in durability was
found between inner heartwood and outer heartwood. Air-dried heartwood showed the highest durability compared to other drying
series. The lowest durability in sapwood and heartwood was found for series dried at the 90°C temperature level with high
material temperature early in drying. The interpretation is that the duration of high material temperature at high moisture
content (MC) is the critical combination for decay resistance in heartwood. Steam conditioning after drying decreased durability
in sapwood. 相似文献
17.
Eitaro Fukatsu Yoko Fukuda Makoto Takahashi Ryogo Nakada 《Journal of Wood Science》2008,54(3):247-251
Variations in carbon content in wood among 102 clones, selected from almost the entire natural distribution area, were investigated
in Larix kaempferi. The average carbon content was 50.50%, 50.94%, and 50.80% in sapwood, heartwood, and whole wood, respectively. The difference
in carbon content between clones was significant. The clonal repeatabilities were 0.46, 0.38, and 0.44 in heartwood, sapwood
and whole wood, respectively. The coefficients of variation in the clonal mean carbon content were only 0.43%, 0.42%, and
0.41% in heartwood, sapwood, and whole wood, respectively. This small genetic variation and resulting small relative genetic
gain of carbon content indicate that the genetic improvement of carbon content by selection has a small effect on the genetic
improvement of carbon sequestration capacity by selection in L. kaempferi. 相似文献
18.
The purpose of this study was to compare the distribution of moisture contents (MCs) along the radial direction during radio-frequency/vacuum (RF/V) drying of log cross sections of heartwood (HLC) where sapwood was removed from a green log cross section and log cross section of mixed sapwood and heartwood (MLC) prepared with debarked logs of Japanese larch (Larix leptolepis) and locust (Robinia pseudoacacia). For Japanese larch, an even distribution of MC was observed over the entire cross section in HLC not only at the initial stage of drying but also up to the completion of drying. Furthermore, the moisture gradient between the outermost slice and the adjacent inner slice was more gradual compared with that in MLC. For locust, the moisture gradient between the outermost slice and the adjacent inner slice became severe as drying progressed. It decreased after reaching the maximum during the middle stage of drying but continued until the late stage of drying. Furthermore, despite the fact that the average initial MC of mixed slice within MLC was higher compared with that in heartwood slice, this trend reversed immediately after drying started. It was suggested that the possibility of formation of border checking would be high during drying the MLC, since it would be so complicate that the sapwood and heartwood reach fiber saturation point together because of differences in their green MCs and permeability between them. 相似文献
19.
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
20.
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