Chemical characterization of Pinus halepensis sapwood and heartwood

ABSTRACT

This paper describes the chemical composition of sapwood (SW) and heartwood (HW) of Pinus halepensis Mill stem. Extractives were first isolated by accelerated solvent extraction and then analysed by gas chromatography-mass spectrometry (GC-MS). The cellulosic polysaccharide content present in the pre-extracted wood samples was determined with acid hydrolysis and GC. The hemicelluloses content was determined with acid methanolysis and GC. Free monomers were additionally analysed by GC. The amount of lignin was determined gravimetrically by the Klason lignin method and the acid-soluble lignin was determined by a UV method. Formic and acetic acids in wood were determined after alkaline hydrolysis and analysed by HP-SEC. It was found that lipophilic and hydrophilic extractives were more abundant in heartwood (1.6% and 2.5%) than in sapwood (1.1% and 1.8%). Celluloses content was higher in sapwood (42.5%) than in heartwood (39.7%), whereas lignin, hemicelluloses and sugar monomer contents were more abundant in heartwood (28.9%, 26.8% and 0.3%) than in sapwood (28.0%, 24.5% and 0.2%). The variation in acetic and formic acids and ash contents between sapwood (0.7%, 0.2% and 0.5%) and heartwood (0.6%, 0.1% and 0.4%) was small. The acetylation degrees were found to be slightly similar in sapwood (0.4) and heartwood (0.3).     

Resistance of Pinus leucodermis heartwood and sapwood against the brown-rot fungus Coniophora puteana

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.     

Modeling of sapwood and heartwood delignification kinetics of <Emphasis Type="Italic">Eucalyptus globulus</Emphasis> using consecutive and simultaneous approaches

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).     

“I-214杨”心材、边材木质素的红外光谱、质子和碳-13核磁共振波谱特征研究

对从杨树心、边材提取的磨木木质素进行了元素分析和红外光谱（FTIR）质子和碳－13核磁共振波谱（^1H,^13C NMR)等化学特征研究。研究结果表明：杨树心、边材木质素的经验式分别为C9H7．16O2．38（OCH3）1．99和C9H8．61O2．73（OCH3）1．33。心材木质素甲氧基含量28．16％,比边材高8．73％。两种木质素均具有典型阔叶材的特征,化学结构类型基本一致,碳骨架结构基本相同,但化学官能团和键型的组成上存在差异。     

Variation in the natural termite resistance of teak (Tectona grandis Linn. fil.) wood as a function of tree age

? Tree age is one of the most important factors to affect the natural durability of wood.

? The purpose of this study was to determine the natural termite resistance of heartwood and sapwood of teak (Tectona grandis Linn. fil.) for trees aged 8, 30 and 51 years. Reticulitermes speratus Kolbe was employed as a test termite using a no-choice feeding method.

? The heartwood and sapwood of all of the trees tested exhibited antitermitic activity. Based on the mean mass loss due to termite activity, the sapwood and heartwood regions of 8-year-old trees are the most susceptible to termites while the heartwood regions of the 30-year-old trees showed termite resistance similar to the termite resistance of 51-year-old trees.

? The mass loss is moderately correlated with n-hexane extractive content, total extractive content, brightness and redness of the wood.

     

Radial distribution of thujaplicins in old growth and second growth western red cedar (Thuja plicata Donn)

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.     

Occurrence and significance of bacteria in living trees of Populus nigra L.

On the occurrence and significance of bacteria in living trees of Populus nigra L. Eleven strains of bacteria were isolated from sapwood and heartwood of living poplar trees (Populus nigra L.) and identified mostly as Erwinia, Xanthomonas, Agrobacterium and Acinetobacter. Most of them were able to attack milled wood and the wood components pectin, hemicelluloses and holocellulose; α-cellulose and lignin were not consumed. The capillary liquid in the xylem of poplar served as a nutrient for the isolated bacteria. The significance of these bacteria for wetwood formation is discussed.     

Clonal variation of carbon content in wood of Larix kaempferi (Japanese larch)

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.     

H-NMR studies of water interactions in sitka spruce and western hemlock: moisture content determination and second moments

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 M_NMR to 4.5 × 10⁹ s^-2 (heartwood) and 4.3 × 10⁹ s^-2 (sapwood) at higher m_nmr. The adsorption and secondary desorption M₂ for the spruce sapwood region decreased from about 5.0 × 10⁹ s^-2 at low m_nmr to about 4.1 × 10⁹ s^-2 near the M_F, whereas M₂ for the spruce heartwood decreased from about 4.3 × 10⁹ s^-2 at low M_NMR to about 3.5 × 10⁹ s^-2 near M_F. 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     

The influence of heartwood on the pulping properties of Acacia melanoxylon wood

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     

Separating Norway spruce heartwood and sapwood in dried condition with near-infrared spectroscopy and multivariate data analysis

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.     

Heartwood and sapwood variation in Eucalyptus globulus Labill. trees at the end of rotation for pulp wood production

The amount of heartwood and sapwood in Eucalyptus globulus Labill. wood was determined in commercial pulpwood plantations at harvest age (12 to 15 years) in four ites in central portugal. twelve trees were sampled in each site at nine stem height levels. Heartwood was present in all the trees up to 82%–87% of the total tree height and amounted to 38%–41% of the total tree volume. The heartwood proportion in the stem cross-section decreased from the base upwards, representing 53.3% and 26.1% of the total area respectively at the base and 55% height level. The sapwood width remained relatively constant along the stem at a mean 38 mm up to the 55% height level. The trees within the site, the height level and their interaction were highly significant sources of variation for heartwood proportion and sapwood width. The heartwood diameter and sapwood width were positively correlated with radial tree growth.     

End grain water absorption and redistribution in slow-grown and fast-grown Norway spruce (Picea abies (L.) Karst.) heartwood and sapwood

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.     

柚木黑色条纹心材的颜色和化学特性

印尼岛的柚木心材在年轮周围显示了不规则的黑色条纹变化。本研究调查柚木黑色条纹心材的颜色和化学特性。利用色坐标（CIELAB）测定颜色特性（pH值、无机物含量、抽出物含量和特性）。结果表明：黑色条纹的颜色较对照少12-15个亮度单位。因此,黑色条纹的颜色与对照比较,有较多的红色,较少的黄色、色彩和色度。黑色条纹心材部分的pH值灰度含量和钙含量都比对照的高。黑色条纹的心材抽出物含量较对照的高。推测当生物活性物质（杀虫剂）明显增加时,心材显示发黑的过程可能是一种防御机制。     

Dependence of shear strength on wood properties in cultivated Larix sibirica

Abstract

Mechanical properties are very important in structural uses of wood. In the case of larch wood, shear strength (SS) may be a limiting property, because the wood is brittle and it splinters easily. In this study, SS of Siberian larch (Larix sibirica) wood was studied in relation to its axial and radial location and to some other wood properties in the part of the trunk that produces logs of good carpentry quality. SS increased by 21–23% from the pith to the outer heartwood at each studied height (butt, 4.5 and 9 m), and it was at its most approximately 7% higher at the butt than at the other studied heights. The main reason for the radial increase in SS was the increase in density caused by wood maturation, but other factors also affected SS, depending on the grouping mode (combined material, radial/axial location). An exception was sapwood, for which no factors affecting SS could be identified. Thus, sapwood may behave differently from heartwood regarding use, even unexpectedly. The results suggest that mature heartwood, but not juvenile wood and sapwood, of Larix sibirica should primarily be used in products that require high SS.     

Impregnation of radiata pine wood by vacuum treatment II: effect of pre-steaming on wood structure and resin content

Radiata pine sapwood and heartwood were dried using high-temperature, conventional-temperature, and air drying schedules with and without pre-steaming. They were then impregnated by vacuum treatment with double-distilled water, toluidine blue, and fluorescein dye. For sapwood, there were only minor differences in uptake between drying methods and when pre-steaming was used. Using microscopy, the primary flow pathways in sapwood were found to be the resin canal network and ray parenchyma cells, which provided conduction without large resistance. In heartwood, uptake was strongly influenced by pre-steaming the green lumber. After pre-steaming heart-wood, there was an increase in uptake from all surfaces but especially from the radial surfaces. Lower extractive contents, disruption of epithelial and ray parenchyma cells, and alteration of the condition of bordered pits were also associated with pre-steaming. It was therefore possible to classify flow paths in radiata pine heartwood five ways, according to uptake values and wood anatomical features.This research was presented in part at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April 1998.     

Characterization and antioxidant activity of Amazonian woods

The heartwood and sapwood characteristics of 11 Amazonian trees were investigated. Whereas 7 of the specimens had densities greater than 0.7 g/cm³, the heartwood density of ipê amarelo (Tabebuia serratifolia), maçaranduba (Manilkara huberi), cumaru-ferro (Dipteryx odorata), and guarita (Astronium lecointei) exceeded 1.0 g/cm³. Jatobá contained small amounts of Klason lignin and α-cellulose, and large amounts of holocellulose and alkali extract, suggesting that it has a high polysaccharide content that can be dissolved in an alkaline medium. The difference in the syringyl/guaiacyl (S/G) ratios of the samples before and after alkali extraction suggests that alkali extracts contain syringyl-type polyphenols. In all of the samples, the heart-wood methanol extracts were larger in volume than the sapwood methanol extracts, and the sapwood alkali extracts were larger in volume than the heartwood alkali extracts. The antioxidant activities of the methanol and alkali extracts were assayed by measuring the levels of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and super oxide dismutase (SOD)-like activity, respectively. The heart-wood methanol extract of jatobá (Hymenaea courbaril) exhibited the highest level of activity (EC₅₀ = 44 mg/l), which exceeded that of α-tocopherol (EC₅₀ = 48 mg/l), and the heartwood alkali extracts of jatobá and ipê amarelo had high SOD-like activity comparable with red wine.     

Chemical composition of earlywood and latewood in Norway spruce heartwood,sapwood and transition zone wood

This study focused on the distribution of wood components along a cross section of a spruce stem. Thin samples of earlywood and latewood were analysed by special micro-scale analytical techniques. Heartwood contained significantly more lignin and less cellulose than sapwood. The total content of hemicelluloses was the same along the radial direction, but the distribution of sugar units differed. The amounts of arabinoglucuronoxylan and pectins were larger in the heartwood. The transition zone between heartwood and sapwood had a specific composition, with less lignin and lipophilic extractives than heartwood and sapwood. For earlywood and latewood, significant differences were found in the distribution of sugar units in hemicelluloses. Latewood contained clearly more galactoglucomannan than earlywood, and conversely less pectins. The lipophilic extractives were also less concentrated in the latewood.Abbreviations EW or E earlywood - LW or L latewood - HW heartwood - SW sapwood - TZ transition zone wood - A.R. annual ring - AcBr Acetyl bromide - Ara arabinose - Xyl xylose - Gal galactose - Glc glucose - Man mannose - Rha rhamnose - GlcA glucuronic acid - MGlcA 4-O-methyl-glucuronic acid - GalA galacturonic acid - o.d. oven dry     

Polysaccharides in some industrially important softwood species

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.     

Some factors influencing susceptibility to discoloring fungi and water uptake of Scots pine (Pinus sylvestris), Norway spruce (Picea abies) and Oriental spruce (Picea orientalis)

Abstract

The heartwood and sapwood from Scots pine (PS), Norway spruce (PA), and Oriental spruce (PO) were tested for susceptibility to discoloring fungi and water uptake. In addition, annual ring width and density were measured. The methods used were Mycologg for testing growth of fungi and a modified version of EN 927-5 to investigate water uptake. For pine, the heartwood showed a lower water uptake and no discoloring fungi growing in the tests. The heartwood had a significantly higher density and smaller annual ring width than the sapwood. In PA the heartwood had significantly lower discoloration than sapwood. The total water uptake in g/m² was significantly higher in sapwood, but not the calculated moisture content. As for wood properties, the density was significantly higher in sapwood compared to heartwood, although there were no differences in annual ring width. Regarding PO, differences in water uptake could be seen between sapwood and heartwood although the densities were similar. These results show that susceptibility to discoloring fungi and water uptake is hard to correlate to a single inherent property when looking at different wood species.