Cesium absorption through bark of Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>)

Absorption of radiocesium (¹³⁷Cs and ¹³⁴Cs) through bark, and its subsequent translocation into wood and needles, has been suggested as a potential source of tree contamination, but the process is not well understood. Field experiments were conducted to confirm whether Cs could enter a Japanese cedar tree through the bark and how Cs moves within a tree. Stable Cs (¹³³Cs) was applied to the bark at 1.2-m height on 10- and 26-year-old Japanese cedars. The ¹³³Cs concentrations were determined in the bark, sapwood, and heartwood (for 26-year-old cedar only) of stem disks from several heights, as well as in current-year needles from the canopy. The ¹³³Cs concentrations were considerably higher in the sapwood and heartwood of stem disks from 1.2-m height in treated trees than in untreated trees, suggesting that ¹³³Cs penetrated the bark to enter the wood. The average ¹³³Cs concentrations were higher in the heartwood than the sapwood, indicating ¹³³Cs accumulation in the heartwood. High ¹³³Cs concentrations in the needles of treated trees implied acropetal movement of ¹³³Cs to actively growing organs. Our results demonstrate that Cs can enter Japanese cedar trees through the bark and that Cs is transported radially to the heartwood and vertically to the apex.     

Decontamination of Cs from Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>) via kraft cooking

To investigate the possibility of decontaminating ¹³⁷Cs-contaminated Cryptomeria japonica wood, kraft pulping was conducted and the Cs behavior in the reaction process was examined. ¹³³Cs-treated or ¹³⁷Cs-contaminated bark, sapwood, and heartwood chips of Cryptomeria japonica were digested using an aqueous solution of NaOH and Na₂S. The pulp was washed with ultrapure water and filtered, after which the filtrate (black liquor) was collected. The black liquor was acidified to separate the supernatant and precipitation. The Cs (¹³³Cs and ¹³⁷Cs) concentrations in the chip and reaction products were measured. As for wood samples, the majority of Cs was present in black liquor, while only a minor amount of Cs was retained in the pulp (<1%). In the case of bark, although the majority of Cs was present in the black liquor, the proportion of Cs in the pulp was much higher than that in the wood pulp. In addition, the Cs in the precipitation of the bark was higher than that in the wood, possibly because the Cs in the bark was combined with some components, which is insoluble in alkaline solution. Our results suggest that ¹³⁷Cs-contaminated Cryptomeria japonica wood can be used in the pulp and paper industries.     

Application of activable tracers to investigate radial movement of minerals in the stem of Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>)

Two activable tracers, Rb and Eu, were injected into the sapwood of Japanese cedars (Cryptomeria japonica D. Don) to investigate the radial movement of minerals in their stems in the resting period. Eight trees of four cultivars, two of which genetically form wet heartwood, were treated near the end of the growing period. At 40 days after the treatment, Rb was detected in the outer heartwood, whereas Eu was not. Radial movement of Rb was more rapid in trees with wet heartwood than in those with normal heartwood. At 204 days after the treatment, more Rb was detected in the heartwood than was found on the first sampling, whereas no Eu was detected in the heartwood. The difference in radial movement between Rb and Eu was considered mainly to be the result of selective transport of beneficial minerals by Japanese cedar. The difference in the rate of radial movement of Rb between wet and normal heartwood became more conspicuous at 204 days after treatment. We concluded that the movement of Rb from the sapwood to the outer heartwood was by active transport through the rays, whereas that in the heartwood was by diffusion due to the gradient of Rb concentration.     

Radial movement of sapwood-injected rubidium into heartwood of Japanese cedar (<Emphasis Type="Italic">Cryptomeria</Emphasis><Emphasis Type="Italic">japonica</Emphasis>) in the growing period

Rubidium solution was injected in the sapwood of a Japanese cedar cultivar in the growing period, and its radial movement in stem was traced to investigate the accumulation of alkali metals in the heartwood. Sapwood-injected Rb was detected in outer heartwood at 10 days after the treatment, and continued increasing at 20 days after. Radial movement of Rb toward heartwood was considered to occur soon after the treatment, and to decline at a certain point of the time after Rb injection ceased. However, Rb continued moving in heartwood probably by diffusion even after the cease of Rb injection. In a series of injection experiment, radial movement of injected Rb is not corresponding to the seasonality of both cambial activity and cytological changes of ray parenchyma accompanied with heartwood formation. From the results on Rb’s behavior, we conclude that accumulation of K and other alkali metals in heartwood of Japanese cedar has two steps, active transport from sapwood to outer heartwood via ray, and diffusion in heartwood, and that these processes proceed independently from both cambial activity and cytological changes of ray parenchyma.     

Radial distribution patterns of the green moisture content in trunks of 46-year-old red cypress (<Emphasis Type="Italic">Chamaecyparis formosensis</Emphasis>)

Understanding the green moisture content and wood density is important for effective forest management. Radial distribution patterns in the green moisture content (MC) and basic density (BD) in stems of red cypress (Chamaecyparis formosensis) were investigated in 69 plantation trees that were 46 years old. An increment core was collected from each sample tree at breast height (1.3 m). Five radial positions were defined: pith piece (Pith), inner heartwood (IHW), outer heartwood (OHW), intermediate wood (TSH), and sapwood (SW). Results showed that the average MC was highly dependent on the individual tree. Average values of the MC obtained from the TSH were significantly lower than those for the other positions. The MC of heartwood was higher than that of SW. Distribution patterns of the MC in the radial direction varied among trees. Radial variations in MC and BD were greater than in between-tree variations. Six types of radial distribution patterns of MC were detected for sample trees. MC values increased with decreasing BD (except for the TSH). Positive correlations were found between adjacent sampling positions in both MC and BD.     

Resistance of wood from black pine (<Emphasis Type="Italic">Pinus nigra</Emphasis> var. <Emphasis Type="Italic">austriaca</Emphasis>) against weathering

At present tapped wood of black pines (Pinus nigra var. austriaca) is mainly combusted. The priority of material use over thermal recycling has led to some considerations regarding the utilization of tapped wood. The high content of extractives suggests a higher natural durability, and therefore, the suitability for outdoor applications. Tapped and not tapped wood boards from black pine (sapwood and heartwood) were subjected to weathering tests to find out its resistance against abiotic stress. Additionally tapped wood particles with a high content of resin were exposed to weathering and to composting. Weathering caused roughness to increase. Infrared spectral characteristics revealed the differences before and after tapping and weathering. Principal component analyses supported the grouping according to the chemical changes. In heartwood the lignin band at 1510 cm^??1 disappears and the typical resin band at 1688 cm^??1 decreases considerably. The lignin band of resinous parts is affected neither by weathering nor by composting. However, the resin band shows an intensity decrease and broadening due to weathering and disappears during composting.     

Wood properties of teak (<Emphasis Type="Italic">Tectona grandis</Emphasis>) from a mature unmanaged stand in East Timor

The wood quality from 50- to 70-year-old Tectona grandis trees from an unmanaged forest in East Timor was assessed. The aim was to evaluate teak in mature stands that had undergone uncontrolled disturbances, e.g., fire and local community usage. Heartwood represented 91% of the tree radius at a height of 1.7 m, and sapwood contained on average nine rings. The mean ring width showed within-tree and between-tree variability. The chemical compositions of heartwood and sapwood were similar. Within-tree chemical variation occurred only in terms of extractives, which increased from the pith (8.3%) to the heartwood-sapwood transition (12.7%) and decreased in the sapwood (9.2%). Overall, the wood properties of teak from a unmanaged forest in East Timor were comparable to those reported for plantation teaks of other origin: 607 kg/m³ basic density, 3.5% and 5.2% radial and tangential shrinkage, 141 N/mm² modulus of rupture, 10684 N/mm² modulus of elasticity, and 50 N/mm² maximum crushing strength in compression parallel to the grain. Disturbances on individual tree growth arising from the unmanaged status of the stand were evidenced by higher within-tree variability of ring width. However, the longitudinal and radial variations of wood density and mechanical properties were of low magnitude and in a degree that did not negatively impact on timber quality.     

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.     

Heartwood, sapwood and bark content of teak trees grown in Karnataka, India

We evaluated heartwood, sapwood and bark content in teak trees. A total of 27 sample plots were laid out in teak plantations raised by State Forest Department in Karnataka covering different age groups...     

Characterization of Douglas-fir grown in Portugal: heartwood,sapwood, bark,ring width and taper

Douglas-fir (Pseudotsuga menziesii) is one of the best timber conifers providing long sawnwood components. Original from North America, it has been planted in Europe on approximately 550 thousand ha. Twenty Douglas-fir trees growing in two sites in Portugal were studied regarding ring analysis, heartwood, sapwood and bark development, and taper. The radial growth rate was 7.1 and 6.6 mm year⁻¹ at stem base for 45- and 50-year-old trees, respectively, in the two sites. Initial growth rate was slower, increasing until about 20 years and decreasing afterwards. Heartwood proportion represented on average 49% of the cross section in the lower part of the stem and decreased upwards. Heartwood formation was estimated to start at a cambial age of 8–9 years and increasing by 0.7–0.9 rings year⁻¹. Sapwood width was on average 75 mm at stem base, decreasing upwards. Bark was 26–27 mm thick at stem base, where it represented 15% of the cross-sectional area and decreased to 3–5 mm at the top. Stemwood and heartwood tapers were on average 15 mm m⁻¹ in the lower stem part and 21 and 18 mm m⁻¹, respectively, in the upper part. Douglas-fir showed a good potential for the mountain areas of Portugal, and under the silvicultural conditions of both stands the trees presented ring homogeneity, small conicity and low taper suitable for long wood components.

     

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     

Circumferential variation of heartwood and stem quality in maritime pine stems

Maritime pine (Pinus pinaster Ait.) is an important timber and pulpwood species covering about 4 million ha in Portugal, Spain and France. This work studied the cross-sectional distribution of heartwood and sapwood along the stem using 3D modelling on 20 trees. The target was to assess the potential of this species for the industrial production of heartwood sawn products. The maritime pine stems were characterized by wide sapwood of 10 cm, in average, and the presence of heartwood at all height levels with constant diameter up to 35 % tree height, decreasing afterwards. In the radial section, the heartwood follows a circumferential-like shape which changes along the stem. Pith eccentricity index values were low and homogeneous regarding to stem and higher for heartwood. Heartwood cross-sectional shape was constant up to 45 % of total height of the tree and more elongated upwards. The constant heartwood diameter, low taper and pith eccentricity index, and an approximate circular shape up to 10 m height indicated these species’ potential to produce solid wood products made out of heartwood.     

Family effects in heartwood content of Eucalyptus globulus L.

Thirty families of Eucalyptus globulus L., established in a first-generation open-pollinated progeny test, were evaluated for the production of heartwood. Five trees of each family were harvested at 9 years of age, total tree height was measured and a cross-sectional disc was removed at 25 % stem height to estimate the amount of heartwood. The heartwood proportion of the stemwood cross-sectional area averaged 41 % with significant between-family variation (P = 0.016) ranging from 27 to 53 %. There were also important within-family differences with coefficients of variation of the mean between 4 and 48 %. Moderate heritability values were obtained for heartwood diameter and proportion (h ² = 0.31 and 0.23, respectively) but low estimates were found for sapwood width (h ² = 0.17). Strong positive genetic and phenotypic correlations of heartwood diameter were found with stem DBH and with heartwood proportion. Both correlation estimates indicated that larger trees tended to have more heartwood. The results indicate that there is an opportunity to reduce heartwood content in E. globulus through selection and breeding.     

黑木相思株内木材基本材性变化与树龄关系的研究

对不同树龄和径向位置黑木相思木材的物理和主要力学性质测定研究表明:黑木相思株内边材、心材密度和主要力学性质随着树龄的增大而增大,径向和弦向的体积干缩率随着树龄的增大而减小;相同树龄黑木相思的边材密度和力学性能比心材小,干缩率比心材大.因此,在利用黑木相思时应对树龄、心边材径向位置加以特别考虑.     

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).     

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.

     

Inter-tree and intra-tree variation in the physical properties of wood of laurel (<Emphasis Type="Italic">Laurus nobilis</Emphasis>)

The laurel (Laurus nobilis L.) is a common species in southern Europe, but the properties of its wood are not well described in the literature and from that perspective any novel information is valuable. Because of that, a group of laurels was felled for the analysis of wood properties on small defect-free specimens (17 trees and 1250 valid specimens). The sampled wood was moderately heavy and unstable. The following mean values were obtained (density at 12% moisture content 699 kg m^?3; basic density 566 kg m^?3; total volumetric shrinkage 18.0%; volumetric shrinkage coefficient 0.59%). Highly significant inter-tree and intra-tree variation was observed for most of the properties considered. The inter-tree variation was attributed to tree dimensions, being remarkable that volumetric, radial and tangential shrinkage coefficients were significantly related to breast height diameter and slenderness. The trends of these variables suggest that in trees older than those used in the study (24–41 years old) the dimensional stability would increase. As regards the inter-tree variation, a low but highly significant decrease was found for density at highest positions in the tree. Volumetric and linear shrinkage diminish very significantly along the stem. Due to the uniformity of density and the increment of wood dimensional stability along the trunk, the harvesting of the full stem is advisable.     

Improvement of penetrability of sugi wood by impregnation of bacteria using sap-flow method

The sap flow method of wood impregnation was conducted to aid the movement of bacteria through the living tree, thereby accelerating their distribution through wood within a short time. When log-pond water containing mixed species of bacteria were introduced in the living trees by butt-end dipping and then laid horizontally for 6 months, bacteria could be delivered by sap flow vertically through the sapwood tracheids up to the high portions from the butt-end of trees; they could be detected in the ray parenchymal cells. The sap-flow method was assumed to deliver the bacteria to sapwood and heartwood at high levels of standing sugi (Cryptomeria japonica D. Don) trees. Degradation of the pit membranes was observed even at more than 3 m upward from the butt-end after the treatment in sapwood, as well as around the butt-end of the trees. The uptake of the aqueous dye solutions in sapwood of the treated logs were about eight times more than those of control specimens after 8h.Part of this report was presented at the 40^th annual meeting of the Japan Wood Research Society, Tsukuba, April 1990; the 41^st annual meeting of Japan Wood Research Society, Matsue, April 1991; and the IUFRO 4^th international conference on wood drying, Rotorua, New Zealand, August 1994     

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.     

Variation in wood density and carbon content of tropical plantation tree species from Ghana

Most research on carbon content of trees has focused on temperate species, with less information existing for tropical trees and very little for tropical plantations. This study investigated factors affecting the carbon content of nineteen tropical plantation tree species of ages seven to twelve and compared carbon content of Khaya species from two ecozones in Ghana. For all sample trees, volume of the main stem, wood density, wood carbon (C) concentration and C content were determined. Estimated stem volume for the 12-year-old trees varied widely among species, from 0.01 to 1.04 m³, with main stem C content ranging from 3 to 205 kg. Wood density among species varied from 0.27 to 0.76 g cm^?3, with faster growing species exhibiting lower density. Significant differences in wood density also occurred with position along the main stem. Carbon concentration also differed among tree species, ranging from 458 to 498 g kg^?1. Differences among species in main stem C content largely reflected differences among species in estimated main stem volume, with values modified somewhat by wood density and C concentration. The use of species-specific wood density values was more important for ensuring accurate conversion of estimated stem volumes to C content than was the use of species-specific C concentrations. Significant differences in wood density did exist between Khaya species from the wet and moist semi-deciduous ecozones, suggesting climatic and site factors may also need to be considered. Wood densities for these plantation grown trees were lower than literature values reported for the same species in natural forests, suggesting that the application of data derived from natural forests could result in overestimation of the biomass and C content of trees of the same species grown in plantations.