Evaluation of the self-bonding ability of sugi and application of sugi powder as a binder for plywood

Binderless particleboards were manufactured from sugi (Cryptomeria japonica D. Don) heartwood and sapwood by hot-pressing (pressure: 5 MPa; temperatures: 180°, 200°, and 220°C; times: 10, 20, and 30 min), and the board properties [internal bonding (IB), thickness swelling (TS), water absorption (WA)] were investigated to evaluate the self-bonding ability. The IB, TS, and WA of the boards from sugi heartwood were better than those of the boards from sugi sapwood at any hot-pressing condition. Therefore, it was suggested that the self-bonding ability of sugi heartwood was superior to that of sugi sapwood. Then, sugi heartwood and sapwood powder with grain size 10 βm were used as a binder for plywoods. Four kinds of plywood were manufactured from the combination of powder and veneer, both of which were prepared from sugi heartwood and sapwood under the same hot-pressing conditions as the binderless particleboard, and the adhesive shear strength and wood failure of the plywood were investigated. As a result, the plywood composed of sugi heartwood veneer met the second grade of JAS for plywood, when either powder was used as a binder, when they were pressed at 200°C for 20–30 min and 220°C for 10 min.     

Butt rot in conifers caused by Serpula himantioides (Fr.) Karst.

Serpula himantioides was found to be a causal agent of butt rot in Douglas fir and Japanese larch in northern Germany. The decay started predominantly from tap roots and main side roots and extended few meters into the stem. In final stages of rot the basal heartwood was completely destroyed and the residual width of healthy sapwood was reduced. Laboratory tests revealed a tolerance by the fungus to extremely acid substrates.     

Comportement in vitro du Sparassis crispa Wulf. ex Fr. et du Sparassis laminosa Fr

Behaviour in vitro of Sparassis crispa Wulf. ex. Fr. and Sparassis laminosa Fr . Sparassis crispa and S. laminosa are described in culture following the method used by Nobles. S. crispa is a very active wood destroying fungus in blocks of Douglas fir (sapwood and heartwood) in laboratory tests. The cauliflower-like fructifications are easily produced on malt-agar and could be produced on a large scale.     

On the loss factor of wood during radio frequency heating

 The radial direction loss factor of full-size western hemlock sapwood and heartwood, as well as western red cedar heartwood timbers was measured using the direct calorimetric method with a laboratory-scale radio frequency/vacuum dryer at the frequency of 13.56 MHz, moisture content range between 10 and 80%, temperature range between 25 and 55 °C, and root mean square (rms) electrode voltages of 0.8 and 1.1 kV, respectively. The results indicated that the moisture content, temperature, electric field strength and wood type significantly affected the loss factor. Empirical regression equations were derived based on the experimental data that made possible the calculation of the loss factor and power density within wood during RF heating. Received 18 January 1997     

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.     

Effect of simulated acid fog on membrane-bound calcium (mCa) in fir (Abies firma) and cedar (Cryptomeria japonica) mesophyll cells

The decline of virgin fir (Abies firma) forest at Mt. Oyama has been reported. Related field observations suggest that high acidity fog is linked with its decline. However, cedar (Cryptomeria japonica) in the same area shows no symptoms of decline. For assessing effects of acid fog on membrane-bound calcium (mCa) of the leaf mesophyll cells, 9-year-old seedlings of fir (Abies firma) and 8-year-old seedlings of cedar (Cryptomeria japonica) were exposed twice a week to simulated acid fog (SAF at pH 3 with pH 5 as control) for 2 h per day in a chamber during May–December 2007 (except August). Current and 1-year-old needles were collected from seedlings and analyzed at 1-month intervals. For current-year needles of fir, mCa levels in cells exposed to SAF at pH 3 were significantly lower than in cells exposed to pH 5, especially during September 2007–March 2008. In contrast, it is noteworthy that mCa levels of cedar were maintained as virtually constant irrespective of SAF acidity, indicating that fir is more sensitive to acid fog than is cedar. Based on these results, mCa loss by acid fog might also be caused in the declining virgin fir forest at Mt. Oyama.     

Virulence of Fusarium oxysporum and F. commune to Douglas‐fir (Pseudotsuga menziesii) seedlings

Fusarium species can cause damping‐off and root rot of young conifer seedlings, resulting in severe crop and economic losses in forest nurseries. Disease control within tree nurseries is difficult because of the inability to characterize and quantify Fusarium spp. populations with regard to disease potential because of high variability in isolate virulence. Fusarium isolates were collected from healthy and diseased seedlings of Douglas‐fir (Pseudotsuga menziesii) and western white pine (Pinus monticola) from a nursery in Idaho, USA. Molecular markers such as DNA sequences (mitochondrial small subunit and nuclear translation elongation factor 1‐alpha) and amplified fragment length polymorphism were used to identify isolates as either F. oxysporum or F. commune. In addition, diagnostic primers were developed to detect and distinguish F. commune from F. oxysporum. In vitro and greenhouse virulence tests were completed on Douglas‐fir germinants and seedlings. For Douglas‐fir germinants and seedlings, F. oxysporum isolates generally caused less severe symptoms, whereas most F. commune isolates caused mortality through damping‐off. This is the first report of direct evidence that F. commune can cause damping‐off disease on Douglas‐fir seedlings under greenhouse conditions.     

Evaluation of the temperature and relative humidity preferences of the western dry-wood termite <Emphasis Type="Italic">Incisitermes minor</Emphasis> (Hagen) using acoustic emission (AE) monitoring

Twenty-four different combinations of six temperatures (15°, 20°, 25°, 30°, 35°, and 40°C) and four relative humidity (RH) (60%, 70%, 80%, and 90%) conditions were used for pseudergates of the western dry-wood termite Incisitermes minor (Hagen). The feeding activities of the termites were monitored by the detection of generated acoustic emission (AE) events from feeder wood blocks in a test chamber. Temperature and RH showed independent and interactive significant effects on the feeding activity of I. minor. The optimal temperature and RH conditions for the feeding activities were 35°C and 70%, respectively, and the optimal combinations were 35°C-70% and 35°C-80% with an exceptionally higher feeding activity at the combination condition of 30°C-70%.     

Treatment of sugi （Cryptomeria japonica D.） sapwood with aqueous solution of acetic acid

Sugi sapwood samples were processed with aqueous solution of acetic acid in order to find the response of the weight of sugi sapwood and the treatment of aqueous solution of acetic acid. The result showed that loss of weight for the treated sugisapwood was about equal to yield of extracts from sugi sapwood, and increased with the increment of the concentration of aqueous solution of acetic acid. Fourier transform infrared spectroscopy spectra changes of the treated sugi wood and extracts from sugi sapwood were analyzed by FT-IR spectroscopic technique. Increasing tendency of absorption intensities of the stretching vibration at 3 400 cm^-1 of hydroxyl group (OH) and C=C in lignin stretching vibration at 1510 cm^-1 of benzene ring inlignin were observed from FT-IR of the treated sugi sapwood. From FT-IR spectra of extracts from sugi sapwood by aqueoussolution of acetic acid, the dissolution of lignin was observed during the treatment with 30% acetic acid solution aqueous.     

Chemical,anatomical and technological properties of Snakewood [<Emphasis Type="Italic">Brosimum guianense</Emphasis> (Aubl.) Huber]

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.     

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.     

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.     

Environmental effects on the color of sugi (Cryptomeria japonica D. Don) heartwood

Sugi (Cryptomeria japonica D. Don) is one of the most important planted trees in Taiwan. The normal heartwood of sugi has a red to pinkish rose color. Unfortunately, this pleasant appearance is susceptible to discoloration after environmental exposures. This discoloration is a serious defect that decreases the value of sugi products. The objective of this study was to investigate the effects of environmental factors such as moisture, oxygen, and lights of different wavelengths on the discoloration of sugi. The results show that under the combined effects of light and oxygen the color of heartwood changes from red (or rosepink) to bluish green. The color further darkens and eventually turns to black with the presence of moisture. As for the effect of light wavelengths on the discoloration of sugi heartwood, it was found that the red color was enhanced after being irradiated with light of wavelengths above 600 nm. Botha ^* andb ^* values increased significantly as a result of such exposure.     

Effect of different drying methods on liquid penetration of Chinese fir plantation wood

Chinese fir plantation sapwood and heartwood boards were treated by three drying methods: radio frequency-vacuum drying (RFVD), conventional kiln drying (KD) and high temperature drying (HTD). The maximum amount of dyeing solution uptake by the capillary rising method was used to evaluate the liquid penetration of the treated wood. The pit aspiration ratio was determined by a semithin section method. Changes in wood microstructure were investigated using scanning electron microscopy. The results show that liquid penetration of Chinese fir sapwood after RFVD is significantly higher than that after KD and HTD. Liquid penetration of Chinese fir heartwood after RFVD is higher than that after HTD. Liquid penetration of Chinese fir sapwood is significantly higher than that of heartwood after three drying treatments. Low pit aspiration ratio and cracks of some bordered pits are the main reasons for the increase in liquid penetration after RFVD treatment. __________ Translated from Scientia Silvae Sinicae, 2006, 42(10): 85–90 [译自: 林业科学]     

Surface-check variation in boxed-heart square timber of sugi (Cryptomeria japonica) cultivars dried by the conventional kiln drying

To investigate the factors affecting the surface-check variation in boxed-heart square timber of sugi (Cryptomeria japonica), surface checks formed by the conventional kiln drying were compared for two stem heights of five cultivars with different wood properties. The total length and average length of the surface checks were greater at the upper part of the stems for all the cultivars. This might be caused by more sapwood at the upper part of the stem, and large drying stresses between the outer sapwood and the inner heartwood. The cultivars, in which tangential shrinkage was large owing to small microfibril angle, formed longer surface checks and smaller bow. There was a positive relationship between surface-check length and tangential shrinkage. The heartwood percentage and tangential shrinkage were thought to be important factors affecting the surface-check variation in sugi boxed-heart square timber.     

Differentiating the two closely related species,Phellinus weirii and P. sulphurascens

Phellinus weirii s.l., an aggressive root rot pathogen, causes extensive wood losses and lowers the productivity of western red cedar (WRC, Thuja plicata), Douglas fir (Pseudotsuga menziesii) and other conifers. This fungus has been recognized as a cedar form (P. weirii s.s.) and a non‐cedar form (P. sulphurascens). Differentiating the two species is difficult because their fruiting bodies and cultural morphologies are very similar. However, differences in growth rate and colony morphology were observed when they were grown on malt extract agar with WRC feeder strips. In addition, different restriction fragment length polymorphism patterns were obtained using (i) the internal transcribed spacer (ITS) region cut with the restriction enzyme RsaI, and (ii) the partial large subunit ribosomal DNA region cut with AgeI and NciI. Furthermore, a new specific primer set was designed from the ITS region of P. weirii s.s. and was used to differentiate it from P. sulphurascens and other decay fungi that are frequently found in coniferous trees. These species‐specific primers will facilitate the detection of P. weirii in standing trees well before visible signs of infection are apparent.     

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.

     

Relationship between <Superscript>137</Superscript>Cs concentration and potassium content in stem wood of Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>)

To utilize forest resources in areas affected by fallout from the Fukushima Daiichi Nuclear Power Plant accident, it is important to understand the mechanisms of ¹³⁷Cs movement through the stem wood of contaminated trees. Understanding the mechanism of absorption and migration of ¹³⁷Cs to stem wood is necessary for clues to the future prediction of the transition of ¹³⁷Cs to xylem. In the present study, radial variations in ¹³⁷Cs concentration were investigated in Japanese cedar (Cryptomeria japonica D. Don) trees collected 1 year and 10 months after the accident. Additionally, the relationship between ¹³⁷Cs concentration and potassium (K) content was established. Trees with a higher moisture content and lower lightness value in heartwood tended to have a higher ¹³⁷Cs concentration in the heartwood. In these trees, ¹³⁷Cs concentration peaked at the heartwood–sapwood boundary and gradually decreased toward the pith. By contrast, K content within the heartwood remained nearly constant along the radial direction. The heartwood-to-sapwood ratio of ¹³⁷Cs concentration was significantly positively correlated with that of K content. Based on these results, we suggest that ¹³⁷Cs movement from sapwood to heartwood might be related to the K content ratio of heartwood and sapwood.     

Biological resistance of Zn-Al metal-coated wood

Sapwood blocks of sugi (Cryptomeria japonica) and akamatsu (Pinus densiflora) were coated with Zn/Al (45%/55%) alloy metal at thicknesses of 20–30, 90–100, and 180–200m by an arc spray gun. They were served for choice and no-choice tests with a brown rot fungus (Fomitopsis palustris), a white rot fungus (Trametes versicolor), and a pest termite (Coptotermes formosanus). Coating thickness of 20–30m was enough to prevent attacks by both test fungi, whereas 90–100m thickness was needed for protection against termite attacks. Exfoliation of the coating layers was observed during the wet-dry process in the tests. The results suggested that Zn-Al alloy metal coating treatment was applicable as an alternative method for the protection of timbers from biological deterioration when combined with an additional treatment creating a vapor barrier.This research was presented at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April 1998     

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.