Surface quality sensing of trembling aspen (Populus tremuloides Michx.) veneer products by near infrared spectroscopy

Abstract

The potential of near infrared spectroscopy (NIRS) to estimate wood moisture content (MC), surface energy characteristics and adhesive bond strength were evaluated on aspen (Populus tremuloides Michx.) veneer subjected to different drying times. For samples dried progressively at 103°C, the best MC prediction model was for the total MC range (0–100%) with an R² value of 0.68. However, exposure at 180°C produced surface colour changes, and the CIE L*a*b* colour parameters measuring colour changes were better estimated using the 400–900 nm spectral data than the 1100–2400 nm spectral data. Increased exposure time at 180°C resulted in lower wettability and, hence, larger contact angles, especially when ethylene glycol was used as probe solvent. Lap shear strength tests on veneers showed that adhesion by phenol formaldehyde resins was impaired by the high temperature exposure; however, the lap shear strength test had high variability so there was not always a clear relationship between contact angle and lap shear strength test.     

基于L*a*b*颜色空间对木材分类的研究

L*a*b*均匀颜色空间具有等距性和色差高分辨力的特点,非常适合色差较小情况下的颜色测量和比较.木材材色分布范围较窄,利用L*a*b*颜色空间中的颜色特征表示木材表面颜色,有利于木材材色之间的比较和划分.基于L*a*b*颜色空间,提取了东北常见五种树种木材图像的颜色特征进行分类研究,通过仿真试验得到了满意的分类结果.     

巨桉不同家系木材表面视觉性质的研究

通过对人工林巨按表面材色的客观定量，对其不同家系的木材表面视觉性质进行了研究。结果表明三个家系巨桉木材表面材色在CIE（1976）L^＊a^＊b^＊的5个色度学指标中，色调角Ag^＊无显著差异，其它显著差异；同时巨按木材材色在株间及高度上差异显著。     

Change in fracturing and colouring of solid spruce and ash wood after thermal modification

Effects of different thermal treatments (maximum treatment temperatures of 200, 210 and 220°C for 2.5 hours) on solid spruce (Picea abies L. Karst.) and ash (Fraxinus excelsior L.) were investigated in this study. The fracture behaviour in radial/longitudinal as well as in tangential/longitudinal and the change of the wood colour (CIEL*a*b* colour space) on all principal anatomical surfaces (cross sectional, radial and tangential) were analysed. The specific fracture energy and the maximum breaking load decreased almost significantly after all thermally treated samples in comparison to the untreated (standard dried) sample. The wood colour changed also significantly, in particular the lightness decreased with increasing intensity of thermal treatment on all investigated surfaces. A comparison of the percentage loss of the different fracture and colour values has shown a strong correlation between the maximum breaking load and the lightness after several thermal treatments, in both investigated crack propagation systems, on all measured surfaces and for both analysed species.     

Genetic variation in wood color and its correlations with tree growth and wood density of <Emphasis Type="Italic">Calycophyllum spruceanum</Emphasis> at an early age in the Peruvian Amazon

Calycophyllum spruceanum (Benth.) Hook. f. ex K. Shum. is an important timber-tree species in the Peruvian Amazon Basin. Markets currently prefer wood with a uniform, light yellow color, but these preferences may change in the future. As farmers and industry commonly use wood from young trees, it is important to investigate genetic and environmental variation in juvenile-wood properties to assess whether tree improvement programs could make adjustments to changing preferences. A provenance/progeny test was established to evaluate genetic variation in growth and wood properties of young trees, the strength of their genetic control as well as their interrelationships both at the genetic and the phenotypic level in different planting zones. This paper presents analyses of variation in wood color at 39 months, and their correlations with tree growth and wood basic density. CIELab means for lightness ranging from black to white (L), green to red hues (a*) and blue to yellow hues (b*) were 67.63, 5.34 and 22.12, respectively; means for chroma (C) and hue angle (h)* were 22.76 and 76.43, respectively (C and h* were estimated from a* and b*). Significant variation due to provenances and especially due to families within provenances was found in some wood color characteristics, and some color characteristics also differed significantly among planting zones. Genetic correlations indicate that, in general, selection of faster growing trees and/or trees with denser wood would have little effect on wood color and its uniformity. In general, wood color had relatively low heritability (h _i ²): among all trees, h _i ² = 0.31 for L; and variance due to families was not significant for a* and b*. Genetic control of color was highest in the planting zone where trees grew most rapidly: h _i ² = 0.48 and 0.52 for a* and b*, respectively; but variance due to families was not significant for L. Results suggest that selection based on wood color would be more effective in zones with more fertile soils and higher rainfall.      

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。     

Kinetics of wood degradation by fungi with x-ray microdensitometric technique

Summary X-ray microdensitometric analysis was employed for the detection of fungi attack in wood of pine and beech in comparison with the studies of specimen weight loss tests. Two species of fungi were used:Gloeophyllum trabeum (Pers.:Fr. Murrill) andTrametes versicolor (L.:Fr. Pilat). We select these species to induce typical decay attack mainly on cellulose in pine (brown rot) and mainly on lignin in beech (white rot). The attack was conducted for 1, 2, 3, 4 and 5 months in sterile laboratory conditions. After 5 months all the values of density components decreased. In beech the loss was of about 25% for all components. In pine the decreasing of the earlywood density component was of about 10% and in latewood of about 22%. The corresponding mass density losses, determined by gravimetric method, were approximately 18% for beech and 16% for pine.The authors wish to thank la Région Rhône - Alpes, Lyon, France for the financial support of this research     

木材材色的定量表征

本文对木材材色的定量表征方法作了简要的评述,并就红种国产针、阔叶树材按CIE(1931)和CIE(1976)(L~*a~*b~*)做了详细的测定和分析。测定结果表明,表色参数(主波长、色纯度、亮度等)要具有可比性,所用的方法和测定条件必须相同。树种之间的色度坐标值的差异大于树种之内的差异。分析木材表面的反射率曲线,不同树种间的材色差异既反映在亮度上,也反映在色调上;但同一树种内的差异主要反映在亮度上。另外,树种之间与树种之内木材表面反射率与波长关系的曲线形状相似,趋向也一致,说明尽管材色的变异性很大,但有一定的规律性。因此采用了主成分分析法,简化表色空间,获得了综合材色参数的实验式;初步测试,实验式具有一定的可靠性与实用意义。为了能直观地表达材色,除了使用综合材色参数外,还给出了孟塞尔标号。     

Physical and mechanical properties and colour changes of fast-growing Gympie messmate wood subjected to two-step steam-heat treatments

This study aimed to evaluate physical and mechanical properties and colour changes of fast-growing Gympie messmate wood subjected to two-step steam-heat treatments. To achieve this, Gympie messmate wood was thermally treated under different conditions. Combined steam (127°C and ～0,1471 MPa) and heat treatments in an oven (180–240°C for 4 hours) were performed. Physical and mechanical properties were evaluated by weight loss, equilibrium moisture content, specific gravity, volumetric and linear swelling and static bending tests, while colour changes were studied using CIEL*a*b* technique. The main findings showed that the steam pre-treatment in autoclave influenced most of the technological properties evaluated, mainly for heat treatments performed in low temperatures (180–200°C). The most significant changes after thermal treatments were observed for dimensional stability, which increased as a function of temperature of treatment. On the other hand, mechanical strength of thermally modified wood was significantly affected, while stiffness did not change. Colour modifications due to the application of two-step steam-heat treatments confirm the possibility to using these samples for aesthetic purposes.     

泡桐木材防变色处理配方优选试验研究

为防止泡桐材的变色降等，采用防变色剂、耐光剂、渗透剂组成的防桐木变色剂配方处理桐木板材，观察其对色度ａ＊、ｂ＊、色差ＤＥ＊、明度Ｌ＊的影响。通过正交试验选择最佳工艺参数。处理后的泡桐板材可达到出口一级品之指标，颜色纯洁，保持木材天然本色。     

Lignin-degrading activity of edible mushroom <Emphasis Type="Italic">Strobilurus ohshimae</Emphasis> that forms fruiting bodies on buried sugi (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>) twigs

Strobilurus ohshimae is an edible mushroom, and it specifically forms its fruiting bodies on buried sugi (Cryptomeria japonica) twigs. In this research, we studied lignindegrading activity of S. ohshimae. We isolated 18 strains of S. ohshimae from various regions of Japan, and determined their lignin degradation rates on sugi wood meal medium. All the strains of S. ohshimae degraded approximately 6%–12% of sugi lignin in 30 days, and these lignin degradation rates were 1.5–3 times higher than those of Trametes versicolor, which is a typical lignin-degrading fungus. Among the three main lignin-degrading enzymes, activity of lignin peroxidase and manganese peroxidase was not observed, while 4340U/g of laccase was produced in 30 days. To investigate the effect of wood species on lignin degradation by S. ohshimae, the lignin degradation rate and laccase productivity on sugi wood meal medium were compared with those on beech (Fagus crenata). In T. versicolor, both lignin degradation rate and laccase productivity were higher on beech than on sugi. Conversely, in S. ohshimae, lignin degradation rate and laccase productivity were higher on sugi than on beech. Therefore, it was suggested that coniferous lignin is not always difficult to degrade for the fungi that inhabit softwood. Part of this article presented at the 54th Annual Meeting of the Japan Wood Research Society, Sapporo, August 2004     

Identification of wood‐decay fungi and assessment of damage in log depots of Western Black Sea Region (Turkey)

The aim of this study was to determine and quantify the wood‐decay fungi found on logs of forest tree species (beech, oak, hornbeam, Scots pine and fir) stored in log depots located in six different provinces in the Western Black Sea Region of Turkey. Additionally, it was aimed to determine the natural durability of some important wood species against the most commonly detected wood‐decay fungi. Eighteen families, 31 genera and 45 species belonging to the division Basidiomycota were detected; Antrodia crassa was identified for the first time in Turkey. The abundance of Panus neostrigosus, Polyporus meridionalis, Trametes hirsuta, T. versicolor and Stereum hirsutumincreased significantly with the holding time of the logs (r = 0.99, 0.87, 0.53, 0.57 and 0.78, respectively, p < 0.05). The majority of the fungal species were detected on logs stored in depots for 4–6 years (66%). The percentage of fungal species found on the logs with a holding time of three years or less was 29%, whereas the percentage for those detected on logs stored for seven or more years was 31%. Among the wood species, the greatest number of fungal species (29) and highest amount of fungi (2,539) occurred on beech wood. Natural durability tests showed that T. versicolor caused the greatest loss of wood mass, with an average of 23%. Field studies and natural durability tests performed in the laboratory showed that beech wood lost the most mass among the timber species studied.     

Aboveground net primary productivity of a beech (Fagus moesiaca) forest: a case study of Naousa forest, northern Greece

Based on allometric relationships and information provided in forest management plans, we determined aboveground net primary productivity (ANPP) for a 10-year period in a Mediterranean beech forest (Fagus moesiaca Cz.) extending across an elevation gradient. The ANPP ranged from 1.87 to 15.71 Mg ha(-1) year(-1), and leaf area index (L*) ranged from 2.3 to 3.6. Although small trees (diameter at breast height < 10 cm) were not sampled, it was unlikely that this accounted for the low L* because there were very few small trees on a per-hectare basis. A weak positive relationship was found between ANPP and L*, and only ANPP was negatively related to elevation. Although L* did not vary with elevation, biomass growth efficiency (ANPP/L*) declined strongly with elevation. Leaf carbon isotope composition, leaf nitrogen content per unit area and specific leaf area of leaves collected from nine trees across an elevation gradient all varied significantly with elevation and were significantly related to one other, suggesting that water limitations at higher elevations may have driven the reduced growth efficiency at the stand level. Strong winds may also have negatively affected ANPP at higher elevations by altering belowground allocation. Further research is needed to test these hypotheses and to determine the belowground dynamics of phytomass in this ecosystem.     

In vitro decay of Aextoxicon punctatum and Fagus sylvatica woods by white and brown-rot fungi

Summary The in vitro decay of Aextoxicon punctatum and Fagus sylvatica wood by the fungi Trametes versicolor, Ganoderma australe, Phlebia chrysocrea and Lentinus cyathiformis was studied by the agar-block method, and then the decayed woods were analyzed by chemical and spectroscopic techniques. The results demonstrated the strong resistance of the A. punctatum wood to the brown-rot fungus L. cyathiformis; the resistance might be related to the low S/G lignin ratio in this Austral hardwood. Wood decay by the Austral white-rot fungi G. australe and P. chrysocrea was rather limited, and preferential degradation of lignin was not produced although all the fungi studied increased wood digestibility. The most characteristic white and brown-rot decay patterns were observed during the in vitro decay with T. versicolor and L. cyathiformis, respectively. Trametes versicolor caused high weight losses and reduced the lignin content of the wood, whereas L. cyathiformis produced a preferential removal of xylan. No important changes in the solid-state ¹³C NMR spectra were observed after wood degradation by T. versicolor, but this technique evidenced an increase in aromatic carbon by L. cyathiformis. This increase was higher than that found in the Klason lignin content, suggesting the presence of altered lignin fractions in the brown-rotted wood.The authors are indebted to Prof. H. D. Lüdemann for the facilities at the Institut für Biophysik und physikalische Biochemie (Regensburg), to A. Navarrete (INIA, Madrid) for her collaboration, and to C. F. Warren (ICE, Alcalá de Henares) for her linguistic assistance. The computer program for spectra treatment was developed by G. Almendros (Centro de Ciencias Medioambientales, CSIC, Madrid). This investigation has been funded by the Spanish Biotechnology Program (Grant BIO88-0185)     

Exploratory study on the impregnation of Scots pine sapwood (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) with different hot melting waxes

Scots pine sapwood (Pinus sylvestris L.) and beech (Fagus sylvatica L.) were impregnated with five waxes. The experiments indicate deep penetration into pine sapwood. Besides the viscosity, an influence of the wax polarity is presumed. Wax penetrates pine wood deeply via the cross-section, but not sufficiently enough to impregnate longer construction elements. However, the radial wax uptake exceeds the uptake via the tangential orientation and guarantees complete soaking of the sapwood tissue. The lateral wax penetration within beech is quite low and irregular. In addition to the temperature, a prolonged process procedure is decisive for an increasing wax uptake. As such, beech wood vessel elements seem to be fully impregnable via the longitudinal surface after a longer process procedure.     

Color variation and correlations in <Emphasis Type="Italic">Eucalyptus dunnii</Emphasis> sawnwood

A study of material thinned from a 9-year-old Eucalyptus dunnii progeny trial revealed that E. dunnii has light yellowish wood that is relatively uniform in color, and varies little within and between trees. The variation in color between half-sib families is small, but is statistically significant (P = 0.008). Most of the color variation relates to the yellowness (CIE b*) of the wood, which in heartwood is moderately heritable (h = 0.6). The color of the endgrain, especially its lightness (CIE L*) and whiteness index (E313), is correlated with basic density, hardness, and rates of shrinkage. The CIE rectangular opponent scale (L*, a*, b*) appeared to be the most informative about wood color and properties, and no additional information was gleaned from an analysis of full spectral data in the range 400–700 nm.     

CIEL*a*b* Measurements to Determine the Role of Felling Season,Log Storage and Kiln Drying on Coloration of Silver Birch Wood

The effects of felling season, log storage and kiln drying on stemwood discoloration of sixty mature silver birches ( Betula pendula ) were studied and provided with CIEL*a*b* colour coordinates. The colour differences were expressed as j E* including split up of j L*, j a* and j b*. The results showed that fresh wood colour depends on the felling season: light and pale colours were recorded for samples taken from autumn- and winter-felled trees, whereas the colour of fresh wood was considerably darker if the felling took place in the spring or summer. After storage, notable changes in colour were observed. After drying, all samples showed low lightness, moderate redness and relatively high yellowness under the drying conditions used in the study regardless of the felling season or duration of storage. The main colour component responsible for the discoloration was lightness, while chroma values redness and yellowness played a minor role.     

A histological investigation of Oriental beech wood decayed by Pleurotus ostreatus and Trametes versicolor

Chemical, light and electron microscopic studies were carried out on wood of Oriental beech (Fagus orientalis Lipsky) decayed by the white‐rot fungi Pleurotus ostreatus and Trametes versicolor for 30, 60 and 120 days according to the modified European standard EN 113. Mass loss as well as lignin, cellulose and carbohydrate content were determined before and after fungal attack. There were no significant differences of wood mass loss and chemical composition between both fungi at the end of incubation. After each incubation period, small specimens were stained for microscopic studies. The micromorphology of fungal cell wall degradation was rather similar for both fungi. Both decreased the cell wall thickness to the same extent. The accumulation of hyphae as well as the rupture of cell walls was also similar. The occurrence of hyphae, cavities in the pits and vessel walls followed nearly the same patterns. The parenchyma cells were completely destroyed. Altogether, both fungi produced a simultaneous white rot in Oriental beech wood.     

Effect of thermomechanical densification on surface roughness of wood veneers

The effect of short-term thermomechanical densification of veneer on the surface roughness and surface anatomical changes in four wood species – alder (Alnus glutinosa Gaertn.), beech (Fagus sylvatica L.), birch (Betula verrucosa Ehrh.), and pine (Pinus sylvestris L.) – was studied. Veneer sheets were densified at a temperature of 100, 150, or 200°C and at a pressure of 4, 8, or 12 MPa for 4 minutes. Seven roughness parameters such as R_a, R_z, R_q, R_p, R_v, R_sk, and R_ku were determined. Profile surface was recorded using a modified Carl Zeiss ME-10 profile gauging profilometer. Surface anatomical changes of veneer were examined using scanning electron microscopy. The results showed that densification temperature and pressure affect surface roughness of veneer. The surface became smoother, and roughness values decreased significantly (except for R_ku which increased slightly) with increasing temperature and pressure of densification. The effect of temperature on surface roughness changes is more pronounced compared with that of densification pressure. The lowest values of surface roughness were recorded for pine veneer samples followed by alder, birch, and beech samples. These results can be used to provide initial data for adhesive application processes in woodworking industry.     

银中杨苗木光需求的图像分析法

近年来,在一些国际农林业学术会议上出现了智能林业的概念(Hirafuji et al.,2008a;2008b),智能林业的主体是林业机器人,与人类信息的70%以上来自视觉一样,机器人的主要信息源也是