Measurement of the uptake of linseed oil in pine by the use of an X-ray microdensitometry technique

Pine sapwood (Pinus sylvestris) was impregnated with linseed oil to three levels of uptake. The distribution of the penetrant was found by taking microdensity measurements of an impregnated sample and then using an ethanol extraction procedure to remove the linseed oil. A second set of X-ray measurements at identical locations in the same sample allowed the linseed oil to be indirectly mapped. An uneven distribution of linseed oil in the specimens with the lowest uptake (25% increase in weight) was seen as sharp gradients in the densitometry curves. With increased filling by the linseed oil, these gradients were gradually smoothed. Microstructural changes in specimens with high uptake were revealed using scanning electron microscopy. Through a combination of X-ray microdensitometry investigation and changes observed in the wood's mechanical properties and morphology, it was concluded that liquid flow during impregnation results in significant damage to the cell structure.     

Evaluation of preservative distribution in thermally modified European aspen and birch boards using computed tomography and scanning electron microscopy

The aim of this experiment was to impregnate thermally modified wood using an easy and cost-effective method. Industrially processed thermally modified European aspen (Populus tremula L.) and birch (Betula pubescens Ehrh.) were collected and secondarily treated at the laboratory scale with the preservatives tung oil, pine tar and Elit Träskydd (Beckers) using a simple and effective method. Preservative uptake and distribution in sample boards were evaluated using computed tomography (CT) and scanning electron microscopy (SEM) techniques. Preservative uptake and treatability in terms of void volume filled were found the highest in Beckers and the lowest in tung oil-treated samples. Thermally modified samples had lower treatability than their counterpart control samples. More structural changes after thermal modification, especially in birch, significantly reduced the preservative uptake and distribution. The differences of preservatives uptake near the end grain were high and then decreased near the mid position of the samples length as compared with similar type of wood sample. Non-destructive evaluation by CT scanning provided a very useful method to locate the preservative gradients throughout the sample length. SEM analysis enabled the visualization of the preservative deposits in wood cells at the microstructural level.     

Prediction of longitudinal shrinkage and bow in Norway spruce studs using scanning techniques

Straightness is one of the most important properties for making timber an attractive material for modern mechanized building. Several studies have shown that a lack of straightness is one of the main reasons for choosing materials other than timber in the construction industry. This paper presents a way to model moisture-induced bow from longitudinal shrinkage data predicted from an analysis of images of the surface of Norway spruce studs. For this study, eight studs (45 × 95 × 2500mm and 45 × 120 × 3000mm) of Norway spruce timber were selected. Bow in these studs was measured at two moisture contents below the fiber saturation point. The studs were then split into three slices 11mm thick, and the surfaces of these slices were scanned to obtain color information and images of the tracheid effect. The slices were cut into sticks with dimensions of 10 × 10 × 200mm. The longitudinal shrinkage coefficient of these sticks was measured. A multivariate model was created to model the longitudinal shrinkage coefficient data from the information in the images. The predicted longitudinal shrinkage data was used to model bow. The mean value of the measured longitudinal shrinkage was 0.0121 (SD 0.0123). The root mean square error of prediction (RMSEP) for the multivariate model was 0.0079, which is regarded as good. Thus, it was possible to model moisture-induced bow with good accuracy using the predicted longitudinal shrinkage data.     

Sap flow of birch and Norway spruce during the European heat and drought in summer 2003

In this study the hydrological regime of Norway spruce (Picea abies) and birch (Betula pendula) growing on heavy soils in the south east of Austria was analysed. Results from the year 2003 characterised by an extremely hot and dry summer are presented in this paper. Due to the extreme weather conditions the soil water content in August 2003 was very low (0.10–0.25 m³ m⁻³) in the topsoil (0–50 cm) with no explicit difference between both tree species.     

Lamellation in the S2 layer of softwood tracheids as demonstrated by scanning transmission electron microscopy

Summary Ultrathin cross sections of the tracheid wall in black spruce and silver fir have been examined at high resolution by scanning transmission electron microscopy (STEM) and by conventional transmission electron microscopy (TEM). For both softwoods, lamellation of the S2 layer was evident but the lamellae were seen more clearly in the STEM photomicrographs. The interlamellar distance was 7.1 nm in the case of spruce and 8.4 nm for silver fir.     

Fibril angle variability in earlywood of Norway spruce using soft rot cavities and polarization confocal microscopy

The main purpose of this study was to investigate the variability of the fibril angle of tracheids in earlywood of Norway spruce (Picea abies L. Karst.). Polarization confocal microscopy was chosen and compared with the method utilizing the orientation of soft rot cavities. There was a significant correlation between the soft rot and polarization confocal microscopy methods, which showed the same trend of high fibril angles in the first part of the earlywood followed by a decrease toward the end of earlywood. This declining trend was less pronounced in annual rings containing compression wood. Moreover, large variations in fibril angle occurred between neighboring tracheids. The investigation also emphasized the differences between X-ray diffraction and microscopic methods, as the large variation seen by the latter methods is not seen by the X-ray diffraction approach because of its large area of measurement. No correlation was found between fiber morphology (i.e., average length, width, density) and the average fibril angle in the investigated annual rings.     

长白山红松云冷杉林碳库研究

东北长白山区一个典型的生态系统的一红松云冷杉林生态系统总的碳贮量为174.3t/hm^2，其中，乔木碳贮量最高，为144．3t/hm^2，约占林分总碳贮量的82．8％，灌木的炭定理一最小，仅为0．018t/hm^2。约占林分总碳贮量的0．01％。草本的碳贮量占林分总碳贮量的2．4％，根系的碳贮量占林分总碳贮量的14．6％，其它占0．24％，系统中主要树种，长白落叶松的碳贮量最高，为54．24t/hm^2；红松，红皮云杉次之，为39．9t/hm^2和37．2t/hm^2；冷杉的最小，为8．25t/hm^2。就系统年凋落的炭贮量而言，针叶最高为924．5kg/hm^2；枝的碳贮量次之，为442．0kg/hm^2；阔叶最少为72．1kg/hm^2。     

大球盖菇液体菌种培养条件的研究

研究大球盖菇液体菌种适宜的培养条件,试验结果表明,大球盖菇液体菌种的适宜培养基配方为玉米粉4%,蔗糖2%,麸皮4%,KH2PO40.15%,MgSO40.05%;最适培养条件是初始pH6,培养温度26℃,培养时间6d,250ml三角瓶装液量80ml,摇床转速160r/min,接种量10%。     

Effects of impregnation and heat treatment on the physical and mechanical properties of Scots pine (Pinus sylvestris) wood

Wood modification, of which thermal modification is one of the best-known methods, offers possible improvement in wood properties without imposing undue strain on the environment. This study investigates improvement of the properties of heat-treated solid wood. Scots pine (Pinus sylvestris) was modified in two stages: impregnation with modifiers followed by heat treatment at different temperatures. The impregnation was done with water glass, melamine, silicone, and tall oil. The heat treatment was performed at the temperatures of 180°C and 212°C for three hours. The modified samples were analyzed using performance indicators and scanning electron microscope micrographs. The mechanical and physical properties were determined with water absorption, swelling, bending strength, and impact strength tests. All the modifiers penetrated better into sapwood than hardwood; however, there were significant differences in the impregnation behavior of the modifiers. As regards the effect of heat treatment, generally the moisture properties were improved and mechanical strengths impaired with increasing treatment temperature. In contrast to previous studies, the bending strength increased after melamine impregnation and mild heat treatment. It is concluded that the properties of impregnated wood can be enhanced by moderate heat treatment.     

Microscopic tensile tests in the transverse plane of earlywood and latewood parts of spruce

This paper presents a method which makes it possible to measure elastic properties of a small group of tracheids in the transverse plane. The method is based on tensile tests under microscope that are performed with the assistance of an image analysis system. The calculation of the strain field is based on a global comparison of the grey levels between each deformed image and the initial image. All tests were carried out within one annual ring of spruce: • radial and tangential Young's modulus and Poisson's ratio can be measured in earlywood with a good accuracy, • radial Young's modulus and Poisson's ratio of tracheids in latewood can be estimated with good confidence, • two tests of very thin samples allowed the evaluation of the tangential elastic modulus in latewood. The small size of the sample together with the local measurement of the strain field permitted us to perform several measurements along one single annual ring. Consequently, it was possible to reveal a good relationship between the mechanical properties and the local density determined by microdensitometry. Received 27 October 1997     

Durability of thermally modified Norway spruce and Scots pine in above-ground conditions

Abstract

One of the main objectives of thermal modification is to increase the biological durability of wood. In this study the fungal resistance of Norway spruce and Scots pine, thermally modified at 195°C and 210°C, was studied with a lap-joint field test. Untreated pine and spruce and pine impregnated with tributyl tin oxide (TBTO) and copper, chromium and arsenic (CCA) were selected as reference materials. The evaluations were carried out after 1, 2 and 9 years of exposure. After 1 and 2 years of exposure mainly discoloration was detected. Only the untreated pine was slightly affected by decay fungi. There were significant differences in the decay ratings of untreated and thermally modified wood materials after 9 years in the field. While the untreated wood materials were severely attacked by decay fungi or reached failure rating, only small areas of incipient decay were detected in the thermally modified samples. Thermally modified pine was slightly more decayed than thermally modified spruce. The only wood material without any signs of decay was CCA-treated pine, since some of the TBTO-treated pine samples were also moderately attacked by fungal decay. The results of the lap-joint test had a good correlation with mass losses in a laboratory test with brown-rot fungi.     

Transversal tracheid dimension in thinned black spruce and Jack pine stands in the boreal forest

Abstract

Commercial thinning has recently been applied in the boreal forest of Quebec (Canada) to increase the volume growth of the residual trees. We aimed to discover if the growth response influences the transversal tracheid dimension of thinned black spruce (Picea mariana (Mill.) B.S.P.) and Jack pine (Pinus banksiana Lamb.) stands at 0.2 m stem height. All 20 studied stands have shown a significant growth response after the treatment (p<0.0001), especially trees with the lowest radial growth before thinning in comparison with the stand mean. Growing conditions met by suppressed trees before thinning might favour them in the competition for light, water and biomass production after the treatment. Trees with a positive growth response did not significantly modify their measured transversal tracheid dimension except for trees which increased twofold their ring-width after thinning. In this case, lumen area and radial cell diameter extended significantly. However individuals with a growth decrease after thinning registered significantly lower values in their ring width, earlywood and latewood cell numbers (p<0.0001) in both species.     

Cone traits of jack pine and black spruce in young seedling seed orchards

The number of fertile and infertile scales, filled and empty seeds, cone volume, seed efficiency and the incidence of insect and disease damage to seed were evaluated for seven jack pine (Pinus banksiana Lamb) and six black spruce (Picea mariana [Mill.] B.S.P.) seedling seed orchards in northern Ontario, Canada. On average, the seed potential of jack pine and black spruce cones was 50 and 82 seeds, respectively. Cone volume and the number of fertile scales were under strong genetic control and well correlated with one another for both species. Seed efficiency values were high for jack pine (60%) but poor for black spruce (24%). The incidence of seed insect damage was less than 2.5% for both species and nil for seed diseases.     

Estimating single-tree branch biomass of Norway spruce with terrestrial laser scanning using voxel-based and crown dimension features

Abstract

Many remote sensing-based methods estimating forest biomass rely on allometric biomass models for field reference data. Terrestrial laser scanning (TLS) has emerged as a tool for detailed data collection in forestry applications, and the methods have been proposed to derive, e.g. tree position, diameter-at-breast-height, and stem volume from TLS data. In this study, TLS-derived features were related to destructively sampled branch biomass of Norway spruce at the single-tree level, and the results were compared to conventional allometric models with field measured diameter and height. TLS features were derived following two approaches: one voxel-based approach with a detailed analysis of the interaction between individual voxels and each laser beam. The features were derived using voxels of size 0.1, 0.2, and 0.4 m, and the effect of the voxel size was assessed. The voxel-derived features were compared to features derived from crown dimension measurements in the unified TLS point cloud data. TLS-derived variables were used in regression models, and prediction accuracies were assessed through a Monte Carlo cross-validation procedure. The model based on 0.4 m voxel data yielded the best prediction accuracy, with a root mean square error (RMSE) of 32%. The accuracy was found to decrease with an increase in voxel size, i.e. the model based on the 0.1 m voxel yielded the lowest accuracy. The model based on crown measurements had an RMSE of 34%. The accuracies of the predictions from the TLS-based models were found to be higher than from conventional allometric models, but the improvement was relatively small.     

Effects of seed water content and storage temperature on the germination parameters of white spruce, black spruce and lodgepole pine seed

The effect of seed water content (WC) (2–3, 5–6 and 22–25%, on a fresh weight basis), storage temperature (+4, −20, −80 and −196°C) and storage duration (6, 12, 24, 48 and 60 months) on the germination of white spruce (Picea glauca (Moench) Voss), black spruce (Picea mariana (Mill.) B.S.P.) and lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) seed was investigated. Germination of white spruce control (untreated) seeds and seeds adjusted to 2–3% and 5–6% WC declined after 48 months of storage at −80 and −196°C, with a further decline at 60 months at −20, −80, −196°C. Germination remained high when control white spruce seeds and seeds with 2–3, 5–6% WC were stored at +4°C, over all storage durations. Generally, black spruce and lodgepole pine exhibited high germination at all storage temperatures at 2–3% and 5–6% WC as well as the control (untreated) seed, for up to 60 months in storage. Germination declined for all three species when seed was conditioned to 22–25% WC. This loss in germination was partially recovered in white spruce seed stored at +4, −20 and −80°C after storage durations of 24, 12 and 48 months, respectively, and in black spruce seeds stored at −20 and −196°C after storage durations of 24 months. Mean germination time (MGT) was relatively constant for all species, under all conditions, except for seed conditioned to 22–25% WC, where MGT increased for white spruce seed stored 48 months at −80 and −196°C, and for black spruce seed stored 24 months at +4 and −80°C and 60 months at −196°C. These results show that the optimal storage temperatures are 4°C for white spruce, and 4, −20, −80, and −196°C for black spruce and lodgepole pine, and 2–6% water content is optimal for all 3 species at these temperatures.     

Effect of half-systematic and systematic thinning on the increment of Scots pine and Norway spruce in Finland

Diameter, height and volume increment of Scots pine (Pinus sylvestrisL.) and Norway spruce (Picea abies (L.) Karst.) stands wereinvestigated in long-term thinning experiments in southern Finland.The measurement period was on average 19 years, and thinningsconsisted of five different treatments: (1) unthinned; (2) selectivethinning from below where thinning intensity was determinedaccording to the number of stems; (3) selective thinning frombelow where thinning intensity was determined according to standbasal area; (4) systematic thinning where corridors were openedat regular intervals in the stand; and (5) half-systematic thinningwhere corridors were opened at regular intervals and the remainingstrips thinned from below, i.e. a combination of selective andsystematic thinning. The selective (basal area) thinning ofScots pine resulted in a volume growth reduction of about 12per cent, but in Norway spruce it resulted in no marked reductioncompared with the unthinned plots. In both tree species, volumeincrement in the half-systematic and selective (basal area)thinning differed only slightly from each other. The systematicthinning resulted in the lowest volume increment. In the systematicthinning, the total yield (m³ ha^–1) somewhat decreasedwith increasing corridor width. In half-systematic thinning,on the other hand, the total yield was not clearly related tocorridor width. A corridor accelerated the diameter incrementof the edge trees. The edge effect progressively diminishedwhen moving deeper into the strip and ended at a distance ofabout 3–4 m from the corridor edge. After the thinning,the height increment first decreased, but later on it recovered.The unthinned plots had more dead trees than the other treatments,but there were no significant differences between the othertreatments. It can be concluded that the prevailing thinningmethod in the Nordic countries, i.e. half-systematic thinning,most probably results in no significant growth and yield losses.     

Preparation of composite board using foil-laminated and plastic-laminated liquid packaging paperboard as raw materials

We investigated the properties of composite board formed using base sheets of aluminum foil-laminated and polyethylene (PE) plastic-laminated liquid packaging paperboard (LP) as an alternative to recycling these items in wastepaper stream. Boards of different specific gravities ranging from 0.55 to 0.75 were made by pressing shredded LP blended with urea resin having resin content of 6%–10% at 180°C. Subsequently, we also prepared mixed particleboard [wood (WD) particles and LP mixed], three-layered particleboard (LP as the middle layer, WD in the upper and lower layers), and wood particleboard all having resin content of 10% and various specific gravities. Static bending and internal bonding strengths and thickness swelling of the specimens were determined to examine their properties. At the same specific gravity, the properties of LP particleboards were affected by their resin content. The modulus of rupture (MOR), modulus of elasticity (MOE), and internal bond strength of the LP particleboards increased with increasing specific gravity of the boards at the same resin content, but thickness swelling of the LP particleboards showed the reverse trend. The average MOR of the LP particleboards approximated that of the mixed particleboards and was greater than those of the three-layered particleboards and wood particleboards. Internal bond strength and thickness swelling of the LP particleboards were smaller than those of the other particleboards. Based on the above observations, we deemed that LP can be made into composite boards with adequate properties either alone or mixed with wood particles.     

Control of tracheid cross-sectional dimensions in Norway spruce and Scots pine wood raw material

Abstract

Wood properties, including tracheid cross-sectional dimensions, show a large degree of variation. To improve the properties of products made from wood, different methods to control variation have been developed. This study aims to determine the theoretical efficiency of three control strategies: the fractionation of pulped tracheids into earlywood and latewood, the separation of juvenile and mature wood, and sorting of logs according to tree size. The efficiency of each method was studied by first constructing virtual trees from measured tracheid cross-sectional dimensions, then simulating the efficiency of above-mentioned methods. The tracheid dimension data include Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.). The simulations show that separation into earlywood and latewood classes has the highest theoretical efficiency and yields the lowest variances in raw material. Classification into juvenile and mature wood groups is the second most efficient method, and the sorting of logs according to the size class of the tree is the least efficient method. It was also concluded that the variation in cell-wall thickness and radial diameter mainly originates from differences between earlywood and latewood, whereas the variation in tangential diameter mainly originates from differences between mature and juvenile wood.