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An extensive summary of publications reporting radial specific gravity (SG) variation for North American conifers is presented. SG varies from pith to bark in three distinct patterns before reaching asymptomatic values: Type 1 (SG increases with cambial age), Type 2 (SG is initially high at the pith, then decreases with cambial age, before increasing), and Type 3 (SG decreases with cambial age). Pinaceae have either a Type 1 or 2 pattern (majority are Type 2). Cupressaceae have a Type 3 pattern, but radial SG data do not exist for some species. We reviewed publications in table 7-1 of Panshin and de Zeeuw (the 1970 edition) which reports SG variation by species and Type (the 1980 edition has an equivalent table but does not reference publications), examining sampling strategies and radial patterns. For a small number of species, Type was either incorrectly interpreted or sampling made a conclusion regarding pattern of radial variation impossible. Specific examples of mislabeled Types reported by Panshin and de Zeeuw for Douglas-fir (Pseudotsuga menziesii), lodgepole pine (Pinus contorta), red pine (Pinus resinosa) and shortleaf pine (Pinus echinata), and western redcedar (Thuja plicata) are described. We conclude for nearly all species the pattern of radial SG variation is consistent; however, different patterns have been reported for eastern white pine (Pinus strobus) and subspecies of Douglas-fir and ponderosa pine (Pinus ponderosa). Key words: North American conifers, specific gravity, radial variation, Type 1, 2, or 3 L'etude presente un resume complet des publications rapportant la variation de la gravite specifique radiale (GS) pour les coniferes d'Amerique du Nord. La gravite specifique radiale varie de la moelle a l'ecorce selon trois schemas avant d'atteindre des valeurs asymptomatiques : Type 1 (la GS augmente avec l'age cambial), Type 2 (la GS est initialement elevee a la moelle, puis diminue avec l'age avant d'augmenter) et Type 3 (la GS diminue avec l'age cambial). Les Pinaceae d'Amerique du Nord ont un schema de Type 1 ou 2 (la majorite des arbres sont de Type 2). Les Cupressaceae presentent un schema de Type 3, mais il n'existe pas de donnees sur la GS radiale pour certaines especes. Nous avons passe en revue les publications du tableau 7-1 de Panshin et de Zeeuw (l'edition de 1970) qui rapporte la variation de la GS par espece et par type (l'edition de 1980 possede un tableau equivalent, mais ne fait pas reference aux publications), en examinant les strategies d'echantillonnage et les modeles radiaux. Pour un petit nombre de ces especes, le type etait soit mal interprete, ou encore l'echantillonnage rendait impossible toute conclusion concernant le schema de variation radiale. Nous decrivons des exemples specifiques de types mal etiquetes rapportes par Panshin et de Zeeuw pour le Douglas (Pseudotsuga menziesii), le pin tordu (Pinus contorta), le pin rouge (Pinus resinosa), le pin a feuilles courtes (Pinus echinata) et le thuya occidental (Thujaplicata). Nous concluons qu'a l'interieur d'une espece individuelle, le modele de variation radiale de la GS est coherent, mais que des modeles differents ont ete signales pour le pin blanc de l'Est (Pinus strobus) et pour les sous-especes de sapin de Douglas et de pin ponderosa (Pinus ponderosa). [Traduit par la Redaction] Mots-cles : coniferes d'Amerique du Nord, gravite specifique, variation radiale, type 1, 2 ou 3, Introduction Wood density or specific gravity (SG), defined as wood density divided by the density of water, is considered by many to be the most important wood property as it [...]

North American conifers exhibit three radial specific gravity (SG) patterns (Type 1, 2, and 3), which balance hydraulic and mechanical requirements. Type 1 and 2 patterns (Pinaceae) have low SG and high microfibril angle (MFA) corewood ensuring compliance, whereas in outerwood high SG/low MFA provide stiffness and strength resisting bending. Hydraulically, corewood, especially in Type 2 species, is resistant to embolism, whereas outerwood has higher specific conductivity. Cupressaceae (Type 3) have hydraulically very efficient, low SG outerwood, facilitating rapid growth. Corewood is flexible, whereas outerwood is mechanically weak and compensated for by more conical stems and durable heartwood (which prevents Brazier buckling). Radially earlywood (EW) decreases, and latewood (LW) increases for all types, whereas %latewood (%LW) increases (Type 1), decreases, then increases (Type 2) and decreases (Type 3). Ring SG increases when increasing LW SG and %LW are sufficient to counteract decreasing EW SG. Shade tolerance, crown recession, hormone gradients, and environmental variation affect patterns. Auxin concentration decreases with increasing distance from juvenile foliage slowing cell division, concomitantly gibberellin concentration (lignification) and carbohydrates (cell wall thickening) increase, producing higher %LW. Across a species range regions receiving relatively high summer rainfall have trees with higher %LW (by ring). [ABSTRACT FROM AUTHOR]

A chemistry-based explainable machine learning (ML) approach was used to predict wood properties using near infrared (NIR) spectral data collected from rough and smooth surfaces, and to provide better understanding of the role of important NIR wavelengths (features) in the performance of ML models. NIR spectra collected from western hemlock (Tsuga heterophylla) and coastal Douglas-fir (Pseudotsuga menziesii) boards with rough and smooth surfaces were fed into random forest and TreeNet; a gradient boosting machine algorithm, for predicting wood density, modulus of elasticity (MOE) and modulus of rupture (MOR). The TreeNet model could predict the MOE, MOR, and density with R2 of 0.66, 0.64, and 0.64 using spectra collected from rough surface and R2 of 0.54, 0.46, and 0.46 using spectra collected from smooth surface. TreeNet outperformed the random forest, and for both ML algorithms higher R2 and lower error were obtained using NIR data collected from rough surfaces. This suggested that for Douglass fir and western hemlock, NIR spectra could be collected on a sawn surface prior to surface planing. However, it is difficult to generalize the impact of surface roughness on the performance of predictive model as different factors (e.g. what constitutes a smooth or rough surface, variability of data set in terms of wood properties) impact the success of predictive models. NIR features having the greatest influence on TreeNet models were examined and consistently had wood chemistry specific band assignments. The most important features occurred in the O-H first overtone, and C–H second overtone regions and a narrow zone (approximately 2400–2500 nm) of the C–H stretch C–C stretch combination region. Important features also differed by property and with surface roughness. Explaining ML model performance using the relative importance of the NIR features showed the importance of wood chemistry related information when developing models, however MOE and MOR TreeNet models based on smooth surface NIR spectra showed an increased importance of water related features. Overall, the chemistry-based explainable machine learning model approach allows for identification of important NIR features, and regions, and aids in understanding how they contribute to the performance of NIR-based wood property predictive models. [ABSTRACT FROM AUTHOR]

The quality control of thermally modified wood and identifying heat treatment intensity using nondestructive testing methods are critical tasks. This study used near-infrared (NIR) spectroscopy and machine learning modeling to classify thermally modified wood. NIR spectra were collected from the surfaces of untreated and thermally treated (at 170 °C, 212 °C, and 230 °C) western hemlock samples. An explainable machine learning approach was practiced using a TreeNet gradient boosting machine. No dimensionality reduction was performed to better explain the feature ranking results obtained from the model and provide insight into the critical wavelengths contributing to the performance of classification models. NIR spectra in the ranges of 1100–2500 nm, 1400–2500 nm, and 1700–2500 nm were fed into the TreeNet model, which resulted in classification accuracy values (test data) of 94.35%, 89.29%, and 84.52%, respectively. Feature ranking analysis revealed that when using the range of 1100–2500 nm, the changes in wood color resulted in the highest variation in NIR reflectance amongst treatments. As a result, associated features were given higher importance by TreeNet. Limiting the wavelength range increased the significance of features related to water or wood chemistry; however, these predictive models were not as accurate as the one benefiting from the impact of wood color change on the NIR spectra. The developed framework could be applied to different applications in which NIR spectra are used for wood characterization and quality control to provide improved insights into selected NIR wavelengths when developing a machine learning model. [ABSTRACT FROM AUTHOR]

Hyperspectral imaging is a technique that combines spectroscopy and imaging. Originally utilized in the 1980's by the remote sensing community it is now utilized in a wide variety of applications. Spectral imaging was first used for the detection of compression wood in the late 1990's and since that time research focused on wood and wood products has steadily increased with a variety of applications reported. While there are several reviews of wood related research utilizing near infrared spectrometers a comprehensive summary of wood—hyperspectral imaging research is lacking. Near infrared hyperspectral imaging systems (NIR-HSI) typically have a wavelength range of 900–1700 nm, whereas short-wave infrared hyperspectral imaging (SWIR-HSI) systems range from 1000 to 2500 nm. We provide a detailed account of the various studies that have been published utilizing both camera types. [ABSTRACT FROM AUTHOR]

Wood stiffness (modulus of elasticity, MOE) is an important property for conifer wood, with the variability in MOE largely being a function of both the specific gravity (SG) (wood density) and the angle of the microfibrils within the S2 layer of longitudinal tracheids. Rapid analysis techniques can be used together to quantify MOE; while SG can be determined with relative ease, this is not the case for microfibril angle, requiring expensive X-ray diffraction equipment. An alternative to microfibril angle is to measure longitudinal acoustic velocity. The objective of this study was to measure and then model the within tree variation in dynamic MOE (MOEdyn) by developing the methodology to measure ultrasonic velocity (USV) in radial samples from pith to bark using ultrasonic frequencies (>20 kHz). A total of 419 pith-to-bark radial strips, collected from multiple height levels in 92 loblolly pine (Pinus taeda) trees, were processed to obtain matching SG (2mm longitudinal) and USV (8.2-mm longitudinal) samples. Ring-by-ring SG was measured using X-ray densitometry and time-of-flight USV was measured at a 10-mm radial resolution from pith to bark. A subset of samples was sent to SilviScan to determine microfibril angle using X-ray diffraction. The relationship between microfibril angle and USV was strong (R 2 = 0.91, RMSE = 2.6°). Nonlinear mixed-effects models were then developed to predict radial variation in SG, USV and MOEdyn. Fixed effects for the models, which included cambial age and height of disk within tree, had pseudo R 2 values of 0.67 for SG (RMSE = 0.051), 0.71 for USV (RMSE = 316 m/s) and 0.69 for MOEdyn (RMSE = 1.9 GPa). When combined with SG measurements from X-ray densitometry, USV measurements from pith to bark are a powerful tool for assessing variability in wood stiffness. [ABSTRACT FROM AUTHOR]

Composition of the southern pine forest is now predominated by two species, loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.), owing to fire suppression activities, natural regeneration on abandoned agricultural lands, and extensive planting. Comparison of the wood and bark physical properties of these pines is of interest in terms of the yields of usable biomass and, for the bark, its ecological functionality on a living tree. Trees from a species comparison study were used to generate wood and bark property data, on a whole-tree basis, and for stem disks collected at breast height. Models were constructed to explain the effect of relative height on wood and bark properties. When comparing the whole-tree data, slash pine wood (0.523 versus 0.498) and bark (0.368 versus 0.311) specific gravity values were higher, both offset by lower moisture contents; slash pine also produced a higher percentage of bark on a dry-mass basis (17% versus 12.5%). Unlike wood properties, bark properties showed significant between-species differences when determined at breast height alone, the exception being moisture content. In terms of yield, harvests of a green tonne of loblolly pine and slash pine would give approximately the same dry mass of wood, but slash pine provides more bark. Key words: bark thickness, moisture content, specific gravity, wood quality, yield. La composition de la foret de pins du sud est maintenant dominee par deux especes, le pin a encens (Pinus taeda L.) et le pin d'Elliott (Pinus elliottii Engelm.) a cause des activites de suppression des feux, de la regeneration naturelle sur les terres agricoles abandonnees et de la plantation intensive. La comparaison des proprietes physiques du bois et de l'ecorce de ces deux pins presente un interet en termes de rendement de la biomasse utile, et dans le cas de l'ecorce, sa fonction ecologique sur un arbre vivant. Les arbres faisant partie d'une etude comparative entre especes ont ete utilises pour generer des donnees sur les proprietes de l'ecorce et du bois sur une base d'arbre entier et pour des rondelles de tige prelevees a hauteur de poitrine. Des modeles ont ete construits pour expliquer l'effet de la hauteur relative sur les proprietes du bois et de l'ecorce. Lorsqu'on les compare sur une base d'arbre entier, les valeurs de densite du bois (0,523 versus 0,498) et de l'ecorce (0,368 versus 0,311) du pin d'Elliott sont plus elevees, compensees dans les deux cas par une teneur en humidite plus faible; le pin d'Elliott produit egalement une plus forte proportion d'ecorce (17% versus 12,5%) sur une base de masse anhydre. Contrairement aux proprietes du bois, les proprietes de l'ecorce des deux especes sont significativement differentes lorsqu'elles sont mesurees a hauteur de poitrine seulement, la teneur en humidite faisant exception. En termes de rendement, la recolte d'une tonne verte de pin a encens ou de pin d'Elliott donne approximativement la meme masse anhydre de bois mais le pin d'Elliott produit plus d'ecorce. [Traduit par la Redaction] Mots-cles: epaisseur de l'ecorce, teneur en humidite, densite qualite du bois, rendement., Introduction The species composition of the pine forest of the southeastern United States has changed over the years, from the vast occurrence of longleaf pine (Pinus palustris Mill.) before colonial [...]

Rubberwood (Hevea brasiliensis Muell. Arg) is underutilized in most developing countries but has potential to be a solution to the shortage of wood for pulp, paper and wood composite products at the end of its production cycle. Determining and understanding its fibre properties (fibre dimensions and morphology) is key in its utilization for pulp and paper as well as composites. This study assessed the effect of age on the fibre properties of rubberwood. Samples of wood at four ages (10, 15, 20 and 25 years) were obtained at both the axial (base and top of merchantable length) and radial direction (innerwood, middlewood and outerwood). Slivers were obtained from the samples and macerated to provide individual fibres for optical measurement. Fibre dimensions at the four ages were measured, and their morphology was determined. Fibre properties and morphology were significantly affected by age at p = 0.05. Average fibre length was 1.47 ± 0.12 mm, with non-constant variation observed across the different ages, and from pith to bark. Average lumen width was 16.87 µm, and fibre diameter ranged from 25.02 µm to 27.23 µm. The fibre properties of rubberwood potentially make it suitable for pulp and paper production as well as wood composite boards. [ABSTRACT FROM AUTHOR]

There is a growing interest in improving wood properties through the appropriate selection of seed provenances within species. In this study, wood density and mechanical properties were investigated for Acacia mangium trees from six different provenances, planted in Quang Tri, Vietnam. Radial and among provenance variation in stress wave velocity (SWV), wood density (WD), dynamic modulus of elasticity (MOEd), modulus of rupture (MOR), and modulus of elasticity (MOE) were determined on a total of 480 small clear specimens (20 × 20 × 300 mm) cut from 30 trees (five per provenance). SWV and selected wood properties near the pith were significantly lower than those near the bark. Differences in all selected mechanical properties among provenances were significant. The highest static properties (MOR and MOE) were found for the Long Thanh provenance indicating its potential suitability for breeding programs in Vietnam focused on improving A. mangium wood quality. A high positive correlation coefficient was found between MOEd and MOE (r = 0.93, P < 0.001) and our results indicate that the stiffness of A. mangium can be predicted using stress wave method provided the density of measured element is known. [ABSTRACT FROM AUTHOR]

The use of clonal varieties in forestry offers great potential to improve growth traits (quantity) and wood properties (quality) of loblolly pine (Pinus taeda L.). Loblolly pine trees established via somatic embryogenesis (clones), full-sib zygotic crosses, and half-sib zygotic open-pollinated families were sampled to identify variation in growth and wood properties among and within clonal lines and zygotic controls. Increment cores 5 mm in diameter were collected at age 4 from a total of 2615 trees. Growth properties (diameter at 1.4 m and total tree height) and wood properties (whole-core density, latewood and earlywood density, and latewood percent) were measured for each tree sampled in the study. Overall, growth properties were better for full-sib seedling than for clonal lines, whereas wood density was higher for clonal lines than full-sib and open-pollinated seedlings. However, there were clonal lines with better growth and higher wood density. Clonal repeatability of both growth and wood properties across sampled sites and genetic correlations between growth and wood traits were determined, with higher repeatability observed for wood traits compared with growth traits. Significant genetic correlations were observed for tree height and wood properties, whereas weak correlations were observed for diameter and wood properties. Resume: L'utilisation de varietes clonales en foresterie presente un fort potentiel pour ameliorer les traits de croissance (quantite) et de proprietes du bois (qualite) du pin a encens (Pinus taeda L.). Des pins a encens issus de l'embryogenese somatique (clones), de croisements de descendances biparentales et de descendances uniparentales allofecondees ont ete echantillonnes pour identifier la variation dans la croissance et les proprietes du bois dans et entre les lignees clonales et les temoins zygotiques. Des carottes de 5 mm de diametre ont ete prelevees a l'age de 4 ans sur un total de 2615 arbres. Les proprietes de la croissance (diametre a 1.4 m et la hauteur totale de l'arbre) ainsi que les proprietes du bois (densite globale de la carotte, densite du bois initial et du bois final et pourcentage de bois final) ont ete mesurees pour chacun des arbres echantillonnes dans l'etude. Dans l'ensemble, les proprietes de la croissance etaient meilleures chez les semis issus de descendances biparentales que chez lignees clonales alors que la densite du bois etaient plus elevee chez les varietes clonales que chez les semis issus de descendances biparentales ou uniparentales allofecondees. Cependant, certaines lignees clonales avaient une meilleure croissance et une plus grande densite du bois. La reproductibilite clonale des proprietes de la croissance et du bois parmi les stations ainsi que les correlations genetiques entre les traits de croissance et de proprietes du bois ont ete determinees; la reproductibilite des traits de proprietes du bois etait meilleure que celle des traits de croissance. Des correlations genetiques significatives ont ete observees entre la hauteur des arbres et les proprietes du bois alors que de faibles correlations ont ete observees entre le diametre et les proprietes du bois. [Traduit par la Redaction], Introduction Genetic improvement programs for loblolly pine (Pinus taeda L.) began in the 1950s in the United States (US) with the aim of producing abundant high-quality seedlings to support planting [...]

In this study, we used both nondestructive and destructive methods for assessing solid wood properties in six Vietnamese grown Eucalyptus clones at 6 years after planting. We measured stress wave velocity in standing sample trees (SWVT), logs (SWVL), and small clear specimens (SWVS) obtained from the trees and logs, and to measure static properties, we used MOE—modulus of elasticity and MOR—modulus of rupture. The highest average MOE and MOR were detected in clones 3 and 5, suggesting that these clones might be more appropriate for breeding programs focused on improving wood quality of Eucalyptus grown in Vietnam. Mean MOE and MOR of the lumber had significant (p < 0.001) relationships with SWVT (r = 0.61 and 0.53, respectively) and SWVL (r = 0.76 and 0.71, respectively). Stress wave velocity measurements of both standing trees and logs can be useful for further segregating Vietnam's Eucalyptus timber resource based on MOE and MOR. For the small clear specimens, the best prediction of stiffness (dynamic modulus of elasticity (MOEd)) was obtained when both SWVS and air-dry density (AD) were used. The coefficient of correlation between MOE and MOEd was 0.93. [ABSTRACT FROM AUTHOR]

Near-infrared spectroscopy (NIRS) allows for the rapid estimation of a wide range of wood properties. Typically, NIRS studies on wood have utilized benchtop spectrometers, but efforts to utilize NIR hyperspectral imaging to examine wood and wood products have increased. Compared to benchtop NIR systems, hyperspectral imaging has several advantages (speed, visualization of spatial variability), but the data typically have a lower signal-to-noise ratio as well as fewer wavelengths saved; thus, hyperspectral imaging systems have a larger spectral sampling interval (SSI). Furthermore, the SSI and wavelength range varies considerably among different HSI cameras. NIR-HSI systems based on indium gallium arsenide (InGaAs) detectors have a wavelength range typically from 900 to 1700 nm, while short-wave infrared hyperspectral imaging (SWIR-HSI) systems based on mercury cadmium telluride (MCT) detectors have the 'full' NIR wavelength range from 1000 to 2500 nm. These factors may influence the performance of wood property calibrations. We compared one NIR-HSI (900–1700 nm) and three SWIR-HSI (1000–2500 nm) commercially available cameras with an NIRS benchtop spectrometer (1100–2500 nm). The performance of specific gravity (SG) and stiffness (MOE) calibration models was compared with one-hundred Douglas-fir (Pseudotsuga menziesii) samples. The limited wavelength range of an NIR-HSI camera provided the best models for MOE, whereas the NIR-HSI and two SWIR-HSI cameras provided similar SG results. SWIR-HSI models heavily favored wavelengths greater than 1900 nm. [ABSTRACT FROM AUTHOR]

: Conventionally, increment cores collected at breast height (1.4 m) have been used to measure wood properties of standing loblolly pine (Pinus taeda L.) trees. This height has been used because of the ease of sampling and cost involved in extracting the cores. In this study, the efficacy of a breast-height core to represent whole-tree specific gravity (SG) and moisture content (MC) was examined. The sampling height that best represents whole-tree SG and MC was identified using the correlation between volume-weighted whole-tree SG and MC with SG and MC measurements collected at different heights within a tree. We found a high correlation between observed whole-disk SG and MC with volume-weighted whole-tree SG and MC at most sampling heights. The strength of the correlation followed a skewed parabolic curve form for both wood properties. The strongest correlations were observed between 4.6 and 6.1 m, with marginally lower correlations at the base of the tree, and the weakest correlations were observed towards the tip of the tree. In addition, it was found that the number of stands and trees that need to be sampled to achieve a certain accuracy in overall mean whole-tree SG and MC was greater if breast height was used as a sampling height compared with the most representative sampling heights identified (4.6 m for SG and 6.1 m for MC). Resume: Les carottes utilisees pour mesurer les proprietes du bois des tiges sur pied de pin a encens (Pinus taeda L.) ont communement ete prelevees a hauteur de poitrine (1,4 m). Cette hauteur a ete utilisee a cause de la facilite d'echantillonnage et du cout d'extraction des carottes. Dans cette etude, nous avons examine si une carotte prelevee a hauteur de poitrine representait efficacement la densite basale (DB) et la teneur en humidite (TH) de l'arbre tout entier. La hauteur d'echantillonnage qui represente le mieux la DB et la TH de l'arbre tout entier a ete identifiee en utilisant la correlation entre la DB et la TH de l'arbre tout entier ponderees par le volume et la DB et la TH mesurees a differentes hauteurs dans l'arbre. Nous avons trouve une correlation etroite entre la DB et la TH observees de rondelles entieres et la DB et la TH de l'arbre tout entier ponderees par le volume pour la plupart des hauteurs echantillonnees. Le degre de correlation suivait une courbe parabolique asymetrique pour les deux proprietes du bois. Les plus fortes correlations ont ete observees entre 4,6 et 6,1 m; les correlations etaient legerement plus faibles a la base de l'arbre et les plus faibles vers le sommet de l'arbre. De plus, le nombre de peuplements et d'arbres qui doivent etre echantillonnes pour obtenir une certaine precision de la moyenne globale de la DB et de la TH de l'arbre tout entier etait plus grand si l'echantillonnage etait fait a hauteur de poitrine comparativement aux hauteurs d'echantillonnage identifiees comme les plus representatives (4,6 m pour la DB et 6,1 m pour la TH). [Traduit par la Redaction], Introduction Loblolly pine (Pinus taeda L.) is the most important plantation species in the southern United States (US) and represents more than half of the standing pine volume in this [...]

Modulus of elasticity (MOE), modulus of rupture (MOR), and specific gravity (SG) are important properties for determining the end-use and value of a piece of lumber. This study addressed the variation in MOE, MOR, and SG with physiographic region, tree height, and wood type. Properties were measured from two static bending samples (dimensions 25.4 mm x 25.4 mm x 406.4 mm) representing each wood type (corewood and outerwood) at heights 2.4, 7.3, and 12.2 m from three trees sampled from 135 loblolly pine (Pinus taeda L.) stands distributed across the natural range of the species. An analysis of variance was conducted to detect the effect of physiographpic region, height, and wood type on each property. Significant regional variation was observed for MOE, MOR, and SG for both wood types with high values in the Gulf and South Atlantic Coastal Plains compared with other regions. A significant height-related trend in MOE, MOR, and SG within a tree was identified; MOE and MOR increased in corewood and decreased in outerwood with height. Maps showing regional variation in MOE and MOR at different heights by wood type were produced and showed significant variation for both properties. Resume: Le module d'elasticite (MOE), le module de rupture (MOR) et le poids specifique (PS) sont des proprietes importantes pour determiner l'usage final et la valeur d'une piece de bois. Cette etude a porte sur la variation de ces proprietes en fonction de la region physiographique, de la hauteur de l'arbre et du type de bois. Les proprietes ont ete mesurees en flexion statique sur deux eprouvettes (dimensions de 25,4 mm x 25,4 mm x 406,4 mm) representant chaque type de bois (bois juvenile et bois mature) a des hauteurs de 2,4, 7,3 et 12,2 m dans trois arbres preleves au sein de 135 peuplements de pin a encens (Pinus taeda L.) distribues dans l'ensemble de l'aire de repartition naturelle de l'espece. Une analyse de variance a ete realisee afin de detecter les effets de la region physiographique, de la hauteur et du type de bois sur chaque pro-priete. Une variation regionale significative du MOE, du MOR et du PS a ete observee dans les deux types de bois, avec des valeurs elevees dans le Golfe et dans les plaines cotieres de l'Atlantique Sud comparativement aux autres regions. A l'interieur de l'arbre, une tendance significative reliee a la hauteur a ete identifiee pour le MOE, le MOR et le PS; le MOE et le MOR augmentaient dans le bois juvenile et diminuaient dans le bois mature en fonction de la hauteur. La cartographie des variations regionales du MOE et du MOR a differentes hauteurs et par type de bois montrent que ces deux proprietes varient grandement. [Traduit par la Redaction], Introduction The southeastern United States is a critically important region of the world in terms of lumber manufacture, with production greater than any other single nation in the world. It [...]

Acoustic tools are increasingly used to estimate standing-tree (dynamic) stiffness; however, such techniques overestimate static stiffness, the standard measurement for determining modulus of elasticity (MOE) of wood. This study aimed to identify correction methods for standing-tree estimates making dynamic and static stiffness comparable. Sixty Pinus taeda L. trees, ranging from 14 to 19 years old, obtained from genetic tests established in the southeastern United States, were analyzed. Standing-tree acoustic velocities were measured using the TreeSonic tool. Acoustic velocities were also recorded in butt logs cut from the same trees using the Director HM200. A strong but biased relationship between tree and log velocities was observed, with tree velocities 32% higher (on average) than the corresponding log velocities. Two correction methods, one for calibrating tree velocities and one for accounting for differences in wood moisture content, were used to determine an adjusted MOE. After correction, adjusted MOE estimates were in good agreement with static longitudinal MOE values measured on clearwood specimens obtained from the trees, and no systematic bias was observed. The results of this study show that acoustic estimates of MOE on standing trees largely depend on how the data are processed and the reference method used. Des outils acoustiques sont de plus en plus utilises pour estimer la rigidite (dynamique) des arbres debout. Cependant, de telles mesures surestiment la rigidite statique, la technique standard pour determiner le module d'elasticite (MOE) du bois. Cette etude visait a identifier les methodes de correction des estimations sur les arbres debout pour rendre les valeurs de rigidite dynamique et statique comparables. Soixante tiges de Pinus taeda L. ont ete analysees. Elles etaient agees de 14 a 19 ans et provenaient de tests genetiques etablis dans le sud-est des Etats-Unis. La vitesse sonique dans les arbres debout a ete mesuree avec l'appareil TreeSonic. La vitesse sonique a aussi ete mesuree dans la bille de pied coupee chez les memes arbres avec le Director HM200. Une relation etroite mais biaisee a ete observee entre la vitesse sonique dans les arbres debout et les billes. La vitesse sonique etait en moyenne 32 % plus elevee dans les arbres que dans les billes. Deux methodes de correction ont ete utilisees pour determiner un MOE ajuste : une methode pour calibrer la vitesse sonique dans les arbres et une autre pour tenir compte de la difference d'humidite dans le bois. Apres avoir effectue la correction, les estimations du MOE ajuste correspondaient bien aux valeurs du MOE longitudinal statique mesure sur des echantillons de bois sain provenant des arbres et aucun biais systematique n'a ete observe. Les resultats de cette etude montrent que les estimations acoustiques du MOE chez les arbres debout dependent largement de la facon dont les donnees sont traitees et de la methode de reference utilisee. [Traduit par la Redaction], Introduction Mechanical properties are the most important wood characteristics for structural applications. Particularly important is the modulus of elasticity (MOE) or stiffness, which provides a measure of a wood member's [...]

Wood properties and growth were measured on breast-height cores and on disks collected at different heights from a thinned and fertilized midrotation loblolly pine (Pinus taeda L.) plantation in the lower Coastal Plain of North Carolina. The study was laid out in a randomized complete-block design receiving four levels of nitrogen (N) fertilizer: unfertilized control and 112, 224, and 336 kg/ha plus 28 kg/ha of phosphorus with each treatment. The effect of fertilization was analyzed for the whole-disk and for a 4 year average following fertilization on data collected from breast-height cores and from disks. The fertilization treatments did not significantly affect whole-disk wood properties but significantly increased radial growth. Fertilization rate of 336 kg/ha N significantly reduced 4 year average ring specific gravity and latewood specific gravity. Wood properties of trees that received 112 and 224 kg/ha N were not affected following treatment. There was no height related trend in wood property changes due to fertilization. Fertilization significantly increased ring basal area and earlywood basal area. In summary, there was a decline in wood properties and an increase in basal area growth immediately after fertilization; both depended on the rate of fertilizer applied irrespective of height. Les auteurs ont mesure les proprietes du bois et la croissance sur des carottes prelevees a hauteur de poitrine et des disques preleves a differentes hauteurs dans une plantation a mi-revolution de pin a encens (Pinus taeda L.) eclaircie, fertilisee et situee dans la basse plaine cotiere de la Caroline du Nord. L'experience etait structuree en blocs complets aleatoires dans lesquels quatre niveaux de fertilisant azote ont ete appliques : temoin, 112, 224 et 336 kg/ha, et 28 kg/ha de phosphore ont ete ajoutes a chaque traitement. L'effet de la fertilisation a ete analyse sur les moyennes des disques entiers et les moyennes des 4 annees suivant le traitement a partir des donnees mesurees sur les carottes et les disques. Les traitements de fertilisation n'ont pas eu d'effet significatif sur les proprietes du bois a l'echelle du disque entier mais ont cause une augmentation significative de la croissance radiale. Un taux de fertilisation azotee de 336 kg/ha a entraine une reduction significative de la densite relative moyenne des cernes annuels et du bois final des 4 annees suivant le traitement. Les traitements de fertilisation azotee a 112 et 224 kg/ha n'ont pas eu d'effet sur les proprietes du bois. Les changements des proprietes du bois dus a la fertilisation n'ont suivi aucune tendance reliee a la hauteur dans l'arbre. La fertilisation a cause une augmentation significative de la surface terriere des cernes et du bois initial. En resume, les proprietes du bois ont decline et la croissance en surface terriere a augmente immediatement apres la fertilisation mais chacun de ces effets dependait du taux de fertilisation utilise peu importe la hauteur. [Traduit par la Redaction], Introduction Midrotation application of thinning and fertilization is a widely accepted management practice in pine plantations growing throughout world. In the southeastern United States the adoption of this practice has [...]

Radial and between-clone variations in stress-wave velocity, air-dry density (AD), and mechanical properties in six clones of 5-year-old Acacia auriculiformis trees planted in Vietnam were investigated. The potential to predict modulus of elasticity (MOE) and modulus of rupture (MOR) using stress-wave velocity of standing trees (SWVT) or small specimens (SWVS) was also examined. The examined SWVT, SWVS, and wood properties differed significantly among clones, particularly with two (clones 1 and 6) well suited for A. auriculiformis tree breeding programs focusing on lumber production, as they had the highest static bending values and no significant difference in AD between positions near pith and bark. At the specimen level, the best prediction of static bending properties could be achieved when both SWVS and AD were used in a model for calculation of dynamic modulus of elasticity (MOEd) in air-dry conditions. Significant correlations between SWVT and average MOE (r = 0.83) and MOR (r = 0.61) of test specimens indicated that the use of stress-wave technique for assessing MOE and MOR for selecting the best A. auriculiformis clones in terms of lumber performance was possible. [ABSTRACT FROM AUTHOR]

The effects of using reduced calibration sets on the development of near-infrared (NIR) calibration models for the prediction of kraft pulp yield in Eucalyptus nitens (Dean & Maiden) Maiden trees were explored. Three selection techniques based on NIR spectral data (CADEX (computer-aided design of experiments), DUPLEX, and SELECT algorithms) and one selection method based on a measured property (RANKING algorithm) were used for analysis and compared against a model using all data. The effect of using calibration sets of different sizes was also evaluated. All sample- selection methods resulted in models of similar performance compared with the model fitted using all samples. For calibration purposes, RANKING selection resulted in models with the lowest errors of cross-validation, followed by the DUPLEX, CADEX, and SELECT methods. In terms of validation, the SELECT and CADEX methods resulted in lower errors of prediction compared with the DUPLEX and RANKING algorithms. In general, cross-validation and prediction errors decreased as the number of calibration samples increased. These results show that it is possible to obtain adequate NIR calibration models with a reduced number of samples allowing the remaining samples to be used for model validation and that sample selection based on NIR spectral data alone is as successful as selection based on a measured property. Les effets lies a l'utilisation d'ensembles reduits de donnees de calibration sur le developpement de modeles de calibration avec des donnees spectrales dans le proche infrarouge (PIR) pour predire le rendement en pate kraft des tiges d'Eucalyptus nitens (Dean & Maiden) ont ete etudies. Trois methodes de selection basees sur des donnees spectrales dans le PIR (algorithmes CADEX, DUPLEX et SELECT) et une methode de selection basee sur une propriete mesuree (algorithme d'ordonnancement) ont ete utilisees pour l'analyse et comparees avec un modele utilisant toutes les donnees. L'effet lie a l'utilisation d'ensembles de donnees de calibration de differentes tailles a egalement ete evalue. Toutes les methodes de selection de l'echantillon ont produit des modeles dont la performance etait similaire comparativement au modele utilisant toutes les donnees. Pour des fins de calibration, les modeles bases sur la selection par ordonnancement avaient les plus petites erreurs de validation croisee suivis par les modeles bases sur les methodes de selection utilisant les algorithmes DUPLEX, CADEX et SELECT. En termes de validation, l'erreur de prediction etait la plus faible avec les methodes de selection qui utilisaient les algorithmes SELECT et CADEX comparativement a celles qui utilisaient les algorithmes DUPLEX et d'ordonnancement. Generalement, les erreurs de validation croisee et de prediction diminuaient a mesure que le nombre d'echantillons servant a la calibration augmentait. Ces resultats montrent qu'il est possible d'obtenir des modeles de calibration adequats pour les donnees spectrales dans le PIR avec un nombre reduit d'echantillons permettant ainsi d'utiliser les echantillons restants pour valider le modele et que la selection des echantillons basee seulement sur des donnees spectrales dans le PIR est aussi valable que la selection basee sur une propriete mesuree. [Traduit par la Redaction], Introduction In near-infrared (NIR) analysis, a multivariate calibration model represents a mathematical expression that relates component concentrations to the absorbances of a set of known reference samples at more than [...]

Abstract: Loblolly pine (Pinus taeda L.) is the most important plantation species in the southeastern United States and specific gravity (SG) is its most important wood quality trait. Analysis of [...]

Data from a variability study of loblolly pine (Pinus taeda L.) based on weighted core specific gravity (WCSG) were examined to show how costs and variance estimates are used in designing efficient sampling strategies. Increment cores for the determination of WCSG were taken from 3957 trees across six distinct physiographic regions in the southeastern United States. More variability was found to exist among stands than within stands. This indicates that reducing the variation of the mean of WCSG can be accomplished by sampling more stands and fewer trees in the region of interest. The number of stands and trees to sample is dictated by the maximum allowable cost and the precision required of the sample mean, and formulas are given for such calculations. The estimate of among-stand variability was found to be similar among the regions of interest, whereas larger within-stand variation was found to exist in the South Atlantic and Hilly regions. The standard error of the mean was found to increase with an increase in the age at which the stand was sampled. When sampling across multiple stands (at any age), little if any gain in the precision of the standard error of the mean is gained by sampling more than 15 trees. In the general case where one is interested only in the value of WCSG in one stand and precision or cost-time factors are not of consideration, it would suffice to sample between 45 and 55 trees at any age. Des donnees provenant d'une etude de variabilite basee sur le poids specifique pondere de carottes de pin a encens (Pinus taeda L.) ont ete examinees pour illustrer comment l'estimation des couts et de la variance est utilisee pour elaborer des strategies efficaces d'echantillonnage. Les carottes utilisees pour determiner le poids specifique pondere ont ete prelevees sur 3957 arbres repartis dans six regions physiographiques distinctes du sud-est des Etats-Unis d'Amerique. Une plus grande variabilite a ete observee entre les peuplements que dans les peuplements. Cela signifie qu'il est possible de reduire la variation de la moyenne du poids specifique pondere en echantillonnant plus de peuplements et moins d'arbres dans la region visee. Le nombre de peuplements et d'arbres a echantillonner est dicte par le cout maximal admissible et la precision de la moyenne de l'echantillon qui est requise; des formules servant a effectuer ces calculs sont fournies. L'estimation de la variabilite entre les peuplements etait semblable d'une region a l'autre tandis qu'une plus forte variabilite a ete observee dans les peuplements des regions de South Atlantic et de Hilly. L'erreur type de la moyenne augmente avec l'age auquel le peuplement a ete echantillonne. Lorsqu'on echantillonne plusieurs peuplements d'ages differents, on obtient peu sinon aucun gain de precision de l'erreur type de la moyenne en echantillonnant plus de 15 arbres. En general, lorsqu'on s'interesse seulement a la valeur du poids specifique pondere dans un peuplement et que la precision ou les facteurs de cout ou de temps ne sont pas importants, il serait suffisant d'echantillonner 45 a 55 arbres peu importe l'age. [Traduit par la Redaction], Introduction The southeastern United States produces 58% of the marketed timber in the United States and 16% of all marketed timber in the world (Wear and Greis 2002). Loblolly pine [...]

Within-tree variation of four handsheet properties (burst index, sheet density, STFI short-span compression strength (STFI) and tensile index) was mapped for loblolly pine trees aged 13 and 22 years using NIR predicted handsheet property data (representing an average of 18 trees for each age). All within-tree maps were similar demonstrating a radial decrease in handsheet properties at all heights, with sheet density and tensile index having the greatest within-tree variation. The corewood zone had the highest values for all properties, while the lowest values were observed in a region consistent with juvenile and transitional outerwood as defined by Burdon et al. (2004). The maps are also similar to, but the inverse of, maps reported in prior studies for density and tracheid coarseness and wall thickness. Relationships amongst the examined handsheet properties and wood and tracheid properties explains the overall similarities of the different maps. The maps provide a representation of within-tree variation of important paper properties at two different ages. An understanding of how these properties vary within loblolly pine trees can aid in better utilization of forest resources. [ABSTRACT FROM AUTHOR]

The objective of this work was to provide a rapid and nondestructive imaging method for evaluating the hygroscopic behavior of thermally modified lignocellulosic materials (softwood and hardwood). The difference in the hygroscopic behavior was explained by moisture content (MC) mapping results and molecular association characteristics of absorbed water (i.e. weakly, moderately, and strongly hydrogen-bonded water molecules) with wood at various relative humidities (RH). To achieve this goal, near-infrared (NIR) spectral images in the wavelength range 1816–2130 nm (covering the combination of stretching and deformation vibrations for OH) were used to visualize MC distributions over the surface of Japanese cedar and European beech samples which had been thermally treated at different temperatures. A curve fitting method was utilized to explore changes in water-wood structure characteristics based on shifts to longer wavelength in spectral signals caused by increasing MC. The curve fitting results support the recent nuclear magnetic resonance (NMR) studies that different bound water stabilities may pool in different compartments of the wood cell wall. Furthermore, water was firmly bound to wood at low RHs and H-bonds gained mobility as the number of absorbed molecules increased. It is concluded that NIR hyperspectral imaging also has the potential to be a complementary methodology for studying the transient changes of wood-water interactions before equilibrium. [ABSTRACT FROM AUTHOR]

The radial variation in cell morphology of ten-year-old Melia azedarach trees planted in northern Vietnam was experimentally investigated. The earlywood fiber lumen diameter and latewood fiber lumen diameter were almost unchanged from pith to 6th ring before significantly decreasing and remaining constant from 7th ring outwards. In contrast, fiber cell wall thickness in both earlywood and latewood increased from pith to 7th ring before becoming stable towards the bark. The maturation age of earlywood vessel lumen diameter estimated by segmented regression analysis indicated that wood of the Melia azedarach could be classified into core wood and outer wood, and the boundary between core and outer wood may be located at 7th ring from pith. This should be taken into account in wood processing using M. azedarach grown in northern Vietnam. [ABSTRACT FROM AUTHOR]

Loblolly pine is a major fibre source for the pulp and paper industry. Here we developed the first nonlinear models to predict the within-tree and regional variation of tracheid length and width for planted loblolly pine. Data were obtained from macerated tracheids and near-infrared spectroscopy calibration models from trees sampled in 109 stands across the southeastern United States. The fixed effects for the final tracheid length model, which included cambial age, height of disk within tree, and physiographic region, explained 71 percent of the variation with root mean square error (RMSE) of 0.28 mm, while the fixed effects for the final tracheid width model explained 57 percent of the variation with RMSE of 1.4 μm. There was significant variation in tracheid properties across the growing regions. Tree maps showing within-tree variability in tracheid properties were produced. Five simulated scenarios were compared using the models developed, with mean tracheid dimensions calculated on a whole-tree basis at a first and second thinnings, and at final harvest. Also from the final harvest, the tops of trees, and outerwood chips produced during lumber manufacturing were also simulated. For the whole tree scenarios, both mean tracheid length and width increased with age, increasing from 2.24 mm and 40.5 μm (age 12), to 2.51 mm and 41.3 μm (age 18), and to 2.73 and 41.8 μm at age 25, respectively. The tops of the trees at age 25 had a mean tracheid length of 2.46 mm and a mean width of 41.0 μm, while the chips had a mean tracheid length of 3.13 mm and a mean width of 42.5 μm. Due to the models representing samples collected from across the southeastern United States, and their relatively high precision, they are suitable for incorporation into growth and yield systems allowing for prediction of tracheid properties. [ABSTRACT FROM AUTHOR]

Wood extractives are considered the major factor determining the natural durability of wood. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was assessed for rapid determination of western juniper (Juniperus occidentalis Hook. var. occidentalis) durability based on extractives in heartwood, sapwood-heartwood and sapwood regions. Durability was assessed by exposing samples to brown-rot decay fungi [Gloeophyllum trabeum (Pers.) Murrill and Rhodonia placenta (Fr.) Niemelä, K.H. Larss. & Schigel] or eastern subterranean termite (Reticulitermes flavipes Kollar). Durability classifications were compared to their extractive contents, along with ATR-FTIR spectra of extracted and unextracted blocks to establish relationships using hierarchical cluster analysis (HCA) and principal component analysis (PCA). Western juniper durability varied with test organisms, but the majority of samples had high fungal and termite resistance. Moderate to weak connections were observed between durability and extractive content, but HCA and PCA analysis were unable to classify durability with accuracy. The absence of non-resistant samples may have influenced the ability of the chemometric methods to accurately categorize durability. [ABSTRACT FROM AUTHOR]