Methodology of Microdensitometric Measurement for Oak Wood <i>(Quercus robur </i>L. and <i>Quercus petraea </i>Liebl): Proposal for a Representative Sampling of Oak Wood Density within Ring

Degron, Robin; Nepveu, Gérard

doi:10.1515/hfsg.1996.50.6.491

Cited by 7 publications

(7 citation statements)

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“…If more than one solution is obtained, the highest value among solutions is chosen. D = a o +a 1 RW+a 2 RW 2 +a 3 RW 3 + a 4 RW 4 +....+a n RW n (1) d 2 D/dRW 2 = 2a 2 +6a 3 RW+12a 4 RW 2 +....+n(n-1)a n RW n-2 (2) where D is ring density; RW is ring width in proportion and a i are parameters to be estimated.…”

Section: Methodsmentioning

confidence: 99%

“…Other laboratories use the minimum and maximum density methods to define the earlywood-latewood transition [2,19]. This method determines the E/L transition from the minimum and maximum density of the densitometry profiles of individual growth rings.…”

Section: Introductionmentioning

confidence: 99%

“…This method determines the E/L transition from the minimum and maximum density of the densitometry profiles of individual growth rings. Few formulas were used previously to define this transition point [2,19]. Although this method is rapid, consistent and easy to be integrated into X-ray densitometry computational programs, it is based on two single values and thus does not consider the variation in the whole intra-ring wood density profiles.…”

Section: Introductionmentioning

confidence: 99%

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Defining the transition from earlywood to latewood in black spruce based on intra-ring wood density profiles from X-ray densitometry

Koubaa

Zhang

Makni³

2002

Ann. For. Sci.

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-Defining the transition from earlywood to latewood in annual rings is an important task since the accuracy of measuring wood density and ring width components depends on the definition. Mork's index has long been used as an anatomical definition of the transition from earlywood to latewood. This definition is arbitrary and extremely difficult to apply to X-ray densitometry. For X-ray densitometry, a threshold density of between 0.40 to 0.55 g cm -3 , depending on species, has been chosen to differentiate between earlywood and latewood density, but this method has shortfall. Therefore, new methods need to be developed and integrated into the computational programs used to generate X-ray densitometry data. In this study, we presented a mathematical method. We modelled the intra-ring wood density profiles in 100 plantation-grown black spruce (Picea mariana (Mill.) B.S.P.) trees using high order polynomials. The correlation between the predicted and the measured densities is very high and highly significant. Based on this model, we define the transition from earlywood to latewood as the inflexion point. Results indicate that wood density at the earlywood-latewood transition point varies from juvenile to mature wood. This method could be easily integrated into any X-ray densitometry program and allows to compare individual rings in a consistent manner.transition / earlywood / latewood / X-ray densitometry / wood density / black spruce / modelling Résumé -Définition de la transition du bois initial au bois final chez l'épinette noire à partir des profiles de densité intra cernes obtenus par densimétrie aux rayons X. La précision de l'estimation des densités et des largeurs du bois initial et du bois final dans un cerne annuel dé-pend de la définition de la transition du bois initial au bois final. L'indice de Mork a longuement servi pour donner une définition anatomique à cette transition. Cette définition est arbitraire et difficile à appliquer en densimétrie aux rayons X. En général, un seuil de densité variant entre 0,40 à 0,55, dépendamment de l'essence, sert à différencier le bois initial du bois final. Cette méthode a certaines limites et d'autres méthodes doivent être développées et intégrées aux programmes de densimétrie aux rayons X. Nous avons utilisé une approche mathématique pour modé-liser les profiles de densité intra cernes dans 100 arbres d'épinette noire (Picea mariana (Mill.) B.S.P.). Le point d'inflexion de polynômes aux degrés élevés a servi pour définir la transition du bois initial au bois final. Les corrélations entre les densités mesurées et prédites sont élevées et significatifs. La transition du bois initial au bois final varie entre le bois juvénile et le bois adulte. Cette méthode est facile à intégrer dans les programmes de densimétrie aux rayons X et permet d'obtenir des comparaisons consistantes entre cernes annuels. transition / bois initial / bois final / densimétrie aux rayons X / densité du bois / épinette noire / modélisation

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Defining the transition from earlywood to latewood in black spruce based on intra-ring wood density profiles from X-ray densitometry

Koubaa

Zhang

Makni³

2002

Ann. For. Sci.

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“…Microdensitometric analysis consisted of drying the wood core at a humidity of 11.8%, cutting it longitudinally into a regular 2 mm×4.5 mm bar (Perrin and Ferrand 1984), and finally exposing its radial-tangential surface to an Xray source using Kodak Professional Industrex AA 400 film and the following irradiation conditions: source to film distance=2 m; accelerating tension=10 kV; flux intensity=10 mA; duration of exposure=2 h. The film was then analysed by a microdensitometer made by the Laboratory of Wood Quality (INRA Nancy, France) (Polge 1966) in a radial direction by a 24-µm moving step window (25 µm in the radial direction and 500 µm in the tangential direction). In order to average the tangential anatomical variation, three joined parallel microdensitometric profiles were measured on each sample, as recommended by Degron and Nepveu (1996b). Ring boundaries were manually positioned to the nearest 25 µm with the software "CERD" (Mothe et al 1998a).…”

Section: Data Collection and Density Measurementsmentioning

confidence: 99%

Long-term changes in wood density and radial growth of Quercus petraea Liebl. in northern France since the middle of the nineteenth century

Bergès¹,

Dupouey

Franc

2000

Trees

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Long-term changes in sessile oak (Quercus petraea Liebl.) growth and wood density were studied using cores collected from 99 even-aged high forest stands between 56 and 187 years old, located in northeastern and north-central France. Growth and density trends were tested by analysis of variance and covariance. Two models were applied to two samples, sample A and sample B (sample B being a sub-sample with limited cambial age and calendar date ranges). Model 1 showed a significant increase in radial growth: +35%, +87% and +66% in earlywood width, latewood width and ring width, respectively, from 1811 to 1993 for sample A. Consequently, there was a positive trend in latewood ratio (+14%). A slight decrease in wood density was found: -3.3% and -5.4% for earlywood and latewood density, respectively. Despite an increase in latewood percentage, mean ring density showed a -2.0% decrease. Model 1 applied to a biomass indicator (density×ring width) showed a 62% increase from 10.4 to 16.8 kg m -3 between 1811 and 1993 for sample A. Results for sample B were slightly different: the increase in latewood ratio was not detected. Model 2 showed a change with time in the positive hyperbolic relationship between mean density and ring width. The results are discussed. The decrease in wood density cannot be explained by N atmospheric deposition or by long-term changes in average temperature. Increasing atmospheric CO 2 levels cannot be invoked owing to the present lack of studies. Finally, hypotheses concerning long-term changes in wood anatomical characteristics are proposed.

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“…In the 20 th century, use of oak in structures decreased due to the increased presence of concrete, steel and graded coniferous wood. An additional restriction to the use of oak is the large variability in the species with regard to density and other characteristics related to quality (Zhang et al, 1994;Degron and Nepveu, 1996).…”

Section: Introductionmentioning

confidence: 99%

Implications in the design of a method for visual grading and mechanical testing of hardwood structural timber for designation within the European strength classes

Muñoz¹,

Gete²,

Saavedra³

2011

For. syst.

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The European strength class system (EN 338:2009) is based on a testing standard (EN 408:2004) that is not easy to use with hardwoods, although some of this type of timber, such as European oak (Quercus robur L.), is highly appreciated for construction purposes. This study proposes specifications for sampling design, visual grading and mechanical testing of oak wood. With this aim, 27 adult oaks were felled and sawn into pieces. A sample of quartersawn planks was selected, then air-dried and planed to 50 × 100 × 2,000 mm. The beams were visually graded in accordance with ten standards, and were mechanically tested, at an average wood moisture content of 21%. The Spanish visual grading standard UNE 56544:2007 was the most effective for categorizing the pieces. According to this standard, 39% of the sampled beams were suitable for structural use. The mean value of modulus of elasticity (11,702 N mm -2 ) and characteristic density (714 kg m -3 ) enable preliminary designation of the wood in visual grade ME-2, to European strength class D40. However, the bending strength was too low for inclusion of the timber in the European strength classes. Criteria are proposed for elaborating visual grading rules for oak wood and for structural beam testing in order to allocate oak visual strength grades into strength classes.Key words: Quercus robur L.; visual grading; sampling design; testing procedure; mechanical properties. ResumenConsideraciones en el diseño de un método de clasificación visual y ensayo mecánico de madera estructural de frondosas para su asignación al sistema europeo de clases resistentes El sistema europeo de clases resistentes (EN 338:2009) se basa en una norma de ensayo (EN 408:2004) que es difícil de aplicar en frondosas, aunque algunas de dichas maderas, como el roble (Quercus robur L.), sean muy valoradas en aplicaciones constructivas. En este trabajo se proponen especificaciones para el diseño de muestreo, clasificación visual y ensayo mecánico de la madera de roble. Para el estudio se apearon y aserraron 27 ejemplares adultos de roble. Se seleccionó una muestra de piezas aserradas claramente radiales, que se secaron al aire y se cepillaron hasta unas dimensiones de 50 × 100 × 2.000 mm. Las viguetas obtenidas se clasificaron visualmente según diez normas de clasificación y fueron sometidas a ensayo mecánico con un contenido de humedad medio del 21%. La norma española UNE 56544:2007 fue la más eficaz en la clasificación visual de las piezas. Según dicha norma, el 39 % de las viguetas muestreadas eran aptas para su empleo en estructuras. El modulo elástico medio (11.702 N mm -2 ) y la densidad característica (714 kg m -3 ) permitirían una asignación preliminar de la madera de la clase visual ME-2 a la clase resistente europea D40. No obstante, la resistencia a flexión era demasiado baja como para la inclusión de la clase visual en el sistema europeo de clases resistentes. Se proponen criterios a considerar en la elaboración de una futura norma de clasificación visual para madera de roble y ...

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Methodology of Microdensitometric Measurement for Oak Wood (Quercus robur L. and Quercus petraea Liebl): Proposal for a Representative Sampling of Oak Wood Density within Ring

Cited by 7 publications

References 2 publications

Defining the transition from earlywood to latewood in black spruce based on intra-ring wood density profiles from X-ray densitometry

Defining the transition from earlywood to latewood in black spruce based on intra-ring wood density profiles from X-ray densitometry

Long-term changes in wood density and radial growth of Quercus petraea Liebl. in northern France since the middle of the nineteenth century

Implications in the design of a method for visual grading and mechanical testing of hardwood structural timber for designation within the European strength classes

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