Radial variation of wood density components and ring width in cork oak trees

Abstract

-The radial variation of ring width and wood density was studied in cork oaks (Quercus suber) using microdensitometry. The observations were made in young never debarked cork oaks (30-40 years of age) and in mature trees under cork production (37-60 years of age). The cork oak wood is very dense (mean ring density 0.86 g.cm −3 , between 0.79 g.cm −3 and 0.97 g.cm −3 ) with a small intra-ring variability (mean earlywood density 0.80 g.cm −3 and latewood density 0.90 g.cm −3 ). The density components decreased from pith to bark more rapidly until the 15th ring, and then only slightly. There were no significant differences in the mean density components between never debarked trees and trees under cork production but their outwards decrease was accentuated in the never debarked trees. The annual growth was high, with a ring width mean of 3.9 mm (4.2 mm in the first 30 years) and the latewood represented 57% of the annual growth.Quercus suber / cork oak / density / ring width / latewood Résumé -Variation radiale des composantes de la microdensité du bois et de la largeur de cerne dans le chêne-liège. La variation radiale de la largeur des cernes et de la densité du bois a été étudiée dans le chêne-liège (Quercus suber) par microdensitométrie. Les observations ont été réalisées dans des arbres jeunes jamais écorcés (âge 30-40 ans) et des arbres en phase de production de liège (37-60 ans). Le bois de chêne-liège est très dense (densité moyenne 0,86 g.cm −3 , variant entre 0,79 g.cm −3 et 0,97 g.cm −3 ) avec une variabilité dans le cerne faible (densité moyenne du bois initial 0,80 g.cm −3 et du bois final 0,97 g.cm −3 ). Les composantes de la densité diminuent du coeur à la périphérie rapidement jusqu'au 15 e cerne, puis plus lentement. Les différences entre valeurs moyennes des composantes de la densité du bois des arbres non écorcés et écorcés ne sont pas statistiquement significatives, quoique la diminution radiale soit plus accentuée dans les arbres non écorcés. La croissance annuelle était élevée avec une largeur moyenne de cerne de 3,9 mm (4,2 mm dans les premiers 30 ans) avec le bois final correspondant à 57 % de la croissance annuelle.Quercus suber / chêne-liège / densité / largeur de cerne / bois final

Wood Density of Northern Red Oak and Pedunculate Oak Grown in Former Brown Coal Mine in the Czech Republic

“…Although a positive correlation between the density and width of annual rings for ring-porous tree species, or between density and proportion of latewood, is generally assumed (Kollmann 1951;Tsoumis 1991), there are also studies in which this has not been confirmed, which suggests that the issue is much more complicated and that the structure of latewood also plays a role. Knapic et al (2007) found no relationship between the width of the annual rings and the proportion of latewood. Bergès et al (2008) reported a weak or insignificant correlation between density and the width of annual rings and proportion of latewood.…”

“…Adamopoulos et al (2007) did not find a significant difference in the wood density between the central and peripheral parts of the trunk. Most studies have reported the opposite trend, i.e., a decrease in density in the direction from the pith toward the bark; for example, Vavrčík and Gryc (2012) reported such a density distribution for Q. robur, Ayobi et al (2011) for Q. castaneaefolia, and Knapic et al (2007) for Q. suber. Panshin and Zeeuw (1980) stated that there was very little consistency and no overall dominance of a single pattern in hardwood tree species for density fluctuation with respect to the height of the trunk.…”

Age trends and within-site effects in wood density and radial growth in Quercus faginea mature trees

“…80 years. Regarding wood density, Q. faginea mature trees showed high values that are similar to other oaks such as Q. suber (0.75 to 1.07 g/cm 3 ) (Knapič et al, 2007(Knapič et al, , 2008 and Q. cerris (0.96 g/cm 3 ) (Dilem, 1995). Despite this similarity, Q. faginea wood density values are higher than those found for the currently highly valued oaks such as Q. petraea (0.66 -0.83 g/cm 3 ) (Bergès et al, 2008), Q. rubra (0.54 -0.76 g/cm 3 ), and Q. robur (0.52 -0.63 g/cm 3 ) (Nepveu, 1984;Genet et al, 2012).…”

Variations in the natural density of European oak wood affect thermal degradation during thermal modification

“…Thus, hardwoods are generally more sensitive to thermal degradation than softwoods, while woods with high densities seem to be more sensitive to thermal degradation than less dense woods ). Relative to intra-species differences, wood quality of European oak is reported to be deeply influenced by ring width depending on ecological factors, soil quality, forest management, tree age, and genetics (Bouriaud et al 2004;Zhang et al 1993;Knapic et al 2007;Bergès et al 2008). In this context, wood density is often used as a functional trait in tree ecology to evaluate wood quality.…”