Heartwood and sapwood in eucalyptus trees: non-conventional approach to wood quality (original) (raw)
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The presence of heartwood influences the use of wood in different ways (Hillis, 1987). The conceptual bases that allowed the precise definition and general physiological aspects involved in heartwood and sapwood formation were consolidated for some time, but some current techniques such as X-ray scans, infrared and gamma rays can be used for more detailed quantification and characterization of heartwood inside the main stem (Gominho, 2003). In this study we used the non-destructive method of gamma radiation attenuation to determine the basic and apparent density at 12% moisture content of wood portions (heartwood and sapwood) of mature trees of four forest species (Eucalyptus grandis Hill ex. Maiden - 18 years old, Eucalyptus saligna - 60 years old, Eucalyptus tereticornis - 35 years old and Corymbia citriodora - 28 years old). Six discs were sampled at breast height (DHB) of each species and the heartwood and sapwood were delimited by macroscopic analysis of the vessels (heartwood characterized by the presence of tyloses in the vessels, and sapwood, by the absence thereof) in each sample. The apparent density values ranged from 672 to 933 kg/m³ in the heartwood wood and 749 to 899 kg/m³ in the sapwood wood. The averages of apparent density did not differ significantly between the wood fractions. Despite the different ages of the plantations, the highest values of apparent density of wood, both in the heartwood and in the sapwood fraction were observed in Corymbia citriodora species. keywords: density, gamma radiation, Eucalyptus, heartwood
Trees-structure and Function, 2009
Heartwood and sapwood development was studied in 18-year-old Eucalyptus globulus trees from pulpwood plantations with different spacings (3 × 2, 3 × 3, 4 × 3, 4 × 4 and 4 × 5 m), on cross-sectional discs taken at breast height. The trees possessed a large proportion of heartwood, on average 60% of the wood cross-sectional surface. Spacing was a statistically significant source of variation of heartwood area, which ranged between 99 and 206 cm2 for the closer (3 × 2) and wider (4 × 5) spacings, respectively. There was a positive and high statistical significant correlation between heartwood diameter and tree diameter (heartwood diameter = −0.272 + 0.616 dbh; r 2 = 0.77; P < 0.001), and larger trees contained more heartwood regardless of spacing. Heartwood proportion in cross-section remained practically constant between spacings but increased with tree diameter class: 55.1, 62.2, 65.0 and 69.5% for diameter at breast height classes <15, 15–20, 20–25 and >25 cm, respectively. The sapwood width did not depend on tree diameter growth and remained practically constant at an average of 18 mm (range 15–21 mm), but sapwood area showed a good linear regression with tree diameter. Therefore, tree growth enhancement factors, such as wide spacings, will induce formation of larger heartwoods that can negatively impact raw-material quality for pulping. The increase in heartwood in relation with tree dimensions should therefore be taken into account when designing forest management guidelines.
Wood research
Six 15-year-old Eucalyptus globulus trees, ranging in wood density from 474 to 575 kg.m-3, were sampled at breast height for anatomical study and fiber measurement. Vessel and fiber dimensions showed an increase from pith to bark, while vessel frequency decreased. Cell wall thickness, fiber length, runkel ratio and coarseness were significantly superior in the high-density genotypes (group A) in almost each section along the radius analyzed. Average cell wall thickness for samples of group A was 3.35 μm, while in group B (the low-density genotypes) was 2.86 μm. The average runkel ratio and coarseness in groups A and B were 0.73 and 7.6 mg/100 m, 0.56 and 6.7 mg/100 m, respectively. Lumen width was significantly different among the groups, being higher in group B, but no significant differences were found for vessel features. Pooled data showed significant correlations between wood density and cell wall thickness (r = 0.52), coarseness (r = 0.40) and runkel ratio (r = 0.41), while co...
The influence of tree spacing in heartwood content in Eucalyptus globulus Labill. Wood Fiber Sci
Heartwood content was studied in 27 Eucalyptus globulus Labill. trees with spacings 3 x 3, 3 x 2, and 2 x 1 (m x m), with 9 years, from a 1st rotation spacing trial. The height attained by heartwood increased with total tree height independently of spacing, and reached on average 45%, 59%, and 62% of total height, respectively, for spacings 2 x 1, 3 x 2, and 3 x 3. In all the spacings, the heartwood radius decreased gradually along tree height, and the radial thickness of sapwood remained practically constant at approximately 16 mm in the lower part of the stem (< 35% of height), and increased upwards. Sapwood thickness did not depend on tree growth rate, remaining constant for all tree diameters. Heartwood diameter increased with tree diameter, with larger trees showing more heartwood regardless of spacing. Sapwood thickness was not correlated with tree radius, but sapwood area showed a good linear regression. The proportion of heartwood volume increased with spacing from 20.3% ...
Determination of physical properties of Eucalyptus cloeziana sp. wood in different dimensions
The Eucalyptus belongs to the family Mirtaceae and has about 600 species with several varieties and hybrids, besides having different types of cells that adapt to perform specific functions. The objective of this study was to evaluate the physical properties of Eucalyptus Cloeziana wood, specifically, apparent density, basic density, moisture content, total volumetric retractability and anisotropy factor. The wood of this species was cut into three different sizes of species according to the current Brazilian standard, the old Brazilian standard and the French standard. The values found were similar to those found in studies of other researchers, which shows a data concordance for the Eucalyptus Cloeziana species.