Abstract
ABSTRACT The objective of this work was to evaluate the influence of different useful areas provided by the planting spacings (3 × 1, 3 × 2, 3 × 3, 3 × 4 m) on the production and permeability of heartwood and sapwood of Eucalyptus grandis and Eucalyptus grandis × Eucalyptus urophylla clones at 4 years old. Regardless of the clone, there was no effect of planting spacing on the heartwood/sapwood relation and wood permeability. All clones showed a heartwood decrease with increased height, regardless of planting spacing, and E. grandis (B) was the only one that had its heartwood percentage positively and significantly correlated with the dendrometric variables (DBH and commercial height). The use of the dymethil yellow compound was indispensable in defining the heartwood and sapwood regions in the samples from 50% of the stem height. The heartwood permeability was low in all evaluated clones, suggesting vessel obstruction by tyloses or other deposits, while sapwood permeability reached 405.4 cm3/cm.atm.s.
Highlights
The proportion of heartwood and sapwood in the wood reflects directly in its use (Déjardin et al, 2010), since generally those that contain a high amount of heartwood are preferentially used in the construction and furniture industry, while trees with a greater proportion of sapwood are indicated for the pulp wood industry and for wood preservation, as they have higher proportions of high-permeability wood
All clones showed a heartwood decrease with increased height, regardless of planting spacing, and E. grandis (B) was the only one that had its heartwood percentage positively and significantly correlated with the dendrometric variables (DBH and commercial height)
The predominant amount of heartwood impedes the passage of water from the interior to the surface of the piece, affecting the drying of the wood (Siau, 1971); this restricts the impregnation of preservatives, resulting in low retention of these products (Valle et al, 2013), increases the consumption of alkali and reduces the yield in cellulose, since the amount of extractives is high (Miranda et al, 2009); and it prevents the gases from permeating the wood, causing cells breakage and fissures in charcoal (Pereira et al, 2013)
Summary
The proportion of heartwood and sapwood in the wood reflects directly in its use (Déjardin et al, 2010), since generally those that contain a high amount of heartwood (higher H/S relation) are preferentially used in the construction and furniture industry, while trees with a greater proportion of sapwood (smaller H/S relation) are indicated for the pulp wood industry and for wood preservation, as they have higher proportions of high-permeability wood. The spacing between the trees influences the dendrometric variables such as height and stem diameter, and heartwood formation (Gominho & Pereira, 2005). The proportion of heartwood and sapwood in young eucalyptus trees is still poorly addressed in wood quality evaluations, it has an impact on several productive processes that use wood as raw material. In this context, the objective of this study was to evaluate the influence of different planting spacings on the production and permeability of the heartwood and sapwood in eucalyptus wood, to quantify the percentage of heartwood in the base-top direction of the stem, and to correlate its production with the trees dendrometric variables
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