Variation of heartwood and sapwood in 18-year-old Eucalyptus globulus trees grown with different spacings |
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Authors: | Isabel Miranda Jorge Gominho Helena Pereira |
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Institution: | (1) Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade Técnica de Lisoa, Tapada da Ajuda, 1349-017 Lisbon, Portugal |
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Abstract: | 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. |
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Keywords: | Eucalyptus globulus Heartwood Sapwood Plant density Spacing |
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