The Influence of Tree Spacing in Heartwood Content in Eucalyptus Globulus Labill

Jorge Gominho, Helena Pereira

Abstract


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% to 41.1% of tree volume, respectively for 2 x 1 and 3 x 3 spacings.

Keywords


<i>Eucalyptus globulus</i> Labill;heartwood;sapwood;spacing;variability

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