Abstract

Wood density and fibre length of Eucalyptus grandis were studied in trees of four age groups (3, 5, 7, and 9 yr) . The average basic density was 495 kg/m3 at 3 yr and there was no significant increase from 3 to 9 yr, whereas 5-yr-old trees had a significantly lower value. Fibre length increased consistently with agefibres of 3-yr-old trees (mean 0. 81 mm) were about 29 shorter than those of 9-yr-old trees (1. 15 mm) . Density did not differ significantly between the locations, but fibres were longer in one location where trees had faster growth. Density declined from stump to 25 of tree height and then gradually increased towards the top in a curvilinear manner, whereas fibre length commonly showed the reverse trend. In 5-, 7- and 9-yr-old trees, average tree density could be predicted with reasonable accuracy using breast height density, but stump level density was a better predictor of average tree density in 3-yr-old trees