Assessment ofwood density of seven clones of Eucalyptus grandis

Abstract

Withthe objective ofevaluating the correlation ofwoodbasic density with age in seven Eucalyptus grandis clones planted in Brazil, five trees in each clone were sampled at the ages of 0,5, 1,5, 2,5, 3,5,4,5 and 7,5 years. The analysis of these samples showed that the intraclonal variation ofthe basic density (except for 0,5 year-old) was very low, while the interclonal variation was moderately high (from 7,5% at 0,5 yearold to 4,1% at 7,5 year old) for all ages. The analysis of variance indicated that the variation between clones, between ages and the clone ( age interaction were all significant (P ≤ 0,01), but the variation ofthe basic density of the trees within-clones were non-significant. The study of temporal stability of the basic density showed that most of the clones behave similarly to the mean clone for all ages. According to the analysis of regression of the mean basic density per clone using temporal-index as predictor it was found that for this group of clones is it possible to predict the basic density of wood produced at one age from its value at another age. Indeed, the correlation of the basic density at different ages within a clone showed that, except for the correlations for woodof0,5 year-old, all other correlations were statistically significant. However, it can be noted that correlations based on more recent ages presentedhigher values ofcoefficient of correlation, even ifthe same time span has been considered. Also, it was shown that was it possible to estimate the basic density using the age ofthe tree as independentvariable through the logarithmic model both for individual clones (R₂ from 75 % to 96 %) and for all seven clones analysed together (R₂ =92%).