Selecting Eucalyptus Clones Using Ultrasound Test on Standing Trees

The production of eucalyptus for the cellulose and paper industry is based on the cultivation of clones, which are obtained by crossing species with desirable characteristics. However, clones that were considered to have great potential have presented serious problems because of permanent bending and breakage, which are caused mainly by wind forces during the early years of growth. Wave propagation methods have shown great potential in applications related to predicting the stiffness of logs and lumber. Based on the premise that the stiffness of the stem is a major contributor to a tree's resistance to the wind, the objective of the present study was to determine whether an ultrasound wave propagation test performed directly on trees would have the sensitivity within a sample group to differentiate between clones and whether this differentiation would be consistent with the differences in stiffness between them. The stem was used to evaluate the stiffness of clones rather than logs, pieces of a structural size, or specimens. A cantilever static scheme and the application of a load near the top of the stem were intended to simulate field conditions. A total of 189 trees were tested from 21 different clones. To differentiate the clones, the ultrasound wave propagation velocity was obtained directly from the trees. The velocity differences among the trees were consistent with the results obtained using the stem stiffness of the same trees.