Quantifying Wood Decay in Sydney Bluegum
(Eucalyptus saligna) Trees
Denise Johnstone, Michael Tausz, Gregory Moore, and Marc Nicolas
Abstract: The evaluation of decayed wood in a tree is essential for tree risk assessment in arboriculture. It is not feasible in practice to measure the amount of wood decay in all the wood of every tree. Therefore, the capacity of a single measurement taken in cross-section to approximate the volume of decay in the wood of a whole tree is the focus of this study. The volume of wood decay in Eucalyptus saligna trees was estimated post harvest by measuring the whole tree wood density of 36 trees. Linear, logarithmic, and multiple regression statistical models were used to examine whether whole tree wood density data could be correlated with three ways of directly measuring wood decay in a single cross-section, two prior to tree felling and one post felling method. The decay estimation techniques were measured in cross-section—a Picus® Sonic Tomograph system, an IML-Resi system, and a visual method. In this study the Resi System for estimating wood decay showed a correlation with whole tree wood density in the entire tree whereas the Picus system and the visual method did not show any statistical correlation with whole tree wood density.
Keywords: Eucalypts; Hazard Trees; Picus® Sonic Tomograph; Resi; Resistograph; Tree Failure; Tree Risk Analysis; Wood Decay