PICUS SONIC TOMOGRAPHY FOR THE QUANTIFICATION OF DECAY IN WHITE OAK (QUERCUS ALBA) AND HICKORY (CARYA SPP.)

摘要

The Picus Sonic Tomograph is a noninvasive tool for assessing decay in trees. It works on the principle that sound waves passing through decay move more slowly than sound waves transversing solid wood. By sending sound waves from a number of points around a tree trunk to the same number of receiving points, the relative speed of the sound can be calculated, and a two-dimensional image of the cross-section of the tree, a tomogram, can be generated. Picus tomography and visual inspection were used to evaluate 27 cross-sections from 13 trees. The tomograms correlated closely with the visual assessment of decay. In 10 samples where no decay was present, Picus found no decay. In the remaining 17 samples, Picus detected less decay than was observed visually. Differences in most cases were small (average of 5% of total area). In terms of predicting the location of decay, on average 3% of the total area was a false positive (where the tomogram showed that decay was present but the cross-sectidn did not), and an average of 8% of the area was false negative (the cross-section showed decay that was not seen on the tomogram).