Effects of brown-rot decay on the electrical resistance of wood and its mechanism

The objective of this study was to investigate the effect of decay on the electrical resistance (ER) of wood with a high moisture content (> 45%) and to try to determine the mechanism. Poplar wood blocks were exposed to a brown-rot decay fungus (Gloeophyllum trabeum (Pers. ex. Fr.) Murr.) for 2 to 12 weeks to obtain different degrees of decay. The ER values of the non decayed and decayed wood at various moisture contents were measured using a voltammetry method and were statistically analyzed. It was found that the ER of the wood blocks decreased with the fungus exposure time. Changes in the ER were quick during the first 2 weeks of exposure, which suggested that it can be used to assess early wood decay. The ER values of the decayed wood at different moisture contents were generally lower than that of the non decayed wood. A large difference (approximately 50 kΩ) was found between them when the wood moisture content was above 45%. Further analysis showed that this was because of the increase in conductive ions in the wood, rather than an increase in the moisture content. These results may be helpful to better detect the internal decay of trees using ER-based methods and could partly explain ER differences in decayed trees.