Detection and delimitation of false heartwood in Populus using an electrical impedance method

Abstract

False heartwood is a major cause of value loss in wood industry. It is characterized by an irregular discoloration in the center of the stem, with high moisture content, limiting its industrial use and reducing the value of the forest. In Populus, this alteration is associated with the presence of an anaerobic bacterial complex consisting mainly of Erwinia sp., Methanobacterium sp. and Clostridium sp. A field study was conducted to estimate the size of this structure in standing trees, in order to detect the presence and delimit false heartwood in commercial plantations of two Populus hybrids. The hypothesis is that the proportion of false heartwood in the diameter of the living tree can be determined by delimiting the area with higher moisture content at the center of the stem, using an electrical impedance probe that penetrates the stem through a hole bored for this purpose. The electronic impedance technique determined the proportion of false heartwood with a standard error of estimation of 0.057 (R2 = 0.83) in comparison to the standard digital image processing method. This result was corroborated by determining highly significant statistical differences in the moisture content between the two areas via conventional oven drying. The study proved that false heartwood can be delimited without tree felling, making it feasible to estimate the magnitude of false heartwood in a forest for raw material planning purposes.