Detecting the presence of red heart in beech (Fagus sylvatica) using electrical voltage and resistance measurements

Abstract

a discoloration of their contents (Panshin and DeZeuw 1980). It is almost ubiquitous in older trees at felling age, but often affects younger specimens too. Healthy red heartwood is mostly considered a visual defect only, but, since beech is most often used in the furniture industry and interior design, red heart causes a major decrease in the perceived value, and leads to a serious drop in the retail price of beech wood (Molnar et al. 2001;Hapla and Ohnesorge 2005).There are several forms of red heart, all of which occur in beech wood. According to the characterisation by Sachsse (1991), they can be classified as red heartwood with round borders and a partly cloudy appearance on the cross-section, wounded heartwood with a small spatial extent, splashing heartwood (or dotty red heart) with jagged borders, and abnormal heartwood with black borders attacked by bacteria. In either case, the borders of red heart do not follow the annual ring boundaries. Figure 1 shows the first type, immediately after felling. In terms of its longitudinal expansion, it is most often spindle-like, but it may also be cone or upside-down cone shaped, or irregular. Red heart can also be classified as healthy or diseased, based on whether or not it has been attacked by fungi, and, as a result, they suffered some strength loss (Rumpf and Biro 2003;Wernsdörfer et al. 2005).Beech red heart has generated considerable research interest over the past decades. Wernsdörfer et al. (2005) provided a very detailed overview of the work done up to that point. Knoke (2002) provided a thorough review of the publications on heartwood formation, and concluded that reducing the amount of discolored timber is possible only based on information about the recent formation of red heartwood. He lamented the fact that non-destructive methods are not yet far enough advanced to provide information on early heartwood formation. AbstractRed heart is one of the most important visual defects in beech wood. Its detection is difficult, since its mechanical characteristics do not differ significantly from sound wood. However, its electric conductivity is different, which offers an opportunity for detecting beech red heart. Initial measurements using a 24-channel impedance tomograph were very efficient in detecting red heart due to its significantly lower electric resistance. High conductivity regions on the resistance map corresponded to the size and shape of the red heart. An 8-detector setup was investigated in a laboratory setting to establish the best electrode arrangement to develop a simple and reliable on-site detection method. On-site measurements, using only four electrodes, proved to be highly reliable to detect the presence of red heart in beech trees of 40-60 cm diameter. In the meantime, the method did not seem capable of determining the extent of red heart. The diameter of the tree was found to have very little effect on the measured voltage. Therefore, there is no need for diameter-correction in the examined diameter range.

Noninvasive Analysis of Tree Stems by Electrical Resistivity Tomography: Unraveling the Effects of Temperature, Water Status, and Electrode Installation

“…However, its application in plant sciences and especially tree physiology has not yet been sufficiently investigated and most studies focused on single species or even tree individuals (e.g. Bieker et al, 2010; Guyot et al, 2013; Martin and Günther, 2013; Goncz et al, 2018). A better knowledge of opportunities and limitations of the method would be a prerequisite to implement ER measurements for a wide spectrum of applications, ranging from tree assessment and determination of wood quality to the quantification of physiological processes in forests.…”

“…Pfautsch and Macfarlane, 2016). Furthermore, ER measurements were used to detect red heartwood formation in European beech (Goncz et al, 2018) and several other traits ranging from seasonal changes in cells to cold injury (see review of Gora and Yanoviak, 2015).…”

Dielectric and surface properties of wood modified with NaCl aqueous solutions and treated with FE-DBD atmospheric plasma

“…Knowledge of the dielectric properties of wood is essential for its efficient use in many engineering applications (Sahin and Ay 2004;Sahin Kol 2009), like for instance, the processes including application of electrical energy to heating, drying, and gluing of wood. Dielectric properties of wood are also important for diagnostic purposes, like for example when measuring the moisture content (MC) and thickness of timber, in the detection of defects, decay, discolorations, sapwood area, pasteurization of wood to eradicate exotic pest infestations in lumber, checking strength characteristics, or nondestructive estimation of surface roughness (Sikder et al 2009;Zhou et al 2013;Goncz et al 2018). Wood and its derivatives have also attracted much research interest as electrode materials for electrochemical energy storage devices, including sodium-ion batteries (Huang et al 2019).…”

Monitoring the Quality and Quantity of Beechwood from Tree to Sawmill Product

“…Several authors have addressed the problem of assessing the quality of produced assortments and the use of different standards (Marenče and Šega 2015, Piškur 2003, Piškur 2009, Piškur and Marenče 2011, Rantaša 2013, Rogelj 2012, Prka and Poršinsky 2009. The quality of assortments is determined on the basis of visual characteristics, which causes classification problems (sometimes subjective) that could be avoided by using modern techniques (Goncz et al 2018) such as measurement using a laser profiling system (Thomas and Bennett 2017) or high-speed computer tomography (Fredriksson 2016). Such studies are often limited to the quality of assortments and their quantities.…”