Assessment of Landscape Tree Vigor Using Cambial Electrical Resistance

Abstract

ABSTRACT:There are various methods to evaluate tree vigor. Cambial electrical resistance represents tree vigor using the method of electrophysiological diagnosis. This study investigated the vigor of several tree species using Shigometer, and compared the differences among the species. The factors, such as foliation, trunk orientation and bark temperature, which affect electrical resistance were also investigated. The needle penetration into cambium was controlled to keep the depth consistent in order to minimize measurement error. Each of three trees were selected from Zelkova serrata, Ginkgo biloba, Metasequoia glyptostroboides, Pinus koraiensis, and Liriodendron tulipifera. The electrical resistances were measured at 60 and 120 cm height of the stem in 4 directions from March until May 2011. The soil conditions in surrounding areas and tree stress responses were also measured. The results were analyzed for the relationship between electrical resistance and the affecting factors. The electrical resistance showed a relatively higher level before foliation until mid-March. The values started to decline from April and recorded a minimal level on May 11. The changes of soil moisture, soil electric conductivity, and tree stress responses during the measurement period showed a similar trend to that of electrical resistance. The Pinus koraiensis, an evergreen conifer, showed few changes on the electrical resistance values during the measurement period. Zelkova serrata, Ginkgo biloba, and Metasequoia glyptostroboides showed the highest bark temperatures and lowest electrical resistances at their south-facing stem. Shigometer can provide measures simple to assess tree vigor in the fields, and to the management of trees.

Effect of transpiration on the physiological vitality of Zelkova serrata

“…Therefore, tree vitality assessments need to be based on quantitative and objective indicators, implying the need for researchers to identify simple and reliable indicators of tree vitality. A common method for tree vitality assessments is to measure the electrical resistance of cambium in the tree trunk using a Shigometer (Kim, Park, et al 2002;Chae et al 2012;Hwang and Kim 2016). Other methods include measuring the decay state of the tree trunk using sound waves (Song et al 2001;Kang et al 2014), assessing water stress using thermal imaging technology (Lee et al 2019), or measuring chlorophyll contents and photosynthesis in assimilation organs (Maxwell and Johnson 2000;Xu and Baldocchi 2003).…”