Detection of Electric Resistivity Tomography and Evaluation of the Sapwood-Heartwood Demarcation in Taiwan Red Cypress (Chamaecyparis formosensis) Trees

Abstract

The proportions of sapwood and heartwood of trees have significant impacts on the utilization of wood. Electric resistivity tomography (ERT) and corresponding electric resistance (ER) value maps were examined in Taiwan red cypress (Chamaecyparis formosensis) trees. The position of the sapwood-heartwood demarcation was measured on incremental cores from living trees and the corresponding ER of the sapwood-heartwood boundary was acquired from the ER map. A positive significant relationship was found between the maximum ER plus minimum ER values (ERmax + ERmin) and ER of the sapwood-heartwood demarcation from the tomographic data. Additionally, the position of the sapwood-heartwood demarcation was determined by corresponding ER, and the critical ER can be established by the value of (ERmax + ERmin) of the tomographic data. The experimental results from this study indicated that ERT technique can be used to determine the position of the sapwood-heartwood boundary and can serve as a technique to determine the healthy condition in the living trees of Taiwan red cypress.