Non-destructive testing of black afara (Terminalia ivorensis A. Chev.) tropical trees using the electrical resistivity method

Document Type

Article

Publication Date

5-19-2026

Department

College of Forest Resources and Environmental Science

Abstract

Non-destructive testing (NDT) of trees is crucial for the effective management and health assessment of arboreal plantations. Unlike traditional destructive sampling, NDT evaluates the structural integrity and health of trees without damaging their biological functions or aesthetic value. The four-point electrical resistivity (ER) method, alongside electrical resistance tomography (ERT), was applied for the early detection of wood decay and hollows in black afara (Terminalia ivorensis A. Chev.) tropical trees. Fifty standing specimens of black afara trees (T1 to T50) were selected for this study with stem diameters at breast height ranging from 57 to 197 cm. The electrical resistivities of the samples were measured using the four-point ER method. ERT tomograms of four selected trees (T22, T29, T30, and T37) with resistivity anomalies, suggesting internal defects, were generated to validate the ER measurements. The influence of internal defects on the ER of healthy specimens was experimentally examined under controlled conditions. Field data showed a consistent increase in ER from sapwood to heartwood, varying from 75 Ωm to 520 Ωm, in the selected healthy trees. Conversely, unhealthy specimens exhibited irregular resistivity patterns, with decayed trees displaying resistivity values four times lower than those of healthy trees and hollowed trees possessing resistivity values three times higher than those of sound trees. ERT tomograms confirmed the results of the four-point ER technique. The outcome of this research would facilitate efficient management practices and risk evaluation of tree plantations in both forest and urban areas.

Publication Title

New Forests

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