Conductivity Analysis and Thermoelectric Behaviour of Larch Standing Trees Under Lightning Currents: Role of Moisture Distribution and Carrier Motion

Abstract

ABSTRACT The direct effects of lightning strikes on forest combustibles form the foundation for predicting lightning‐induced forest fires. Accurate assessment of lightning impact is hindered by limited knowledge of the conduction characteristics of standing larch trees. This paper introduces a method to measure both local and overall conductivity of trees in the Daxing’an Mountains, China, considering factors such as internal structure, moisture content, and voltage amplitude. A thermoelectric coupling simulation model was developed based on wood’s partial conductivity to analyse the electric‐thermal field distribution within standing trees under lightning impulses. Results reveal that carrier motion in wood is primarily influenced by electric field strength, cell membrane barriers, and polar group density. Conductivity increases with moisture content until saturation. Wood structure and cell arrangement also affect conductivity, with partial conductivity increasing from the heartwood to the bark. Additionally, axial conductivity is significantly higher than radial conductivity. Under lightning impulses, the thermoelectric behaviour of trees is influenced by moisture distribution, with areas of elevated current density and temperature shifting from bark to heartwood as moisture decreases. These findings provide a basis for understanding the thermoelectric damage and ignition mechanisms of trees in lightning‐induced forest fires.