<b>Electrophysiological activity in</b> <i> <b>Pinus halepensis</b> </i> <b>: a consistent electrical potential relationship between woody and needle tissues</b>

This study investigates the electrophysiological activity of <i>Pinus halepensis</i> to determine whether electrical responses differ among tree organs. Weekly bioelectric voltage measurements were conducted over one year in fifteen trees located in Gátova (Valencia, Spain), comparing electrical potentials between woody (trunk and twigs) and fine tissues (needles). Stainless-steel and platinum electrodes were used to record voltage signals, which were analyzed through linear regression and mixed-effects models. Results showed that voltages in the trunk were consistently higher than in the needles, yet both exhibited synchronized seasonal dynamics driven by shared physiological and environmental factors. The needle-to-trunk voltage ratio remained stable at approximately 60%, except during a summer drought, indicating coherent electrical coupling across organs. A strong linear relationship (R² = 0.98) confirmed that trunk signals serve as reliable surrogates for needle potentials. Organ-level analysis revealed a clear voltage hierarchy (trunk > twig > needle), largely attributable to anatomical and impedance differences. These findings identify the trunk as the optimal electrode placement site, enabling robust, non-destructive, and continuous measurements that can support future applications in wildfire risk assessment and forest monitoring.