Self‐ and Electrodic‐Potential Response to Hydrological and Biogeochemical Processes in the Soil‐Tree Continuum

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Abstract
Forest sustainability is regulated by the interplay between water and biochemical fluxes within the soil–tree continuum. However, capturing the daily to seasonal interplay of these ecohydrological and biological processes remains a major challenge. Instrumentation is typically compartmentalized—soil, roots, or trunk—hindering a unified understanding of the continuum. Here, we explore the potential of passive electrical methods to concurrently track water and biochemical fluxes across the soil–tree interface. Self and electrodic potential, depending on electrode type, respond to water flow, chemical and thermal diffusion, and redox gradients. We propose an electro‐hydro‐biogeochemical conceptual model linking electrical potential generation to tree transpiration, water uptake, hydraulic redistribution, and soil respiration. Using electrical potential monitored within the soil and across the soil‐root‐trunk continuum at the H.J. Andrews Experimental Forest, Oregon, USA, during summer 2023, we tested this model via daily correlations with sap flow, soil moisture, and carbon dioxide. Despite disturbances caused by wildfire smoke, electrical signals revealed strong correlations with daily patterns and event‐driven perturbations (e.g., wildfire smoke) of hydrological fluxes and biological activity in both trees and soil. Water fluxes emerge as the primary driver of self and electrodic potentials, with redox gradients also playing a significant role across the soil–tree continuum. This study presents a framework for using passive electrical methods as proxies for monitoring forest ecohydrological resilience.
Funding Information
  • U.S. Department of Energy (DE‐SC0023312)
  • National Science Foundation (EAR‐2121659)
  • National Science Foundation (EAR‐2305616)
  • National Science Foundation (GRFP‐2234662)
  • National Science Foundation (LTER8 DEB‐2025755)

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