Yes, trees can conduct electricity, but their ability to carry an electrical current is poor compared to common metal conductors. The mechanism of conduction is not the flow of electrons through solid wood but rather the movement of charged particles within the tree’s water content. This limited conductivity is tied to the biological processes that transport water and nutrients throughout the plant structure.
How Water and Ions Create Conductivity
The primary reason a living tree can conduct electricity is the presence of sap, which is a solution of water and dissolved minerals. Pure water is a weak conductor of electricity, but the tree’s sap is far from pure. It contains mineral salts and ions, such as potassium, calcium, and chloride, absorbed from the soil. These dissolved ions act as charge carriers, transforming the water into an electrolyte solution.
The vascular system of the tree, specifically the xylem and phloem tissues, transports this electrolyte solution throughout the trunk and branches. The overall electrical conductivity of the tree is directly proportional to the concentration of these mobile ions within the sap. This reliance on ionic movement means that the tree conducts electricity much less efficiently than materials like copper.
Quantifying Tree Electrical Resistance
Electrical resistance is a measure of a material’s opposition to the flow of electric current, and trees exhibit very high resistance. The resistance of wood is highly sensitive to its moisture content, which is the largest factor determining its ability to conduct. Dry wood, such as kiln-dried lumber, is an excellent electrical insulator, with a resistance that can exceed 100 trillion Ohms.
A living tree trunk contains a high percentage of moisture, often 50% or more. This high water content dramatically lowers the resistance, making the living wood significantly more conductive. For example, wood resistivity may drop from approximately 10 billion Ohms per centimeter at 12% moisture to about 10 million Ohms per centimeter at 20% moisture content. The resistance also varies based on the species’ density and the direction of the grain, as current flows more easily along the longitudinal path of the water-carrying cells.
Lightning and the Pathway of Energy
The most dramatic example of a tree conducting electricity occurs during a lightning strike, which involves immense voltage and current. When lightning strikes a tree, the current typically travels along the path of least resistance, which is often the outside of the trunk just beneath the bark. This outermost layer, the sapwood and cambium, contains the highest concentration of water and nutrients, making it the most conductive part of the tree.
The tree’s high electrical resistance causes the massive current to generate an extreme amount of heat almost instantaneously. This intense heat rapidly boils the sap into superheated steam, causing an explosive effect. Since the steam is trapped within the tree’s rigid cellular structure, the sudden expansion of the water vapor generates immense internal pressure.
This pressure is powerful enough to rupture the trunk, causing the bark to be stripped away or the wood to be splintered and blown apart. The pathway of the current is often visible as a spiral scar left by the explosion of tissue. Standing near a tree during a thunderstorm is extremely dangerous, not only due to the direct strike but also because of the side flash or ground current that can spread outward from the base of the struck tree.
Internal Electrical Signaling
Completely separate from the physical conduction of external current, trees use low-voltage electrical signals for internal communication. These biological signals, known as action potentials and variation potentials, are functionally analogous to nerve impulses in animals. They are transmitted through the plant’s living cells via a rapid, temporary exchange of ions, such as calcium, potassium, and chloride, across cell membranes.
These signals transmit information quickly over long distances within the plant, coordinating physiological responses to environmental cues. For instance, a tree might generate an electrical signal in response to a mechanical wound, a sudden temperature change, or an insect attack. The electrical impulse travels to other parts of the plant, triggering defense mechanisms or changes in gene expression.
These internal electrical events operate at very low voltages, often measured in millivolts, with some reported signals in young trees reaching up to 0.6 volts. This bioelectrical activity is an organized, controlled biological process designed for intercellular communication, distinct from the uncontrolled, high-current, and destructive external conduction that occurs during a lightning strike.