Lightning can have a variety of effects on a tree. What exactly happens depends upon several factors including what kind of tree it is how much moisture it contains and the overall health of the tree at the time of the strike and the intensity of the lightning strike.
If the outer layer of bark is soaked from excessive rainfall the lightning may travel along the outside of the tree to the ground resulting in little damage. At other times though intense lightning bolts may split trees in two and cause them to burst into flame from the inside out.
In most trees the area just under the bark layer contains moisture in the form of sap and water. Since water is a better electrical conductor than wood lightning striking a tree tends to travel just underneath the bark. The explosive expansion of the lightning’s return stroke will literally blast off the bark and sometimes some of the wood along the length of the lightning channel. The result is a visible scar along the trunk of the tree.
Often the core of the lightning channel will carve a half-inch wide groove in the wood in the middle of the scar. If the lightning flash consisted of more than one return stroke there may be two or more of these grooves in the scar.
A tree that has been hit by lightning may survive for many years even with extensive injuries. Lightning-damaged trees however will often be more susceptible to other types of damage such as that from insects disease and decay.
This is an example of a “scarred” tree. At the approximate age of 64 this tree was struck by lightning. This tree continued to survive with the lightning “scar” for approximately 51 years. Notice how the “scarred” side grew. Tree age – 115
This “slice” of the tree was donated to your Museum. The tree was harvested in the Moyie Springs area.