Damage to a Hemlock (Tsuga canadensis) tree from a lightning strike. Some trees escape completely unharmed by a direct hit, while others sustain moderate to heavy damage. Death of a tree is common in the latter instance. In this case, tree scarring occurred because 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 the 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 leaving a visible scar. Athol, MA.