A bolt of lightning can destroy a tree in less than a second.  Trees can be blown apart, stripped of their bark, or set on fire by lightning strikes.  People or animals standing under a tree can be killed when lightning strikes the tree.

It has been observed over the years that some trees are more likely to be struck than others. Trees that stand alone in open landscapes, the tallest trees in an area, or trees standing on a hill have a higher probability of being struck by lightning.

Many circumstances warrant protecting a tree from lightning.  Historic trees, trees of great economic value, or large trees within 10 feet of a structure are all candidates for lightning protection.  Trees on a golf course or in a park where people seek refuge during a storm should be equipped with lightning protection systems.

A lightning protection system works by creating an alternate path (of lower resistance) for the electrical charge of a lightning strike to follow.

(From the International Society of Arboriculture)