Lightning Protection in Trees

By Phil Berwick
Certified Arborist

During lightning storms we see only part of what is happening. We do not see with our eyes the thousands of ‘feelers’ all around us, that trees are sending up into the atmosphere, all attempting to ‘connect’ with the charges that are marching through the sky. Lightning strikes, one of the biggest threats to trees can be prevented. When spring and summer storms come rumbling from the west and lightning is blasting and bouncing down from one end of the horizon to the other, trees are getting shattered. The severity of the wounding varies depending on the species and the time of year. If a tree is struck in spring when it has much ‘energy’ and there is sufficient moisture in the ground, it has a better chance of recovery than a hardwood getting hammered in the heat of summer.

After a strike, there needs to be a waiting period of a couple weeks so that the portion of branches or limbs that are going to die are revealed. Then, after inspection by an arborist, if the tree has not been rendered hazardous, tree surgery can take place so that new (callous tissue) can begin to seal over the open wound.

If the wound is not readily evident, damaged sapwood goes unnoticed and decaying occurs over time under the bark. But even still, if discovered in time, tree surgery can open a wound up to the air and light and that wound can compartmentalize. The injury or wound will always be there, but the decay process will be slowed down.

A lightning protection system is a fail proof and worthwhile investment in especially a large irreplaceable tree. A system in a tree, if close to a house, can intercept lightning from striking the house as well. It will NOT attract lighting. The way lightning works is that negative charges build up low in a cloud and descend in steps as positive charges in the ground (‘feelers’) rise up the tree to meet it. A lightning protection system either intercepts the charge rising or the charge falling, and either an explosion happens a hundred or more feet above the tree, ends up at the ground rod, blown up outside the drip line and just below the ground.

Phil Berwick is an International Society of Arboriculture certified arborist and president of Living Tree Care, a tree pruning and preservation company. 314-961-8733 (tree).