Lightning is the greatest natural destroyer of property, including thousands of trees that are struck every year. Lightning strikes can damage the trees, as well as pose additional risks if the trees are located near homes or other property.
Lightning protection systems are installed in susceptible (or lightning-struck trees) to reduce the risks and dangers associated with growth and stability issues. The objective of a tree lightning protection system is to provide a preferred path to ground for the electrical charge; protected trees are not a safe haven from lightning strikes, they simply control the flow of the charge.
Although some species of trees are more susceptible to lightning than others, the largest determining factors are location and size. Trees more susceptible to strikes include:
- Trees close to water
- Trees on hilltops or on slopes facing the prevailing direction for approaching storms
- The tallest tree in a group
- Trees growing in the open or small groups
- Trees that border woods or line a street
- Trees in local areas or geographic regions with a history of lightning strikes
So how do you decide which trees should be protected from lightning strikes? If your trees meet any of the following criteria, it may be worthwhile to consider installing a lightning protection system:
- Trees with trunks within 10 feet of a structure, or with branches that extend to a height above the structure. This is because of the danger of side flash (when lightning strikes something close to where you are standing and then jumps from that to you), fire, or superheating of the moisture in the tree, which could result in the splintering of the tree.
- Trees of historical interest
- Trees of unusual value
- Shade trees within 10 feet of a building; trees with branches overhanging building
- Tall trees in recreational or park areas
- Trees that are more likely to be struck by lightning due to their location, such as isolated trees on a hill, in a golf course, or in a pasture, etc.
An arborist or professional tree care company can inspect your potentially susceptible tree to determine whether it needs a lightning support system, and can suggest/mount the proper installation method, if necessary. Lightning protection systems need to be inspected on occasion, to ensure that the system remains in good operating condition.
Use TCIA’s search tool to hire a professional arborist or tree care company.
If it’s determined that the tree is not at high risk of failure and does not need a lightning protection system, appropriate treatments may consist of water management, removal of damaged bark, limiting bark desiccation, pruning, fertilization, pest monitoring and pest management. An arborist or professional tree care company will be able to advise on proper maintenance methods.
Get a quick overview of what the national standards for tree lighting protection are and how they are used.
Watch A300 Lightning Protection for Trees (with Steve Nagy from Davey Tree) on Youtube