Which Trees Can Withstand Lightning?
It’s been a wet summer so far with heavy rain, flooding and furious thunderstorms. Critters like you and I have the option to seek shelter from the storm, but plants have no choice but to be battered by wind and rain. Lightning in particular is a serious threat to trees. A direct hit from a lightning bolt can cause a tree to explode, injuring anyone nearby and potentially starting a dangerous wildfire. Not all trees, however, are equally threatened by lightning. Some are even immune.
So if you’re caught in a thunderstorm and you have the erroneous idea to shelter under a tree, which tree is the least stupid choice to shelter under? Height is the first factor to consider. Taller trees are obviously better lightning rods; that’s a no-brainer. Next, consider the area of the tree. Wider trees that occupy more space are also more at risk. Location matters too. A tree on higher terrain is in more danger than one at or below sea level. Are there other trees around, and are they taller than your tree of choice?
Next, you’ll want to consider the tree’s explodability. Lightning strikes are very rapid, hot events. As lightning travels through a tree, it is met with resistance. This resistance generates heat that causes moisture in the trunk to rapidly expand. This can result in a catastrophic explosion. Trees that have denser wood and thicker trunks, however, are more likely to withstand these superheating events. Moisture is another factor. The more saturated a tree’s wood, the more conductive to electricity it becomes. The more conductive the wood is, the less resistance is generated, which means less heat and a reduced chance for an explosion.
The last factor to consider is species. Oaks, maples, poplars, ash, spruce, fir, pine and tulip-trees are common victims of lightning strikes. Birch, beech and horse-chestnut are less likely to be struck. The reason why seem to be bark texture. Trees like the beech tree have smooth bark that saturates quickly in the rain. Oaks and maples, on the other hand, have rough bark and do not saturate easily. Other trees, such as the holly tree, have distinctively shaped leaves that some people believe can act as mini-electricity conductors, protecting the tree from strikes . . . but good luck hiding under a holly tree, right? Those things are dense and pointy.
In summation, if caught in a thunderstorm, DO NOT SEEK SHELTER UNDER A TREE. That’s a terrible idea. You will have no where near enough time to consider tree species, local topography, bark texture, wood density and trunk diameter. Seek shelter and if none can be found, crouch in a ball on the ground with your ears covered or hide under a cliff or rocky outcropping.
Works Cited:
"Lightning: Lightning Safety Tips.” cdc.gov, 02 July 2021, https://www.cdc.gov/disasters/lightning/safetytips.html.
Mitolo, M., Pons, E., & Zizzo, G. (2021). A Methodology for Protection of Trees Against Lightning Strikes as a Measure to Prevent Fires and Loss of Human Life. IEEE Transactions on Industry Applications.
DeRosa, Ernest (1983). “Lightning and Trees.” Journal of Arbriculture. 9:2.
Brian Rutter, PhD, is the cofounder of Thing in a Pot Productions and a postdoctoral researcher in plant biology at Indiana University. Subscribe to our newsletter to receive our “Things About Things – Odd Facts About Plants” and video production tips in your inbox every month!