By Naturalist Eric D’Aleo
Last month, I was walking through the forest at Squam Lakes Natural Science Center near the Piper homestead on Mt. Fayal while leading a program when I came across an unexpected surprise: A large pine tree struck by lightning about 80 feet from the foundation of the old homestead. Ancient cultures long feared lightning believing it was a weapon of the gods. The Greeks thought Zeus hurled lightning, while the Vikings believed Thor produced lightning as his hammer struck an anvil while riding his chariot across the clouds. Indian tribes in North America believed lightning was due to the flashing feathers of a mystical bird whose flapping wings produced the sound of thunder. Why was this tree singled out for such wrath?
I had never come across a relatively recent lightening strike before and immediately began searching around the tree for clues and evidence to provide information about what had happened. By observing the color of the scar was blond and not gray, I knew lightning struck the tree within a year. Looking closer, I also saw some pitch had flowed out from the edges of the bark by the scar.
As I looked around, I noticed other equally tall pine trees were unscathed and wondered why lightning had struck this particular tree. There appears to be no pattern or “norm” that determines which trees lightning strikes. The height, geographic location, and species of tree, as well as proximity to building structures are factors affecting the likelihood of whether or not a tree is struck. Trees that stand-alone, rise above other trees, or are close to water are the most likely candidates. Some tree species are more likely to receive a lightning strike than other species, including oaks, elms, pines, spruce, poplars, maples, and ash, while beech, birch, and horse chestnut receive fewer strikes. Trees that are deep-rooted, decayed, and dying are more prone to being struck by lightning than shallow-rooted and healthy trees. A tree closer to a building is more likely to be hit than another tree ten feet further away, assuming that they are the same species and height.
Why does lightning strike a tree in the first place? Trees act as lightning rods because electricity seeks the path of least resistance when conducting electrical charges from the clouds to the ground. Although wood is a poor conductor, moisture from sap and water inside a tree conducts electricity much better than air, thereby completing the circuit from ground to sky. Large, tall trees that carry a high volume of water during the summer when electrical storms are common are most likely to be victims of a lightning hit.
As I headed back, down the slope to the Webster Building I didn’t think the tree would survive long due to the complications from the lightning strike and the competition and crowding of other healthy trees a few feet away. Who knew that even today the force of lightning could still fill us with as much awe and wonder as it did for ancient cultures?