Photo: Lightning Scar on Ponderosa Pine Tree
From the files of Donald R. Kirk:
Part 2. Lightning Scars
In my previous blog I told of a horrendous storm in the night while camped in the Warner Mountains. Next morning we find a tree with a fresh lightning scar that runs from crown to ground. This can occur because the bark of trees has an inner layer that conducts water from the ground to the leaves or needles. Since water is a much better conductor of electricity than air, when lightning hits a tree, this layer offers a good path to the ground.
Not all lightning scars go straight down the tree. On a hike in the Snake Range of Nevada, I found a large juniper that had a scar spiraling three times around the tree from top to bottom. The juniper remained healthy because most of its water-conducting tissue also spiraled around the tree from the roots to the crown.
Trees may be severely damaged by lightning. I once saw a tall cherry tree shattered by a powerful strike. Split wood, broken branches, leaves, and bark were spread on the ground. All that remained was a splintered stump.
What kind of tree is struck the most? I’ve heard it said that birch and aspen trees are never hit by lightning. I don’t know about birch trees because I have never lived where they grow, but I have found lightning scars on aspen throughout the West. One writer that I read regularly believes oak trees are struck the most. But, he lives in an oak forest located in a thunderstorm prone area. I suspect it’s the tallest trees that are struck the most.
The canyon floor is wide here, this ponderosa pine is well over 100 feet tall, and there are no nearby trees even half as high. Even so, this tree has been growing here for decades and shows only one scar. Many pines on the high ridge at the head of the canyon bear multiple lightning scars, due to the increased exposure.
Our kids want to know if the tree will die. I say it is very unlikely. While the scar has left the tree open to insect damage, this huge pine is healthy. Oozing sap is already protecting the wound. Besides, the exposed wood is a strip only three inches wide. I have seen lightning scars a foot across, and the tree still survived.
Seed cones from years past litter the ground around the tree. Ponderosa cones are quite prickly to pick up because the sharp claws on the cone scales point outward. I gingerly pick up a cone and stare at it in surprise. No prickles! The scale claws point inward. I inspect a dozen cones from this tree. On all of them the prickles point inward!
I know that Jeffrey pine cones are not prickly because the scale claws point inward, and Jeffrey cones are larger than these, five to ten inches long. Ponderosa cones are only three to five inches long and are very prickly. Quickly, I inspect the cones of several nearby ponderosas. They are the right size, but none are prickly. Suddenly, I recognize this tree…to be continued.