Stately ash tree was standing there minding its own business when lightning struck

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If an ash tree gets struck by lightning in the woods and nobody hears it, does it make a sound?

Hank and I wandered through one of our favorite old woodlands last weekend and stopped with a sharp, audible, “What in the world!?!”

Then we noticed all of the ferns in a circle 20 feet across had died suddenly and crumpled in place, charred, and a trail of dead undergrowth snaking off to the east where no path had been before.

“Lightning!” my husband diagnosed. We both studied the big old ash at the center of that crispy circle. Sure enough, two great vertical splits cleaved the trunk’s bark up to a height of about 8 feet. Through the gashes, freshly exposed wood gleamed in the sunshine.

Our eyes followed the tree trunk up where there seemed to be no damage, up to where the main branches angled off. At about 60 feet up on one main limb, some bark was blasted away, exposing more tender, pale wood. Way up another 30 feet, the ash tree reached out above the forest canopy. “There!” I said pointing to an area of splintered branches, twisted twigs and charred foliage. “That’s where it hit!”

I stood still, trying to imagine the sound of that tree being blown apart. In one instant, thousands of volts of electricity had rammed through 100 feet of moist, living tissue. It would have been thrilling, I thought, then realized that, had I been standing this close to the strike, I might well have lost my hearing or had blunt-force trauma from the shock waves slamming outward. This sort of concussive injury causes traumatic brain injury. Suddenly, the idea didn’t seem so exciting at all.

The answering electrical spasm from the moist soil around the tree could have just jolted me off the ground or done far worse. That is the phenomenon that can kill a whole herd of cows, instead of just the one or two directly hit in a field.

Trees like this ash spend their lives struggling to get their heads above all their fellows. Once out in the sunshine, these solar-powered wonders grow even faster, shading – and stunting – surrounding trees. The tallest tree wins, but it also attracts lightning.

That’s why trees are frequent conductors of lightning to the ground. Since sap is a relatively poor conductor, its electrical resistance causes it to be heated explosively into steam, which blows off the bark outside the lightning’s path. The boiling steam vents wildly, adding its scream to the ear-shattering sound of the exploding tree.

In years to come, this ash tree’s bark may overgrow the damaged area and may cover it completely, leaving only a vertical scar. If the damage inside is severe, the tree may not be able to recover, and decay will set in, eventually killing the tree. We have walked this road for years and intend to stroll it together for many more. We can follow the ash’s fate. In the case of tall, tall trees, lightning does often strike twice, so the scene may repeat itself. A healthy tree can even survive this awful fate.

But ash face another, far more deadly danger, swift, silent and fatal. This one is a pretty little beetle, the emerald ash borer. The insect stowed away on a shipment of wood from China. It has no natural predators in the United States, so its population has exploded here. One borer lays scores of eggs into the bark of an ash tree. Tiny grubs hatch, burrowing around and chewing through thousands of the blood-vessel-like tubes that transport sap just under the bark. Then the grubs change into a pupa stage while they grow beetle parts: legs, wings, iridescent green wing covers, antenna and more. Finally they emerge and chew their way out through the bark, leaving D-shaped holes. Now they go about mating and lay thousands more eggs on the tree.

This alien species can kill a tree in one or two seasons. Compare that to a massive lightning strike. Since there is nothing here that can kill the beetles, it seems there is nothing we can do to save our ash trees from the fate of our elm trees. That beautiful species was wiped out all across the country when another alien, the Dutch elm disease, reached the United States.

How can we fight these alien invaders? All we can do is try to slow the spread of emerald ash borers is to make it against the law to carry firewood across state lines. The grubs and pupa may travel hidden under elm bark as far and as fast as cars and trucks can carry them. On their own, the little buggers can only fly so far to find new, uninfected ash trees to infect, and they will. Unless scientists find a solution, all the ash trees in the forests will fall, whether we hear them or not.

Guilford naturalist Kathleen Kudlinski is the author of “Boy, Were We Wrong About Dinosaurs,” Dutton, grades 2-5, as well as 40 other children’s books. Contact her at kathkud@aol.com or c/o the Register. Drop by www.kathleenkudlinski.com right now for a quick, daily nature note at my POND SIDE PLACE blog/website, or visit my writer’s group at http://writeupouralley.com/, or watch my “Horse Indian Wolf” book video at http://www.youtube.com/watch?v=psR4UGFSVe8.