ICE STORMS PROVIDE INTERESTING ENVIRONMENTAL PERSPECTIVES

by Whit Gibbons

February 1, 2004

We all know that adversity should be viewed as opportunity. Thus, as I sat last night warmed only by burning logs in the fireplace and surrounded by a dozen candles for light, I knew that the ice storm that had eliminated all electrical power for the last three days must be an opportunity. Living in the dark and cold surely should provide ecological perspectives that are not readily apparent when the furnace is blowing warm air, lights are blazing, and hot coffee is ready minutes after you turn the pot on in the morning.

Actually, "storm" may be a bit of an overstatement, because we usually associate wind with a storm, and an ice storm can be as gentle as a light, misty rain. The only catch is that while it is raining, the temperature hovers at or slightly below the freezing mark. The precipitation is not snow but instead steady light rain that coats limbs, leaves, and power lines, and then freezes before reaching the ground. The buildup is gradual. The effects can be devastating for those of us dependent on electricity, and on roads free of ice and fallen trees.

Our pioneering ancestors would be wondering what the problem is. Doesn't it always get dark at night and cold in the winter? Someone who lived in a cave or teepee would assume you just went to bed earlier on a winter night as always and got up later the next morning. A rainy night in the 1800s that left trees drooping from the weight of ice was no different from any other night. You went into your candle-lit, stove-warmed house when it got dark. Getting your car out of the driveway on a sheet of ice was not an issue.

The aftermath of an ice rain can be an absolutely beautiful sight with an awesome sound track, another form of Nature's no-charge entertainment. I stood on the back porch absolutely enthralled with the gunfire popping of trees, as limbs and even foot-diameter trunks broke like kindling. Northerners may have impressive blizzards, but a southern ice storm is not to be trifled with by man or beast.

From an ecological perspective, ice storms can be instructive about how plants and animals can be well adapted for one type of weather but be at the mercy of the elements for another. Evergreen, or nondeciduous, trees such as pines, cherry laurel, and live oaks do well in a cold sunny winter because they continue to photosynthesize, producing sugars for nourishment. But seeing broken, twisted evergreen shrubs and trees across the landscape brings to mind the point that an advantage in one situation can be a cost in another.

Evergreen species vary greatly. Longleaf and loblolly pines are better adapted to cold conditions than the more southerly slash pines. And although a longleaf or loblolly may forfeit a few limbs, many slash pines are unlikely to make it through a first-class ice storm. Laden with a sheet of ice, their more brittle limbs break, and with their more shallow root systems even a slight wind will make the entire tree topple over. Slash pines do best in Florida and other points south where ice storms are unlikely to occur.

Despite the perils of being evergreen, magnolia trees with their big leaves seem less affected by a steady drizzle of freezing rain that coats every living and nonliving thing in the region. Native magnolias may fare better because of an adaptation less prevalent in many other nondeciduous trees. Magnolias have a heavy waxy coating on the leaf surface that sheds water like a duck's back. In addition, magnolias have drip tips at the ends of the leaves, which point directly downward, so that water hitting the leaf collects in the furrow down the middle and is immediately escorted to the ground. Thus the rain usually does not stay on a magnolia leaf long enough to freeze, although natural pruning will still take its toll of magnolias with weakened or diseased limbs.

Many more biological and ecological issues remain to be contemplated about how nature's creatures, including us, respond to ice storms. But I think I'll save those for tonight, while I am under the covers during 12 hours of dark and cold.



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