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Winter’s barren woods conceal dynamic life force

By Ben Moyer for The 5 min read
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It’s all around us every day and right now it looks as bleak and barren as the recent full moon. For those reasons it’s easy to overlook the amazing truths about deciduous forest, the dominant living feature across this part of the planet–Pennsylvania, the Laurel Highlands and Fayette County included.

Most trees in deciduous forests–also known as broadleaf forest–lose their leaves in winter. That’s such a routine and seasonally expected event that we forget it’s a marvelous adaptation that enables trees to make efficient use of our warm, wet summers while also coping with snowy cold winters. Unlike birds, trees can’t migrate south. So, they had to come up with a way to endure winter’s ravages with their roots sunk into soil.

What to us is a beautiful green summer setting is to deciduous trees a powerfully productive food factory, and the basis for all other life. The broad but thin leaves allow maximum capture of solar rays and easy passage of gasses and water by a nearly weightless organ. This sunlight-capture is an efficient way of harnessing energy during the summer yet those same leafy assets are a liability in winter as our recent blizzard affirms. If leaves remained in place all year they would snag the weight of heavy snow and tear the tree apart. Likewise, the moisture within leaves would freeze, expand and rip the leaves themselves to shreds.

Deciduous forests even invest in their own future. The millions of leaves they drop every autumn decompose to enrich the soil in which new seedlings will root and grow.

Deciduous forests dominate the earth’s land masses at mid-latitudes in regions with moderate climate and abundant precipitation.

They occur–or did occur–in three principal zones around the globe–eastern North America, much of Europe, and eastern Asia, principally in China. The deciduous forests of eastern North America are the most extensive and complex in the entire world. Especially diverse are the woodlands of the southern Appalachians where around 90 broadleaf species can be counted.

Here in western Pennsylvania we can find somewhere around 40 species of native deciduous trees on any ambitious walk through the woods. Our principal broadleaf trees are about a half-dozen different oaks, a like number of maples, several hickories, plus our tulip poplar, black cherry, black birch, cucumber magnolia, American beech, basswood, black locust and many others encountered less frequently. Sadly, our once dominant broadleaf, the American chestnut, is now absent except for spindly shoots that still thrust up from surviving roots. The American chestnut succumbed to a fungal blight that “hitch-hiked” into North America on Asian chestnut trees imported for landscaping plantings early in the last century. The blight spread west and south from Long Island, New York and within about 30 years this enormously important tree was essentially extinct as a functioning forest component.

But there’s good news, too, about deciduous forest. Pennsylvania’s forests are primarily this type and the state boasts far more forest than it did 100 years ago. The most significant land use change across the eastern United States over the past half-century is the return of forest to previously cultivated farmland. In this returning forest oaks have taken over the role of the now-gone chestnut, dropping acorns for wildlife food and supplying the wood product needs of a nation and beyond. Today, this state is nearly 60 percent forested, just about the same proportion of forest cover that graces Fayette County. Some northern Pennsylvania counties such as Cameron, Warren and Potter exceed 90 percent forest cover.

Forests are personally important to outdoor enthusiasts. Around here, all our outdoor recreation–hunting, fishing, hiking, camping–in one way or another depends on deciduous forest. But woodlands aren’t just pretty to look at or a place to play outdoors. According to the U.S. Forest Service surveys, forests rank second behind agriculture alone in their total economic impact on our state’s economy. In Penn’s Woods nearly 75,000 jobs are linked in some way to forests and forest products.

Ever wonder how many leaves are on a typical tree like a maple or oak? I don’t know the answer and had never thought about it before beginning this column. Curious, I searched Internet sites that discussed the topic and found a number of creative ways people had devised to estimate this. The simplest and most interesting calculation was made by a Michigan family raking leaves. The kids asked their dad how many leaves were on the big tree in their yard. He didn’t know but they raked all the leaves into a neat pile, then pulled out a sample occupying roughly one cubic foot. They counted 50 leaves in their sample and then estimated the volume of their raked mound to arrive at somewhere between 40,000 and 60,000 leaves on their backyard tree. Their results compared favorably with more formally scientific methods I encountered on the web.

That solemn woodland across the road or behind the house may seem drab and lifeless at the moment. But it’s a dynamic community of efficiency and power. In a few months it will prove that once again, green, vibrant and restless on the wind.

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