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HOW TREES GET TWO OR MORE TRUNKS

| The Parklands
HOW TREES GET TWO OR MORE TRUNKS

In a forest, trees grow skyward, reaching for gaps of light in the canopy. Most tree species have a single “leader” that dominates by chemically suppressing side branches from bending upward and reaching higher. Conifers, such as pine and spruce are particularly good at this, but deciduous hardwoods do it also. It is this dominant leader that forms the trunk of the tree as it reaches ever skyward.

Consider the following scenarios: a beaver gnaws a young ash tree along a stream; a fire burns through a dry oak and hickory forest; a person cuts down a sugar maple for furniture. For many tree species this would spell the end—just the stump left to rot. However, the species listed in these examples, and many more, have the ability to resprout after such disturbance.

We call this adaptation “coppicing.” Anyone who has walked in a deciduous broadleaf woods has undoubtedly seen such trees. The photos here show coppiced trees, identifiable by their multiple trunks. Usually, two, but sometimes three or four or more, the new stems emerge from the edge of the stump. For all trees in our region, the living tissue of the tree occurs only in the outer half-inch or so, just below the bark. For a large tree, say 15 inches in diameter, numerous sprouts will shoot up around the edge of the stump. But only a few of these stems will survive.

Competition among the stems causes most to die. The final number of stems is determined by the diameter of the stump (the original trunk). Larger-diameter stumps will allow more sprouts than smaller diameter stumps. If a very small diameter tree, say 4 inches, is cut (or burned), the emerging stems will compete until just one stem is left and as it grows it will be impossible to tell it was a resprout.

The (new) coppiced stems of a tree will grow slower than the original tree. So while a single tree trunk 12 inches in diameter may be only 50 years old, a coppiced pair of trunks (such as those in the photo) may be 90 years or more. A coppiced tree with three trunks will grow more slowly than a two-trunk coppice tree. It is important to remember that the age of the stump (and therefore the whole tree) of a coppiced tree is often much older that the new sprouts, even if those sprouts are rather old. There are coppiced trees in The Parklands that can be confidently dated to over three hundred years—100 years for the new stems, and about 200 more years for the original tree.

Once you’ve found a coppiced tree you can look for more clues to determine the reason the original stump resprouted. Look for signs of fire in the form of basal scars and charcoal in the surrounding area. For logging, look for stumps, other coppiced trees of the same age, or slash piles (branches). Trees cut by beaver will occur very close to water. Flooding can also break trees, leaving a stump that might resprout.

In addition to the oaks, maples, and ash trees listed here, other deciduous hardwoods such as elm, hickory, cherry, and walnut also coppice. Cone-bearing trees, such as pines and cedar in our area, do not coppice.

With an understating and a search-image for coppiced trees, you will be able to read more deeply into the history of any tree as well as the forest and the processes that shape them. You will also be able to read deeper into the cultural landscape of the Parklands at Floyds Fork and beyond.

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