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Pay attention to tree roots in North Country spring

Posted 5/13/13

By PAUL HETZLER Even though they primarily consisted of snow, those April showers have indeed brought May flowers. And May flowers, as the saying goes, bring heavy equipment. If you’re not familiar …

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Pay attention to tree roots in North Country spring

Posted

By PAUL HETZLER

Even though they primarily consisted of snow, those April showers have indeed brought May flowers. And May flowers, as the saying goes, bring heavy equipment. If you’re not familiar with that saying, it could be because I just made it up. With the soil in our region drying out in a hurry, folks are breaking ground on those exciting plans they’ve been dreaming about over the winter, perhaps a solarium addition with built-in hot tub, or an exciting new leach field.

If you have trees in your yard, those projects, essential or just fun, can cause havoc with their root systems.

Tree roots extend -- or would very much like to extend -- about three times the branch length. And they’re surprisingly fragile: 90 percent are in the top ten inches of soil, 98 percent in the top 18 inches. Arborists refer to a root plate because in profile, a tree’s root system looks pretty flat. Think about the root plates you’ve seen on windthrown trees.

Keeping in mind the area and depth of a tree’s root zone, consider how your project may impact your trees. Some injuries are unavoidable -- the foundation has to go where it has to go. But you can look for ways to route underground utilities away from tree roots. And very importantly, Make sure trucks and other equipment access the site in a way that minimizes compaction. One pass with a cement truck can be equivalent to a trench!

Typically, construction damage takes three to five years to become evident, and symptoms can continue for five to ten years after that. Often the tree goes into a slow, prolonged decline over many years, and opportunistic agents like fungi or insects get the blame for the tree’s ultimate demise. A healthy tree responds to insect feeding by manufacturing chemicals known to scientists as “Bad Tasting Stuff” to repel them (bugs, not scientists). Healthy trees can wall off decay internally. Root-damaged trees are too weak to take these protective measures.

While reading this you may be wondering, what’s for supper, or perhaps, how do trees in those little concrete tree pits in the sidewalk survive? Since those trees were put there when young, they haven’t come to depend on a normal root system. They’ve adapted to available root space, and are technically “unhappy.” Trees which mature with ample root area and then get their roots cut or damaged to the size of tree pits are considered “dead.”

When driving over roots can’t be avoided, mulching the root zone, 4 to 6 inches deep can help reduce compaction. Fence off the root area so no one drives, parks or stages fill there. Telling contractors to be careful isn’t enough – they’re focused on their job, and it’s easy to have “construction site creep” (not referring to the any worker) encroach on the roots. Remember that an event which damages roots usually takes years to show symptoms.

Paul Hetzler is a forester and a horticulture and natural resources educator for Cornell Cooperative Extension of St. Lawrence County.