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PROTECT YOUR TREES AGAINST CONSTRUCTION DAMAGE

You're building a new house or putting a major addition on your existing home and you've asked the builder to preserve a big white oak that you like. That's a smart request because good trees add monetary value and visual interest to property.

"Trees break up the architecture of a home and soften the hardscape," says Andrew Koenig, an arborist with Bartlett Tree Experts in Yorktown, Va. The company has offices throughout the country www.bartlett.com).

"It's important to take care of them any time there's heavy construction equipment in your yard."

The digging and trenching that's done during construction and installing underground utilities often severs portions of the roots of trees in the immediate area. Even installing an underground irrigation system can cause damage because 90 percent of a tree's root system lives in the top 6 to 12 inches of soil. Cutting one major root can cause the loss of 5 to 20 percent of the root system, according to the International Society of Arboriculture.

In addition, heavy construction equipment running around the yard compacts soil around tree roots and prevents them from getting the oxygen they need.

Finally, when construction is done and the yard is graded and landscaped, extra soil is often piled over tree roots, causing them to smother. As little as 2 to 6 inches of additional soil over roots can be detrimental to their health. You also want to avoid this type of soil buildup when you create planting areas around and under trees.

There are steps you can take to protect that oak, or any other trees, against construction damage, says Koenig and other arborists. Most importantly, install protective barriers around each tree's root system. Generally, allow one foot of space from the trunk for each inch of trunk diameter, according to the society of arboriculture. Keep that area clear of building materials, waste and excess soil, and instruct that no digging or trenching or other soil disturbance is allowed in that fenced area.

"Orange fencing is the most visible barrier," says Koenig. "It is an easy solution to say "do not enter.' "

In addition, you should evaluate the tree's branch structure to see if lower limbs need to be pruned to allow access for construction equipment.

After your house or addition is complete, trees in the construction area should be fertilized, mulched and any bark wounds properly shaped. And keep them watered when there is inadequate rainfall. You also need to check for insect damage because pests such as borers are inclined to attack stressed trees, especially if no earlier preventative treatments were done.

If you do all this and you still worry the trees suffered construction damage, there is a new technique called "root invigoration" that can help keep them healthy.

Because root invigoration is such a new process, results are just beginning to get noticed.

Last year, York County hired Bartlett to use the process on 11 American hornbeams at the county courthouse and a spruce at York Hall, says Joanne Chapman, landscape maintenance coordinator for the county in Virginia. So far, the stressed hornbeams look better structurally, and the spruce is retaining better needle coverage.

Tree tips

Early spring and fall are the ideal times to plant new trees. These cool seasons allow new roots to establish themselves before hot, dry weather arrives.

Before digging, contact your local utility company to get your underground utility lines marked; usually the service is free.

Here are some tree-planting guidelines from the International Society of Arboriculture at www.treesaregood.com" target = "NEW"> www.treesaregood.com:

Dig a wide, shallow hole three times as wide as the root ball but only as deep as the ball. The majority of tree roots grow in the top 6 to 12 inches of the soil. If planted too deeply, roots have difficulty developing, due to a lack of oxygen.

Identify the trunk flare, the spot where the roots spread at the base of the tree. This point should be partially visible after the tree has been planted.

Straighten the tree in the hold before you fill with soil. Fill the hole about one-third full and gently pack soil around the base of the root ball. Cut and remove any burlap, string or wire around the root ball, if it's balled and burlapped.

Continue filling the hole, firmly packing soil to eliminate air pockets that can cause the roots to dry out. To avoid this problem, add the soil a few inches at a time and settle with water. No fertilizer is needed.

Mulch around the tree to help retain moisture, keep out weeds and protect the trunk from mechanical damage from lawn mowers and weed eaters.

For more tips on selecting, planting and caring for trees, visit the National Arbor Day Foundation at www.arborday.org. To find a certified arborist, visit the society of arboriculture at www.treesaregood.com

Visit Bartlett Tree Experts, which has sites throughout the country, at www.bartlett.com.