Building Around Trees

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Published on: May. 2, 1998

Last revision: Oct. 28, 2010

As aspiring homeowners contemplate a wooded lot, they usually imagine their dream home surrounded by healthy, vigorous trees that shade the summer sun and whisper with every breeze. After the home is built, however, the trees that made the location desirable often are either gone or dying, the victims of damaging construction work.

No matter how good our intentions, any construction work near trees will have some impact on them, because of the close relationship between a tree and the soil surrounding it. Trees are much more than the visible trunk, branches and leaves.

Their root systems, close to the surface and wide spreading, are easy to damage, even far from the trunk. Trees cannot be repaired or restored to their original condition after a construction project is finished. Therefore, it is better to prevent construction injuries to trees, rather than attempt to treat them after the fact.

How Trees Are Harmed by Construction

Trees can be harmed by construction work in several ways. Any break or tear in a tree's bark disrupts the flow of vital fluids and exposes wood to invasion by disease and decay microorganisms, which the tree must then expend energy to deal with. A trunk wound does not always cause corresponding loss of branches or foliage, so the consequences may not be fully apparent. But a large wound in the trunk of a tree is serious-it cannot be repaired and will almost certainly result in future decay and loss of stem strength.

Just as serious, although not as visible, is damage to the root system. Roots can be severed by excavation or smothered by earth fill or compacted soil.

Compaction, the loss of tiny air spaces within the soil from foot or vehicle traffic, is especially insidious. Not only will existing tree roots be affected, but future root growth also will be impaired. Symptoms of root damage from compaction include slow growth and branch dieback in the top of the tree. Soil compaction may kill trees, although no other damage occurs. New trees, shrubs or ground covers planted in the dense soil also will suffer.

Injuries are cumulative. Construction work will compound problems trees may have received from earlier drought, insects or other natural causes. This means that trees in poor condition before construction work are not as likely to tolerate further damage. It also means that trees that do not succumb to construction disturbance may be left weakened after the work is

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