Building Around Trees

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Published on: May. 2, 1998

Last revision: Oct. 28, 2010

add to the cost of the project, but also will increase the chances of saving trees.

If branches or roots must be severed, cut them with care. Generally, remove entire limbs or branches at their origin. Use the 3-cut method to avoid stripping bark below the limb and to promote proper wound closure. Roots should be cleanly cut with a saw to maximize root regeneration and minimize chances for decay. Do not leave ragged ends. Dig carefully around large roots and allow them to pass through a trench. Place utility pipes or lines below the roots. Backfill trenches with loose soil placed on top.

Use wood chips as a protective blanket over the ground. A layer 4 inches or more deep will help prevent soil compaction, especially where construction work near trees cannot be avoided. Chips help protect soils anywhere on the site where new trees, shrubs or turf will be planted. Replenish chips as they deteriorate or wear thin.

Avoid post-construction activities which could further stress weakened trees. Refrain from adding topsoil around trees, installing underground irrigation pipes or using herbicides within tree rooting areas. Do not prune trees heavily, until normal growth rate returns.

Plan for new trees, shrubs, and ground covers, which are compatible with a wooded environment. Plant shade tolerant shrubs and small trees around saved trees to maintain a wooded appearance and help preserve the original root environment. Retain and expand the natural forest floor with bark mulch. Plant turfgrasses in more open, sunny areas where they will grow better and compete less with tree roots.

Building homes, offices or other buildings on wooded sites requires taking precautions to preserve the trees. Consider tree needs before construction begins. Find the best trees and concentrate on saving them. You may wish to protect small trees that have the potential to grow into shade trees.

During construction, protect as much undisturbed area around each tree as possible, remembering to take into account both the visible and the fragile underground parts of the trees. Finally, continue to care for your trees after construction is finished. Your efforts on behalf of the trees will make your dream home in a woodsy setting a reality.

How Much? How Close?

No two trees will react the same to disturbance because of differences in soil type, species, age and condition. Healthy trees generally can tolerate limited injury if they have a good growing environment for recuperation. The more severe the damage and adverse the growing conditions, the higher the risk.

How close to the tree can a tree's roots be cut?

An easily recognizable limit for root disturbances is the ground outside the branch spread, or dripline. Soil excavation inside this point may result in some root loss. But if damage is not done on all sides, a healthy tree can likely tolerate it. If roots are exposed, cut them off cleanly with a saw to promote better regrowth.

How much soil can be added over the roots?

Preferably, none. Added soil can suffocate roots from lack of oxygen. If soil must be added, use the thinnest possible layer of loose soil over the smallest possible area. Think in terms of inches rather than feet. Willows or cottonwoods can tolerate more fill, ashes less and white oaks little, if any, added soil.

How much soil can be removed around a tree?

Because many fine roots are at or near the surface, lowering the grade around trees should be avoided. A healthy tree may tolerate removal of a few inches of soil inside the dripline on one side.

How many limbs can be removed?

Because leaves manufacture food for a tree, removal of more than one fourth of the live branches threatens a tree. Weak trees, or trees with root damage, for example, may tolerate less. Removing dead limbs will not hurt a tree.

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