Since You Asked...The Davey Tree Expert Company About Surface Roots

My Japanese laceleaf maple tree has surface roots that just dare me to trip over them or clip them with the lawn mower. And my big American elm has a girdling root. You might have the same problems and wonder, as I have many times, whether exposed or girdling roots pose a serious threat to your valuable trees.

So I contacted Nicole Wisniewski at The Davey Tree Expert Company. Nicole consulted with company arborists, and now we can clear the air.

The Davey Tree Expert Company

Q. What are the common causes of exposed tree roots?

A. There are several reasons for surface tree roots. Some species, like maples, are simply more prone to this than others. Older trees also tend to show more roots than younger trees. But this often happens when there's little or poor soil in the area, poor drainage, or as a result of poor planting practices.

Q. Do exposed roots present special dangers to the tree?

A. While surface roots may be unsightly, they rarely pose a threat to the tree.

Q. What should be done about them?

A. There's usually little you can do about exposed tree roots. Arborists don't advise trying to prune or cut away any of these roots, to avoid damaging the tree itself.

But if the tree is planted too close to a home or other structure, or if roots are causing damage to a structure, you may want to consider having the tree removed or transplanted to prevent potential or further damage. Professional arborists can assist in this.

Adding soil to the exposed root area may help cover exposed tree roots, but this might be short term. As the tree grows, so will the roots, and it's only a matter of time before they resurface. Also, soil fill over a root system will reduce oxygen availability [to roots].

Q. What should be done about exposed roots that have been damaged by mowers or foot traffic?

A. A professional arborist can assess the tree to determine if there has been significant damage, and help root-prune to preserve the tree and reduce tripping hazards.

Q. What should be done about "root strangling" (roots growing atop other exposed roots)?

Girdling root on an elm.

A. Girdling roots are roots that grow around other roots or trunks, putting pressure on them—thus, "choking" and compressing the water and nutrient-conductive tissues.

Recommendations vary with respect to the value and practicality of removing girdling roots. For instance, girdling roots may be supplying a significant part of the tree with nutrients and water, and removal of these roots may further stress the tree.

A professional arborist can assess the status, and provide solutions, using proper techniques to remove some roots if necessary. When dealing with girdling roots, sooner is better [than later] to prolong the life of the tree.