Tree Roots

[Gary Brown]

Hi,

I am doing some landscaping and encountering a lot of tree roots. I am concerned about harming trees by cutting the roots. My main concern is a 20 ft Japanese maple where the terracing starts. The roots behind and to the side of the tree won't be affected. But there is an area about six feet in front of the tree and two feet down where I'm seeing some large roots. I can't be sure which tree they are from (the area is surrounded by oaks only one of which is close). What need I do about those roots?

Thanks, Gary

[David E. Ross]

If these are mature trees -- and I would certainly think a 20-foot Japanese maple is mature -- I would consult with an aborist.

In some cases, it is indeed possible to cut as much as a third (or even more) of the major roots near the surface without injuring the tree. This depends on the variety of the tree, whether there are also deep roots, the soil condition, and what else you are planning to do. Sometimes, merely terracing near a tree is bad; sometimes the entire tree can be dug up (cutting many, many roots) and moved.

[Una]

Ditto the advice to consult a qualified arborist, meaning an arborist who has a professional certification.

Does the project require cutting these roots? Likely they belong to the maple.

Cutting a tree's roots inside its drip zone stresses the tree. My street was trenched a few years ago, including a perpendicular trench from the street to each house. Trees whose drip zones were across the trenches suffered extreme stress. To compensate for lost roots, some residents had the tree crowns cut back and I had a large maple treated with a hormone to suppress above ground growth. That maple lost 50% of its feeder roots and looked like it would not survive the injury. All these trees are doing well now. Some residents did nothing as far as I know and their trees are okay. Some residents did nothing and their trees are dead.

Una