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

On 8/11/10 9:37 PM, Gary Brown wrote:
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

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.

--
David E. Ross
Climate: California Mediterranean
Sunset Zone: 21 -- interior Santa Monica Mountains with some ocean
influence (USDA 10a, very close to Sunset Zone 19)
Gardening diary at http://www.rossde.com/garden/diary

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