white pine roots

[chapmac2]

I have a couple of 50 - 60-ft white pines that are about 6 feet from a stone wall I'm preparing to re-build.  I'm excavating for a footing and avoided the roots near surface there.  I want to make the footing same level, but fear cutting these roots, some of which are 2-3 inches around.

Q:  Am I risking these trees if I cut these surface roots?  I'll only go down a foot or so.  The wall is straight and just one side of the trees.  When I'm done I'll plant more of same trees along the wall, but maybe a bit further away from wall!  The wall has to stay where it is.

A forester/tree supplier told me to ask a "certified tree expert."
Thanks,
 Reed

[Larry Tucei]

Reed,  I'm not an arborist but I do know a tree can recover from limited root cutting. How much cutting would be the question? It you are just cutting roots on one side of the trees they may be fine. My concern would be what would the reaction from chemicals in the concrete be to the trees. Lets see what some of our resident experts have to say on this.   Larry

[chapmac2]

Thanks Larry.  It'll be a footing of "blend," mixed gravel and fine, crushed rock.  The wall will be mostly just the local stone, but some hidden mortar.
 I appreciate your taking the time to write me an answer.
 My forester/supplier friend suggested if I go ahead and cut those roots, to be sure I use tree spikes (fertilizer) and water frequently to help them recover.
 Best,
 Reed

[AndrewJoslin]

White pine have shallow horizontal root systems, some large structural roots (holding up the tree) are often very close to the surface so it's very problematic to cut those. Just a heads up on stone walls over the root zones of larger trees: Whenever there are strong winds the movement of the trunk is going to cause the root plate to move up and done slightly. If the wind is strong enough combined with rain to soften the ground the stone wall will be disturbed. I know of a situation where a dry stone wall has to be re-stacked every year where it's over the root plate of an 80 foot blue spruce. The tree is a big lever and it just knocks the wall down when the gusts are strong and sustained with rainy weather. You might consider building the portion of the wall over the white pine root zones as dry walls (no mortar or dug footing). Depending on weather you may only have to re-stack a few stones every few years. Your trees will be happy and structurally sound, and you can keep the wall looking nice with a little maintenance here and there.
-AJ
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[chapmac2]

Thanks Andrew.  Much appreciated.  I've also gotten so feedback from Rutgers Master Gardener Helpline.  I think it'll be no cutting.  I'll work around the big roots.  Your advice is very helpful.  Nice tip about the dry wall.
 Best,  Reed