Cutting surface roots of river birch
What would happen if I cut the surface roots of a 30 to 35 foot mature (has been pruned) river birch? Our lawn is very small - approx. 24' x 35'. The tree is approx. 20 feet from the house, 8 feet from the concrete drive, 8 feet from the front concrete sidewalk. The roots are interfering with ryerson edging around beds and the small grass surface.
I have to first caution you that cutting roots you run the risk of making the tree unstable and in a big wind event the tree is likely to fall over if it has not had enough time to re-anchor itself. You are also removing the tree's ability to seek out nutrients and water to support its growth. This job will result in tree stress that may have an impact on the overall health of the tree and make it more susceptible to insect and disease infestation.
Roots should be cut in the fall. Obviously you want to cut as far away from the trunk as possible.
Make clean cuts by removing soil away from the root only where you want to cut so that a cut can be made without disturbing the rest of the roots. Leave the roots in place. Don't lift the root to be cut before cutting. After cutting, allow the cut end of the root to dry out for a few hours to a half day before covering over again with soil. I do not believe that you need to remove the cut root from the soil- It will rot away. Pulling it up will create unnecessary root disturbance.
Try to remove as little as possible to accomplish your goals. Don't remove more than 25% in any one year.
After cutting, consider laying down a vertical barrier to prevent continued root growth.
If tree stability is a worry ( if you in a windy area or with a very water table) you might consider total removal and replacement with a less shallowly rooted tree.