What happens when a root is cut?
Tree roots should be cut using the same procedures that are used for cutting branches. Like branches all cuts should be clean straight cuts. But there is one big difference between branches and roots. That difference is that roots can grow roots from the end of a cut root.
Trees do not repair damage to roots. They respond to damage by either trying to wall off the damaged site. Or they grow new roots at the damaged site. A root is cut like the one below. The cut is made to remove roots from a plant bed. The cut is made by a sharp shovel resulting in a perfect clean, straight cut. The plant bed has several such roots that were going into the plant bed and were cut.
Now the tree responds to the damage. Like a Hydra in mythology, where once there was one root, now there will be many roots.
For many new roots can grow from the end of a cut root. They will all be growing in the direction where the root was growing. As the roots grow one will over time become the main root. But several side roots will also be expanding. The plant bed that the single roots was removed from will now provide a great environment for these several new roots to expand into.
This shows why when you cut roots out of a plant bed they can grow back into the plant bed and take over.
