How much of the tree roots can be disturbed before the tree will decline?
Tree roots can normally grow to that of two and one-half times the height of the tree. The area under the canopy of the tree is commonly referred to as the critical root zone. The amount of critical root zone lost is directly related to the amount of die-back in the crown of the tree. In an oak tree, if more than 30 percent of the critical root zone is lost, the tree will die. However, soft wood trees, such as box elder, can tolerate far more root disturbance.
