One of the leading causes of tree damage from construction is root severing, or cutting the roots of the trees too short for the tree to adequately absorb the nutrients. White and Black Oak trees, Black Walnuts, Hawthorne trees and Sugar Maples are especially sensitive to root severance. About 90% of a tree’s root system sits in the top three feet of soil, and directly under the main branch body, which arborists call the Protected Root Zone or PRZ. It may be a good idea, when building on a property with any of these sensitive trees, or when adjusting a driveway or expanding your home, to have an arborist and your architect or developer consult on how to achieve the desired development while also preserving these trees. A common practice is to mark the PRZ with bright colored fencing, and having an arborist schedule regular visits to the property to observe the tree’s health.