Forestry expert witness Russell E. Carlson, RCA, BCMA, Tree Tech Consulting, writes on Guidelines for Protection of Trees on Construction Sites:
To preserve certain mature trees within a construction site some precautions must be taken to assure that neither the trunk, limbs nor root system of the tree are excessively damaged. The root system of a tree is the most vital and the most delicate part of the plant, and the most easily damaged.
The root system extends far from the trunk, often beyond the drip-line of the tree. The fine absorbing roots, those that collect water and nourishment for the tree, are located primarily within the top eight to twelve inches of the soil. (See Figure 1) The roots and the soil in this surface layer must be protected from injury.


