Construction around trees causes major disruptions to the tree roots, disruptions that can result in trees becoming hazardous. Again this week, Dennis Tompkins, certified arborist, has contributed to this column. In order to understand the effect of construction on big tree health, it's necessary to imagine how the root structure looks underground. Many people believe that tree roots descend dozens of feet into the ground, balancing the big top of the tree with a similar underground mass. This doesn't happen.
Roots are essentially shallow, even on big trees.
Most feeder roots that take up nutrients lie within two feet of the surface. They are located near the outer edges of tree root systems and usually extend well beyond a tree's drip line. Large anchoring roots located closer to the trunk typically extend down another two to three feet. Soil compaction by heavy equipment, trenching for water or utility lines or changing the grade for landscaping can damage or cut roots. Also, grading, bulldozing, and rearranging or adding soil over a large area may change natural drainage systems.