Trenching near trees can severely damage root systems. Trenching for utilities can also cause substantial root damage and should be done far away from existing trees. In new developments, this can be done easily. Where the trench must pass under or near a tree, avoid substantial injury by using a power auger to bore a tunnel under the roots. Cleanly prune cut roots and refill trenches as soon as possible to prevent excessive moisture loss.
Wounds make the tree highly susceptible to root pathogens and decay fungi.
Decline and death can result if more than 40 percent of the stem or roots are damaged or killed. Stressed trees are also more susceptible to Insects such as bark beetles and borers. Within two years of adding 12 inches of soil, this tree died. It subjects roots to improper gas exchange and can lead to carbon dioxide or toxic gas buildup. Major changes in grading require an air supply to the roots.