Question
During renovation, a neighbor moved in a lot of dirt to landscape part of his
yard. He has added about 1 -2 feet of dirt around several assorted trees. Won't
this kill them?

Answer
More than likely they will start to die back in a year or so and over time they will die. Raising the grade can suffocate the roots. The amount of damage depends in part on the kind of tree, the depth of the fill, and the soil texture of the fill. Several inches of fill over the root system will adversely affect most kinds of trees. Some can be adversely affected by less than an inch of added soil depth. Sandy or gravelly fills are less damaging than heavier fills such as silt or clay. Fill dirt frequently is added around existing mature trees so that a level or more visually desirable lawn can be established. Fill dirt changes the ratio of oxygen to carbon dioxide around tree roots and the roots may subsequently die.