What effects will construction activities have on nearby trees?

FAQ
Question: 

What effects will construction activities have on nearby trees?

Answer: 

Construction of buildings, patios, garages, driveways, sidewalks, and roads often compromises the growing environment of nearby trees.  The majority of a tree’s roots are located in the top 12 to 18 inches of soil and often extend well beyond the edge of the tree canopy (dripline).  Changing the grade by removing or adding soil around existing trees can cause extensive root damage.  Removing soil can disturb and injure many of the tree’s roots.  Adding soil can reduce the movement of oxygen to tree roots, causing them to die.  Trenching often severs major portions of the tree’s root system.  Soil compaction by heavy equipment and foot traffic reduces the supply of oxygen to the root system.  Mechanical damage to the trunk of a tree caused by construction equipment can strip off bark and damage vascular tissue, reducing nutrient and water movement in the tree.  Open wounds created by these injuries can serve as entryways for insects and decay-causing fungi.  Severe construction damage can cause affected trees to decline and die. 

The best way to minimize damage to a tree during construction is to do nothing around, in, or on top of a tree's root system.  Construct a sturdy fence at least at the outer dripline of the tree and allow zero activity within this area.  Prohibited activities inside the dripline of the tree include lowering the grade, adding soil, trenching, parking or operating machinery in the area, and storing supplies, soil, or excavation materials.