Construction & siting issues   Planning ahead in order to save existing trees is important. The three main reasons trees are lost during (or shortly after) construction is (1.) soil compaction, (2.) severed roots, and (3.) drainage changes. By changing the grade of the land, water flow patterns change. As a result, the amount of moisture a tree or plant community is accustomed to receiving will be altered. The plants may be too wet or too dry.       Source of damage Methods of damage prevention Soil Compaction 1. Place barriers to foot and vehicular traffic around root zone.   2. Spread several inches of wood chips over root zone.   3. Bridge root areas with plates of steel.     Severed Roots 1. Minimize excavation by raising paved driveways.   2. Trench utilities in a route that avoids tree roots.   3. Reduce trenching for foundations by using posts and pillars instead of footers and walls.     Drainage Pattern Changes 1. Areas receiving too much water should have a drainage system.   2. Areas deprived of water may require irrigation.     Source: A City Among the Trees (City of Seattle Urban Forest Coalition, 1998)