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V. Tree & Site Related Disturbances. <br />A. Tree protection zones, specimen trees or stands of trees designated to be saved <br />must be protected from the following damages which may occur during all <br />phases of land disturbance and construction processes. Methods of tree <br />protection and disturbance prevention are provided in Section VI. <br />1. Direct physical root damage <br />2. Indirect root damage <br />3. Trunk and crown disturbance <br />B. Direct physical root damage most frequently occurs during site clearing and <br />grading operations, where transport or feeder roots are cut, torn or removed. <br />1. Transport and feeder roots tend to tangle and fuse among the roots of <br />adjacent trees. The removal of trees with heavy machinery along the <br />outer periphery of a tree save area cause root damage. <br />2. The most substantial form of root damage for all root types occurs in the <br />form of cut roots. Roots are cut in grade reduction, or from trenching for <br />underground utilities, sanitary sewer or storm sewer lines. <br />3. A more subtle type of root damage is the loss of feeder roots. Feeder <br />roots normally occur within the organic layer and the surface four (4 ") <br />inches of top soil, subsequently, these roots can be easily damaged by <br />the track action from a single bulldozer pass. The stripping of top soil <br />within a tree's critical root zone can totally eliminate its feeder root <br />system. <br />C. Indirect root damage through site modification can result from positive grade <br />changes, temporary storage of fill material, the sedimentation of erosion <br />materials, soil compaction and soil chemical changes. <br />1. Positive grade changes from fill and sedimentation causes a decrease in <br />soil oxygen levels. An increase in soil carbon dioxide and other toxic <br />gasses can also occur, leading to large areas of anaerobic conditions. <br />Anaerobic soil conditions cause a decrease in the root respiration <br />process, which is essential for the uptake and transport of minerals and <br />nutrients. <br />2. Anaerobic soil conditions are also produced by soil compaction, the <br />increase in soil bulk density with a decrease in soil pore space. <br />Compacted soil is also impervious to root penetration and this inhibits root <br />development. Soil compaction is generally caused by the weight and <br />vibrations of heavy machinery, vehicle parking and the storage of fill <br />and /or construction materials within the critical root zones of trees. <br />3. Changes in soil chemistry will adversely affect tree survival. The most <br />frequent occurrence is the change (decrease) in soil acidity by concrete <br />washout. Most trees native to Anoka County area prefer slightly acidic <br />6 <br />