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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 (477 <br /> ) <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 />