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• <br />• <br />• <br />compaction, and soil chemical changes. <br />1. Positive grade changes from fill and sedimentation <br />causes a decrease in soil oxygen levels. An increase in soil <br />carbon dioxide and other toxic gases can also occur, leading <br />to large areas of anaerobic conditions. Anaerobic soil <br />conditions cause a decrease in the root respiration process <br />which is essential for the uptake and transport of minerals <br />and nutrients. <br />2. Anaerobic soil conditions are also produced by soil <br />compaction, the increase in soil bulk density with a decrease <br />in soil pore space. Compacted soil is also impervious to <br />root penetration, and thus inhibits root development. Soil <br />compaction is generally caused by the weight and vibrations <br />of heavy machinery, vehicle parking, and the storage of fill <br />and/or construction materials within the critical root zones <br />of trees. <br />3. Changes in soil chemistry will adversely affect tree <br />survival. The most frequent occurrence is the change <br />(decrease) in soil acidity by concrete washout. Most trees <br />native to the Anoka County.awe prefer slightly acid soils; <br />concrete residues are highly basic. The leakage or spillage <br />of toxic materials such as fuels or paints can be fatal for <br />trees. <br />D. Trunk and crown disturbances are generally mechanical in <br />nature and are either caused directly by clearing and grading <br />machinery, or indirectly by debris being cleared and falling <br />into trees marked for protection. <br />1. Common forms of damages include stripped bark and <br />cambium, split trunks, and broken limbs. <br />2. Damage also occurs from the posting of signs such as <br />building permits, or survey; markers on trees. <br />3. Indirect damage can be caused by the placement of <br />burn holes or debris fires too close to trees. The possible <br />range of damages include scorched trunks with some cambial <br />dieback, the loss of foliage due to evaporative heat stress <br />(leaf desiccation), and completely burned trunks and crowns. <br />SECTION VI METHODS OF TREE PROTECTION <br />A. Planning and considerations. Tree space is the most <br />critical factor in tree protection throughout the development <br />process. The root system of trees can easily extend beyond <br />the dripline of the tree canopy (Figure 3). The root system <br />within the dripline region is generally considered to be the <br />critical root zone. Disturbance within this zone can <br />directly affect a -tree's -chances root zones.the following <br />4t-avrivirtrik shall apply: <br />1. The use of tree save islands and stands is <br />encouraged rather than the protection of individual (non - <br />specimen) trees scattered throughout a site. This will <br />facilitate ease in overall site organization as related to <br />tree protection. <br />2. The protective zone of specimen trees or stands of <br />trees or otherwise designated tree save areas shall include <br />