Appendix E Tree Protection Zones TRUNK DIAMETER MINIMUM PROTECTION REQUIRED AROUND TREE Trunk diameter (BH) 20 cm 25 30 35 40 45 50 55 60 75 90 100
Distance from trunk 1.2 m 1.5 1.8 2.1 2.4 2.7 3.0 3.3 3.6 4.5 5.0 6
Tree root protection criteria: Douglas fir - Pseudotsuga menziesii Generally these trees have good to moderate tolerance for construction, tolerant of some grade change, to 25% of root zone. Mature trees need 1.00 ft per inch diameter of trunk at 4.5ft breast height. Young trees need .75 ft per inch diameter of calliper. Grand fir - Abies grandis Generally moderate to poor construction tolerance Mature trees need 1.25 ft per inch diameter Young trees .75 to 1’ per inch diameter Western hemlock - Tsuga heterophylla Generally poor to moderate tolerance susceptible to wind throw, intolerant of grade changes Young trees need 1’ per inch diameter Mature trees need 1.25’ per inch diameter Western red cedar - Thuja plicata Generally these trees have poor to moderate, sensitive to grade changes & water table change. Mature trees need 1.25 ft per inch diameter young trees need 1’ per inch diameter
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