Measure the trunk diameter at 54” above grade and multiply it by 10. For trees with more than one stem (arising at or below 54 inches) the trunk size shall be measured at the smallest diameter point below the main union of all stems unless the union occurs below grade, in which case each stem shall be measured as a stand-alone tree. For oak trees, if one stem is ten inches or more in diameter, the tree will constitute one Heritage Tree. For all other species, if one stem is fifteen inches or more in diameter, the tree will constitute one Heritage Tree. Use the Tree Diameter Measurement Guide to measure the trunk diameter of any tree.