46 Shade Planning for America’s Schools Chapter 6 Because ultraviolet (UV) radiation can be reflected off ground and building surfaces, the planning team should make notes regarding the surfaces and finishes of each of the buildings and play areas on the school grounds. Creating a Tree Inventory The next task will require a degree of horticultural expertise. The planning team should inventory each tree and planted area on the school grounds, noting for each: • Species. • Estimated height. • Trunk diameter. • Condition (e.g., broken branches, dead limbs), paying particular attention to any that appear to be unhealthy. • Estimated diameter of the tree’s canopy, that is, the upper part which includes the branches and leaves. • Density of the tree’s canopy. Trees should be numbered on the site plan and a separate set of notes should record the team’s findings regarding each. Where densely planted areas of mixed species exist, notes should be made on which ones predominate. Attachment B is an example of a tree inventory data sheet. Estimating the Height and Trunk and Canopy Diameters of a Tree There are many ways to estimate the height and canopy diameter of a tree. Following is one method: a. One member of the planning team first measures his or her own height in inches or feet. b. The team member then stands next to the tree while another team member stands about 20 paces away. c. With one eye closed, the second team member holds a pencil vertical at arm’s length and covers part of the pencil so that the visible part is the same apparent length as the team member standing next to the tree. d. Still keeping one eye closed, the second team member then moves the pencil up the tree and measures how many times taller the tree is than the team member standing next to it. e. Multiply that number by the first team member’s height and the result is a good estimate of the tree’s height. f. To estimate the canopy diameter, the second team member again closes one eye and holds the pencil at arm’s length, covering part of the pencil so that the visible part is the same apparent length as the tree height. g. The pencil is then turned horizontal and, measuring at the canopy’s widest point, used to determine how many times wider the canopy is than the tree’s height. To determine the diameter of a tree, simply measure the tree’s circumference, usually at about 3 feet above the ground, and divide it by 3.14.
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