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Determining Age -Class <br />In order to assess the age -class of a tree, the diameter at breast height (DBH) and the crown width can be <br />utilized. These measurements help in the identification of the age and the growth of a tree. <br />Measuring Diameter at Breast Height (DBH) <br />Diameter at breast height is a standardized point on a trunk, 4.5 feet from the base of the tree. This <br />measurement is used to estimate age and volume of trees. To measure the DBH you can use a diameter <br />tape (D-tape), or you can measure the circumference of a tree with a standard measuring tape and convert <br />the measurement to diameter by dividing the circumference by pi (3.14). <br />Using a D-tape <br />• All breasts are not 4.5 feet off the ground! Determine breast height on your own body by <br />measuring 4.5 feet up from the ground - remember where that point on your body is; it will make <br />measurements in the field go quickly. <br />• When measuring a tree, wrap the D-tape completely around the tree at your breast height until the <br />zero on the tape reaches the tape again. Record the number where the zero meets the tape again. If <br />the tree is on a slope, take the measurement on the uphill side of the tree (Figure 2). <br />• Remember to read the correct side of the D-tape: <br />o The right side: measures using distances that have been converted to diameter <br />o The wrong side: measures in standard feet <br />1. TREE ON SLOPE <br />dbh <br />4 <br />2. TREE ON LEVEL 3. LEANING TREE <br />GROUND <br />--DAM POINT <br />36. <br />DIAM P) NT ' 4 Il . ' <br />4_ TREE FORKING AT OR <br />ABOVE 4 Ir2 FEET <br />5_ TREE DEFORMED <br />AT 4 1/2 FEET <br />I <br />¢IAM POINT r <br />- <br />5. TREE FORKING BELOW <br />4 I/2 FEET <br />3' R <br />NOR E I 1 <br />• <br />1 IMAM POINT <br />71. <br />_L <br />7. BOTTLENECK TREE <br />Figure 2 - Measuring DBH <br />13 <br />