Measuring Tree Diameter
One measurement that can be taken with a Biltmore or tree scale stick is diameter. To measure diameter, first establish the point to be measured on the tree. This point will be diameter at breast height (DBH), which is 4.5 feet above the ground. Find the "Diameter of tree (inches)" side of the stick (Fig. 1). Stand facing the center of the tree and hold the stick horizontally at arm's length so you can see the measurement increment. Line up the zero end of the stick with the left side of the trunk of the tree and look (do not move your head) to the point where the right side of the trunk meets the stick (Fig. 2).
Figure 1. The diameter measurement on a tree scale stick.
Figure 2. Displaying proper techniques of measuring diameter with a tree scale stick.
To account for the tree not being round, take a second measurement 90° to the first and average the two. When on sloping ground, always measure on the uphill side of the tree. Diameter is usually measured to the nearest inch, but if many trees are being measured, 2 inch classes are used.
Measuring Tree Height
To measure tree height using a Biltmore or tree scale stick, find the side of the stick that gives the number of logs. On tree scale sticks it may be found on the narrow side of the stick and may be labeled Merritt Hypsometer (Fig. 3).
Figure 3. The Merritt Hypsometer side of tree scale sticks.
Stand 66 feet from the tree and hold the stick vertically at arm's length, making sure the log measurement side of the stick is visible. Line up the zero end of the stick with the base of the tree. Without moving your head, look at the predetermined cutoff point for the measurement of the top of the tree. The location at which this point intersects the stick is the height measurement in logs (Fig. 4). Read to the nearest half-log. If height measurement is desired in feet, the conversion factor is 16 feet for each log.
Figure 4. Demonstrating the use of a tree scale stick to measure tree height.
Reference: The Virginia Tech College of Natural Resources. Forestry Equipment. http://dendro.cnre.vt.edu/forsite/2003presentations/studentswordfiles/dawn/treeheight.htm.