Tree diameter, merchantable tree height, and grade can be used to determine the volume of useful wood in a tree.
Tree diameter is measured on the main stem 4.5 feet above ground on the uphill side of a tree. This is referred to as diameter at breast height (DBH). DBH usually is measured to the nearest inch using a steel diameter tape that is calibrated to permit direct tree diameter readings.
To measure tree diameter with a diameter tape, wrap the tape around the tree at breast height, perpendicular to the lean of the tree, standing on the uphill side of the tree (Figure 2-1). If there are branches or other protrusions at DBH, place the tape at the first unobstructed location above them. If the tree forks below DBH, consider each stem to be a separate tree and record separate measurements for each tree.
If you don?ft have a diameter tape, measure tree circumference by wrapping a normal tape measure around the tree at breast height, then dividing the resulting circumference in inches by 3.14 to deter- mine DBH.
Figure 2-1. Measure stem diameter at breast height (DBH) Woodland Stewardship