Measuring Tree Heights for Urban Forest Inventories
Note: These instructions are for SUUNTO clinometers with a topographical scale (feet).
A clinometer is an instrument that measures slope.
The concept of the clinometer is rooted in the trigonometry of a right triangle. The volunteer measures slope (the hypotenuse, or rise over run) twice. First, measure to the top of the tree. If you stop here, you have only measured the tree starting at the height of your eye. So you must then measure to the base of the tree (where the tree meets the ground), creating two right triangles. Add these two measurements together to get height.
Step 3: Remaining 66 feet from the tree, measure the base of the tree. This measurement represents the lower triangle in the graphic above. Add the two measurements, in feet, together. The sum is the total height. For example, you get 30 feet to the top, and negative 5 feet to the bottom. The total height of the tree is 35 feet.
Information Sheet 2008 (POD-01-16)
By Jason Gordon, Assistant Extension Professor, Forestry.