TREE MEASUREMENTS

Say you want to figure out the volume of a tree before cutting it down. Not only can you determine the volume of the tree, but you must be able to gather evidence of the tree height and diameter. This can be done through gathering two simple measurements by using a standard tape and a clinometer.

STEP 1: Determining Tree Diameter

Using Standard Tape, measure the circumference of the tree at breast height (around 4.5 ft). Once you have obtained the circumference then divide the number by pi (3.14), which gives the diameter at breast height (DBH). The DBH will be used to determine the volume of wood within a tree. By determining the DBH this measurement can be used to evaluate the use of the tree in the market. Click here for a website that shows the uses of the tree according to it DBH. There is also a diameter tape (or pi tape) that already determines the diameter of the tree without the calculations. It is good practice for secondary students to learn basic math skills using Standard Tape.


STEP 2: Determining Tree Height

The one tool that will be used to determine tree height is a clinometer. There are other methods than using a clinometer, but it offers a reliability that the other measurements do not.

1. First is to measure 66' (ft) away from the base of the tree to use the clinometer. One can pace the amount of 66' so that a long tape measure is not needed. For example: requires 13 paces (two steps) for me to go 66'. Record measurement.
2. Determine the A (+) angle by looking through the viewer until merchantable height is reached (place in which there are few branches or tapers to 4' for pulpwood and 6' for saw-timber). Record measurement.
3. Determine the B (-) angle by looking through the viewer to the point in which the log will be cut, which is 2' from the ground. Record measurement.
4. Determine the tree height by subtracting the A (+) angle by the B (-) angle (be sure to move the decimal over two: 70% = 0.70). Then take the calculation and time it by 66' (which is the DBH) to determine the tree height.

 STEP 3: Determining Board Foot

Board Foot (12'' X 12'' x 1'') is a standard of measurement that is used to determine how much wood is within a tree. Use the lab provided for instructions on how to determine board foot. (Forestry Measurements)