Making a DBH Tape
A DBH tape is used to measure the diameter of a tree at a height of 1.35 meters from the ground. DBH(Diameter Breast Height) is measured by converting the circumference of the tree into a diameter measurement. This can be done by measuring the circumference then dividing by pi, or by using a DBH tape. A DBH tape already divides the measurements by recording the 3.14 cm mark as 1 cm. When wrapped around the tree, the measurement read is the diameter (the distance across the tree)
To make a DBH tape, mark off, each pi centimetres on a piece of plywood that is at least 1.8 meters long. Use a square to extend these marks across the board. Pin down, at both ends of the board, the heavy plastic strapping found in lumber yards. Using a permanent liquid marker, mark the strapping at each pi cm. Number off each mark on the strap, starting at 0. These tapes are very durable.