An Improved Tree Height Measurement Technique Tested on Mature Southern Pines
by Don C. Bragg. SOUTH. J. APPL. FOR. 32(1) 2008, pp. 38-43.http://www.nativetreesociety.org/specialreports/bragg/Bragg2008A.pdf
Virtually all techniques for tree height determination follow one of two principles: similar triangles or the tangent method. Most people apply the latter approach, which uses the tangents of the angles to the top and bottom and a true horizontal distance to the subject tree. However, few adjust this method for ground slope, tree lean, crown shape, and crown configuration, making errors commonplace. Given documented discrepancies exceeding 30% with current methods, a reevaluation of height measurement is in order. The sine method is an alternative that measures a real point in the crown. Hence, it is not subject to the same assumptions as the similar triangle and tangent approaches. In addition, the sine method is insensitive to distance from tree or observer position and can not overestimate tree height. The advantages of the sine approach are shown with mature southern pines from Arkansas.
Available for download as part of the Native Tree Society Special Publication Series: NTS SP #18