The Sine Method as a More Accurate Height Predictor for Hardwoods
by Don C. Bragg, In: Buckley, David S.; Clatterbuck, Wayne K. (eds.). Proceedings of the 15th Central Hardwood Forest Conference. General Technical Report SRS-101. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station: 23-32. Published in April 2007.http://www.nativetreesociety.org/specialreports/bragg/Bragg2007b.pdf
Abstract—Most hypsometers apply a mathematical technique that utilizes the tangent of angles and a horizontal distance to deliver the exact height of a tree under idealized circumstances. Unfortunately, these conditions are rarely met for hardwoods in the field. A “new” predictor based on sine and slope distance and discussed here does not require the same assumptions for accurate height determination. Case studies using a sycamore (Platanus occidentalis L.), a water oak (Quercus nigra L.), and a southern red oak (Q. falcata Michx.) from southern Arkansas are presented to emphasize the sensitivity of the tangent method to erroneous measurement procedures. When heights were measured properly and under favorable circumstances, the results obtained by the tangent and sine methods differed only by about 2 percent. Under more challenging conditions, however, errors ranged from 8 to 42 percent. These examples also highlight a number of distinct advantages of using the sine method, especially when exact tree height is required.
Available for download as part of the Native Tree Society Special Publication Series: NTS SP #17