Title: CALCULATION OF TREE VOLUME AND SURFACE AREA BY THE HEIGHT-ACCUMULATION METHOD Abstract approved: L.

This study was initiated to determine the accuracy and limits of the height-accumulation method of measuring tree volume and surface area for Pacific Northwest second-growth trees. Thirty trees were selected from various thinning treatments in a 55 year old Douglas-fir forest. Each tree was measured with the highly accurate Barr and Stroud optical dendrometer and height, surface area, and cubic-foot volume were calculated on a Control Data Corporation 3300 electronic computer. A Spiegel-Relaskop was used to measure taper steps for height-accumulation. These results were then compared with the dendrometer results to determine the accuracy of this technique. The Relaskop was found to be inadequate when used alone, but when a 4-power telescope was mounted, it greatly enhanced the use-fulness of the instrument. The telescopic Spiegel-R elaskop, using the height-accumulation method, was found to be capable of measuring volume with compar-able accuracy to the optical dendrometer. The study revealed that volumes determined using height-accumulation, measured with a telescopic Spiegel-Relaskop, in conjunction with point sampling should estimate volume of a stand as accurately as any other c±uising:tech. nique. In addition this method, like other recently developed rrieth-ods, eliminates the use of volume tables and their inherent biases