Abstract:
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 usefulness
of the instrument.
The telescopic Spiegel-Relaskop, using the height-accumulation
method, was found to be capable of measuring volume with comparable
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 cruising technique. In addition this method, like other recently developed methods,
eliminates the use of volume tables and their inherent biases.
