- Clendenen, Gary W.
USDA Forest Service, Pacific Northwest Research Station, Forestry Sciences Laboratory
Volume estimates using the tarif system often assume a single mean tarif number for an even-aged stand. Consistent trends of tarif number with dbh within plots were found in a set of 67 plots in western Oregon and Washington. Effects of these trends on plot and diameter class volume estimates, and on heights estimated from these volumes, were examined. Total plot volume estimates were apparently not biased, but substantial biases were found in estimates of volumes and heights by dbh class. Height samples should be representative of the range of diameters, adequate to detect trends in tarif number, and adequate to support alternative methods of volume and height estimation.