Regression equations that predict the foliage and roundwood biomass by diameter classes: 0.0-0.5 cm, 0.5-1.0 cm, 1.0-3.0cm, 3.0-5.0 cm, 5.0-7.0 cm and 7.0-10.0 cm given diameter at breast height (dbh) were developed for lodgepole pine and white spruce. Common to the Prairie Provinces the allometric model y = adbh fit the data well for all component categories except the roundwood classes > 3.0 cm. the r2 values generally exceed .80 and SEE were small. The larger size classes are best predicted by multiplying the number of trees affected by a constant. The management value of this new information is significant when viewed from an ecologic perspective.© The Canadian Institute of Forestry/Institut forestier du Canada. Abstract reproduced by permission.