Biomass Estimation Errors Associated with the Use of Published Regression Equations of Paper Birch and Trembling Aspen

Since forest biomass contributes a significant proportion of global carbon cycle, obtaining accurate estimate of forest biomass is important. The root mean squared error (RMSE), the percents of the mean observed values were used to compare the precision of local and published biomass equations for paper birch and trembling aspen. With the exception of stemwood biomass equations, the biomass equations for these two species tended to be stand specific. Measured as percent of mean observed values, the values of biomass/tree predicted from the published equations for paper birch varied from 49.9% to 140.2% for foliage and from 155% to 238.7% for live branches; the estimates for trembling aspen ranged from 71.8% to 81.3% for foliage and from 55.3% to 164.5% for live branches. There were large discrepancies between the measured data and the published equations in graphical form as well as biomass estimates, particularly for foliage, live branches, and stembark. Clearly, published regression equations should be checked for their applicability before they are used to estimate the biomass of particular stands.