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

Abstract

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.

Estimating coarse roots biomass in young silver birch stands on post-agricultural lands in central Poland

“…As shown by Bijak and Zasada (2007), who applied nine various functions from the literature for estimation of belowground biomass of Scots pine stands, results can vary significantly regarding the formulae. Wang et al (2002) found large discrepancies between measured data and estimates based on the previously published equations. They suggest careful checks of the equations taken from the literature for their applicability in local conditions.…”

Release of mercury from Rocky Mountain forest fires

“…In the aspen plots sampled during this study, the canopy cover was very sparse owing to low stem density at both the ∼75 year old BC stand and the ∼130 year old GK stand. We estimated aspen foliar mass using an allometric equation based on tree diameter at breast height (DBH) from Freedman et al [1982] and Wang et al [2002] for trembling aspen (ln (Foliage (kg)) = −4.0359 + 1.6093*ln(DBH), where DBH = 15 cm at BC; DBH = 25 cm at GK). Considering both sites, and based on an observed stem density of approximately 20 stems per 0.1 hectare, we estimate a foliar mass of 0.3 to 0.6 × 10 6 g foliage ha −1 .…”

Allometric biomass equations for young trees of four broadleaved species in Albania

“…Extrapolation below or above these ranges could lead to substantial differences between the true and predicted values (Zianis & Mencuccini 2003). Since allometric relationships between biomass and tree variables vary across species, tree size and age, the use of such models in other geographic areas is not suggested because this may lead to incorrect estimations (Harding & Grigal 1986;Wang et al 2002;Zianis & Mencuccini 2003;Zabek & Prescott 2006). Finally, the biomass equations were developed on a relatively narrow DBH and H range and their application to large trees outside these ranges may be associated with larger errors in biomass prediction.…”