Estimating shrub biomass from basal stem diameters

For 25 northern Rocky Mountain shrub species, linear regressions are presented for total aboveground weight on basal stem diameter (average r2 of 0.91) and for leaf weight on basal stem diameter (average r2 of 0.74). The percentage of stem-wood weight in diameter classes of 0 to 0.5 cm, 0.5 to 2 cm, and 2 to 5 cm varies with basal stem diameter and species growth characteristics (as shown in figures). For these classes, diameters of stem wood averaged 0.21 cm, 0.76 cm, and 2.37 cm, respectively; however, some species differed significantly from these averages. Coefficients of variation ranged from 60 to 340 for shrub weight per unit area sampled in 12 stands. Some distributions were positively skewed. Implications for sampling are discussed.