Forest-Based Biomass Basic Computations - Mathematics and Statistics for the Environment - page 329

Top Height
(4-inch diameter)

Aboveground Tree
Biomass (Includes Foliage)

Merchantable Stem
and Bark Biomass

Stump Height
(12 inches)

Belowground
Coarse Root Biomass

FIGURE 13.1 U.S. forest inventory data. (Adapted from Jenkins, J.C. et al., A Comprehensive Database
of Diameter-Based Biomass Regressions for North American Tree Species , Gen. Tech. Rep. NE-319, U.S.
Department of Agriculture, Forest Service, Northeastern Research Station, Newtown Square, PA, 2004.)

category of volume or biomass units, and Figure 13.2 illustrates indirect methods of large-scale
biomass estimation. Total volume or biomass includes stem, bark, stump, branches, and foliage,
especially if evergreen trees are being measured. When estimating biomass available for bioenergy,
the foliage is not included, and the stump may or may not be appropriate to include depending on
whether harvest occurs at ground lever or higher. Both conversion and expansion factors can be used
together to translate directly between merchantable volumes per unit area and total biomass per unit
area, as demonstrated by the simple volume to weight conversion process shown below.

Volume/Merchantable

Biomass/
Merchantable

Volume/Stem

Volume/Total

Biomass/Stem

Biomass/Total

FIGURE 13.2 Indirect methods of large-scale biomass estimation. (Adapted from Somogyi, Z. et al.,
European Journal of Forest Research , 126(2), 197-207, 2007.)