Measurement
Biomass expansion factor
A biomass expansion factor converts the volume or mass of a tree trunk into the mass of the whole tree above ground, adding branches, twigs and leaves. It is used when only stem measurements are available, for example from a timber inventory.
The factor changes with species, age and stand density. Young trees carry a larger share of their mass in branches and leaves than old ones do.
Roots are handled separately, through a root to shoot ratio. A carbon estimate should say which of the two it includes, because leaving one out understates the total and counting one twice overstates it.