Calculating untrimmed biomass
Two calculations were required to calculate the dry biomass of the
untrimmed part (i.e. that still standing): one for the small branches
accompanied with leaves and twigs and the other for the large branches.
The untrimmed biomass is the sum of the two results:
B untrimmed dry = B untrimmed dry branch + B dry section
Each section i of the large branches was considered as a cylinder of
volume (Smalian’s formula):
Vi =π/8 Li (D21i +
D22i)
Where Vi is the volume of section i, Li its length, and
D1i and D2i are the diameters of the two
extremities of section i. The dry biomass of the large branches is the
product of mean wood density and the total volume of the large branches:
\begin{equation}
\text{B\ }\text{dry\ section}\ =\ R\ \times\sum_{i}\text{Vi}\nonumber \\
\end{equation}Where the sum corresponds to all the sections in the large branches, and
where mean wood density is calculated by:
\begin{equation}
R\ =\ \frac{B_{\text{\ dry\ wood}}^{\text{aliquot}}}{\text{V\ }_{\text{fresh\ wood}}^{\text{aliquot}}}\nonumber \\
\end{equation}The dry biomass of small untrimmed branches, twigs and leaves was
calculated from the regression model developed between the basal
diameter of the trimmed branches and biomass of trimmed branches, twigs
and leaves. This model is established by following the same procedure as
for the development of an allometric model. Power type equations were
used:
B dry branch = a + bDc
Where a, b and c are model parameters and D branch basal diameter. Using
a model of this type, the dry biomass of the untrimmed branches and
their components (twigs and leaves) is:
B untrimmed dry branch=\({\sum_{j}{(a\ +\ bD}}_{j}^{c}\) )
Where the sum is all the untrimmed small branches and their components
and Dj is the basal diameter of the branch j (Picard et al .,
2012).