Calculating the biomass of the trunk
The truncated cone volume formula was used instead of the cylinder
formula, for larger trees their diameter measured at two meters
interval. For each log i, the circumferences at the two extremities were
measured: circumference C1i is the circumference of the
log taken at the bottom end and circumference C2i is the
circumference of the log taken at the upper end. This was conducted to
calculate the volume of the fresh log using the truncated cone volume
formula (or Newton’s formula):
Vfrais,i = Li ×\(\frac{\pi}{3}\) ×
(R21i +
R1iR2i +
R22i)
Where Li is the length of log i, and
R1i= \(\frac{C1i}{2\text{\ π}}\); R2i =\(\frac{C2i}{2\text{\ π}}\)are the radii of log i at its
two extremities. The dry biomass of the trunk is the product of mean
wood density and total volume of the trunk
B dry section = ῥ ×\(\sum_{i}\text{Vi}\), where the
sum corresponds to all the sections in the trunk (Picard et al .,
2012).