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).