2-2-3- Step 3- Estimating carbon storage in an individual
tree unit
Once the biomass of a single tree was calculated using the allometric
equations, carbon storage in the above-ground biomass (trunk and crown)
and the below-ground (root) was calculated through equation 1 and
2(Aboal et al., 2005, Kirby and Potvin, 2007, Pearson, 2007, Peichl and
Arain, 2006).
\begin{equation}
C_{\text{AGB}}=AGB*C\%\ \ \ \ \ \ \ \ Eq.1\nonumber \\
\end{equation}\begin{equation}
C_{\text{BGB}}=BGB*C\%\ \ \ \ \ \ \ \ Eq.2\nonumber \\
\end{equation}Where CAGB indicates carbon in the above-ground biomass
(kg ), AGB is the above-ground biomass of tree (kg ),
CBGB is the amount of carbon in below-ground biomass
(kg ), BGB stands for the below-ground biomass(kg ), and C%
is carbon percentage (the amount of carbon storage in biomass or carbon
conversion efficient). The results of previous studies showed that the
carbon conversion ratio in the biomass of different tree species varies
between 44.4% to 55.7%, and usually in most studies, it is equivalent
to an average of 50% of the dry mass (Elias and Potvin, 2003; Singh et
al., 2011; Zhang et al., 2009; Zhu et al., 2010). While, in this
research, to estimate the amount of carbon in the biomass, instead of
using the coefficient (50%), we used the photosynthesis chemical
equation. The well-known chemical photosynthesis equation is explained
as follows (Blankenship, 2014):
\begin{equation}
{6CO}_{2}\ \left(264\ g\right)+\ 6H_{2}\text{O\ }\left(108\ g\right)+light\rightarrow C_{6}H_{12}O_{6}\ \left(180\ g\right)+\ {6O}_{2}\ \left(193\ g\right)\ \rightarrow\ Amylase\ (162\ g)\nonumber \\
\end{equation}The molecular weight of carbon dioxide is 44.9595 g / mol ;
therefore, plants absorb six molecules of CO2, i.e., 264
gram of carbon dioxide, 162 gram of amylase, or dry matter (Blankenship,
2014). Therefore, it can be said that each kilogram of dry matter
(produced by trees) absorbs 1.629 kilograms of carbon dioxide. Based on
this equation, considering that the atomic weight of carbon is 12.01
grams, therefore, for absorbing 6 molecules of carbon dioxide, around 72
grams of carbon is fixed in the biomass. In general, for every kilogram
of dry matter produced in a tree, approximately 453 grams of carbon is
stored in the biomass of a tree.