2.5 Carbon analysis
Samples of biomass were ground in liquid nitrogen in a mortar and pestle
to a particle size of 500 μm. The oil-bath
K2Cr2O7 titration method
was used for estimating organic C in the plant tissues (Dong 1997), and
organic C content of the soil samples was estimated using the
K2Cr2O7 volumetric
dilution heating method (Nelson and Sommers 1982).
Calculating total carbon storage and statistical analysis
Carbon content of trees, herbs, and litter was determined by multiplying
the respective biomass by its C content. The total stock of soil organic
C (SOC) to a depth of 100 cm was calculated based on its organic C
content, sample depth, and bulk density (Guo and Gifford 2002) as
follows: SOC = BD × Cc / 100 × D, where BD is soil bulk
density (g/cm³), Cc is soil C concentration (%), and D
is soil sampling depth (cm). Ecosystem carbon storage was calculated as
the total of each component (trees, herbs, litter, and soil):
\begin{equation}
C_{T}=C_{t}+C_{h}+C_{l}+C_{S}\nonumber \\
\end{equation}where CT is total ecosystem C, Ct is the
total C stored in trees (t/ha); Ch, that in herbs
(t/ha); Cl, that in litter; and Cs, that
in soil (t/ha in each case).