Biofuels & Forest Soil Carbon
Using Forest Residues Reduces Soil Carbon Stock
ScienceDaily (May 21, 2008) – The use of harvest
residues for energy production decreases soil
carbon stocks. These changes in soil carbon
stocks are remarkable compared to the other
greenhouse gas emissions caused by the use of
forest residues for energy. On a national scale,
soil carbon stocks play an important role in
forest carbon balances.
Changes in soil carbon stock need to be assessed
reliably and transparently because we need more
information on the effects of climate change and
forest management on soil carbon. This is also
stressed by climate conventions which have set
practical reporting requirements for changes in
soil carbon stock.
The large spatial variability of soil carbon goes
together with relatively slow changes in stocks,
which, in turn, hinders the assessment of soil
carbon stocks and their changes by direct
measurements. Models therefore widely serve to
estimate carbon stocks and stock changes in soils.
A recent doctoral thesis developed and tested the
soil carbon model YASSO for upland forest soils.
The model was aimed to take into account the most
important processes controlling the decomposition
in soils, yet remain simple enough to ensure its
practical applicability in different
applications. The model was applied to study the
effects of intensified biomass extraction on the
forest carbon balance, to estimate the effects of
soil carbon deficit on net greenhouse gas
emissions of energy use of forest residues and to
assess the national scale forest carbon balance
for Finland’s forests.
YASSO managed to describe sufficiently the
effects of both the variable litter and climatic
conditions on decomposition. When combined with
the stand models or other systems providing
litter information, the dynamic approach of the
model proved to be powerful for estimating
changes in soil carbon stocks on different scales.
1. Liski, J., Palosuo, T., Peltoniemi, M. &
Sievänen, R., 2005. Carbon and decomposition
model Yasso for forest soils. Ecological
Modelling 189(1-2): 168-182.