Soil Carbon: a Critical Natural Resource – Wide-scale Goals, Urgent Actions - Soil Carbon: Science, Management and Policy for Multiple Benefits - page 14

monitoring can be used to advise farmers,
professionals and policy makers, as well as
for education purposes at different levels.

biomass fuel production. This accounting
should include both indirect effects on land
use and fertilizer use and its consequences,
including the release of nitrous oxide, a
powerful heat-trapping gas, to the atmosphere
(Melillo et al ., 2009).
There is also evidence that some native
vegetation (e.g. native grassland perennials)
for biofuels could provide more usable bio-
energy, larger reductions of greenhouse gas
emissions and less agrichemical pollution
than if the land were to be converted to pro-
ducing annual bioenergy crops (Tilman et al .,
2006; Don et al ., 2012). Targeting degraded
lands for biomass fuel production has been
suggested as a potential way to reduce com-
petition with food production and the
negative effects of clearing natural vegeta-
tion and forest, particularly if perennial
biomass fuel crops were grown (Kgathi
et al ., 2012). These perennial crops, if well
identified, could contribute to increasing
SOC on those degraded lands. There is
therefore a need for full cycle analyses of
biomass fuel production technologies and
management regimes that take full account
of the losses and gains of SOC (Davis et al .,
2009; Gnansounou et al ., 2009). Research
should focus on monitoring the impact of
land-use change for biomass fuel crop pro-
duction on SOC losses and gains for proper
guidelines on management for long-term
benefits.

Energy supply

Increasingly, plants are being grown to pro-
duce bioenergy, especially as the price of
fossil fuels increases and efforts to miti-
gate climate change grow. The use of bio-
mass for energy production is considered a
promising way to reduce net carbon emis-
sions and mitigate climate change (Don
et al ., 2012). The role of biomass in energy
supply is expected to rise dramatically over
the coming decades as cellulosic biofuel pro-
duction becomes widespread. Reilly et al .
(2012) project that an aggressive global bio-
fuels programme could meet 40% of the world's
primary energy needs by 2100. A large land
area, perhaps as much as 21 × 10 6 km 2 , would
be required to produce biomass fuel crops
at this large scale (Wise et al ., 2009; Reilly
et al ., 2012). In light of these facts, the goal
is to increase biomass fuel production to
meet the demand for energy while increas-
ing SOC.
As for food production, sustainable
biomass fuel crop production will rely on
an increase of SOC as a driver of processes
regulating nutrient availability for use by
these crops. However, land-use change to
biomass fuel crops, particularly the conver-
sion of native vegetation or peatlands, can
result in carbon emissions from soil and
vegetation in amounts that would take dec-
ades or centuries to compensate (Anderson-
Teixeira et al ., 2009; Gasparatos et al ., 2011).
The potential losses of soil carbon can coun-
teract the benefits of fossil fuel displacement
to the extent that biomass fuels from drained
peatlands lead to emissions that, per unit of
energy produced, exceed by far those from
burning fossil fuels (Couwenberg, 2007;
Couwenberg et al ., 2010).
Maintaining or increasing biomass fuel
production per unit area will require the care-
ful management of soil carbon stocks over
vast areas of the global landscape. Soil carbon
management must be considered explicitly
in carbon accounting efforts associated with

Biodiversity

Soil carbon is a primary ecosystem energy
source that underpins the structure and
function of terrestrial ecosystems, and thus
the capacity of these ecosystems to main-
tain biodiversity. As illustrated in Fig. 2.2 ,
decline of SOC comes as a second threat to
soil diversity (Jeffery et al ., 2010). Add-
itionally, most of the other identified threats
such as soil compaction and soil erosion
are related to SOC losses and can be counter-
acted by an increase of SOC. Restoration
projects around the world demonstrate that
increasing SOC in degraded soils enhances
not only biodiversity per se but also a range
of ecosystem goods and services that can