Fen Management Handbook - Scottish Natural Heritage

the peat carbon store is depleted through aerobic respiration. Restoration of high
water levels will halt (and probably reverse) this depletion. Chapter 12 of Rydin and
Jeglum (2006) gives an extremely detailed summary of the productivity and carbon
balance of peatlands.
Predicting the net carbon sequestration which would result from a planned project
is not necessarily straightforward. A high proportion of previous studies have
concentrated on ombrogenous bogs, and relatively little information is available
for fens. Measurement of carbon cycling is resource intensive, and there are
further complications to take into account. Some question the role of wetlands
as greenhouse gas regulators, as the release of methane under the anaerobic
conditions caused by raised water levels, is approximately 23 times more potent
as a greenhouse gas than CO 2. Scientific investigation of the relative effects and
amounts of CO 2 and methane release from unsaturated and saturated wetland
peats respectively is at an early stage. Interestingly, methane production from
saturated peat is known to be higher from sedge-dominated peat than from
moss-dominated peat, and also higher from high-pH peat than from low-pH peat,
suggesting that there is a higher methane production potential in fenland peat than
in bogland peat.
Carbon offset funds are a potential source of finance for fen creation or restoration.
These funds have been established to allow consumers to offset their carbon
emissions by donating proportional amounts of money. Money is invested in
development schemes which reduce greenhouse gases, including projects based
on carbon sequestration, but most carbon offset funds currently only invest in
schemes in the developing world. Establishment of a local carbon offsetting scheme
to support a wetland, or group of wetlands, might be more successful.
There may also be potential to use the UK Government’s Shadow Price for Carbon
(SPC) as matched funding for a project. Put simply, the SPC is based on an
estimate of the damage costs of climate change caused by each additional tonne of
greenhouse gas emitted by a proposed project. Annual SPCs have been published
by DEFRA for 2007 to 2050. The 2009 SPC is £26.50 per tonne of CO 2, and
since each tonne of elemental carbon is equivalent to about 3.5 times its weight in
CO 2, the equivalent SPC for elemental carbon is £97.26 per tonne.
An illustration of the concept of carbon sequestration
To illustrate this concept, and to assess the possible magnitude of the sums involved,
a simple calculation has been carried out based on the annual carbon balance for
wetland meadow habitat within Tealham and Tadham Moor SSSI in the Somerset Levels,
published by Lloyd (2006). This study found that the site was loosing a significant amount
of soil (peat) carbon (59 gC m-2 a-1 ), which was attributed to soil respiration resulting
from inappropriately low soil water levels. The following assumptions were made for the
calculation:
A project to raise the water levels to an appropriate level would prevent 59 gC m-2 a-1 leaving the site; this ignores any potential sequestration if peat growth resumes under
higher water levels. Water levels are raised over an area of 100 ha, or about 1/9th of the
SSSI.
For the first year of operation, the retained carbon has an SPC value of £5,738, and if the
project has a life expectancy of five years, the total SPC value would be £29,860 (using
the SPC rates for 2010-2014). These are clearly significant sums, and demonstrate
the importance of carbon sequestration through wetlands under the UK government’s
valuation. Whilst this valuation does not represent ‘real’ money available for projects, it
could account for a healthy proportion of a contribution to a match-funding agreement for
many projects. It is also possible that the SPC will change in the future, as appreciation
of the effects of climate change improves.
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