CLM20-2 full issue-1 - Flipbook - Page 25
A guide to conservation land management and greenhouse gas emissions
of different habitats although, as described later,
such changes are also likely to affect their value
for wildlife. We will now look at each of these
approaches in more detail.
Rewetting drained blanket bog and
lowland raised mire
Rewetting drained peatlands reduces, and should
ultimately prevent, the release of large quantities
of CO2 that occurs through drying out and
oxidation of peat. The rewetted habitat ought
eventually to recommence accumulating carbon
in its peat, albeit with some initial release of
methane following rewetting (e.g. Wilson et al.
2016). The expected climate benefits of rewetting
peatland, together with different types of habitat
creation/restoration, are shown in Figure 2. It
may come as a surprise that rewetting peatland
does not result in very large climate benefits per
unit area per year, particularly compared to some
forms of habitat creation. It is, nevertheless, a
very important measure, owing to the extensive
areas of drained upland peatland in Britain,
the fact that if left drained this will continue
releasing CO2 for a very long time because of
the large quantities of carbon accumulated in
its peat, and because of the multiple benefits
that the restoration of such habitat provides.
As well as benefitting wildlife, rewetting upland
peatlands can reduce flood risk and discoloration
of drinking water, the latter reducing the costs
of water treatment (e.g. Armstrong et al. 2010;
Wilson et al. 2010).
The situation regarding the effect on the climate
of removing conifer plantations on deep peat is
more complex. It is thought that the first crop
of trees planted on drained deep peat typically
sequesters more CO2 than is released from the
drying out, oxidising peat. From the second
rotation onwards, tree growth is likely to be
lower, and the quantity of CO2 sequestered less
than that released from the oxidising peat. If
blanket bog re-establishes following tree removal
and drain-blocking, it should recommence
accumulating carbon in peat, albeit again with
some initial release of methane.
Creating semi-natural habitats on
formerly intensively managed farmland
Creating semi-natural habitat on formerly
intensively managed arable land and agriculturally
improved grassland can both offer significant
The creation of wet woodland on ex-arable on organic soils should provide the greatest climate benefits per
unit area. The soil is kept wet enough to prevent oxidation of the underlying peat and the growth of trees
accumulates carbon. Jim Laws/Alamy Stock Photo
Conservation Land Management Summer 2022 | Vol. 20 No. 2 23
