Fen Management Handbook - Scottish Natural Heritage

extensive areas of wetlands which would otherwise have been drained and used
for intensive agriculture. A number of birds such as bittern and reed warbler, and a
wide range of invertebrates, are associated with commercially cut reedbeds. Reed
grown for commercial purposes has to meet certain criteria in terms of strength,
shape and height, and is typically harvested from pure beds of common reed
(Phragmites australis). Cutting biennially on a double wale cycle is preferable to
annual (single wale) cutting because the areas left uncut each year in the longer
rotation provide a refuge for birds and invertebrates. Tied bundles of cut reed are
removed from site, often by boat, ready for sale to local thatchers. Removal of all
of the material from the site without the need for burning or piling makes it more
environmentally friendly than some other management methods. As well as the
cost effectiveness of cutting reed for sale, additional benefits of commercial cutting
include the small size machines typically used which limit the level of disturbance,
and consistency in management by one or two people which allows opportunity for
them to build up a detailed knowledge of the site.
Commercially grown great fen-sedge (Cladium mariscus) is cut on average every
three to four years, which allows time for regrowth to harvestable length, and is also
ideal for most fen plant communities. If the sedge beds are left much longer than
four years before cutting, they may become non-commercial and the accumulation
of plant litter shades out some of the smaller associated plant species. On
seasonally flooded fens, cutting is usually carried out in summer which allows the
cut stems to grow above the anticipated floodwater level in winter. If the sedge is
cut later in the year or grazed, the sedge beds can be destroyed by winter flooding.
However, at Bure marshes NNR, winter cutting has been undertaken successfully
by cutting the vegetation much higher with a scythe.
6.3.2 Small scale conservation cutting and mowing
In contrast to commercial reedbeds, mixed reed and sedge-dominated fen habitats
usually yield poor quality thatching material and are consequently of low economic
value, but these mixed stands are of significant value for conservation because
of the diversity of flora and fauna they support. Cutting or mowing has become
a widely-practised conservation management technique to maintain open fen,
allowing more flexibility than grazing, and scope to adapt the method of mowing or
cutting to meet individual site requirements.
Mowing an area of wet fen
associated with a spillway
adjacent to North Esk Reservoir
on the Pentland Hills, near
Edinburgh. Sheep had
preferentially grazed extensive
drier areas to which they had
access, resulting in the fen
becoming rank. A scythe
attachment powered by a BCS
Bankcommander tractor unit
was used for mowing, and a
CAEB mini-baler for baling,
powered by the same tractor.
The resultant bales were heavy
and difficult to move, but the
fresh regrowth after mowing
prompted the sheep to resume
grazing of the fen (A. McBride).
No outlets yet exist for material cut for conservation purposes, which is usually
raked into habitat piles that benefit invertebrates or burned on site (see 6.4.3).
However, trials in the Broads to turn cut reed into small pellets for use in multi-fuel
burners for small-scale heat generation, are now complete. The technology for
harvesting, processing and burning pellets is now well established. However, there
are a number of constraints which must be met for the process to be economically
viable. Further information on the development of reed pellets may be found in the
final report produced by the Broad’s Authority in 2010.
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