Fen Management Handbook - Scottish Natural Heritage

Introducing grazing on fens with a long history of mowing is likely to have a
considerable impact on vegetation composition and associated invertebrates.
Depending on the conservation objectives for the site, such changes may or may
not be desirable.
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Species-rich fen being
rapidly colonised by willow
and downy birch due to lack
of grazing management. If
left unchecked, the scrub
will quickly develop into
wet woodland, shading out
the species-rich fen sward
below (B. Hamill).
On some low productivity sites, grazing may not be necessary to maintain short
open fen, for example on base-rich groundwater-fed fens where phosphorus,
one of the two major plant nutrients, combines with other chemical complexes
making it unavailable to plants. This emphasises the importance of assessing the
hydrological functions of the fen when setting management objectives (see Section
3: Understanding Fen Hydrology and Section 4: Understanding Fen Nutrients).
6.2.2 Assessing whether grazing is feasible
The following factors need to be considered in deciding whether grazing is feasible
for any particular fen.
Ground stability Ground stability is a fundamental consideration in deciding
whether grazing is feasible. Many fens have developed on
floating mats (schwingmoor) over open water, through which
animals can break through and drown. On sites where the
safety of livestock would be at risk, alternative methods of
management such as cutting or mowing should be introduced
to reduce biomass and halt habitat succession.
Flooding Flooding can have serious consequences for animal welfare,
through potential drowning and/or deprivation of food and
shelter. Rapidity of flooding is important to take into account as
well as frequency of flooding. Grazing is only feasible on sites
prone to rapid flooding if there are sufficient resources to check
stock frequently and to move them quickly to another safe site
as and when required.