Fen Management Handbook - Scottish Natural Heritage

Fens usually feature a range of different associated habitats, and the overall
stocking density is determined by the relative proportions of habitats in the area to
be managed. In general, it is best to graze fen habitats in conjunction with adjacent
semi-improved or improved grassland which give livestock a choice of forage, helps
maintain stock condition and usually means that the fen is lightly grazed. The figures
below are a general guide, drawing on experience of grazing a range of different
fens.
Open bog 0.02 LU/ha/yr
Fen/swamp 0.1 LU/ha/yr
Wet purple moor-grass heath 0.25 LU/ha/yr
Semi natural grassland 0.3 to 0.5 LU/ha/yr
Rush pasture 0.4 LU/ha/yr
Improved grassland 0.8 to 3.0 LU/ha/yr
One livestock unit (LU) is equivalent to one adult cow. One sheep is equivalent to 0.15 LU.
In general, extensive grazing at low stocking rates is recommended with
livestock free to roam widely across large management units.
Intensive grazing (i.e. stocking at high densities or well above normal recommended
stocking rates) is generally not advisable on fens because wet soils are easily
damaged by poaching. However, short periods of 2-3 weeks grazing in dry weather
may be used to check scrub growth, where identified as appropriate within the fen
management plan.
Always start grazing with low numbers, and adjust the stocking rates as the results
of the grazing become apparent.
6.2.7 The benefits of extensive (low intensity) fen grazing
Careful monitoring
is required to avoid
overgrazing and poaching,
as in the foreground of this
picture, or undergrazing, as
in the background
(P. Corbett).
– Promotes structural diversity – extensive grazing creates good structural
diversity in the sward (height and density).
– Creates ecotones and habitat diversity – in an extensive system grazing
animals create ecotones, for example, at the transition between scrub and fen.
In year-round grazing systems, animals make seasonal use of the site, move
around and change grazing patterns according to the seasons, as their dietary
requirements adjust to the changing environment.
– Wet sites can be grazed – water buffalo, Highland cattle and Hebridean sheep
are able to graze schwingmoor (a floating mat of vegetation) and very wet peat,
including areas flooded with significant surface water, provided dry areas are
also available.
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