Fen Management Handbook - Scottish Natural Heritage

Case Study 6.2
Fen Vegetation Management
– Mid Yare
The RSPB Mid Yare Reserve in the Norfolk Broads is a good example of the effects
on fen vegetation and molluscs of four years of light grazing by Highland cattle.
The aims of grazing were:
– to increase structural diversity of the fen to increase the range of microhabitats
available for invertebrates
– to prevent vegetation succession,
– to increase or at least maintain the species-richness of the vegetation
Grazing management
The grazing unit was 13.6ha in extent and consisted mainly of tall-herb fen most
similar to S25 reed Phragmites australis-hemp agrimony Eupatorium cannabinum
tall-herb fen (see map). The fen had previously been mown on a fairly ad hoc
basis, and was then heavily grazed by cattle in summer in 1996 and 1997 and left
unmanaged in 1998. Highland cattle were introduced in 1999. Initially the fen was
grazed year-round at densities of between 0.30-0.65 livestock units/ha, but this led
to the following concerns:
– Difficulties accessing the fen for welfare checks during flood periods.
– The cattle flattened most dead reed in search of winter food, impacting on overwintering
invertebrates and breeding birds.
– There was excessive hoof growth, requiring time consuming and expensive
trimming, due to the absence of hard ground
Cattle have subsequently been moved to a drier area from December to March,
which allowed retention of standing reed. The stony tracks on the winter grazing
area also removed the need for foot-trimming. Although the cattle have had access
to green vegetation throughout the year, because of its limited availability under
snow, ice or floodwater, poor quality hay has also been provided to supplement
their diet between January and February.
Phasing out horned animals was suggested because of safety concerns, but
observations showed that horns are important to the animals’ social behaviour,
and for scratching and pushing through scrub. Instead, the handling pen was
redesigned, which together with careful planning and direction of handling activities,
avoids the need to be in a confined space with the cattle.
The cattle have exhibited very few health problems, but they have declined in
condition at 10-12 years old, at which stage older cattle have been individually
culled from the herd. Establishing a mixed age structure early on was essential to
ensure gradual replacement of older animals, which allows knowledge of the site to
be passed on within the herd.
Monitoring and review of outcomes
It was realised at the outset that grazing had the potential to damage the mollusc
fauna of the fen, which included the BAP Priority Species Desmoulin’s whorl snail
(Vertigo moulinsiana). Monitoring was therefore set up to determine the effects of
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