Fen Management Handbook - Scottish Natural Heritage

many of the scarce invertebrates on the Moss have very specific requirements
for the presence of scrub – the requirements of the leaf beetle illustrate a classic
conflict of management interest.
Habitat requirements of leaf beetle
This attractive beetle, which resembles a small ladybird, has currently only been
identified on Wybunbury Moss and on a single site near Loch Rannoch in Scotland.
Until recently its habitat requirements were poorly understood, with casual
observations suggesting a preference for small sallow and downy birch saplings.
At Wybunbury, the bulk of the population is concentrated on one willow bush in the
centre of the Moss. Its larval stages were unknown although the British RDB (Shirt,
1987) suggests an association with ants nests.
In 2001 English Nature commissioned Leeds University to undertake research into
the ecology of a number of the nationally rare Cryptocephalus beetles. Four years of
observation revealed C. decemmaculatus to be a very immobile insect, loath to fly
more than a few metres at a time and requiring hot, sunny days before it will take to
the wing. The larvae were found to inhabit the leaf litter amongst Sphagnum moss
at the base of the willow bushes. The population study confirmed that the majority
of adult beetles were concentrated on one bush in the centre of the site (orange
star on map) with a very small population along the northern edge of the Moss.
As such, the status of the species was extremely threatened and it was therefore
concluded desirable to provide a suitable habitat corridor to allow the beetle to shift
its population to a series of new south-facing glades along the northern perimeter.
Current management
Current management of Wybunbury Moss aims to achieve favourable condition of
plant communities whilst addressing the needs of the invertebrate assemblage. A
programme of tree clearance has been underway since the early 1990s to restore
former areas of oligotrophic mire and open fen. In general it takes the Moss a
couple of years to re-wet following tree removal, a period in which treatment of
scrub regrowth is necessary. It is the management of scrub regrowth that is used
to provide suitable conditions for C. decemmaculatus.
Approximately 20% of scrub regrowth is
allowed to re-grow and reach a height of 3m
before being controlled, initially including
all regrowth of Salix spp. In subsequent
management, a willow bush is retained at
least every 5 metres, creating a series of
stepping stones (green dots on map) from the
current leaf beetle population to new southfacing
glades that have been created along
the northern boundary. By 2007 the beetle
had moved as far as the orange dot, with
populations on several bushes between here
and the original colony.
Future plans
Ultimately, once the beetle has spread to the new
glades along the northern boundary, the levels of
scrub in the centre of the site will be reduced to the
5% required to achieve favourable condition of the
mire and open fen communities. A fringe of scrub
will also be retained between the open mire and fen
communities and the peripheral fen woodland will
be managed by regular coppicing.
100
Sphagnum lawns
merging into scrub