difference in invertebrate assemblages between cut and carefully burnt wet
reedbed (Ditlhogo et al. 1992). However, it is important not to burn in dry con-
ditions in summer or autumn, when the fire will be hotter and burn deeper into
the litter, and is likely to be more damaging to invertebrates. Cutting is only prac-
tical during dry conditions or if the water is frozen solid enough to allow access.
Lowering water levels to enable cutting in winter can compromise attempts to
attain suitable water levels for breeding birds in early spring.
Although cutting or burning in winter may be necessary to prevent succession
in reedbeds, it can leave areas bare and unsuitable for nesting birds the following
spring. In southern Europe, where regrowth of reed is rapid, winter reed cutting
only reduces densities of early nesting, resident passerines (Poulin and Lefebvre
2002). In northern Europe, where regrowth of reed is slower, it also reduces den-
sities of later arriving migrant warblers (Graveland 1999). Winter cutting also
eliminates moth larvae which overwinter in reed stems, and provide food for
some reedbed passerines. However, a recent study in southern France suggested
that total invertebrate prey availability for reedbed passerines was actually higher
in annually cut reedbeds than uncut ones (Poulin and Lefebvre 2002).
Any deleterious short-term effects of cutting or burning can be reduced by
managing areas in rotation, thus increasing the range of conditions in the
reedbed as a whole by providing different stages of regrowth. The frequency of
winter reed cutting used to arrest succession varies between sites, but is typically
once every 5–10 years. Commercial cutting of reed takes place on a 1–2 year
rotation to provide high densities of strong, straight reed stems suitable for
thatching. Annual cutting of large areas of reedbed is detrimental to some nest-
ing birds and damaging to its invertebrate fauna. Therefore, a compromise
between the needs of commercial cutting and conservation is to cut only a pro-
portion of the reedbed for thatching, and to do this on a 2-year rotation (Hawke
and José 1996).
Grazing can be used to reduce the dominance of reed, and at high levels can
convert fen to mire and wet grassland. Judicious grazing by cattle or ponies can
be used to create patchy, open reed interspersed with shallow water and grass-
land. This is considered the most productive part of some wetlands in northern
Europe for breeding waterfowl.
Succession in reedbeds can also be reduced by raising the level of the water
relative to that of the surface of the substrate. The timing and duration of flooding
influences conditions for feeding and nesting. Maintaining water levels above
ground level allows fish to penetrate the margins of reedbeds and thereby provide
feeding conditions for birds such as Bitterns (Tyler 1994). Prolonged flooding of
reedbeds in summer probably also increases the invertebrate food supply for
358 |Habitat management