Manage wetlands or ponds by grazing or cutting to prevent succession
Overall effectiveness category Awaiting assessment
Number of studies: 3
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Background information and definitions
Wetlands support a number of specialist butterfly and moth species, but this habitat requires some form of disturbance to prevent succession into scrub or woodland. In natural systems, this may have been provided by seasonal flooding and wild grazing animals, but flooding may not be possible in wetlands constrained by surrounding human land use. Cutting or mowing wetlands, or grazing with domestic livestock, may be able to replace natural disturbance regimes, but the frequency and timing of management may be important for benefitting, or avoiding harm to, particular species.
For studies on the creation or restoration of wetlands by either multiple actions (which may include grazing or cutting) or where the specific action is not clear, see “Restore or create wetlands and floodplains”. For studies on other actions for wetland management and restoration, see “Replant native vegetation” and “Natural system modifications – Use prescribed fire to maintain or restore disturbance in grasslands or other open habitats”.
For studies on the using of grazing and mowing to manage other semi-natural habitats, see “Employ areas of semi-natural habitat for rough grazing (includes salt marsh, lowland heath, bog, fen)”, “Change mowing regime on grassland” and “Manage heathland by cutting”.
Supporting evidence from individual studies
A replicated, site comparison study in 1994–1996 in a fenland in Overijssel, the Netherlands (Pullin 1997) found that three recently cut fen habitats had fewer large copper Lycaena dispar batavus eggs and lower caterpillar survival than two uncut fen habitats. There were fewer large copper eggs on plants in cut fen meadows (0.2–0.3 eggs/plant) than on plants in cut (0.3–0.8 eggs/plant) or uncut (1.8–1.9 eggs/plant) watersides, and the most eggs were found in uncut fen edges (4.2–5.7 eggs/plant). No eggs were found in cut reed fields. In addition, no caterpillars were found in cut fen meadows (from 70 eggs), and caterpillar survival was only marginally higher in cut watersides (11–13 caterpillars from 102 eggs) than in uncut watersides (11–23 caterpillars from 280 eggs) or uncut fen edges (13–31 caterpillars from 425 eggs). Five fenland habitats with different management were surveyed. Fen meadows were cut in patches in August–September; watersides were split into cut (in the preceding year) or uncut areas; fen edges along old ditches were uncut; and reed fields were cut commercially in winter. In August 1994 and 1995, the number of eggs were counted on every water dock Rumex hydrolapathum encountered 1 m either side of 2–5 transects/year (40–200 m long) through each habitat type. In late May 1995 and early June 1996, the number of surviving caterpillars were counted on the same plants.Study and other actions tested
A replicated, site comparison study in 1996 in 24 montane fens in Switzerland (Wettstein & Schmid 1999) found that fens managed by mowing had more species of butterfly than fens managed by cattle grazing. The species density of butterflies was higher on mown fens (8.9 species/transect) than on grazed fens (7.7 species/transect). Twelve of 23 fens (0.8–15.4 ha) were managed by mowing, and 11 by cattle grazing. From July–August 1996, butterflies were surveyed once on a 10-minute walk along each of three 540-m transects/fen.Study and other actions tested
A replicated, site comparison study in 1996–1998 in nine fens in Overijssel, the Netherlands (Nicholls & Pullin 2000) found that fens cut in autumn or winter had lower large copper Lycaena dispar batavus caterpillar survival than uncut fens. The overwinter survival of large copper caterpillars in fens cut in autumn or winter (2–3%/year: 5/176 caterpillars found) was lower than in unmanaged fens (15–20%/year: 36/222 caterpillars found). In 1996–1998, four fens within a 3,500-ha lowland bog in the Netherlands were cut in autumn or winter, and five fens were not cut. In 1996–1997, wild large copper eggs were counted on every great water dock Rumex hydrolapathum plant encountered along a transect through each site. Plants were revisited three weeks later, and in April the following year, to record caterpillar survival.Study and other actions tested
Where has this evidence come from?
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This Action forms part of the Action Synopsis:Butterfly and Moth Conservation
Butterfly and Moth Conservation - Published 2022
Butterfly and Moth Synopsis