Scrapes
Scrapes are simple shallow excavations in ground with a seasonally high water table, and provide areas of standing water or wetland, according to seasonal fluctuations. They are invaluable for invertebrates, as well attracting amphibians and water fowl. Scrapes can vary in size from small depressions in rough grassland on farms or commons, to much larger areas managed to provide habitat for wintering and passage waders. The latter type are of most value when situated close to known migration routes, near the coast or other wetland areas. For further details see Merritt (1994).
Small scrapes can be excavated in any area where the ground conditions are suitable. The scrape should be sited away from all sources of nutrient-rich or polluted runoff. The size can be varied according to particular sites or target species, but would normally need to be about 7-8m (8-9 yards) in diameter, gently sloping to a depth of about 500mm (18”). Poaching of the ground by stock is beneficial in creating bare mud and ‘hoofprint pools’ for invertebrates, and bare ground for plant colonisation. However, too high a stocking density will only result in a muddy hollow which will be of limited value and will certainly look unattractive. The presence of good wildlife habitats nearby, such as rough grassland, scrub and woodland, will increase the value of the scrape.
Marshes
Marshes near to new ponds can be easily created using, as necessary, the same method of artificial lining as the pond. A marshy area can also usefully serve as a silt trap and filter for water entering the pond. The lining should be a minimum of 300mm below water level, backfilled with soil to about the water level. See Chapter 7 – Artificial linings for more details on artificial linings. Water can be supplied to the marsh by an open inlet, or via a perforated pipe below the surface. Suitable plants are listed here.
Existing areas of damp ground can be improved as a marshy habitat by slowing the flow of water by a low impoundment, or by diverting rainwater or stream water into hollows. Seasonal drying out is not necessarily a problem. Leaking ponds, especially cracked concrete ponds, may be best turned into marshes.
For details of large-scale creation of marshes and wet grasslands: Burgess, Neil D and Hirons, Graham JM (1990).
