Wet grassland and grazing marsh

Wet grassland and grazing marsh

Many wet grasslands provide very valuable habitat for breeding and over-wintering birds.

Other areas of wet grassland can be rich in wildflowers. Wet grassland also contains seasonal water-filled hollows, permanent ponds and networks of ditches which can be very important for a number of invertebrate, amphibian, reptile, mammal and plant species.

What

Wet grassland and grazing marsh occurs on low-lying, level land often within river or coastal floodplains. These grasslands have high water tables and can be temporarily under water during periods of high rainfall or river flooding. They are primarily managed for grazing, but some are managed as hay meadows.

Cattle grazing on the salt marsh. Freiston Shore RSPB reserve. Lincolnshire, England. July 2006.

Why

Wet grasslands were once widespread in the UK, particularly in major river floodplains. Only a small proportion now remains and much of this has declined in wildlife value through improved drainage, fertiliser and herbicide applications, or eutrophication from agricultural runoff.

Wet grassland provides excellent habitat for breeding waders such as lapwings, which prefer short grazed swards, and snipe which like a more varied sward height. The large number of invertebrates present in soft damp soils, ditches and ponds, provide important food for adult birds and their chicks, and several bat species also use these areas for foraging. Wet grassland is also used extensively by wintering wildfowl and by reptiles, for example grass snakes which feed on the amphibians which frequent these habitats.

Ditches, ponds and temporary wet areas are exceptionally important for a number of plants and invertebrates including a number of rare snails, as well as being valuable breeding and feeding areas for amphibians, dragonflies and water voles.

Wet grassland can be very rich in wildflowers, including great burnet, bird’s-foot trefoil, pepper saxifrage and marsh marigold.  Many areas are quite agriculturally improved, however these can still provide valuable pollen and nectar resources for insect pollinators, including rare bumblebees.

Water vole Arvicola terrestris, sitting on rock near to water, Derbyshire, England, March

How

Grazing and/or cutting should be managed to provide a range of sward heights and structure across a farm or floodplain.

Management may also be tailored to meet the needs of a particular group of species (for example ground-nesting or over-wintering birds). Some wet grasslands have been traditionally managed as floodplain or water meadows, and in these areas hay meadow management should be continued. Ditches and other water features are incredibly important for plants, invertebrates and amphibians and should be managed sensitively and protected from agricultural runoff. Water level management is important, in particular the maintenance of a high water table in spring and summer, and management of winter flooding.

Grazing

Grazing should be managed to produce a varied sward, with short grassland and taller tussocks. Cattle are better at creating a diverse sward than sheep and their trampling can also create small areas of bare or muddy ground important for invertebrates. Grazing should be avoided or reduced when birds are nesting to prevent loss of nests. Livestock also provide a supply of dung, which is important for dung beetles and other species including the hornet robberfly. Use of avermectins can harm these insects and reduce food for the bats and birds which feed on them.

Relaxing grazing in spring or summer will allow common wildflowers such as red clover, white clover, common bird’s-foot trefoil, buttercups and thistles to flower, all of which are valuable for bees including the brown-banded carder bee and the potter flower-bee.

Managing water levels

Wet grasslands and the water features within them provide important habitat for amphibians and invertebrates, which in turn provide food for breeding waders and their chicks. Maintaining high water levels throughout the spring and summer will assist birds with their feeding by keeping soils soft and moist. Where fields are drier, shallow scrapes or deeper pools can be created, ideally with muddy margins and sparse marginal vegetation in which adult and young birds can find food.  As there are no fish in these scrapes and pools they provide good breeding areas for frogs and newts. Ideally seasonal pools should be designed to hold water until at least the end of June with some holding water through to early October.

Water levels in ditches should be maintained at a reasonably high (close to field level) throughout the year. If water levels fluctuate too rapidly this can impact on some invertebrates and other wildlife.

Rush Management

Scattered rush cover provides important nesting and shelter for breeding waders, amphibians and invertebrates. It is advisable to implement rush management gradually over a number of years as making too rapid changes may have detrimental impacts on some wildlife. As a guide, <30% rush cover will provide habitat for most wildlife but more may be beneficial for some wildlife. If rushes need to be managed this is best achieved by rotational cutting or weed wiping carried out outside of the bird breeding season. Ideally any cuttings should be removed from the site and cattle put on the land to eat re-growth.

Management of ditches and ponds

Clean freshwater ditches and ponds support a large number of plants, amphibians and invertebrates, including soldierflies, water beetles, dragonflies and water snails. Plants found in or beside ditches, such as lesser water-parsnip, crowfoots and spearworts are important nectar sources. Good water quality is critical. Nutrient enrichment promotes algal growth which can choke ditches and ponds and impact on other wildlife. Fertiliser and pesticide use should be carefully managed in the vicinity of ditches and ponds, and any supplementary feeding moved to drier areas.

Ditches need managing if they silt up and become choked with vegetation. Ensure there is a continuity of habitat for wildlife by managing ditches in rotation. Ditch work is best carried out in early winter (November–December). Carefully clear short sections and/or clear only one side of a ditch at any one time. Work towards a rotation of >5 years and ensure some stretches of ditch remain full of vegetation at any one time.

Marginal vegetation around ditches and other water bodies can be rich in plants species and is very valuable for invertebrates. Well managed grazing will create diverse vegetation including taller areas of plants, which are beneficial for spiders and damselflies and bare muddy areas which are beneficial to other invertebrates. Cattle are good at producing bare muddy areas, however it may be necessary to exclude stock from some ditch or pond margins. Areas of scrub or un-grazed rough grassland alongside fenced off ditches provide important nesting, shelter, and foraging for song birds, invertebrates, amphibians and reptiles.

hairy dragonfly

In practice

Here are some useful case studies and articles about how farmers are putting Farm Wildlife into practice on their farms

Case Study: Restoration of rank wetland habitats to benefit waders

By Kathryn Smith | 4th August 2016

Author: Dan Brown, Dr Duncan Allison & Sarah Bird Farm: Anston Farm, Dunsyre, South Lanarkshire Aims: Anston is a 651 ha mixed upland livestock farm in South Lanarkshire. A variety of habitats can be found across the farm. The hill ground includes dry heath and acid grassland, whilst the upper in-bye fields contain a mixture […]

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Case Study: Wet grassland for breeding waders in Oxfordshire

By Kathryn Smith | 6th October 2014

Author: James Taylor Farm: North Aston Farms, Oxfordshire The family has owned the farm since 1907, and we brought management back ‘in-house’ in the 1960s. We converted to organic status over a ten year period from about 1982 and continued as a mixed farm until 2006, when we decided to become purely a livestock enterprise. […]

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