Grazing marsh is a

British Isles The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isles (O ...

term for flat, marshy grassland in

polder A polder () is a low-lying tract of land that forms an artificial hydrological entity, enclosed by embankments known as dikes. The three types of polder are: # Land reclaimed from a body of water, such as a lake or the seabed # Flood plain ...

s. It consists of large grass fields separated by fresh or

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

ditches, and is often important for its wildlife.

History

Grazing marshes were created from

medieval In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire a ...

times by building sea walls (earth banks) across tidal

mudflat Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal f ...

s and

salt marsh A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is domin ...

to make polders (though the term "polder" is little used in Britain). Polders in Britain are mostly drained by gravity, rather than active pumping. The original tidal drainage channels were augmented by new ditches, and flap valves in the sea walls let water drain out at low

tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables can ...

and prevent the sea or tidal river from entering at high tide. Constructing polders in this way is called ''inning'' or ''reclaiming'' from the sea. Grazing marshes have been made in most lowland

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environme ...

in Britain, often leaving only the river channel and the lowest part of the estuary tidal. In a few cases (such as Newtown Harbour on the

Isle of Wight The Isle of Wight ( ) is a Counties of England, county in the English Channel, off the coast of Hampshire, from which it is separated by the Solent. It is the List of islands of England#Largest islands, largest and List of islands of England#Mo ...

, and Pagham Harbour in

West Sussex West Sussex is a county in South East England on the English Channel coast. The ceremonial county comprises the shire districts of Adur, Arun, Chichester, Horsham, and Mid Sussex, and the boroughs of Crawley and Worthing. Covering an a ...

) the sea walls have been breached, and the estuaries have returned to a tidal state. Grazing marshes have also been made on low-lying open coasts. Many grazing marshes were inned in stages, and the old sea walls (called ''counter walls'') may be found marooned far from the current sea wall. Land levels on either side of a counter wall often differ by several metres. Paradoxically, the lower side is the land inned earlier, because sediment continued to build up on the side that remained tidal.

Wildlife

Wintering wildfowl are characteristic of grazing marshes, often including large flocks of

Eurasian wigeon The Eurasian wigeon or European wigeon (''Mareca penelope''), also known as the widgeon or the wigeon, is one of three species of wigeon in the dabbling duck genus ''Mareca''. It is common and widespread within its Palearctic range. Taxonomy T ...

brent goose The brant or brent goose (''Branta bernicla'') is a small goose of the genus '' Branta''. There are three subspecies, all of which winter along temperate-zone sea-coasts and breed on the high-Arctic tundra. The Brent oilfield was named after ...

white-fronted goose The greater white-fronted goose (''Anser albifrons'') is a species of goose related to the smaller lesser white-fronted goose (''A. erythropus''). It is named for the patch of white feathers bordering the base of its bill, in fact ''albifrons ...

and

Bewick's swan The tundra swan (''Cygnus columbianus'') is a small swan of the Holarctic. The two taxa within it are usually regarded as conspecific, but are also sometimes split into two species: Bewick's swan (''Cygnus bewickii'') of the Palaearctic and the ...

. Many of these birds are hunted by predators such as peregrine and marsh harrier. In summer, waders such as

common redshank The common redshank or simply redshank (''Tringa totanus'') is a Eurasian wader in the large family Scolopacidae. Taxonomy The common redshank was formally described by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of hi ...

Eurasian curlew The Eurasian curlew or common curlew (''Numenius arquata'') is a very large wader in the family Scolopacidae. It is one of the most widespread of the curlews, breeding across temperate Europe and Asia. In Europe, this species is often referred ...

and

northern lapwing The northern lapwing (''Vanellus vanellus''), also known as the peewit or pewit, tuit or tew-it, green plover, or (in Ireland and Britain) pyewipe or just lapwing, is a bird in the lapwing subfamily. It is common through temperate Eurosiberia. ...

breed. The ditches often have a range of salinity, depending on how close to the sea wall they are. The more saline ditches host specialist brackish-water plants and animals. These include, for example, the rare brackish amphipod '' Gammarus insensibilis'' and sea club-rush (''Bolboschoenus maritimus''). Fresher ditches may support rare animals, such as the great silver water beetle (''Hydrophilus piceus'') and the great raft spider (''Dolomedes plantarius''), and a wide range of pondweeds (''

Potamogeton ''Potamogeton'' is a genus of aquatic, mostly freshwater, plants of the family Potamogetonaceae. Most are known by the common name pondweed, although many unrelated plants may be called pondweed, such as Canadian pondweed (''Elodea canadensis'') ...

'' and relatives). The grassland vegetation usually has a fairly small number of species, but those present are often scarce elsewhere, such as sea arrowgrass (''Triglochin maritimum''), divided sedge (''Carex divisa'') and strawberry clover ''Trifolium fragiferum''.

Conservation

Many grazing marshes have been converted into

arable land Arable land (from the la, arabilis, "able to be ploughed") is any land capable of being ploughed and used to grow crops.''Oxford English Dictionary'', "arable, ''adj''. and ''n.''" Oxford University Press (Oxford), 2013. Alternatively, for th ...

, often using pumped drainage to lower the water levels enough to grow crops. The low ditch levels and agricultural runoff combine to remove much of the aquatic wildlife, although the arable fields may still be used by some wintering wildfowl. Some areas of grazing marsh and other polder land have been used to recreate tidal habitats by a process of managed retreat. Many of the larger areas of grazing marsh bear nature conservation designations, including Site of Special Scientific Interest,

Special Protection Area A Special Protection Area (SPA) is a designation under the European Union Directive on the Conservation of Wild Birds. Under the Directive, Member States of the European Union (EU) have a duty to safeguard the habitats of migratory birds and cert ...

Special Area of Conservation A Special Area of Conservation (SAC) is defined in the European Union's Habitats Directive (92/43/EEC), also known as the ''Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora''. They are to protect the 220 habitats and a ...

and

Ramsar Site A Ramsar site is a wetland site designated to be of international importance under the Ramsar Convention,8 ha (O) *** Permanent 8 ha (P) *** Seasonal Intermittent < 8 ha(Ts) ** Pevensey Levels in

East Sussex East Sussex is a ceremonial and non-metropolitan county in South East England on the English Channel coast. It is bordered by Kent to the north and east, West Sussex to the west, and Surrey to the north-west. The largest settlement in East ...

* Romney Marsh in

Kent Kent is a county in South East England and one of the home counties. It borders Greater London to the north-west, Surrey to the west and East Sussex to the south-west, and Essex to the north across the estuary of the River Thames; it faces ...

and

*The

Somerset Levels The Somerset Levels are a coastal plain and wetland area of Somerset, England, running south from the Mendips to the Blackdown Hills. The Somerset Levels have an area of about and are bisected by the Polden Hills; the areas to the south are ...

*The

Thames Estuary The Thames Estuary is where the River Thames meets the waters of the North Sea, in the south-east of Great Britain. Limits An estuary can be defined according to different criteria (e.g. tidal, geographical, navigational or in terms of salini ...

marshes in

and

Essex Essex () is a county in the East of England. One of the home counties, it borders Suffolk and Cambridgeshire to the north, the North Sea to the east, Hertfordshire to the west, Kent across the estuary of the River Thames to the south, and G ...

*Marshes along the River Wantsum in

—formerly the Wantsum Channel separating the

Isle of Thanet The Isle of Thanet () is a peninsula forming the easternmost part of Kent, England. While in the past it was separated from the mainland by the Wantsum Channel, it is no longer an island. Archaeological remains testify to its settlement in an ...

from the mainland * Moss Valley, Derbyshire {{Agriculture in the United Kingdom Ecology Agriculture in the United Kingdom