NVC community W5 is one of the woodland communities in the British National Vegetation Classification system, characterised by a canopy of alder over a field layer of sedges and reeds, often over a peaty substrate. It is a form of primary woodland around freshwater lakes and bogs, or as a component of river valley wetlands, and is one of seven woodland communities in the NVC classed as wet woodlands. It was once very common but is now rare and localised.
W5 Alnus glutinosa-Carex paniculata woodland is rather local, but widespread but throughout the lowlands of England, and more rare in Wales and Scotland. It occurs on moist, peaty soils, particularly on or around lakes and peat bogs with a fluctuating water level, although it can also be found on neutral to acid mineral soils in suitable locations. Its characteristic (constant) tree species are alder, downy birch and various species of willow. [1]
The habitat is typically a seasonally flooded landscape in which trees can only become established if they are tolerant of waterlogging (mainly only alder and willow) and have a dry foothold, such as a clump of greater tussock sedge. Around the margins of a lake, grey willow typically forms a distinct band over the deeper water, with increasing amounts of alder beyond that. The canopy is initially rather open, with a thick layer of sedges under the trees, but it can close over and produce a rather bare ground layer with only sparse clumps of herbs and ferns.
There are many rare and scarce plants that are restricted to or characteristic of W5 woodland. These include fibrous tussock-sedge, elongated sedge, cowbane, crested buckler-fern, milk parsley and marsh fern. [1]
W5 Alder carr is thought to have been very widespread in the past, before much of Britain's low-lying wetlands were drained. Only small quantities now remain, but it is nevertheless one of the most characteristic types of woodland. Many examples of ancient or semi-natural W5 woodland are now protected as nature reserves or sites of special scientific interest, including those at Wicken Fen, Sweat Mere and Rhos Goch. [2] It is a Priority Habitat under the UK Biodiversity Action Plan. [3]
There are three subcommunities: [1]
W5 woodland often occurs in a zone around freshwater lakes or peat bogs, where it is seen as part of the hydrosere from open water to dry woodland. Typically, there is an area of reeds or sedge in the wettest areas, with some scrub invasion leading to W1 Salix cinerea woodland. W5 occurs to the landward side of this, followed by dry woodland that might be W6 A. glutinosa or W10 Quercus robur woodland. In some places a W5 woodland may have birch instead of alder, but it is distinguished from W4 Betula pubescens woodland by the acidity of the soil, and the presence of purple moor-grass or an abundance of Sphagnum mosses in that community. [1] [2]
There is no direct equivalent to W5 in the European EUNIS habitats system, but it is encompassed within the F9.2 willow carr and fen scrub [6] and the G1.52 alder swamp woods on acid peat. [7] Throughout northern Europe, river valley alder woods analogous to the W5c subcommunity are widespread. [8] Woodland very similar to W5 occurs on the peaty soils of lower Normandy and Brittany, where it is divided into two types: forêts humides à aulne glutineux (wet alder woodland) and, for the Chrysosplenium subcommunity, forêts riveraines à frêne élevé (riparian ash woodland). [9]
In Britain, an important early study was by Marietta Pallis in the Norfolk Broads in the 1900s. She described the formation of "swamp carr" from tussock sedge swamps, "fen carr" from reedswamp, and "ultimate carr" from both of these as they mature. The first two types had a ground flora that was largely similar to the precursor vegetation, but the ultimate carr had more trees and shrubs. Although Pallas's studies were of the development of secondary woodland, she considered the ultimate carr to be a climax community. [10] [2] All three of Pallis's vegetation types would be considered W5 in the NVC. [1]
In 1938 Roy Clapham described the hydrosere around Sweat Mere in Shropshire, [2] which includes what is possibly the first example of an ancient woodland alder carr to be recorded. The Shropshire-Cheshire plain once contained vast areas of wet woodland (even the names Shrewsbury and Shropshire derive from Old English words for (alder) scrub); and many small areas still persist. [11] A later analysis by Sinker et al. divided the alder woods into four types, following the system developed by G.F. Peterken: 7A valley woods, 7B wet valley woods, 7C plateau alder woods and 7D slope alder woods. Of these, only 7B is similar to W5b and 7D may be W5c in the NVC; 7A could be analogous to W7 while 7C is perhaps W4. [12] [5]
In County Durham, Gordon Graham lumped alder and willow carr into his WOC9 community in a study in the in the 1970s and 1980s. The Witton-le-Weir alder woods stands in particular seem to belong to W5. [13]
Askham Bog is small area of peat bog and Site of Special Scientific Interest situated within the Vale of York in North Yorkshire, England. It lies to the south-west of York, north of Copmanthorpe and near Askham Richard and Askham Bryan. It is regarded as one of the most ecologically diverse sites in Northern England.
The British National Vegetation Classification or NVC is a system of classifying natural habitat types in Great Britain according to the vegetation they contain.
This article gives an overview of the woodland and scrub communities in the British National Vegetation Classification system.
NVC community W1 is one of the woodland communities in the British National Vegetation Classification system; it is one of seven woodland communities in the NVC classed as "wet woodlands".
A hydrosere is a plant succession which occurs in an area of fresh water such as in oxbow lakes and kettle lakes. In time, an area of open freshwater will naturally dry out, ultimately becoming woodland. During this change, a range of different landtypes such as swamp and marsh will succeed each other.
NVC community W2 is one of the woodland communities in the British National Vegetation Classification system. It is one of seven woodland communities in the NVC classed as "wet woodlands".
NVC community W3 is one of the woodland communities in the British National Vegetation Classification system.
Street Heath is a 12.5 hectare biological Site of Special Scientific Interest 4 km west of Glastonbury in Somerset, notified in 1966. It next to the Glastonbury Canal and Ham Wall nature reserve. Street Heath has itself been designated as a Local Nature Reserve.
Scotstown Moor is in the north of Aberdeen, Scotland.
Cors Caron is a raised bog in Ceredigion, Wales. Cors is the Welsh word for "bog". Cors Caron covers an area of approximately 349 hectares. Cors Caron represents the most intact surviving example of a raised bog landscape in the United Kingdom. About 44 different species groups inhabit the area including various land and aquatic plants, fish, insects, crustaceans, lichen, fungi, terrestrial mammals and birds.
A wet woodland is a type of plant community. It is a biodiversity habitat in the United Kingdom as part of the British National Vegetation Classification system.
NVC community W7 is one of the woodland communities in the British National Vegetation Classification system; it is one of seven woodland communities in the NVC classed as "wet woodlands".
The Wilderness is a Site of Special Scientific Interest which is located on the Isle of Wight, England. It is close to the village of Rookley in the valley of the River Medina. The Wilderness is an area of wet woodland over a quite deep peat soil with adjacent areas of unimproved acid grassland and wet grassland. The SSSI covers an area of 12.59 hectares, the boundaries being reset in 1984 to exclude an area of grassland which had been artificially improved.
Trodds Copse is a 25.23 hectare biological Site of Special Scientific Interest (SSSI), in central Hampshire, notified in 1989. It comprises ancient semi-natural woodland, unimproved meadows and flushes.
Waldridge Fell is a Site of Special Scientific Interest located immediately south-west of Chester-le-Street in the northern part of County Durham, England. It is one of the largest areas of lowland heath in County Durham and contains the only lowland valley-mire in the county. The fell is home to a number of plants and insects that are scarce to rare elsewhere in the county.
Porth Hellick is a tidal inlet on the south coast of St Mary’s, the largest island in the Isles of Scilly.
Bewick and Beanley Moors is the name given to a Site of Special Scientific Interest (SSSI) in north Northumberland, in the north-east of England. The moors are asserted to be of national importance by Natural England for the extent, quality and diversity of upland types including heaths, fens, wet grassland, flushes, mires and blanket bogs, together creating an extensive mosaic habitat supporting an exceptional community of amphibians. The moors are important, too, for their relict juniper woodland and scrub.
Mar Field Fen is a Site of Special Scientific Interest, or SSSI, north of Masham, North Yorkshire, England, in a rural area known as Marfield. It is situated on land containing woodland carr, fen, spring-fed marshy grassland and drier calcareous grassland, between the River Ure to the east and Marfield Wetland nature reserve to the west. As "one of the best examples of fen habitat in the Vale of York," it is a protected habitat for a variety of plants, including the common butterwort, a carnivorous plant. There is no public access to this site.
Carex elongata, the elongated sedge, is a species of flowering plant in the family Cyperaceae, native to Europe, the Caucasus, western Siberia, Kazakhstan, and the Altai. It occurs in boggy woodland and wet meadows, where it forms dense tussocks up to about 1 m tall.
NVC community W4 is one of the woodland communities in the British National Vegetation Classification system, characterised by a canopy of downy birch over a field layer of purple moor-grass or other calcifugous herbs on a peaty substrate. It usually forms as a secondary woodland over partially drained bogs or wet heaths.