Reedbeds

Reedbeds are wetlands dominated by common reed, often growing alongside a range of other wetland plants. The water table is typically at or above ground level for most of the year. Reedbeds often occur in association with other wetland habitats such as open water, ditches, carr (wet) woodland and wet grassland.

Reedbeds provide an important habitat for birds, including a number of nationally rare species. Characteristic breeding species in Carmarthenshire include reed warbler, reed bunting and Cetti’s warbler. Reedbeds also provide important roosting and feeding sites for migratory and wintering birds such as the rare bittern, which is recorded at the National Wetlands Centre, Llanelli. A range of invertebrates adapted to wetland habitats can be found, such as the various dowdy wainscot moths or the colourful scarlet tiger moth and again includes a number of rare species.

Over the centuries many reedbeds have been lost through drainage and agricultural intensification. More recently other examples have been lost or degraded through development and pollution. Many sites have also suffered from a lack of or inappropriate management, leading to scrub encroachment and succession to woodland.

Reedbed and wetland habitat creation and enhancement has taken place within the Llanelli Millennium Coastal Park, and at the National Wetlands Centre at Penclacwydd. The importance and vulnerability of reedbeds and other wetland habitats is a focus of their work and the site is now used by thousands on wintering wildfowl and waders.

Current Status in Carmarthenshire

Locally important reedbed sites occur around the Witchett Pool at Laugharne–Pendine Burrows, at Ffrwd Fen near Pinged and at Llangennech overlooking the Loughor estuary. A number of smaller (but collectively significant) examples also occur along the Llanelli coast, from Kidwelly to Bynea. In Carmarthenshire, eight SSSI include at least some reedbed habitat.

Carmarthenshire’s reedbeds support significant numbers of breeding reed warbler, sedge warbler, Cetti’s warbler and water rail.

Current Factors Affecting the Habitat

• Drainage for agriculture and water abstraction.
• Urban and/or industrial development.
• Lack of or inappropriate management, leading to scrub encroachment and succession to woodland.
• Pollution (toxic chemicals, eutrophication, siltation).

Fens

Fens are complicated peat-based wetlands which receive water and nutrients from both ground water and rainfall. There are two main types of fen habitat: topogenous fens which include basin and floodplain fens in which water movement is generally vertical; and soligenous fens such as flushes and valley mires where water movement is predominantly lateral.

Fens can also be described as 'poor-fens' or 'rich-fens' according to their chemical composition. The water moving through poor-fens is derived from base-poor, acidic rocks such as granite or sandstone. Such fens often occur in the uplands and they can also be associated with lowland heaths. They are typically acidic and are characterised by carpets of bog mosses (Sphagnum species). In contrast rich-fens are fed by calcareous waters and are mainly confined to lowland areas or to limestone areas in the uplands.

Fens can support a diverse range of plants and animals, particularly dragonflies and other aquatic invertebrates. Base-rich fens tend to be especially species-rich and are therefore of particular conservation interest.

Current Status in Carmarthenshire

In Carmarthenshire acid (poor-fen) flush occurs throughout the county, being especially widespread in the uplands and upland fringes. In contrast basic (rich-fen) flush is very rare. Some areas of valley mire occur around the upland fringes, but basin and floodplain mires are scarce. In Carmarthenshire, 15 SSSI include at least some fen vegetation.

Current Factors Affecting the Habitat

• Agricultural intensification and drainage.
• Abandonment or decline of management, including grazing or mowing, leading to scrub invasion.
• Excessive water abstraction from underground aquifers, leading to lowering of water tables and changes in hydrological regimes (not a significant factor in Carmarthenshire at present).
• Eutrophication, particularly from agricultural sources.
• Agricultural run-off and afforestation have affected valley fens in particular.

Lowland Raised Bog

Lowland raised bogs are a rare component of a Welsh peatland habitat, which have developed over thousands of years. They form on waterlogged ground in lowland areas such as the head of estuaries, on river floodplains and in depressions in the landscape. As plant material slowly degrades, peat accumulates pushing the bog surface above ground water level to form a characteristic gently curving dome. Since the bog surface is isolated from the influence of ground water, it receives water and nutrients exclusively from rainfall. The acidic peat which develops may attain a thickness of 10 or more metres, which contains a record covering many thousands of years of vegetation and climate change in the form of plant and animal remains and inorganic deposits. Once destroyed, this peat record can never be recreated.

Lowland raised bogs support a range of specialised plants, such as peat forming bog mosses (Sphagnum species), cross-leaved heath, heather and cotton grasses. A mosaic of pools, hummocks and Sphagnum lawns is often a feature of the raised bog surface. This variation in habitats (‘microtopography’) can give rise to a range of plant assemblages, each determined by the varying water regimes. Lowland raised bogs can also be of importance for birds and a number of uncommon invertebrate species are associated with this habitat.

The extent of lowland raised bog in the UK has declined dramatically over the past two centuries, mainly through drainage for agriculture and through afforestation and commercial peat extraction. Furthermore, much of the remaining resource has declined in condition.

Current Status in Carmarthenshire

Carmarthenshire is a significant area for lowland raised bog, containing three relatively intact sites. Cors Goch, Llanllwch to the west of Carmarthen is a particularly good example and an important site. This bog has various rarities such as the bog rosemary and insectivorous sundews. It is one of the few Welsh sites for the small red damselfly and the bog bush-cricket, and one of the few UK localities for the black bog ant.

There is also a degraded example at Gorslas, a damaged one (by peat digging) north of Hendy and two south-west of Carmarthen – the small Beacon Bog near Llangynog.

In Carmarthenshire all three intact raised bogs are notified as SSSI. Furthermore, parts of Cors Goch, Llanllwch and the raised bog system at Carmel are also a National Nature Reserve.

Current Factors Affecting the Habitat

The stability of lowland raised bogs is influenced by factors that either affect the rate of water loss from these waterlogged systems; raise the level of nutrients in the ecosystem, leading to changes in plant species growing there; or result in a loss of bog vegetation that would normally inhibit water loss. The following factors are likely to bring about such changes and harm raised bog systems:

• Agricultural practices - principally drainage, although under-grazing and over-grazing are also factors at some sites.
• Perimeter drainage.
• Water abstraction from underlying aquifers.
• Extraction of peat or underlying mineral resources.   
• Afforestation.
• Scrub encroachment, leading to a drying out of the bog surface.
• Human impacts - including landfill or reclamation for development.
• Pollution from adjacent land uses, such as landfill or agricultural run-off.
• Atmospheric nitrogen deposition and climate change are factors that might significantly impact upon raised bogs in future.

Coastal and Floodplain Grazing Marsh

Grazing Marsh is described as periodically inundated pasture or meadow, which is drained by a network of ditches to maintain water levels. They typically occur on low-lying coastal land – often reclaimed from tidal influence by sea defences – or along flat river floodplains.

Most grazing marshes consist of grassland that is either managed as pasture or cut for hay or silage. This grassland is often agriculturally improved, although stands of semi-natural grassland may occasionally be present. Other habitats such as open water, wet grassland and swamp can also occur.

The associated ditch systems contain either fresh or brackish water and are often of importance for plants, invertebrates and mammals, notably the rapidly declining water vole. Grazing marshes can also be important for breeding birds such as snipe, lapwing and curlew, whilst wintering wildfowl including Bewick and Whooper swans often occur in winter.

Current status in Carmarthenshire

The most important coastal grazing marshes in Carmarthenshire occur in the lower Gwendraeth and Pendine areas. The marshes here are relatively intact and consequently retain significant wildlife interest. The Pendine marshes, for example, are of particular importance for wintering golden plover and, at times, wintering lapwing. A formerly extensive area of grazing marsh also occurs along the Llanelli coast to the east, however much of this has been degraded or lost to urban and industrial development.  These areas make up the characteristic coastal floodplain area of this area of Carmarthenshire but were once inundated by the sea before being reclaimed for agriculture. The scarce black poplar is found here along with elms that have survived Dutch Elm disease.

The ditch systems around the Machynys and Bynea areas south-east of Llanelli are important for water voles, this being the most important areas for the species in West Wales. Little owls  Barn owls by night and kestrels by day hunt over the rough, rushy pastures on these coastal flats.

Floodplain grazing marsh occurs along the lower reaches of the main river valleys. The Afon Tywi supports the most extensive areas but significant stands also occur along the Loughor, Taf, Gwendraeth Fach and Gwendraeth Fawr.

In Carmarthenshire substantial areas of coastal grazing marsh lies within SSSIs.

Current Factors Affecting the Habitat

• Excessive drainage, resulting in the loss of associated wetland habitats
• Agricultural intensification, resulting in habitat loss and nutrient enrichment of watercourses.
• Industrial and/or urban development.
• Pollution of watercourses.