Coastal Vegetated Shingle

Although limited in their range across the globe, shingle beaches are widely distributed around the coast of the UK, where they develop in ‘high-energy’ environments. Most examples consist of simple fringing beaches within the reach of storm waves, where the shingle remains mobile and any vegetation is restricted to temporary strandline communities. In contrast, vegetated shingle structures above the reach of wave action are rare, and support specialised communities of plants and invertebrates.

The typical vegetation of shingle structures consists of pioneer species on the seaward edge, which are able to withstand exposure to salt spray and a degree of burial and erosion. Further from the shore more stable vegetation develops, including a range of grassland, lowland heath, moss and lichen communities. Shingle structures may also support colonies of breeding birds including gulls, waders and terns. Diverse invertebrate communities also occur, with certain species entirely restricted to shingle habitats.

Current Status in Carmarthenshire

Two coastal vegetated shingle structures occur in Carmarthenshire: at Penrhyngwyn, Machynys to the south of Llanelli, and Morfa Bychan to the west of Pendine.

The structure at Penrhyngwyn consists of approximately 0.25 km of shingle beach. It is the remnant of a once larger shingle spit, much of which has now been modified or destroyed by sea defence works and industrial dumping. What remains, however, is of considerable interest for its vegetation and invertebrates. Plants of note include the Nottingham catchfly Silene nutans and yellow horned-poppy Glaucium flavum. It is also one of only two Welsh sites for the specialist millipede Thalassisobates littoralis and several other uncommon invertebrates have been recorded.

Morfa Bychan is a small shingle bay head beach and is noteworthy for the presence of sea stork’s-bill Erodium maritimum, which is rare in the county.

Both Carmarthenshire examples lie within larger SSSIs.

Current factors affecting the habitat

• Sediment supply – necessary for future growth of the habitat (this may occur sporadically in response to storm events rather than as a continuous process).
• Natural mobility – many shingle structures exhibit significant movements over time in response to natural coastal processes.
• Exploitation – many larger shingle structures have been used for aggregate extraction; others have also been subject to industrial and/or housing development.
• Coastal defences – can cause significant modifications to shingle structures and interrupt natural coastal processes.
• Access and recreation – shingle structures are fragile habitats and are susceptible to damage through inappropriate recreational use and, in particular, vehicular use; breeding birds are also susceptible to disturbance.
• Rising sea levels – could have a future impact, particularly if associated with increased storminess.

Coastal Saltmarsh

Coastal saltmarshes comprise the upper, vegetated parts of intertidal mudflats, located between mean high-water neap tides and mean high-water spring tides. Saltmarshes require a net accumulation of sediment and shelter from strong wave action. Many are therefore found in sheltered estuarine situations.

Many of the plants that occur in saltmarshes are halophytic (salt-tolerant) and are adapted to regular immersion by the tides. They typically exhibit a zonation determined by the frequency of immersion that particular species can tolerate. Although plant species diversity tends to be low, in Wales about 50 saltmarsh species are considered to be nationally rare or scarce.

Saltmarshes provide important high tide roosting areas for wading birds and wildfowl feeding on adjacent mudflats. They also act as breeding sites for a variety of species and provide winter feeding grounds for large flocks of wild duck and geese. Saltmarsh and saltmarsh transition zones, particularly where freshwater seepages occur, can support a number of uncommon invertebrate species. Saltmarshes also provide sheltered nursery sites for several species of fish.

Coastal saltmarshes are dynamic systems which typically experience natural fluctuations, especially along the mobile seaward edge. Erosion and accretion in response to natural coastal processes is therefore a characteristic feature of saltmarsh habitats. Despite their dynamic nature, however, saltmarshes often provide an effective means of dissipating wave energy and thus can play a significant role in coastal defence.

Current Status in Carmarthenshire

One of the most important areas for this habitat in Wales is the Carmarthenshire coast and the Burry Inlet, which supports the second largest continuous stand of saltmarsh in the UK, only the Wash having a larger area. The Tywi, Taf and Gwendraeth estuaries also hold significant areas of saltmarsh.

Of the various saltmarsh communities identified in Carmarthenshire, there is a particularly good representation of the internationally important ‘Atlantic salt meadow’ type. Ungrazed saltmarsh, itself a scarce resource, is also well represented on the Taf and Gwendraeth estuaries.

The Carmarthen Bay and Estuaries Special Area of Conservation, includes the Burry Inlet and the Taf, Tywi and Gwendraeth estuaries, has been designated partly because of its saltmarsh habitat. A Carmarthen Bay and Estuaries cSAC Relevant Authorities Group has been established to deliver the conservation objectives of the site.

A Shoreline Management Plan has been developed for the Carmarthen Bay coast, which recognizes the environmental value of Carmarthenshire’s saltmarsh systems, as well as their potential role in coastal defence. This is being reviewed at the moment.

The various saltmarsh sites in the county are grazed to varying degrees, producing a diversity of vegetation structure.

Current Factors Affecting the Habitat

• Land reclamation for both industrial and agricultural development.
• Erosion and accretion – both of these processes can affect saltmarsh sites, although there is a net loss of saltmarsh in the UK at present.
• Coastal defence works can affect local sedimentation patterns.
• Heavy grazing affects the structure and composition of saltmarsh vegetation, resulting in a short homogenous sward. This, however, can be attractive to wintering waders and passage wildfowl and waders. A tussocky structure resulting from less intensive grazing favours breeding waders.
• Agricultural improvement has affected the upper parts of certain saltmarsh sites.
• Eutrophication from fertilizer run-off or sewage can also lead to algal growth on saltmarshes.
• Spread of the invasive cord-grass Spartina anglica.
• Damage from human activities such as pollution (including oil pollution), fly tipping and military use.

Maritime Cliff and Slope

Sea-cliffs occur where the land and the sea meet, and such habitats (and associated slope) are primarily concentrated in area of harder lower Palaeozoic rocks in the north and west of Britain. However, ‘soft-cliff’ habitats also occur and are of considerable value for wildlife.

The vegetation of maritime cliff and slope varies according to several factors: the extent of exposure to wind and salt spray, the chemistry of the underlying rock, the water content and the stability of the substrate. A range of habitats may develop including lichen communities, grassland communities, heath and scrub and even stunted woodland.

Current Status in Carmarthenshire

A high proportion of Carmarthenshire’s coastline is dominated by sand dune, whilst the built up south-east corner is fringed by man-made sea defences. Although fossil cliff lines (e.g. east of Pendine) may occur behind the dunes and other habitats, there are two main cliff and slope concentrations in the county:

• The Old Red Sandstone cliffs west of Llansteffan, between the mouths of the Rivers Tâf and Tywi; with a minor outlier south of Ferryside.
• The more extensively cliffed areas along the Amroth–Marros–Pendine length of coast.

Unlike Pembrokeshire, our cliffs are not home to colonies of seabirds, but on cliff sections such as west of Pendine and on the Llansteffan Peninsula there are scatterings of gulls, fulmars and the predatory peregrine. However there are plants of distinction such as the native maiden-hair fern on a tufa-cliff near Craig Ddu.

The Craig Ddu–Wharley Point (biological) SSSI (part owned by the National Trust) and Creigiau Llansteffan GCR site occur near Llansteffan, whilst Marros–Pendine Coast SSSI (mixed biological/GCR interest) occupies a considerable length of the county’s western cliffline.

Current Factors Affecting the Habitat

In terms of extent, this habitat is not threatened. However, there has been deterioration in the quality of cliff and grassland (and consequent loss of dependent species) due to a cessation of former agricultural use, i.e. grazing. This has led to the replacement of flower-rich cliff top grassland by scrub or rank grasses. In all areas, plants of early successional or semi-xerophytic (dry-high sunshine) conditions, assemblages of scarce aculeates (bees and wasps) and ants - as well as the open, grazed feeding territories of chough, would have been adversely impacted.

Coastal Sand Dunes

Coastal sand dunes develop where there is a sufficient supply of sand in the intertidal zone to form a beach plain, the surface of which dries out between tides. The dry sand is blown landward and deposited above the high tide mark, where it can be trapped by specialised dune-building grasses, before eventually being colonised by more stable plant communities.

Wales is particularly important for western calcareous dune systems and the prevailing westerly winds have produced some outstanding hindshore systems. These form where large quantities of sand are driven inland over a low-lying terrain. Other dune systems include bay dunes, where a limited sand supply is trapped between two headlands, and spit dunes which form as sandy promontories at the mouth of estuaries.

Sand dune systems are typically composed of a number of different zones, including embryonic and mobile dunes, semi-fixed dunes, fixed dune grassland and dune slacks (which occupy damp depressions between dune ridges). Dune heaths can also develop where the ground surface becomes acidified through leaching.

Sand dune systems, especially calcareous ones, can support an extremely diverse range of plants and animals and provide a habitat for a variety of specially adapted species, including a number of uncommon plants, fungi and invertebrates.

Sand dunes are dynamic systems which often exhibit significant natural movements. Such mobility is intimately linked to natural coastal processes including erosion and accretion. The most important sand dune systems are typically those which display full and uninterrupted ecological zonations, particularly along the often highly mobile seaward edge, where natural geomorphological processes can freely operate.

Current Status in Carmarthenshire

Carmarthenshire has more dunes than nearly all of the other Welsh counties. Two major sand dune systems occur, namely Laugharne–Pendine Burrows and the Pembrey Coast SSSI; there are also smaller examples at Llansteffan, Ferryside, Burry Port and Llanelli. Historically, these would have been grazed – indeed the dunes at Pembrey for example, once held profitable flocks of many thousand sheep, as well as some cattle and horses. Because of this cessation of grazing – principally in the 1920s at Pembrey when a start was made on planting the area with conifers, and as late as just before World War II at Pendine – the vegetation has become considerable ranker. Not only has the invasive sea buckthorn spread, but other trees and shrubs, coarse grasses and perennials changed of the rather bare open habitats favoured by such rarities as the fen orchid. The once present fen orchid is now extinct at Pembrey and virtually so at Pendine, though discussions to initiate management are still on-going at both sites.

Nevertheless, the dunes are still exceedingly rich in wildlife, with a range of habitats represented from the foreshore, through wet dune slacks (‘hollows’) to young alder, willow and birch woodland. Hares still have a stronghold on the open areas (and, incidentally, also in the open rides of Pembrey Forest), whilst a rare beetle Panageus crux-major was discovered at Tywyn Point in 1985. Many other rare or scarce invertebrates have been found in Carmarthenshire’s dune systems – with marsh fritillaries in wet slacks at RAF Pembrey and over 30 species of butterfly seen on the same duneland area. Marbled whites are a typical species, but there are also small blues, grizzled skippers and the brown argus. Orchids grow in these wet slacks, with different species of orchid and other flowering plants on the drier dune grasslands.

Grazing  has been introduced at Laugharne–Pendine Burrows and Pembrey  and sea buckthorn clearance has already been carried out at Pembrey.

A Shoreline Management Plan has been developed for the Carmarthen Bay coast, which recognizes the environmental value of the Laugharne–Pendine and Pembrey dune systems. The plan recommends that, in the main, natural coastal processes should be allowed to continue at both sites.

Mechanical beach cleaning is currently restricted to just a short section of Pembrey, where recreational use is highest.

A large proportion of the UK sand dune resource is also notified as Sites of Special Scientific Interest (SSSI). Again both Laugharne–Pendine Burrows and Pembrey are afforded SSSI status. Furthermore part of Pembrey is also designated as a Local Nature Reserve (LNR).

Current Factors Affecting the Habitat

• Erosion and accretion. The seaward edges of sand dunes can be highly mobile and most sand dunes systems in the UK are displaying net erosion. Insufficient sand supply and adverse weather patterns are frequently the underlying causes of sand dune erosion.
• Grazing. Grazing is necessary to maintain fixed dune communities.  Undergrazing results in the spread of coarse grasses and eventual succession to scrub and woodland. Conversely overgrazing can be damaging to fixed dune grassland and heath.
• Recreation. Damage to sand dunes can arise through excessive pedestrian and, especially, vehicular use. Loss of habitat can also occur through golf course developments.
• Sea defence and stabilization. Practices such as sand fencing and marram grass planting are frequently used to stabilize eroding dunes where a threat to adjacent land uses is perceived. Such measures can greatly affect the natural dynamics of dune systems, often resulting in the loss of mobile dune phases.
• Beach management. Mechanical beach cleaning can result in the damage or removal of pioneer dune stages and associated specialist species.
• Forestry. As well as the direct loss of habitat, forestry plantations on dune systems can result in a lowering of the water table and consequent loss of dune slacks.
• Sea buckthorn. Although sea buckthorn is native to eastern England and south-east Scotland, this shrub has been widely introduced at sand dune sites elsewhere, where subsequent invasion has often been a problem.
• Other human influences. Sand dunes have in the past been affected by housing and industrial developments, waste tips, fly tipping and sand extraction. Rising sea levels is likely to become an increasingly significant factor in the future, while the disruption of coastal processes through marine dredging is another potential factor.