Gro Ty'n Yr Helyg

Site of Special Scientific Interest · 52.3696, -4.0635

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Also within

Dyfed County

Climate exposure

This is about exposure to a nationwide pressure this habitat type carries — not a verdict on this site's own management.

Coastal

Coastal habitats are exposed to sea-level rise and storm erosion. Where hard sea defences sit behind them, there's nowhere landward to retreat to — a squeeze that keeps compressing the habitat no matter how well it's managed.

Habitats

Coastal vegetated shingle, Fast flowing river and stream, Mixed scrub, Montane scrub

Geology & landscape

Landscape processes: Coastal, Fluvial

Description

Description Ty’n yr Helyg is of special interest for its outstanding assemblages of invertebrate species associated with river shingle habitats. The site consists of a shingle bar on the Afon Ystwyth 1 km south-east of Llanfarian. The highly specialised fauna is known to include 8 Red Data Book (RDB) and 13 other nationally scarce species, making it one of the richest examples of a river shingle invertebrate assemblage known in the UK. Of particular interest is the endemic rove beetle Thinobius newberyi, occurring here at one of only three known localities. The shingle feature has developed around the inside of a meander on the north bank of the Afon Ystwyth. River action, including flood spates, has sorted the shingle into a range of sizes forming distinct bands of gritty sands, fine gravels and coarse pebbles. A few small, linear, semi-permanent pools are present within former river channels to the rear of the open shingle. The structural diversity is critical in providing a range of niches for the invertebrate inhabitants. Topographic variation also provides raised shoals above mean summer water levels. These form important refuges for invertebrates, allowing them to migrate up and down the shingle during spates. In addition to T. newberyi other RDB species are the beetles Lionychus quadrillum, Bidessus minutissimus, Lathrobium dilutum, Neobisnius prolixus, Stenus incanus, Brachygluta pandellei and the five-spot ladybird Coccinella quinquepunctata, the last a characteristic member of river shingle environments in Ceredigion. T. newberyi has not been seen outside Wales since the 1930s, despite repeated searches of former localities, and was thought extinct until discovered on the Ystwyth and Rheidol in 1987. It is also known from a single locality on the Afon Tywi. The large and spectacular wolf spider Arctosa cinerea, resident at a number of shingle sites along the Afon Ystwyth, has been recorded. Other noteworthy members of the shingle fauna include the rove beetles Deleaster dichrous and Hydrosmecta subtilissima, the click beetle Fleutiauxellus maritimus, the money spider Caviphantes saxetorum and the dance fly Tachydromia halidayi. Away from the river a broad hinterland of infrequently inundated coarse grassland and closed scrub, dominated by common gorse Ulex europaeus, has colonised older deposits of stable shingle. This marginal vegetation forms an integral component of the invertebrate habitat functioning as a refuge for insects during flash floods at any time of year and providing daytime-retreats for nocturnal foragers as well as places for hibernation in winter. The five-spot ladybird Coccinella quinquepunctata is frequently encountered hunting aphids on broom Cytisus scoparius bushes and occasionally on other vegetation such as black knapweed Centaurea nigra and thistles Cirsium spp.. This ladybird can occasionally be found on bare shingle. Otters Lutra lutra are known to regularly frequent this stretch of the Afon Ystwyth. Water voles Arvicola amphibius also occur. Remarks: Otter Lutra lutra and water vole Arvicola amphibius are listed in Schedule 5 of the Wildlife and Countryside Act 1981 (as amended) and Otter additionally in Annexes II and IV of the European Council Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora.

Species mentioned

English name
search for this in other sites		 Latin name
search with Google		 IUCN / Red List Type Family
Hydrosmecta subtilissima Not listed in GB list beetle staphylinidae
Neobisnius prolixus LC beetle staphylinidae
ladybird Scymus schmidti Not listed in GB list beetle ladybird coccinellidae
5 spot ladybird Coccinella quinquepunctata Not listed in GB list beetle ladybirds coccinellidae
no common name Deleaster dichrous LC beetle rove staphylinidae
otter Lutra lutra LC carnivore mustelidae
black knapweed Centaurea nigra LC herb asteraceae
water vole Arvicola amphibius EN rodent cricetidae
broom Cytisus scoparius LC shrub fabaceae
gorse Ulex europaeus LC shrub leguminosae
grey wolf spider Arctosa cinerea LC spider wolf lycosidae

Plant communities

A9 — Fast flowing river and stream, Marginal and inundation, Pond ditch and canal, Sluggish river and stream

Potamogeton natans community

Schoenoplectus lacustris, Juncus bulbosus, Sparganium angustifolium, Sparganium erectum, Sparganium minimum, Alisma plantago-aquatica, Lobelia dortmanna, Equisetum fluviatile, Myriophyllum alterniflorum, Elodea canadensis, Lemna minor, Lemna trisulca, Nymphaea alba, Callitriche platycarpa, Callitriche stagnalis, Littorella uniflora, Potamogeton natans, Ranunculus trichophyllus, Glyceria fluitans, Chara subspinosa

A14 — Fast flowing river and stream

Myriophyllum alterniflorum community

Isolepis fluitans, Juncus bulbosus, Fontinalis antipyretica, Lobelia dortmanna, Equisetum fluviatile, Myriophyllum alterniflorum, Lemna minor, Callitriche stagnalis, Littorella uniflora, Potamogeton filiformis, Potamogeton gramineus, Potamogeton natans, Ranunculus peltatus, Chara spp., Nitella hyalina

A17 — Chalk river and stream, Fast flowing river and stream

Ranunculus penicillatus ssp. pseudofluitans community

Berula erecta, Nasturtium officinale, Elodea canadensis, Lemna minor, Callitriche stagnalis, Veronica beccabunga, Polygonum amphibium, Polygonum hydropiper, Potamogeton crispus, Potamogeton pectinatus, Ranunculus penicillatus ssp. pseudofluitans

A18 — Fast flowing river and stream

Ranunculus fluitans community

Fontinalis antipyretica, Fontinalis squamosa var. curnowii, Myriophyllum alterniflorum, Myriophyllum spicatum, Elodea canadensis, Mentha aquatica, Lemna gibba, Lemna minor, Potamogeton perfoliatus, Ranunculus fluitans, Glyceria fluitans, Phalaris arundinacea

MC6 — Coastal vegetated shingle, Hard cliff and cliff slope

Atriplex prostrata-Beta vulgaris ssp. maritima sea-bird cliff community

Daucus carota, Sonchus oleraceus, Taraxacum officianalis, Tripleurospermum maritimum, Cochlearia officinalis, Silene uniflora, Spergularia rupicola, Atriplex hastata, Malva arborea, Plantago coronopus, Armeria maritima, Polygonum aviculare, Rumex crispus, Bromus hordeaceous, Catapodium marinum, Dactylis glomerata, Festuca rubra

SD1 — Coastal vegetated shingle, Sand dune

Rumex crispus-Glaucium flavum shingle community

Solanum dulcamara, Crithmum maritimum, Cirsium arvense, Cirsium vulgare, Helminthotheca echioides, Hypochaeris radicata, Jacobaea vulgaris, Lactuca serriola, Leontodon saxatilis, Senecio viscosus, Sonchus arvensis, Sonchus asper, Tripleurospermum maritimum, Crambe maritima, Cerastium fontanum, Honckenya peploides, Sagina apetala, Silene uniflora, Atriplex prostrata, Sedum acre, Euphorbia paralias, Lathyrus japonicus, Geranium robertianum, Glaucium flavum, Plantago coronopus, Plantago lanceolata, Rumex crispus, Potentilla anserina, Ammophila arenaria, Arrhenatherum elatius, Elytrigia atherica, Elytrigia juncea, Festuca rubra, Holcus lanatus, Lolium perenne

SD2 — Coastal vegetated shingle, Sand dune

Honkenya peploides-Cakile maritima strandline community

Salsola kali, Achillea millefolium, Cirsium arvense, Eryngium maritimum, Hypochaeris radicata, Senecio vulgaris, Sonchus arvensis, Tripleurospermum maritimum, Cakile maritima, Cerastium diffusum, Honckenya peploides, Silene uniflora, Stellaria media agg., Atriplex glabriuscula, Atriplex laciniata, Atriplex littoralis, Atriplex patula, Atriplex prostrata, Sedum acre, Polygonum oxyspermum subsp. Raii, Rumex crispus, Potentilla anserina, Agrostis stolonifera, Ammophila arenaria, Arrhenatherum elatius, Elytrigia juncea, Elytrigia repens, Festuca rubra, Leymus arenarius, Poa annua

SD3 — Coastal vegetated shingle, Sand dune

Matricaria maritima-Galium aparine strandline community

Bolboschoenus maritimus, Juncus bufonius, Juncus gerardii, Ligusticum scoticum, Matricaria discoidea, Sonchus arvensis, Sonchus asper, Tripleurospermum maritimum, Mertensia maritima, Cakile maritima, Cochlearia officinalis, Honckenya peploides, Stellaria media agg., Atriplex glabriuscula, Atriplex patula, Atriplex prostrata, Triglochin maritimum, Plantago maritima, Armeria maritima, Rumex crispus, Glaux maritima, Galium aparine, Agrostis stolonifera, Elytrigia repens, Festuca rubra, Holcus lanatus, Leymus arenarius, Poa annua

W20 — Montane scrub

Salix lapponum-Luzula sylvatica scrub

Salix arbuscula, Salix cinerea, Salix lapponum, Salix myrsinites, Salix phylicifolia, Salix reticulata, Empetrum nigrum, Calluna vulgaris, Salix lanata, Vaccinium myrtillus, Vaccinium uliginosum, Carex atrata, Carex bigelowii, Carex binervis, Carex flacca, Luzula multiflora, Luzula sylvatica, Huperzia selago, Selaginella selaginoides, Aulacomnium palustre, Mnium hornum, Philonotis fontana, Plagiomnium undulatum, Rhizomnium punctatum, Dicranum bonjeanii, Dicranum majus, Dicranum scoparium, Fissidens adianthoides, Racomitrium lanuginosum, Calliergonell cuspidatum, Ctenidium molluscum, Hylocomium splendens, Hypnum callichroum, Hypnum cupressiforme, Palustriella commutatum, Plagiothecium denticulatum, Plagiothecium undulatum, Pleurozium schreberi, Ptilium crista-castrensis, Rhytidiadelphus loreus, Rhytidiadelphus squarrosus, Rhytidiadelphus triquetrus, Sanionia uncinata, Scorpidium revolvens, Thuidium tamariscinum, Atrichum undulatum, Polytrichastrum alpinum, Sphagnum capillifolium, Sphagnum fallax, Sphagnum girgensohnii, Sphagnum palustre, Sphagnum russowii, Sphagnum squarrosum, Sphagnum subnitens, Sphagnum teres, Barbilophozia barbata, Chiloscyphus polyanthos, Diplophyllum albicans, Lophocolea bidentata, Plagiochila porelloides, Ptilidium ciliare, Scapania undulata, Cladonia squamosa, Peltigera canina, Angelica sylvestris, Caltha palustris, Hieraclium spp., Saussurea alpina, Solidago virgaurea, Campanula rotundifolia, Succisa pratensis, Valeriana officinalis, Rhodiola rosea, Vaccinium vitis-idaea, Thymus praecox, Epilobium anagallidifolium, Dactylorhiza viridis, Euphrasia officinalis, Rhinanthus minor, Oxalis acetosella, Oxyria digyna, Polygonum viviparum, Rumex acetosa, Anemone nemorosa, Ranunculus acris, Thalictrum alpinum, Alchemilla alpina, Alchemilla glabra, Filipendula ulmaria, Geum rivale, Galium boreale, Galium saxatile, Saxifraga aizoides, Saxifraga hypnoides, Saxifraga oppositifolia, Saxifraga stellaris, Viola riviniana, Agrostis canina, Agrostis capillaris, Anthoxanthum odoratum, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Nardus stricta, Dryopteris dilatata, Phegopteris connectilis

W21 — Hedgerow scrub, Mixed scrub

Crataegus monogyna-Hedera helix scrub

Hedera helix, Salix cinerea, Acer pseudoplatanus, Ilex aquifolium, Betula pendula, Corylus avellana, Fagus sylvatica, Quercus robur, Fraxinus excelsior, Malus sylvestris, Sorbus aria, Taxus baccata, Ulmus glabra, Ulmus procera, Sambucus nigra, Viburnum lantana, Euonymus europaeus, Cornus sanguinea, Juniperus communis, Ligustrum vulgare, Clematis vitalba, Rhamnus cathartica, Crataegus laevigata, Crataegus monogyna, Prunus spinosa, Juncus effusus, Plagiomnium undulatum, Brachythecium rutabulum, Kindbergia praelonga, Rhynchostegium confertum, Tamus communis, Heracleum sphondylium, Torilis japonica, Arum maculatum, Arctium minus, Cirsium arvense, Lonicera periclymenum, Moehringia trinervia, Silene dioica, Stellaria graminea, Stellaria holostea, Stellaria media agg., Calystegia sepium, Mercurialis perennis, Geranium robertianum, Iris foetidissima, Glechoma hederacea, Lamium purpureum, Origanum vulgare, Stachys sylvatica, Teucrium scorodonia, Allium ursinum, Hyacinthoides non-scripta, Circaea lutetiana, Rumex sanguineus, Anemone nemorosa, Ranunculus repens, Fragaria vesca, Geum urbanum, Potentilla sterilis, Poterium sanguisorba, Rosa arvensis, Rosa canina, Rubia peregrina, Rubus fruticosus agg., Galium aparine, Urtica dioica, Viola riviniana, Anisantha sterilis, Arrhenatherum elatius, Brachypodium pinnatum, Brachypodium sylvaticum, Bromopsis erecta, Dactylis glomerata, Elytrigia repens, Holcus lanatus, Holcus mollis, Poa trivialis, Asplenium scolopendrium, Pteridium aquilinum, Dryopteris filix-mas

W22 — Hedgerow scrub, Mixed scrub

Prunus spinosa-Rubus fruticosus scrub

Hedera helix, Acer campestre, Corylus avellana, Ulex europaeus, Prunus spinosa, Plagiomnium undulatum, Brachythecium rutabulum, Eurhynchium striatum, Kindbergia praelonga, Thuidium tamariscinum, Atrichum undulatum, Lophocolea bidentata, Achillea millefolium, Cardamine flexuosa, Lonicera periclymenum, Moehringia trinervia, Silene dioica, Silene uniflora, Stellaria media agg., Mercurialis perennis, Geranium robertianum, Stachys sylvatica, Teucrium scorodonia, Hyacinthoides non-scripta, Oxalis acetosella, Digitalis purpurea, Plantago lanceolata, Veronica chamaedrys, Armeria maritima, Rumex acetosa, Filipendula ulmaria, Geum urbanum, Rosa canina, Rubus fruticosus agg., Rubus idaeus, Galium aparine, Urtica dioica, Viola riviniana, Agrostis capillaris, Brachypodium sylvaticum, Dactylis glomerata, Festuca rubra, Holcus lanatus, Holcus mollis, Poa trivialis, Asplenium scolopendrium, Pteridium aquilinum, Dryopteris borreri, Dryopteris filix-mas