Traeth Pensarn

Also within

Clwyd County

Climate exposure

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

Habitats

Coastal vegetated shingle

Geology & landscape

Geological Period: Carboniferous · Rock Type: Carboniferous Limestone, Glacial Till, Limestone

Landscape processes: Coastal, Glacial

Description

Description Traeth Pensarn is of special botanical interest for its vegetated shingle beach plant communities. The site support both ‘pioneer’ and ‘stable vegetated’ shingle, extending approximately 1.7km along the Pensarn beach, from the promenade westward towards Llanddulas. Biology The shingle ridges of Traeth Pensarn are predominantly composed of locally derived Carboniferous Limestone together with a mixture of calcareous sand within the shingle and non-limestone material from the Irish Sea glacial till. Owing to the occasional movement of shingle and inundation by sea water during high tides and storms, many areas of the frontal ridge are relatively bare of vegetation. Interspersed within the storm crest shingle are characteristic ‘pioneer’ species such as yellow horned-poppy Glaucium flavum, curled dock Rumex crispus and the locally rare sea kale Crambe maritima. Regularly associated with these are plants such as sea fern-grass Catapodium marinum, sea beet Beta vulgaris ssp. maritima, sea campion Silene uniflora and sea mayweed Tripleurospermum maritimum. Where shingle has become buried in sand, species such as sea holly Eryngium maritimum, sand couch Elytrigia juncea lyme grass Leymus arenarius and sea sandwort Honckenya peploides are more typical. Inland of the storm crest, shallow ridges of shingle are covered by a fine veneer of sand with a relatively closed grassland vegetation sward. This ‘stabilised shingle’ is characteristically colonised by red fescue Festuca rubra, common restharrow Ononis repens, smooth hawk’s-beard Crepis capillaris, sea mouse-ear Cerastium diffusum, kidney vetch Anthyllis vulneraria, lady’s bedstraw Galium verum, sea radish Raphanus raphanistrum ssp. maritimus and yarrow Achillea millefolium. The stability of the shingle is further illustrated by the occurrence of sand loving bryophytes such as Tortula ruralis ruraliformis and Brachythecium albicans. Historically the Nationally Scarce oysterplant Mertensia maritima has occurred at the site. In front of the shingle bank, the foreshore is mostly composed of medium to coarse sand. Near shore rises of parallel sand banks are typically colonised by the isopod Eurydice pulchra and amphipods such as Bathyporeia sp. The rest of the mid and upper shore characteristically supports areas of lugworm Arenicola marina, whilst in wetter lower shore areas lugworm and sand mason worm Lanice conchilega are most abundant.

Species mentioned

Insects to look out for

These moths, butterflies and beetles are known to feed on plants recorded at this site, and carry a notable UK conservation status — but a host-plant being present doesn't mean the insect has actually been recorded here. Treat this as "worth watching for," not a confirmed sighting.

Host-plant data: Cook et al. (2025), Traits data for the butterflies and macro-moths of Great Britain and Ireland, 2024, UK Centre for Ecology & Hydrology / Butterfly Conservation; and Padovani et al. (2020), Database of Insects and their Food Plants (DBIF), UK Centre for Ecology & Hydrology (both Open Government Licence). Contains data supplied by UK Centre for Ecology & Hydrology.

Plant communities