Coastal Vegetated Shingle Structures of Great Britain: Appendix 1

Coastal vegetated shingle structures

of Great Britain:

Appendix 1. Shingle sites in Wales

P. Sneddon & R.E. Randall

Girton College Cambridge

March 1993

ISBN 1 873701 30 6 Full set ISBN 1 873701 15 2 Main report ISBN 1 873701 16 0 Appendix 1. Wales ISBN 1 873701 17 9 Appendix 2. Scotland ISBN 1 873701 18 7 Appendix 3. England

Design: Nick Davidson, JNCC Cover design: Nature Conservation Bureau Ltd.

Originally printed by: Lake-Shore Graphics, Nottingham.

Converted to digital format from the original by GeoData Institute, University of Southampton: 2009

2 Contents

Page No.

Preface - JNCC's coastal survey programme 5

Background 6 Acknowledgements 7 Introduction 8 Methods 9 Introduction to Welsh shingle sites 12 Site reports 14 17 Llanddulas 19 Gronant 20 Red Wharf Bay 21 Traeth Dulas 24 Cemlyn Bay 26 Dinas Dinle 29 Pontlyfni 30 Aberdesach 31 Afon Dwyfor 33 Pen-y-chain 36 Criccieth 39 Aber Dysynni 43 Traeth Tanybwlch 46 Crabhall Saltings 48 Pennard Burrows 51 Pwll du 54 East Aberthaw Porthkerry

References 56

4 Preface - JNCC's coastal survey programme

The work reported here was originally Branch of the Joint Nature Conservation commissioned by the Coastal Ecology Committee's support unit and the results Branch of the Nature Conservancy are being published as part of the Council's Chief Scientist Directorate in Branch's publication programme. 1987. The survey forms part of an attempt to describe the size, location and This report provides a classification of quality of the main coastal habitats in the main shingle plant communities found Great Britain (saltmarshes, sand dunes, on stable or semi-stable shingle structures vegetated shingle, sea cliffs, strandlines, in Great Britain. It does not attempt to 'reclaimed1 land and maritime islands). provide an assessment of the comparative nature conservation values of the sites The collection of basic data on the main surveyed. The more detailed descriptions coastal habitats is an important first step presented as appendices to the main in identifying the most important sites, report can be used to provide a first establishing a basis for monitoring and indication of importance in relation to the understanding the impact of management size of site and the number and operations and major development representation of the plant communities. projects on them. Further information can be obtained A survey of saltmarshes in Great Britain from: was completed in 1991 and surveys of the majority of sand dune sites in Dr J.P. Doody. Coastal Conservation England and Wales, and a selection of Branch, Joint Nature Conservation the most important in Scotland, have Committee, Monkstone House, City been completed. Responsibility for Road, Peterborough, PE1 1JY, UK. completing the existing round of survey passed to the Coastal Conservation

5 Background

A survey of shingle structures in Great conducted within the framework of the Britain was initiated in 1987 under National Vegetation Classification (NVC) contract to Girton College, Cambridge in order to assess the applicability of from the Nature Conservancy Council. existing NVC categories to the shingle communities and, where appropriate, to This research project provides: extend the NVC by highlighting any new communities identified. At the start of a. an overall report which combines all the project only one community was data in order to determine which plant specifically attributed to the shingle communities are found on shingle at a substrate - SD1, within which two sub- national level, and how these relate to communities had been recognised. This existing NVC categories; and reflected the limited data supply for the shingle substrate at that time. b. written descriptions and maps of the major plant communities at each site The main report provides a summary surveyed, which are collated into classification which is discussed more regional reports for Wales, Scotland fully in the detailed account of Sneddon and England; (1992). This report on the sites in Wales forms Appendix 1 to the main report This report gives a preliminary (Sneddon & Randall 1993). Further description of the results of site surveys reports are Appendices giving site conducted in Wales. It forms part of the descriptions for Scotland and Wales. wider study of the vegetation of shingle structures in Britain. This work has been

Acknowledgements

The production of this report would have Cemlyn Bar Nature Reserve during the been impossible without the cooperation site visit. of all regional staff in North Wales, Dyfed/Powys, and South Wales regions. Finally, many thanks to Ian Agnew and In each case help was given in the the Cambridge Geography Department identification of sites and in obtaining Drawing Office who produced the base permission for access to those sites for maps for this report. fieldwork.

Thanks should also be offered to The P. Sneddon North Wales Naturalists' Trust who R.E. Randall allowed access to restricted areas of

6 Introduction

The term shingle may be applied to any beaches. The first has been mentioned sediment which has a mean grain size of earlier, the mobility of the beach. between 2 and 200 mm. Sediments below Clearly, if a beach is highly mobile then that size are termed sand, silt or clay, a seed is likely to be washed away before according to mean grain size, while it is able to germinate and so the particles of a diameter greater than 200 mm frequency of inundation of a site will are termed boulders. This empirical have an important influence on the distinction reflects a biological distinction vegetation of that site. Indeed, this factor based on environmental factors such as was recognised by Scott (1963) in his moisture content which lead to differing classification of vegetation on shingle habitats associated with each sediment. which divides shingle vegetation into five categories according to the stability of Shingle may occur as a riverine sediment sites. but in the UK it is most commonly found in marine environments around the coast. A second factor determining the Indeed, approximately one third of the establishment of vegetation on shingle is coastline of England and Wales is bordered the presence of a fine matrix in the by shingle. This marine sediment may have shingle (Fuller 1987). The nature of the been derived from three major sources: fine matrix has been shown to influence the type of vegetation with four types of a. by rivers transporting shingle to the shingle substrate identified by Scott coast; (1963); pure shingle, shingle with a sand admixture, shingle with silt and, finally, b. as glacial sediments deposited offshore shingle with wrack (rotting seaweed). which have been reworked with rising sea levels to be deposited along the The final factor influencing the presence coast; and finally, of vegetation on a shingle beach is the hydrological properties of the shingle. c. shingle may result from active erosion Clearly, shingle has a high porosity and of existing coastal cliffs such as the low water retention. However, this is flint shingle derived from chalk cliffs overcome to some extent by the presence found along much of the south coast. of a fine matrix which serves as a reservoir of water, which is critical at the Five types of shingle beach have been germination stage of seed development. recognised (Sparks 1972, Chapman Once established, the vegetation relies on 1976): adaptations to drought conditions in the form of thick leaf cuticles and the a. fringing beaches; mulching effect of wetter shingle by dry b. spits; shingle layers above to provide an c. bars; adequate water supply (Fuller 1987). d. apposition beaches/cuspate forelands; e. barrier islands. To sum up, the establishment and maintenance of a permanent flora on These categories vary according to their shingle beaches is dependent upon the mobility and oceanicity and they, mobility, matrix characteristics and therefore, offer different habitats. moisture conditions of that beach. It has been shown by Randall (1977) that For a more detailed introduction see the three key factors are required to enable final report (Sneddon & Randall 1993). the establishment of vegetation on shingle

7 Methods

Each site was surveyed within the biological, which may provide a useful framework of the National Vegetation supplement to the quadrat data collected Classification (NVC). The field in terms of the analysis of community techniques were based, therefore, on types. those outlined in the NVC field manual. Site data, such as land use and any Individual sites were identified from forms of disturbance, were collected at habitat maps held by the Nature each site, while additional site Conservancy Council (NCC), through information such as % SSSI coverage consultation with the then Chief and past land use were recorded, based Scientist Directorate of NCC, and, at a on information collected prior to local level, with the NCC regional fieldwork. staff. Clearly, not all shingle sites fall into the category of shingle structures. The quadrat data were entered onto a Equally, not all shingle sites are computer which organised them into vegetated, e.g. Hell's Mouth. Some classificatory units to be used for sites have, therefore, not been included mapping. The programmes used were in this survey. In addition, time TWINSPAN and TWINTAB as constraints led to concentrating on the specified by the NVC. These packages survey of the vegetation of larger sites. combine quadrats of similar floristic composition into groups and these Sites were firstly surveyed by eye to groupings were then compared with identify stands of homogeneous those already identified by the NVC vegetation to be used as mappable keys and tables. These units were then units. Within these stands, vegetation used for mapping. was sampled using a 4x2 m quadrat, found to be the most appropriate size Two methodologies for mapping in the for the vegetation types encountered, field were employed according to the and consistent with the quadrat size availability of aerial photographs. previously adopted at other shingle sites Where such photographs were readily (Ferry & Waters 1985; Ferry et al available at a suitable scale, these 1990). Wherever possible, a minimum would be used to map units in the field. of five quadrats was placed in each However, availability was rather stand of vegetation, however, in some limited and the second method was cases time constraints permitted only most commonly adopted. This method one sample per stand. involved sketching units onto an enlarged 1:10000 map of the sites, on All species of vascular plants, which the position of individual bryophytes and lichens (excluding quadrats was marked. The preliminary saxicolous lichens) were recorded for mapping was used in conjunction with each quadrat and each species' the classification provided by abundance/cover measured using the TWINSPAN to allow more accurate Domin scale. In addition, soil depth mapping onto a final map. and pH were noted, along with the vegetation height and evidence of Fieldwork on Welsh sites was grazing. conducted between May and August 1989. Target notes were used to describe any features of interest, either physical or Nomenclature follows Clapham, Tutin & Moore (1987).

8 Introduction to Welsh sites

Much of the Welsh coast is bordered by Penmaenmawr - a newly constructed shingle deposits; however, in many cases promenade, covering a potential area of the geomorphology of the coastline stable shingle, had been opened the day precludes the formation of major shingle before fieldwork at that site was due to structures, with development often commence. restricted to simple fringing beaches. The north Welsh coast is generally In many cases the Welsh shingle is found fringed by glacial deposits, alluvium or with varying amounts of sand admixed, aeolian sand. Shingle is found in whereas in others the shingle provides a association with large quantities of skeleton for the growth of sand dunes, aeolian sand at Gronant. At the actively e.g. Traeth Dulas on Anglesey. growing eastern end of the spit the shingle remains visible in the sand but The distribution of vegetated shingle moving westward the sand cover structures in Wales is largely controlled increases to form a large dune system. by the presence of a suitable supply of shingle and the amount of sand available Further west, around Abergele and (if too great it leads to sand capping thus Llanddulas a drift terrace built up against masking the shingle below) and, finally, pre-glacial cliffs is identified by Steers by the configuration of the coastline such (1964) as being the source of shingle for that wave and tidal conditions favour the beaches which have formed in the deposition of shingle structures. area. For descriptive purposes the coast may There is some controversy concerning the be divided into three major components: origin of the shingle along this coast. The the north coast including Anglesey and distribution of shingle east of the Clwyd the north Lleyn peninsula; the Cardigan cannot, it seems, be explained by littoral Bay section running from Hell's Mouth drift because the Clwyd would deflect on the Lleyn peninsula down to St any littoral currents running along the Bride's Bay; and the south coast, defined shore. The shingle east of the Clwyd as stretching from St Bride's Bay to could not, therefore, be derived from the Cardiff. boulder clay exposures at Llanddulas. Steers (1964) has postulated that the The major shingle sites identified are shingle east of the Clwyd must have shown in Figure 1. The northern unit of originated offshore. This conclusion is the coast provides a large number of the supported by the increased accumulation potential sites, eight in total. A closer of shingle following gales. inspection of these sites reveals, however, that most are relatively small Anglesey provides three potential sites, and many contain a high proportion of the first at Red Wharf Bay being a very aeolian sand. Indeed, as mentioned small shingle/sand spit winch grows out earlier, Traeth Dulas comprises sand from the western edge of the bay over the dunes over a shingle skeleton. intertidal sand and silt. This stretch of coastline is subject to high Traeth Dulas, however, is an example of levels of recreational pressure. Indeed a northerly grown spit with a shingle base Steers (1964) claims that but with over 20 cm of blown sand providing a largely dune influenced "The whole length of coastline from vegetation. Llandudno to Point of Air is unfortunately spoiled in various ways." The final site on Anglesey is Cemlyn Bar. This is mainly pure shingle and has led to Steers cites sea walls, promenades and the formation of a lagoon behind it at the quarrying of headlands as examples of head of Cemlyn Bay. typical disturbance to the coast. This is still the case, and at one site -

Figure 1 Sites in Wales with shingle structures covered by this survey

10 On the northern Lleyn peninsula, the gravel fan at Llwyngrwill but this spit is prevailing SW winds, in conjunction with sand capped. longshore drift, have led to the northerly growth of Morfa Dinle, a shingle spit Further south, the Aber Dysynni spit skeleton with sand capping. In places the offers another example of an extensive shingle is found near the surface and shingle mass with a sand overlay. This these areas were included in the survey shingle spit has deflected the outlet of the while dune areas were excluded. Dysynni and led to the formation of Broadwater, a lake of significant Turning now to consider the Cardigan ecological interest. The sand capping Bay unit of beaches, the stretch of here is less well developed than at Ro coastline running from St Tudwall's Wen and shingle still exerts an influence peninsula to Criccieth comprises over the vegetation. "a series of arcs made up by bays Perhaps the largest almost pure shingle backed by shingle and sand with eastern structure in this unit is Traeth extremities of bays marked by small Tanybwlch, the shingle ridge which outcrops of resistant igneous rocks" extends from the Alt Wen cliff south of (Steers 1964). Aberystwyth north to the harbour wall. This shingle spit has deflected the The beaches between Pwhelli and Ystwyth almost one mile north of its Criccieth are composed of fiuvioglacial original course. sands and gravels which are not derived from marine origins. The shingle content The Newgale shingle beach comprises increases eastwards from Pwhelli with a one and a half miles of well-rounded large shingle structure deposited at Pen- stones of local origin - Cambrian y-chain. Here, three to four storm ridges carboniferous sandstone and porphyries. have built up as a result of the Pen-y- chain headland acting as a groyne. The Glacial material has been reworked at the almost pure shingle foreshore gives way head of the estuary at Dale where to older shingle ridges with over 20 cm Crabhall Saltings has been deposited sand capping in an extensive dune behind the Pickleridge pebble bank. system. Boulder clay cliffs and glacial gravels east of Pen-y-chain provide Pembrokeshire offers few examples of abundant shingle and its eastern large shingle structures. Around the movement has resulted in the deflection mouth of the Thaw, however, there is a of Afon Dwyfor by almost one mile. The collection of coarse shingle which has Pen-y-chain shingle based spit is covered travelled from the east and has formed a with dunes. spit across the old estuary mouth. The boulder clay cliff at Criccieth also In addition, there is a small shingle based provides a suitable shingle source which spit, capped with sand, across the river has led to the formation of a large mouth at Pennard Burrows. Pwll du expanse of shingle three quarters of a provides an example of a shingle mile east of the town. This shingle apposition beach with three major ridges. embankment runs along the coast to Finally, Porthkerry pebble ridge is a Graig Dhu and former breaches are small, largely bare, shingle bar across an evident in the shingle fans spread out old river valley. over the lacustrine sediments behind. At Graig Dhu the shingle increases in both In general the shingle beaches of Wales amount and overall size. provide clear examples of the sandy/shingle habitat with pebbles The central section of Cardigan Bay is derived from reworked glacial drift. characterised by northerly growing spits. The shingle spit at Ro Wen has been supplied by material from the large

11 Site Reports

The rest of this report provides detailed defined using a numbering system reports on all the sites visited during the prefixed by "SH" to identify it as a course of the survey. shingle unit. The number listed represents an end group identified in Site names are those of the shingle the computer classification. Thus, structures present at the site, and so SH60 represents the 60th unit some differ from the named localities identified in the computer in Figure 1. The summary information classification. The final part of the at the start of each site report lists the community listing is a species location of the site by county and by definition in which the species listed Ordnance Survey grid reference for represent the major constants in that the centre of the surveyed site. For community. Note that in some cases some large linear sites the grid the community names in these keys references for the extremes of the refer to a preliminary version of the surveyed site are given. The community classification - more conservation status of the site is listed, recent community names for each along with the site area and dates of community code are listed in Table 3 field survey. of the main report Sneddon & Randall (1993). Note that for some sites only a representative part of the vegetated Some listed communities have prefix structure was surveyed. The surveyed part letters other than "SH". These are NVC of the structure is that shown on the site community codes for habitats other than map. The area measurement given is that shingle, except for the code "T" which for the shingle structure, both bare and refers to additional target notes collected vegetated, in only the surveyed part of site. during the shingle survey (see Methods). Each site description gives a general It should be noted that the shingle introduction to the site giving classification unit definition may not geomorphological details and outlining site exactly match the species composition boundaries. This is followed by sections on described in the vegetation section of the the threats to the site and any current site site report. This is because the definition is management. only an abbreviated description. For full details on the shingle classification units The final section of each site report see the final report (Sneddon & Randall provides a detailed floristic description of 1993). the plant communities found on the site. The communities, as defined in the shingle Where vegetation survey was undertaken classification, are then used for mapping where the shingle structure proved to be purposes. These communities are listed entirely unvegetated or others had been also in a key to the maps given at the end wholly or largely destroyed by of the vegetation section for each site. developments or other human uses. These Shingle communities are sites are identified in the relevant site report.

Figure 2 General key to symbols on site maps

13 Llanddulas

Clwyd. SH 930783 the form of dumping soil, presumably from Conservation status: SSSI the caravan site or Ty Crwn. This has led to Area: 15.9 ha the introduction of ruderal species alien to Fieldwork dates: 12-14/6/89 shingle e.g. Papaver rhoeas. Perhaps more worrying, however, is the Introduction The shore between Colwyn Bay and clearance of natural vegetation along the Abergele forms part of a series of almost caravan site wall. This area has clearly continuous fringing beaches (Randall, been disturbed with visible ridge and Sneddon & Doody 1990). At Llanddulas furrows. The clearance has led to the the reworking of glacial drift has resulted in formation of a scrubby grassland the deposition of a set of parallel storm community with a high ruderal content ridges in the form of an apposition beach. comprising Bromus sterilis, Sisymbrium The site consists of an active shingle officinale and Papaver rhoeas, and which foreshore backed by an apposition beach in parts has been planted by caravan owners with garden species such as although the ridges are no longer distinct. wallflowers. Clearly, this not only The area is bounded at the rear of the site represents a loss of natural vegetation but by a railway embankment and caravan the presence of this modified seed source park. To the east the construction of an could have serious repercussions for esplanade and parking area has destroyed secondary succession following any further the stable shingle. The beach ridges are disturbance. composed almost entirely of locally derived limestone with a significant fine matrix The site is lightly grazed by rabbits. composed of calcareous sand. In addition, the sand provides a thin capping layer at the Management At the eastern end of Llanddulas beach rear of the site. SSSI concrete posts have been positioned to prevent vehicular access to a small part Threats of the foreshore. This delimits the area The site suffers from widespread and where Mertensia maritima had been found locally severe disturbance largely due to up to 1987, the last Welsh station for this indiscriminate parking by vehicles. While nationally rare species. During this visit to several tracks are clearly visible being Llanddulas beach, however, there was no delimited by an absence of any vegetative sign of the Mertensia within this plot and it cover, drivers are by no means restricted to seems unlikely that any plants would have these tracks. The siting of the caravan park survived the severe storms of February at the rear of Llanddulas beach has not only 1990. reduced the total area of shingle vegetation but has led to increased vehicular pressure While the SSSI site does appear to be in on the site. In the past Ty Crwn (the house equilibrium, with little active erosion or at the western end of the site) has moved deposition, it is interesting to note that its garden boundary to incorporate part of recent stabilisation works have been carried the shingle beach. out at the base of the cliffs at the western end of the site. This sea defence takes the In addition, recreational pressure at a more form of groynes and large blocks of rock general level has led to disturbance of the and concrete. Such an obstacle may starve natural vegetation through trampling and Llanddulas beach of its foreshore shingle the accumulation of litter on the beach. input which is supplied from the west (Steers 1964). Additional sea defence At the western end of the site, an area of works to the east of the site in the form of scrub vegetation marks local disturbance in groynes have caused concern over damage

14 to Mertensia maritima populations in the past. Within this community there are patches where Plantago lanceolata and Rumex Vegetation cripus littoreus become locally dominant The site is floristically simple with the in the Festuca, Ononis grassland. foreshore vegetation characterised by the presence of pioneer species typically Disturbance of this community at its associated with sandy shingle such as eastern end close to the storm crest has led Rumex cripus littoreus, Crambe maritima to the introduction of pioneer species such and Glaucium flavum, whereas the as Rumex cripus littoreus and Crambe increased proportion of fine matrix at the maritima within an open version of the rear of the site leads to a closed grassland grassland. vegetation indicative of the sandy shingle substrate. There is relatively little east/west There is a small patch of mixed grassland differentiation in vegetation except that the at the western end of the site which is a vegetation is slightly better developed on Festuca rubra-Dactylis glomerata the wider, less disturbed western end. community with some Arrhenatherum elatius and Poa compressa. This The foreshore is typified by the sandy community is relatively species-rich with a shingle pioneer community characterised high herb content including Vicia sativa by the constant presence of Elymus farctus and Centaurea nigra. boreali-atlanticus and Eryngium maritimum with Taraxacum offlcinale officinale agg., Community key as an additional constant. This is a SH67 Festuca rubra - Dactylis glomerata - generally species-poor community with Lottum perenne - Bromus hordeaceus sparse cover - on average each quadrat mixed grassland; contains at least 50% shingle and sand. Honckenya peploides and Sonchus asper are SH66 Festuca rubra - Plantago lanceolata frequently associated with this community - Lotus corniculatus grassland with while occasional associates include Rumex crispus littoreus; Desmazeria marina and Erodium cicutarium. This community extends along SH54 Festuca rubra - Plantago lanceolata the entire length of the foreshore of the - Lotus corniculatus grassland with site. herbs such as Achillea millefolium; At the eastern end of the site the level of SH30 Elymus farctus boreali-atlanticus - disturbance increases and this has led to the Honckenya peploides - Eryngium destruction of much of the mature maritimum pioneer community. vegetation and the presence of a pioneer community behind the storm crest. On the rest of the site, behind the storm crest, the stable shingle ridges are dominated by a Festuca rubra, Ononis repens, Lotus corniculatus grassland typical of sandy shingle sites. This community is species-rich with associated herb species such as Achillea millefolium, Anthyllis vulneraria, Cerastium diffusum, Crepis capillaris and Galium verum. The stability of the area supporting this community is illustrated by the presence of arenicolous bryophyte species, in particular, Brachythecium albicans and Tortula ruralis ruraliformis.

Figure 3 Llanddulas 16 Gronant

Clwyd. SJ 100860 Management Conservation status: SSSI While there is no stabilisation work on the Area: 1.94 ha site, there are groynes and sea defence Fieldwork date: 26/6/89 works nearby. Introduction The bare shingle ridge is fenced off and Gronant dunes represent the final remains wardened during the tern breeding season. of a much larger dune system in North Wales. This site is primarily a sand dune The site has not been grazed. system with one main dune ridge in the west which divides into a series of ridges in Vegetation the east up to the Prestatyn Gutter. The major community found on the shingle at the eastern end of the Gronant dune There is a bare shingle ridge which has system is a sandy pioneer community. This grown out at the northern limit of the shore is characterised by the presence of Elymus from the major dune ridge. This is a bare farctus boreali-atlanticus and Honckenya spit/ridge and is not greatly elevated and so peploides. The area is highly dynamic and, may be subject to frequent inundation at hence, cover remains low with an average high tides. Thus, there is no vegetation on of 90% of each quadrat comprising bare the ridge despite nutrient enrichment from shingle or sand. In places, the Elymus the terns which breed there each year. farctus boreali-atlanticus is found in association with Sedum acre and Rumex At the eastern limit of the Gronant system, cripus littoreus. there is a high shingle content in the deposits which form the distal end of the The small depression behind the initial spit, adjacent to the Prestatyn Gutter. This storm ridge supports a slightly different shingle appears to form a layer over the flora which is a variation of the previous sand and the presence of sand is reflected community. It comprises Elymus repens in the sandy-shingle communities. This and Elymus farctus boreali-atlanticus found outer ridge is clearly moving back over the in association with saltmarsh species such substrates behind as seen by the bare as Aster tripolium, Puccinellia maritima., shingle fans on the lee of the ridge. Limonium vulgare and in some cases Beta vulgaris maritima. There is a lower area behind this ridge which supports a community reflecting a Community key mixture of shingle, sand and silt and is an SH29 Elymus farctus boreali-atlanticus - area which clearly gets flooded on a Honckenya peploides - Rumex cripus regular basis. This slack gives way to a littoreus pioneer community; second sandy, shingle ridge. T1 Elymus farctus boreali-atlanticus - Threats Honckenya peploides - Rumex cripus The site may be characterised as a sandy littoreus pioneer community with shingle spit with local evidence of Aster tripolium, Limonium vulgare recreational pressure. There has also been and Puccinellia maritima. localised vehicular damage to the site but this has resulted in only negligible damage. A golf course has destroyed much of the sand dune habitat.

Figure 4 Gronant

18 Red Wharf Bay

Anglesey, Gwynedd. SH545802 varying proportions. This Lolium Conservation status: none community is relatively local to Red Wharf Area: 0.28 ha Bay and is best defined as a subgroup of a Fieldwork date: 9/6/89 much broader Lolium perenne, Trifolium repens community. Introduction The main body of the spit supports a This site comprises a very small, highly Festuca rubra, Plantago coronopus sandy, calcareous shingle spit which grows grassland with Armeria maritima. out into the north western section of the However, the disturbance appears to have bay. led to a complicated mixture of minor Threats associates including Cochlearia officinalis, The site suffers from high levels of Plantago maritima and Honckenya recreational pressure across the entire spit. peploides. Many boats are moored here and the spit provides easy access to the moorings. Community key Indeed, several rowing boats are pulled up SH67 Festuca rubra - Dactylis glomerata - onto the spit. The recreational pressure Lolium perenne - Bromus hordeaceus takes the form of trampling, litter, and grassland; nutrient inputs from dogs walked on the site. The site is in equilibrium and is SH35 Armeria maritima rich Festuca rubra unaffected by grazing. grassland. Vegetation SH27 Tripleurospermum maritimum - The sandy nature of the substrate is Atriplex prostrata - Rumex crispus reflected in the vegetation of the spit with a littoreus pioneer community; sandy-shingle pioneer community 53 around the seaward edge. The proximal end of the spit, next to the mainland, is largely bare but moving towards the distal end the vegetation becomes a closed turf. The vegetation on this site has been disturbed and this is reflected in the mosaic of different communities present and locally monospecific stands. However, at a broader level, the vegetation may be divided into three main categories. The first is a very open, sandy pioneer community found on the steep exposed foreshore, and is characterised by the presence of Rumex crispus littoreus, Tripleurospermum maritimum and Honckenya peploides. The second community, found at the distal end of the spit is a Lolium perenne grassland with Festuca rubra, Poa pratensis and Trifolium repens found in

Figure 5 Red Wharf Bay

1 19 Traeth Dulas

Anglesey, Gwynedd. SH 485888 site supports a typical sand dune flora of Conservation status: SSSI Ammophila arenaria grading back into Area: 3.18 ha Festuca rubra and Lotus corniculatus Fieldwork date: 8/6/89 grassland, and then into Rosa No vegetation survey pimpinellifolia and Ulex europaeus.

Introduction As a result, this site was not surveyed as Traeth Dulas is a shingle spit growing part of the shingle survey. across the Dulas bay from the southern Coed y Cell cliffs. The bay contains much intertidal shingle which has clearly been reworked at the coast to form the skeleton of the spit. However, the shingle is capped by wind blown sand which has collected to a depth of at least 30 cm, with shingle only visible around the foreshore. At the leeward side of the distal end of the spit, by the creek mouth, shingle appears at the base of the sand and supports an ephemeral, largely pioneer vegetation of Atriplex portulacoides, Plantago maritima and Armeria maritima thus reflecting its proximity to the saltmarsh. This is, however, strandline vegetation and is below high water mark as witnessed by the driftline of fresh seaweed on top of the flora. Some shingle appears at the surface of the spit, however, this has been thrown up on top of the sand and probing reveals that there is sand immediately below the surface. Vegetation The depth of sand capping has a major influence on the vegetation on the spit and this

Figure 6 Traeth Dulas

2 20 Cemlyn Bay

Anglesey, Gwynedd. SH 331932 north-west end for the installation of a Conservation status: SSSI, Nature reserve - weir. There is no vehicular access to the North Wales Naturalists' Trust (leased site, nor is there any sea defence work. from The National Trust) Area: 2.95 ha There is little evidence of rabbit activity on Fieldwork dates: 6-7/6/89 the bar. Vegetation Introduction This site provides examples of pure shingle This site is a classic example of a shingle pioneer communities on the foreshore, a bar. The bar has isolated the inner part of more mature grassland on the stable areas Cemlyn Bay from the sea. Landward of the at either end of the bar, shingle/saltmarsh bar there is a brackish lagoon which is grassland communities along the linked to the sea via a weir at the northwest lagoon/bar margin and patches of scrub end of the bar. vegetation. There is some evidence of east west differentiation, both in terms of The bar comprises flat pebbles with an different communities and of detailed average diameter of 5 cm. There is clear species composition within these sorting and grading of the shingle from the communities. east (smallest) to the west and also the typical sorting associated with a normal A Rumex cripus littoreus, Crambe beach profile. maritima community occupies a zone running along much of the length of the The bar has a little coarse sand admixed foreshore extending from the active storm with the shingle at either end, with a sand crest back down onto the lee slope. This capping up to 20 cm and a narrow strip of strip of pioneer vegetation is relatively shingle/silt composition along the leeward narrow at the south-eastern end but lagoon edge. The shingle is derived from occupies a wider belt on the central section as far afield as Scotland and the Lake of the bar which is subject to greater District and is glacial in origin. maritime influences, being particularly narrow at this point. Within this general The bar is, on average, 50 m wide Rumex - Crambe community, typical of although this figure increases to 80 m in pure shingle sites, there are areas where places. The central section of the bar is other associates become locally important occasionally subject to overtopping and and this has led to a shift in classification this results in the landward movement of definition, but when viewed at a local level the bar. it is clear that these should be considered sub-groups of the original community. Within the brackish lagoon behind the bar, This is clearly illustrated in quadrats which there exist small shingle islands which contain Silene uniflora in association with provide a nesting site for various species of Rumex and Crambe. tern during the breeding season. The islands are largely bare of vegetation as At each end of the bar, where it widens, they are subject to flooding. the pioneer community gives way to grassland communities. However, there is Threats/management some differentiation in the type of The presence of a tern colony has resulted grassland. At the south-eastern end of the in active wardening of the bar during the bar, where sand capping is greatest, the breeding season and pedestrian access to grassland is characterised by a Festuca the site is greatly restricted. Hence, this rubra, Elymus repens, Dactylis glomerata site is largely undisturbed except for past coarse mixed grassland with Holcus gravel extraction and reworking at the lanatus present in small quantities. This

21 community may also contain limited herb species, typically, Plantago lanceolata, A narrow strip, no more than two metres Galium venan and Taraxacum cfficinale wide, of a shingle/marsh community runs officinale agg.. Moving north-west along along the lagoon/bar margin. This area the bar, this community then grades into supports a Festuca rubra, Agrostis a slightly different grassland community stolonifera saltmarsh community which, at which is less diverse. In this case the its eastern extreme, develops into a more Festuca rubra and Holcus lanatus overtly saltmarsh association as the bar become increasingly important widens. Here the vegetation closely components of the community and they resembles SM16 Festuca rubra - Agrostis are associated with Arrhenatherum stolonifera - Glaux maritima - Juncus elatius, Poa pratensis and Plantago effusus community. lanceolata with the occasional presence of Scilla verna. Moving further north- The final type of community found at west along the bar this community is Cemlyn is the scrub vegetation which is replaced by a more pioneer grassland found in small patches towards the rear of which may be defined as a Festuca rubra, the bar at either end. This community is Rumex cripus littoreus, Tripleurospermum Ulex europaeus dominated and is found in maritimum grassland. This is consistent dense patches providing almost total cover. with the increased maritime influence on It is found in association with various the lee slope as the bar narrows at this grasses, commonly Festuca rubra, point. Anthoxanthum odoratum and Dactylis glomerata. This mixed grassland in turn gives way_ to a very different Festuca grassland. This Community key community is a Festuca rubra, Armeria SH109 Ulex europaeus - Rubus fruticosus - maritima grassland with an unusually high Agrostis capillaris scrub. Beta vulgaris maritima content. It rapidly grades into a community which is SH80 Agrostis stolonifera - Festuca rubra even more pioneer in nature and offers saltmarsh community; less cover. It comprises a sub- community of the broader Festuca rubra, SH70 Festuca rubra - Silene uniflora ~ Lotus Tripleurospermum maritimum, Silene corniculatus grassland; uniflora association with Beta vulgaris maritima as the differential species. This SH68 Festuca rubra - Plantago lanceolata community is found along much of the - Poa pratensis grassland; length of fee lee slope of the bar at its narrowest point and up to the north- SH34 Festuca rubra - Armeria maritima - western end. Plantago maritima grassland; As the bar widens at the north-western end the broader area of shingle at the SH16 Beta vulgaris maritima - Festuca storm crest down to the Beta vulgaris rubra - Tripleurospermum maritimum maritima community at the base of the community; lee slope is occupied by a Festuca rubra grassland indicative of drier more stable SH9a Crambe maritima - Rumex cripus conditions. It is characterised by the littoreus pioneer community; constant presence of Festuca rubra, Plantago lanceolata and Lotus SH6 Silene uniflora - Crambe maritima corniculatus with a high herb content. pioneer community; Typical associated herbs include Anthyllis vulneraria, Crepis capillaris, SM16: Agrostis stolonifera - Festuca rubra Hieracium pilosella, Galium verum and - Glaux maritima - Juncus effusus Sedum anglicum. There is also the grassland. additional presence of Aira caryophyllea and Koeleria macrantha in small amounts.

Figure 7 Cemlyn Bay

23 Dinas Dinle

Gwynedd. SH 440585 - SH 440575 form of trampling. Other than the Conservation status: none destruction of much of the site for parking, Areas: 1.9 ha (south), 2.1 ha (north) vehicular damage is limited. Fieldwork dates: 24-25/6/89 Management Introduction The site is grazed by rabbits. There is little The beach running north from Dinas sea defence work other than the gambions Dinle up to Morfa Dinle comprises a although the site is clearly subject to shingle foreshore growing into a shingle- erosion. based spit. The foreshore, particularly in the south, represents a sandy-shingle Vegetation fringing beach. On the spit proper there Five communities may be recognised at is a tall storm crest above the fringing this site, all of them characteristic of a beach which falls away steeply behind to sandy shingle substrate. The most a flatter area occupied by the airport. The widespread community is a Festuca rubra, spit consists of a shingle skeleton Ononis repens grassland with a high herb supporting a major dune system as sand content including Thymus polytrichus capping. britannicus, Hypocheris radicata, Lotus corniculatus and Anthyllis vulneraria. In At the proximal end of the spit, between some areas there is a significant lichen and the end of the car park and the start of bryophyte component in this community, the dunes, there is a small area of in particular, Cladonia macilenta and predominantly shingle-based substrate Tortula ruraliformis, which are indicative with shingle clearly visible although there of more stable conditions. is also a major sand component (see Figure 8). This rapidly grades into sand Another community commonly found on dunes with associated dune communities. shingle at Dinas Dinle is similar in species composition to the previous one. It is a Festuca rubra,, Plantago lanceolata Threats Running south from the spit there was, in grassland with Lotus corniculatus as a key 1977, a thin strip of sandy shingle which species and it is characterised, in this supported a relatively closed grassland instance, by the absence of Ononis repens. community. However, this area has since There is a small area occupied by another been greatly reduced in floristic interest similar community which is similar to the by the provision of parking bays on this Festuca grassland already discussed but in area, thus destroying its interest as a this case its presence on the storm crest has shingle site. All that is left is a bare led to the introduction of maritime pioneer fringing beach with gambions to protect species such as Silene uniflora and against the erosion of the parking bays. Honckenya peploides in the grassland. Additional herb associates include Lotus Further south still, beyond the Dinas corniculatus and Galium verum. Dinle embankment, there is a very small area of undisturbed shingle supporting a The fourth community is also Festuca sandy shingle grassland community (see rubra dominated with Ononis repens but is Figure 9). This area had extended further differentiated from the community south in the past but much of the area has discussed earlier by the constant presence been disturbed by ploughing which has of Armeria maritima and Plantago led to the introduction of an open ruderal coronopus. This is indicative of more community. maritime influences and it is found in a small patch on the storm crest where it is The site has obviously suffered subject to more salt spray. widespread and moderate recreational pressure in the

24 The final community emerges in the SH53 Festuca rubra - Ononis repens - pioneer section of the classification. It Anthyllis vulneraria grassland; occupies a small area on the seaward margin of the site and is a Festuca rubra, SH48 Festuca rubra - Plantago lanceolata Ammophila arenaria grassland with Rumex - Hypnum cupressiforme - Lotus crispus littoreus. corniculatus grassland; Community key SH46 Festuca rubra - Ceratodon SH54 Festuca rubra - Plantago lanceolata purpureum - Sedum acre grassland; - Lotus corniculatus grassland; SH28 Honckenya peploides - Elymus pycnanthus - Ammophila arenaria pioneer community with Rumex crispus littoreus.

Figure 8 Dinas Dinle (north) Figure 9 Dinas Dinle (south)

25 Pontlyfni

Gwynedd. SH 433533 Conservation status: none Vegetation Area: 2.54 ha There are three major communities at this Fieldwork date: 23/6/89 site with an additional two communities found in small quantities. Introduction A key community which occupies the This site comprises a small sandy fringing southern foreshore at this site represents an beach extending north from the holiday example of a sandy pioneer community. It camp up to Afon Llyfon. The beach is characterised by the presence of forms a spit across the Afon Llyfni Elytrigia farctus boreali-atlanticus and although this has been subject to coastal Eryngium maritimum. Common associates stabilisation works with recent placement are also typical of sandy shingle substrates of gambions on either side of the river including Tripleurospermum maritimum, mouth. Rumex crispus littoreus and Honckenya peploides. This community offers only To the north of Afon Llyfon the sandy limited cover with, on average, 60% bare shingle ridge continues but the proportion sand and shingle in each quadrat. of sand increases greatly with little shingle visible. In the far south, where there is active erosion, this community grades into an Threats ecologically similar community being This northern part of the site has been arenicolous and pioneer in nature, but with greatly disturbed in recent years with the Ammophila arenaria and Honckenya construction of a new sewage works. This peploides becoming locally dominant. appears to have destroyed much of the original shingle vegetation (see Randall, The second major community is found on Sneddon & Doody 1990) both directly, by top of the stable shingle ridge, actual loss of land to the works, and immediately behind the foreshore. This indirectly through the disturbance of the community is a Festuca rubra, Plantago natural flora by tyre tracks of the heavy lanceolata grassland with Ononis repens machinery used in construction, and the and Rumex crispus littoreus as additional subsequent introduction of ruderal species constants. The presence of Rumex crispus which now dominate the foreshore littoreus separates this grassland from community. other Festuca rubra, Plantago lanceolata grasslands and reflects the degree of South of the Afon Llyfni there is a maritime influence on this community due relatively well developed foreshore to its proximity to the sea. pioneer community with a closed Festuca rubra sward behind on the more stable Indeed, where this stable area widens in shingle. This part of the site suffers from the north, adjacent to the tiny spit, the widespread recreational pressure although maritime influence is reduced slightly and damage remains light. the above community grades into a Festuca rubra, Ononis repens grassland Management with Lotus corniculatus and Plantago Immediately behind the foreshore the land lanceolata as occasional associates. is fenced off for livestock fanning and represents some loss of original vegetated North of the Llyfni, the area of vegetated shingle which can now be seen through shingle has been greatly reduced and what the grass. There is no grazing on the remains has been subject to high levels of beach. disturbance. This is reflected in the major community here. It is characterised by the The site suffers from erosion at its constant presence of Rumex crispus southern end near the campsite. littoreus,

26 Tripleurospermum maritimum and Community key Potentilla anserina and keys out to SH66 Festuca rubra - Plantago SH27a, an example of a relatively lanceolata - Lotus corniculatus species-poor pioneer community. grassland; However, this particular community is more diverse in terms of species SH54 Festuca rubra - Plantago composition than would be expected of lanceolata - Lotus corniculatus SH27a. This may reflect an area which grassland with Ononis repens; supported a more permanent flora in the past but which has reverted to a SH29 Elymus farctus boreali-atlanticus pioneer nature through disturbance. - Honckenya peploides - Rumex Additional constants here include crispus littoreus community; Holcus lanatus, Agrostis stolonifera and Cirsium arvense. In one area SH28 Honckenya peploides - sampled Plantago lanceolata was Ammophila arenaria - Elymus found to be locally dominant within pycnanthus pioneer community; this pioneer community. SH27a Rumex crispus littoreus - There is a small patch of the Festuca Tripleurospermum maritimum - rubra, Plantago lanceolata, Ononis Potentilla anserina pioneer repens community on this northern community side of the river mouth.

43 F i gure 10 Pontlyfni 28 Aberdesach

Gwynedd. SH 425515 Threats Conservation status: none The original double ridge system has been Area: 1.39 ha destroyed by the construction of a car park Fieldwork date: 23/6/89 which has led to the clearance of any No vegetation survey natural vegetation.

Introduction The construction of holiday cottages has This beach was an example of a double also reduced the area of natural shingle ridge system with the frontal ridge vegetation. separated from the second landward ridge by Afon Desach in 1982 (Randall, There is widespread recreational pressure Sneddon & Doody 1990). However, when on the site, no doubt heightened by the car visited as part of the shingle survey in park although the damage to the shingle is 1989, this site was found to comprise only generally light. a fringing beach in front of the holiday cottages. This was made up of boulders The site was not included in the survey due with sand admixed. Indeed, the entire site to its reduction in size and the high sand is generally very sandy grading into pure content of the intact beach. sand in the north.

Figure 11 Aberdesach.

29 Afon Dwyfor

Gwynedd. SH 475375 Conservation recreational pressure. There has been no status: none Area: 0.86 ha stabilisation work on the site or adjacent to it. Fieldwork date: 21/6/89 Vegetation The only natural shingle community on this Introduction site runs around the seaward edge of the spit Afon Dwyfor is a very small shingle and comprises a Honckenya peploides - site but forms part of the wider unit of Ammophila arenaria - Rumex crispus sites stretching along the coast from littoreus open grassland community. The Pwhelli to Criccieth. The site comprises sandy nature of the substrate is clear from the a shingle based spit which has deflected occasional presence of additional arenicolous the course of the Dwyfor eastwards. species including Carex arenaria and This is an example of a sandy shingle Euphorbia paralias. In some cases the site, with some shingle visible around Ammophila arenaria is replaced locally by the foreshore, but with the more stable Elymus farctus boreali-atlanticus but the parts of the site having a sand capping associates remain the same with Honckenya of up to 20 cm. peploides as a constant throughout. The main body of the spit supports, Community key therefore, a sand dune flora which has SH28 Honckenya peploides - Elymus been widely and in parts heavily grazed. pycnanthus - Ammophila arenaria The shingle flora surveyed consisted of pioneer community with Elymus a strip of natural vegetation at the high farctus boreali-atlanticus instead of E. water mark. pycnanthus. Threats/management There is limited access to the site such that there is negligible disturbance from

Figure 12 Afon Dwyfor

30 Pen-y-chain

Gwynedd. SH 440355 Conservation status: none The pioneer communities are characterised Area: 6.30 ha by the constant presence of Rumex crispus Fieldwork date: 22/6/89 littoreus and Tripleurospermum maritimum. They are very open in nature with around 95% bare sand and shingle in each quadrat. Introduction Within this major grouping there appear to This site comprises an apposition beach be two sub-communities. which has been deposited at the eastern end of a coastal arc. It has been laid down The first is commonly found along the against the resistant igneous headland of foreshore and on the flatter crest of the Pen-y-chain. A series of sandy shingle storm ridge, and in this case the Rumex storm ridges have been deposited and are crispus littoreus and Tripleurospermum largely bare, supporting only a limited maritimum are associated with Glaucium pioneer flora above high water mark. This flavum and Cerastium diffusum. There are lack of vegetation illustrates the high other species which may be found as energy nature of the beach. Further inland occasional associates and they also reflect the shingle ridges are overlain by up to 20 the sandy nature of this site. These include, cm of sand and sandy heath communities Cakile maritima, Cochlearia officinalis and are present. This part of the system was not Honckenya peploides. surveyed. The proportion of sand within the shingle also increases to the west. The second sub-community found in this zone occurs primarily along the active Threats foreshore and is differentiated from the There is very little recreational pressure on first by the constant presence of Atriplex the site which has limited access mainly prostrata with the Rumex and from the beach to the west. Tripleurospermum. This may reflect the higher level of organic input in the active The shingle has, in the past, been used as a storm crest zone. rifle range which has clearly led to some disturbance but equally will have restricted On the lee of the main shingle ridge there access to the site. Current disturbance takes is a much more mature, well developed the form of localised vehicular tracks vegetation, reflecting, perhaps, the although damage to the shingle is increased sand content on this side of the negligible. slope. The cover here is much greater with little bare sand or shingle visible. Management The sand dune part of the site is currently These communities are heathland in nature grazed by sheep and cows which provide with Festuca ovina, Calluna vulgaris and nutrient enrichment to an otherwise Erica tetralix as the constants found in nutrient-poor environment. There has been varying proportions with Scilla verna, the no other agricultural improvement to the moss Pleurozium schreberi, and site. Anthoxanthum odoratum. Indeed, the quantity of Anthoxanthum varies Vegetation considerably across this part of the site and This site provides examples of pioneer this is the basis of a distinction between communities, found on the shingle storm two sub-communities identified, the first ridges, and of transitional heathland being described as a Festuca ovina, Erica communities which are found on the lee of tetralix, heathland where Anthoxanthum is the storm slope and then develop into not a major component, while the second is mature heathland on the dunes behind. an Anthoxanthum odoratum, Festuca ovina heathland with Calluna vulgaris and Erica

31 tetralix in smaller, but generally SH61 Festuca rubra - Anthoxanthum equal, amounts. odoratum - Lotus corniculatus grassland; In places there is an absence of heathland species, and here the vegetation SH27a Tripleurospermum maritimum - comprises a herb-rich Festuca ovina, Atriplex spp. - Rumex crispus littoreus Plantago lanceolata grassland. pioneer community;

Community key SH24 Rumex crispus littoreus - SH92a Calluna vulgaris ~ Cladonia Tripleurospermum maritimum - impexa heathland, Anthoxanthum Glauciumflavum pioneer community; odoratum -Festuca ovina sub- community; SH24a Rumex cripus littoreus - Tripleurospermum maritimum - SH62 Festuca ovina -Agrostis stolonifera Glauciumflavum pioneer community, -Poa pratensis - Anthoxanthum Cerastium diffusum sub-community; odoratum grassland;

Figure 13 Pen-y-chain

32 Criccieth

Gwynedd. SH 525375 now vegetated. Additional stabilisation Conservation status: none works at the site include beach feeding Area: 19.64 ha with boulders at the actively eroding Fieldwork date: 21/6/89 eastern end, and the placing of wooden fencing and railway sleepers behind the Introduction central section of tie storm crest to halt the This site lies at the eastern end of a stretch creep of shingle towards the railway line, of coast characterised by a series of arcs, which marks the back boundary of the site at this point. with deposits of shingle and sand collected against the resistant headlands at the east of The site is currently grazed by sheep and each arc. cattle. The beach to the east of Criccieth Vegetation comprises a shingle beach with a minor This site offers examples of a variety of sand matrix. The shingle is disc shaped and sandy shingle communities, both pioneer in ranges in size from 5 to 8 cm. The shingle nature and more mature grassland foreshore runs from the car park at the communities. In addition there is a small main beach east to the Craig Dhu area of wetter ground around the ditch headland. The railway runs at the back of which supports a very different the site for much of its length. community. The site consists of a very active storm Pioneer communities run along the top of ridge which widens at its eastern end to the current storm ridge. The major pioneer form a minor apposition beach. This has community consists of scattered Rumex formed not through the repeated deposition crispus littoreus plants. This most closely of shingle storm ridges, but rather through resembles SH24 which is a Rumex crispus the landward movement of the beach by littoreus, Tripleurospermum maritimum, overtopping and breaching, which has led Glaucium flavum community, but to shingle fans spreading onto the highlights the problems of dealing with sediments behind. largely monospecific stands within the shingle classification. In places along the There is a ditch behind the storm crest on foreshore Rumex crispus littoreus is found the flatter lee area and this has clearly in association with other species such as flooded in the past with associated flora Silene uniflora, Tripleurospermum resulting. Behind this there is a raised maritimum and Atriplex prostrata. This terrace which marks the back of the site. community may be defined as SH27 Tripleurospermum maritimum, Rumex Threats crispus littoreus. Clearly, the monospecific There is much litter on the site, Rumex crispus littoreus stands may be particularly in the strandline on the considered a sub-group of this community. foreshore. The more stable shingle behind the storm Whilst there is some recreational pressure crest supports two major communities. The on this site, its distance (c. 1 km) from the first is found at the eastern end of the main beach means that disturbance from shingle and is characterised by the constant such pressure is limited. presence of Festuca rubra, Plantago lanceolata and Hypochoeris radicata. This Management grassland is species rich supporting many There has been some artificial reworking herbs such as Thymus polytrichus of the shingle at the eastern end, with two britannicus, Silene uniflora and Sagina banks of finer gravel deposited; these are apetala. This is a relatively mature community and largely undisturbed as illustrated by the

33 presence of bryophyte and lichen species Around the ditch which runs along the including Rhytidiadelphus squarrosus and back of the site there is a community Peltigera canina. indicative of wetter conditions, SH32, which is a Festuca rubra, Plantago In addition, this community includes a maritima, Glaux maritima grassland which number of spring annual grasses such as is, in this case, rather impoverished having Aira praecox and Poa annua which may been recently flooded. indicate that it represents a sub- community of the more general Festuca, Community key Plantago community. This may be a SH24 Rumex crispus littoreus - result of grazing of the community Tripleurospermum maritimum – leading to bare patches which are Glaucium flavum pioneer subsequently colonised by annuals. community; This sandy grassland shows a slight SH27 Tripleurospermum maritimum - variation in the west with the increased Atriplex prostrata - Rumex crispus presence of Cerastium semidecandrum littoreus community with Silene and Carex arenaria. This represents a uniflora; sub-community of the original grassland reflecting an increased sand content in the SH49 Festuca rubra - Lotus corniculatus - shingle matrix. Thymus polytrichus britannicus - Cladonia Jurcata grassland with a In parts this community is tending high annual content e.g. Aira towards sandy heathland with the praecox; presence of small amounts of Calluna vulgaris and Erica tetralix. SH109 Ulex europaeus - Rubus fruticosus - Agrostis capillaris scrub; At the rear of the site there is a small patch of Ulex europaeus, Rubus SH32 Festuca rubra - Plantago coronopus fruticosus scrub. grassland.

Figure 14 Criccieth

35 Aber Dysynni

Gwynedd. SH 582027 This site is one of the few Welsh sites Conservation status: SSSI supporting a breeding colony of terns, Area: 19.3 ha although none bred in 1989. While the Fieldwork date: 1/6/89 presence of the colony increases the number of visitors to the site, the Introduction restriction of access to the bare shingle At Aber Dysynni a small shingle spit nesting area serves to preserve that part of growing northwards has led to the the site which supports pioneer formation of the Broadwater lagoon communities important to this study. behind. The shingle spit extends north from Twywn and has some sand Beach stabilisation measures are seen capping on the inland ridges. It is a south of the spit and take the form of very complex coastal system with a groynes but there has been little further small depression trapped between alteration. The site suffers slight erosion at ridges, which is frequently flooded, the distal end, perhaps due to shingle even in summer. This leads to the starvation caused by the groynes. presence of saltmarsh influenced communities in close juxtaposition with The site is widely grazed by rabbits but the shingle and sand habitats. Such overall damage is light. diversity within a relatively small area Vegetation is unusual. The sandy nature of this site is reflected in the plant communities present. At the A railway line running along the coast southern end of the site, where there is provides a convenient rear boundary for sand capping to a depth of 15 cm on the site. This is an example of a shingle average, the two key communities are site with a high proportion of interstitial more commonly associated with sand and capping sand - only around 10% of dunes. The first, which occupies the area the site offers a pure shingle habitat, immediately behind the storm crest, is an much of which is restricted to the bare Ammophila arenaria, Festuca rubra sandy foreshore where pebbles are on average grassland with Senecio jacobaea and Carex 15 cm in diameter. arenaria as additional constants. This is a species rich community with occasional Threats herb associates including Rhinanthus The proximity to Twywn encourages minor, Viola riviniana and Vicia sativa. widespread use of the site for This community most closely resembles recreational purposes resulting in a the existing sand dune community SD7 light level of disturbance limited to Ammophila arenaria, Festuca rubra semi- litter and the presence of footpaths fixed dune community. across the site. This then grades into a more fixed Damage by vehicles is localised and grassland at the rear of the site which minor. However, there appears to be an comprises a Festuca rubra, Carex arenaria area immediately behind the active dominated grassland, with the presence of storm crest which has undergone major Poa subcaerulea and Dactylis glomerata as reworking and been cleared of minor associates. It appears to be similar vegetation in the recent past. This has to the Carex, Festuca, Agrostis grassland resulted in ridges and furrows running community defined as SD12, although in perpendicular to the coast, which this case it is Festuca rubra rather than support an open sandy shingle Festuca ovina which is found. SD12 is grassland with a high Lotus typical of stable, acid dunes and is corniculatus content. commonly associated with lower areas in Management

36 old dune systems. It is often indicative of Community key leached conditions. SH70 Festuca rubra - Silene uniflora - The major community on the northern part Lotus corniculatus pioneer of the spit is found on the old shingle community; ridges. Such areas support a Festuca rubra, Plantago lanceolata, Lotus corniculatus SH67 Festuca rubra- Dactylis glomerata - grassland with a high herb content. Lolium perenne - Bromus hordeaceus Anthyllis vulneraria and Trifolium repens grassland; serve as particularly useful indicators for this community. In certain areas this SH66 Festuca rubra - Plantago lanceolata dominant community forms a mosaic with - Lotus corniculatus grassland; other Festuca grassland communities according to the local abundance of SH53 Festuca rubra - Ononis repens - particular associate species. Anthyllis vulneraria grassland; An example of such a mosaic patterning SH49 Festuca rubra - Lotus corniculatus - may be seen landward of the lagoon where Thymus polytrichus britannicus - Cladonia furcata is found in small amounts Cladonia furcata community; and so quadrats thrown in this area key out to a different community. Ononis repens> SH33 Plantago coronopus - Festuca rubra Desmazeria marina and Dactylis glomerata also become locally important species - Armeria maritima grassland; within the general Festuca grassland on the shingle ridges. SH28 Honckenya peploides - Elymus pycnanthus - Ammophila arenaria Pioneer communities are found along the community northern exposed seaward edge of the spit on the tern breeding area. These SH23 Tripleurospermum maritimum - communities are very open with around Euphorbia paralias - Silene uniflora 90% bare shingle or sand in each quadrat. pioneer community; The major pioneer community in extent comprises an open Tripleurospermum SD12 Carex arenaria - Festuca ovina - maritimum, Silene uniflora assemblage Agrostis grassland. with Lotus corniculatus, Euphorbia paralias and Eryngium maritimum as SD7 Ammophila arenaria - Festuca rubra frequent associates indicating the sandy grassland. nature of the substrate. This community is seen to be more developed on parts where cover is greater and the Tripleurospermum and Silene are found in association with Festuca rubra. There is no pattern to this development which is very localised. The disturbed area supports a very open version of the Festuca rubra, Plantago lanceolata, Ononis repens community. The area around the lagoon supports a shingle/saltmarsh community which comprises a Festuca rubra - Armeria maritima - Agrostis stolonifera grassland with halophytic herb associates such as Glaux maritima and Limonium vulgare.

Figure 15 Aber Dysynni 38 Traeth Tanybwlch

The entire spit suffers from widespread Dyfed.SN 577800 recreational use but the extent of the SSSI damage is only moderate. Parking areas on Area 5.6 ha the more sandy, southerly shingle have Fieldwork dates 30-31/5/89 destroyed patches of vegetation and led to a minor litter problem. In addition, the Introduction flatter 'flood plain1 was being used for Traeth Tanybwlch comprises a sandy camping, with locally severe effects on the shingle spit running northwards along the vegetation through flattening and coast from the Alt Wen cliffs up to the pier attenuation. This is also a major litter forming the southern barrier to source. Aberystwyth harbour, thus deflecting the natural path of the Ystwyth. At the There is easy vehicular access to the whole southern end of the spit the deposits are spit, although this is largely restricted to large boulders or cobbles and are clearly tracks due to the gradient of the slopes. derived from the adjacent cliffs. North of Vehicular damage may be described as this there is a general increase in sand local in extent but of a moderate level over content within the shingle, indeed, in parts those areas affected. the sand becomes dominant. The maritime influences on the spit appear The foreshore is very steep and is clearly to be in dynamic equilibrium although active, being devoid of vegetation, a there may be erosion of the northern typical example of a high energy beach. leeward slope. There are no stabilisation Indeed, the active nature of the existing works on this site. storm crest is reflected in the lack of vegetation, even on the lee of the storm There is no evidence of grazing crest down to the track which runs the length of the spit. Vegetation This site provides examples of sandy There is some evidence for undercutting of shingle grassland communities, scrub the spit by the Ystwyth at the northern end communities and some interesting pioneer where slumping on the leeward slope has associations. led to bare shingle being exposed and the need to shore up the track. Perhaps the most interesting feature of one pioneer community is its location on the There is a gradation of the vegetation from lee of the slope which would normally be relatively pioneer around the track to more stable than the foreshore. However, closed turf further down the lee slope. This the undercutting at the northern end of the gives way to a steep section of slope which spit has led to a renewal of the pioneer is bare in places with only patches of phase in floral development at this site. vegetation, and below this a flatter area. There is then a sharp break of slope down This pioneer community comprises a very to the river which supports a closed open Silene uniflora, Rumex crispus vegetation reflecting the higher silt and littoreus association with Plantago water content. maritima and Armeria maritima as minor constants, reflecting the influence of the Between the track and the Ystwyth the river behind the spit. shingle has been stable for a long period. This is reflected by the presence of scrub The major pioneer community in the south, species e.g. Prunus spinosa. where the sand content is greatest, may be described as a Rumex, crispus, Glaucium Threats/management flavum association typical of sandy shingle

39 sites which contains occasional herb by the constant presence of Agrostis associates such as Sedum anglicum and stolonifera and Holcus lanatus with Plantago lanceolata. In this case the Potentilla anserina, Armeria maritima community is found on the storm crest as and Rosa tomentosa as occasional expected. There is a slight variation on associates. This is a relatively species- this community in areas where poor community. Tripleurospermum maritimum is an additional constant, and this may A narrow strip of the spit running along represent a sub-group of the original the river margin supports a community Rumex, Glaucium community where a which reflects the marsh influences higher level of organic material is found. associated with the silt from river sediments. This community is This community is found in close characterised by the constant presence of proximity to a more closed Festuca rubra, Festuca rubra, Armeria maritima, Sedum anglicum, Ceratodon purpureus Plantago maritima, Agrostis stolonifera grassland with Silene uniflora, Armeria with Silene uniflora, Cochlearia maritima, Plantago coronopus and Lotus officinalis and Lotus corniculatus as corniculatus as additional minor constants frequent associates. In places, where the indicating the more maritime nature of the amount of Festuca rubra decreases, this community. It is thought that this community grades into an Armeria represents the next stage in the seral maritima, Silene uniflora, Cladonia development. verticilliata community. The constant presence of lichens indicates the Most of the site, however, supports a increased stability of this community and closed Festuca grassland which commonly this is consistent with its position on the comprises a Festuca rubra - Ononis southern half of the lee slope. repens herb rich grassland. This community is typically associated with On the middle section of the lee slope the sandy shingle and this is reflected in the steep slope has areas of what appears to largely southern distribution of the be bare shingle, although a closer community in the area with highest sand inspection reveals that there is a very content. open vegetation. These patches support a sub-community of the more general Silene Variations on the general Festuca uniflora - Festuca rubra - Plantago grassland include a Festuca rubra, lanceolata grassland. In this instance the Plantago lanceolata grassland with Lotus constant presence of prostrate Prunus corniculatus and Sedum anglicum as spinosa necessitates the redefinition of frequent associates. This community is the community. The Prunus and the not as diverse as the previous grassland presence of saxicolous lichens indicates and is primarily Festuca dominated. In the great age of these patches which places, however, the presence of a well remain largely bare. developed bryophyte flora indicates the stability of this shingle community. There are patches of scrub developed on the stable parts of the lee slope and these A further grassland found in small are either Ulex europaeus dominated amounts across much of the spit is a with Prunus spinosa or Rubus Festuca rubra, Trifolium repens fruticosus, or a purely Prunus spinosa, dominated herb-rich grassland. The herb Rubus fruticosus association. In each case component of this community comprises the open nature of the scrub cover is Cerastium semidecandrum, Centaurea such that there are more associates than nigra and Achillea millefolium as frequent are normally found in such communities. associates. These associates commonly include Dactylis glomerata, Rumex acetosella, At the break of the lee slope poor Festuca rubra and Plantago lanceolata. drainage conditions have resulted in a strip of wetter ground which supports a different grassland. This community is characterised

Community key SH119 Rubus fruticosus - Arrhenatherum SH60 Agrostis stolonifera - Holcus lanatus elatius scrub; - Trifolium repens .community; SH108 Ulex europaeus - Rubus fruticosus SH50 Festuca rubra – Aira praecox - scrub; Plantago lanceolata with Armeria maritima grassland; SH74 Agrostis stolonifera - Trifolium repens - Festuca rubra grassland with SH47 Festuca rubra - Lotus corniculatus - Holcus lanatus; Plantago lanceolata grassland; SH70 Festuca rubra - Silene uniflora -Lotus SH46 Festuca rubra - Ceratodon corniculatus community; purpureus - Sedum anglicum grassland; SH68 Festuca rubra – Plantago lanceolata - Poa pratensis grassland with SH34 Festuca rubra - Armeria maritima - Trifolium repens; Plantago maritima marsh community; SH66 Festuca rubra - Plantago lanceolata - Lotus corniculatus community. SH24 Rumex crispus littoreus - Tripleurospermum maritimum – SH65 Festuca rubra - Achillea millefolium Glaucium flavum pioneer - Lotus corniculatus - Silene community. uniflora grassland;

41 Figure 16 Traeth Tanybwlch

Crabhall Saltings

The site has been grazed lightly by rabbits Dyfed. SM 817060 in most places and there has been some Conservation status: SSSI shaping of the scrub vegetation by rabbits. Area: 3.5 ha Fieldwork dates: 28-29/5/89 It seems that there may have been artificial reworking of the distal end of the spit to maintain the brackish lagoon. Introduction This site represents the only shingle Vegetation structure on the Pembrokeshire coast This site offers examples of shingle considered of a sufficient size to survey. It vegetation with a major saltmarsh influence comprises a spit growing north-east from and, in some cases, this has led to Dale across the estuary. There is also an difficulty in interpreting the quadrats incipient spit growing from the opposite within the shingle classification. side of the estuary. The resulting saltings trapped behind the spits provide an The small spit growing out from the important nesting site for a diverse eastern edge of the estuary supports a Beta avifauna. The main shingle ridge has also vulgaris maritima, Festuca rubra pioneer led to the formation of a brackish lagoon community with occasional associates behind and this also supports many including Tripleurospermum maritimum different bird species. and Atriplex prostrata which is similar to the community found at Cemlyn on The spit has been protected at its narrowest Anglesey. On the lee of this spit there is a point, 300 m from the proximal end, with very narrow strip of Atriplex portulacoides the placement of large boulders to dominated vegetation which is clearly a strengthen the exposed seaward foreshore. saltmarsh community reflecting the frequency of flooding of this part of the At its distal end, the spit has been site. This community was separated from reworked by the river to form several the main data set at an early stage in the hooks and there is sand capping to a depth analysis and keys out SM14. of 20 cm on the laterals which support a scrub-type vegetation. Indeed, at the distal The Beta vulgaris maritima, Festuca rubra end of the spit generally the amount of community occurs also on the foreshore of sand within the shingle increases the main spit running along the main arm considerably. of the spit. A more closed version of this community is seen on the lee slope of the Threats spit where undercutting has led to slumping A coastal path runs along the length of the and much bare shingle visible on a very spit and it is possible to cross to the steep slope (44 degrees). This community opposite bank at low tide. This clearly comprises Beta vulgaris maritima and heightens the recreational pressure on the Festuca rubra with additional grass species site but damage attributable to this is as minor associates, e.g. Dactylis negligible. There is no vehicular access to glomerata, Holcus lanatus, and the spit. Desmazaria marina, while its proximity to the lagoon behind is reflected in the Clearly, there is erosion on the main ridge presence of Cochlearia officinalis and of the spit but there is some evidence to Tripleurospermum maritimum. suggest that the distal end is accreting with a large area of low lying sandy shingle. There are areas supporting scrub vegetation at either end of the main spit. At the distal Management end, on the recurved hook, two scrub communities are represented. The first is

43 Primus spinosa dominated with dense Sedum acre, Ceratodon purpureus Prunus cover shading out many potential grassland. Elsewhere there is a mosaic of associates. In this instance the Prunus is Festuca dominated grasslands with the found with Urtica dioica and the shade- local importance of Desmazeria marina and tolerant moss Eurynchium praelongum. In Lotus corniculatus forming the basis of the places, however, the Prunus is replaced by mosaic differentiation. Rubus fruticosus to form a Rubus, Urtica dioica community. There is an area of relatively bare shingle visible on the major recurve of the spit. At the proximal end of the spit, on the lee This area supports an Arrhenatherum slope extending back to the mainland, there elatius, Geranium robertianum community are also two types of scrub community. with few associates. In places the One is a variation of the Prunus scrub seen Geranium robertianum becomes dominant. at the distal end. In this instance, however, This community has been noted at there is less clear delineation between the Dungeness and Pwll du and closely two species and it is the more common resembles the NVC U24 community. Prunus spinosa, Rubus fruticosus scrub community with Hedera helix and Urtica Community key dioica as minor associates. SH122 Prunus spinosa - Eurynchium praelongum scrub; The second type of scrub is a Ulex europaeus, Rubus fruticosus community SH123 Prunus spinosa - Rubus fruticosus - typical of many shingle sites. The presence Arrhenatherum elatius community; of Solanum dulcamara as a minor associate is, however, relatively unusual. This SH107 Ulex europaeus - Rubus fruticosus - community occupies the area nearest to the Arrhenatherum elatius scrub; car park. SH79 Festuca rubra - Agrostis stolonifera Running along the top of the spit and out grassland; onto the wider recurved area at the distal end, there is a mixed community which is SH67 Festuca rubra - Dactylis glomerata - hard to define in the classification as it is Lolium perenne - Bromus hordeaceus unique to Crabhall. It comprises a dwarf grassland with Ulex europaeus; Ulex dominated grassland with the Ulex growing in association with Dactylis SH46 Festuca rubra - Ceratodon glomerata, Anthoxanthum odoratum, Festuca rubra and the annual Aira purpureus - Sedum spp. community; caryophyllea, along with various herb species, in particular, Vicia saliva, SH43Dicranum scoparium -Festuca rubra- Plantago lanceolata and Lotus Plantago lanceolata grassland; corniculatus. SH34 Festuca rubra - Armeria maritima - There is a stable pure grassland with clear Plantago maritima grassland; maritime influences also found at the distal end of the spit. This comprises a Festuca SHI6 Beta vulgaris maritima - Festuca rubra, Armeria maritima, Plantago rubra - Tripleurospermum maritimum coronopus community with a high lichen community; content including, Cladonia chlorophaea, C. impexa and C. rangiformis along with SM14 Atriplex portulacoides salt-marsh; the constant presence of the moss Ceratodon purpureus. Lichen heath U24 Arrhenatherum elatius - Geranium incorporating those species is characteristic robertianum grassland. of a sandy/shingle substrate. This community keys out to SH48 within the shingle classification a Festuca rubra,

Figure 17 Crabhall Saltings

45 Pennard Burrows

W. Glamorgan. SS 540870 Vegetation Conservation status: SSSI, National Trust. The vegetation on this site reflects the high Area: 1.11 ha sand content within the shingle matrix. This Fieldwork date: 27/5/89 is seen both in the pioneer communities and the more mature grassland Introduction communities. Pennard Burrows consists of a small sandy The foreshore of this spit is characterised shingle spit growing out from the eastern by a very open sandy pioneer community edge of Three Cliffs Bay. The shingle here with Honckenya peploides as the constant is visible on the active foreshore and on species. It has Elymus pycnanthus and the main body of the spit at its proximal Eryngium maritimum found in association end. As the spit widens at its distal end the with Honckenya peploides and is found all sand content increases and sand capping along the foreshore of the spit. A species- occurs. The spit encloses a relatively small rich variation on this community, which is saltmarsh with an Armeria maritima and characterised by the additional presence of Festuca rubra sward, which is lightly Ammophila arenaria and Beta vulgaris grazed. Behind that there is a large dune maritima, is largely confined to patches on system protected by the spit. the lee of the spit at its proximal end where There is evidence of erosion at the distal lobes of shingle have been driven over end of the spit with undercutting of the marsh and sand sediments behind. sand capping. At the proximal end of the The major area of the spit, at its broad spit, recent overtopping of the shingle has distal end supports a Festuca rubra, led to lobes of shingle being thrown out Plantago lanceolata herb-rich grassland. onto the marsh and dunes behind. The The herbaceous component of this shingle here is largely bare except for the community includes Rhinanthus minor, presence of a driftline indicating the recent Thymus polytrichus britannicus, Trifolium history of the lobes. The bare shingle dubium and Anthyllis vulneraria, while the supports a sandy shingle pioneer flora presence of Rhytidiadelphus squarrosus while the sand capping provides a base for indicates the undisturbed nature of this closed grassland/scrub communities. area. While not a major site in a national Behind this community, on the lee of the context, this provides an additional spit, there is a narrow strip of a different example of sandy shingle communities. Festuca grassland. In this case, while its position would suggest a more mature The pebbles are 5 cm diameter on average community, this area is a more open with which is slightly smaller than those on an average of 10% bare sand or shingle in other sites in the region, each quadrat. It is species-poor by comparison with the previous grassland Threats/management with Festuca rubra as the dominant species This area is subject to moderate found in association with Plantago recreational pressure in the form of coronopus, Sagina apetela, Ceratodon trampling, a little litter and, more purpureus and Armeria maritima. It is destructive for the vegetation, evidence of clearly influenced by the marsh behind the recent bonfires on the spit. spit and is probably flooded on occasion. There is no vehicular damage to the site as On the arm of the spit running from half access is restricted to a footpath. The site way along to the wider distal end is a Ulex is lightly grazed by rabbits and horses. scrub community found across many shingle sites. In this instance the Ulex

46 europaeus offers almost total cover in each quadrat with few associates. Typically SH33 Plantago coronopus - Armeria these few include Rubus fruticosus and the maritima community; moss Pleurozium schreberi. This part of the spit is the most exposed and has the SH30 Honckenya peploides - Elymus greatest depth of sand capping. farctus boreali-atlanticus - Eryngium maritimum pioneer community, with Community Key Elymus pycnanthus instead of E. SH108 Ulex. europaeus - Rubus fruticosus - farctus boreali-atlanticus; Eurynchium praelongum scrub; SH28 Honckenya peploides - Elymus SH54 Festuca rubra - Plantago lanceolata pycnanthus - Ammophila arenaria - Lotus corniculatus herb rich pioneer community grassland;

Figure 18 Pennard Burrows

47 Pwll du

W. Glamorgan. SS574875 Management. Conservation status: SSSI, National Trust, AONB. There is no grazing on this site. Area: 2.63 ha Vegetation Fieldwork date: 26/5/89 Vegetation is largely restricted to the lows between the shingle ridges where the shingle Introduction is mixed with a high proportion of silt, and to Pwll du beach is a good example of a pure the older ridges at the rear of the site. shingle apposition beach which has diverted the course of Bishopston Pill. It Although this is a relatively small site, it comprises three major shingle ridges which supports a wide variety of communities one of are almost like spits, growing out from the which is nationally rare. In particular, this western cliffs and stopping just short of the site offers interesting shingle/marsh eastern cliff where the freshwater stream communities. drains into the sea. A small, interlocking ridge has grown out from the eastern side. There are two major vegetation types found There is a significant difference in pebble at this site, the first being grassland sizes on this ridge and the major shingle communities, and the second scrub structure where pebbles are much larger communities. (10 cm on average). The major grassland community, found on the There is little differentiation in pebble size pure shingle ridges, comprises a herb-rich across the beach profile. However, the Festuca rubra, Plantago lanceolata shingle at the rear of the site is very community which is clearly very stable with angular suggesting deposition in a different a well developed lichen and moss sequence to the newer ridges. The existing component. The herb associates found in this foreshore of very rounded pebbles, from community include Arenaria serpyltifotia, material derived from glacial drift, Lotus corniculatus, Leontodon hispidus and supports a steep and bare slope. Thymus polytrichus britannicus, while the following lichens are commonly found – The presence of the freshwater stream has Cladonia foliacea, C. rangiformis and C. had a major impact on the vegetation furcata. behind the shingle ridges, where alluvium associated with freshwater flooding has led Where this community is in close proximity to fen type communities. The alluvium was to the marsh sediments there is a slight found to a depth of over 10 cm and so this variation in the species composition, with area was excluded from the survey. Armeria maritima and Phragmites australis found in small amounts within the Festuca Threats dominated grassland, along with Ceratodon There is a small village at the base of the purpureus and Sedum acre. Interestingly, this western cliffs and this has clearly affected community is also found on the smaller the level of recreational pressure on the site shingle spur which grows out from tie although damage is limited to the eastern side of the bay but in this case it occasional garden escape, dumping of occurs on top of the ridge. garden rubbish and one bonfire site. There are localised vehicle tracks at the western There is further zonation within the Festuca edge of the site but these have caused light rubra grassland to a less diverse community, damage to only one community. a gradation which occurs moving down the Otherwise, there has been very little spur towards the marsh sediments. This disturbance to the site. community is Festuca rubra dominated but with pioneer

48 associates such as Tripleurospermum a Rubus fruticosus, Teucrium scorodonia, maritimum, Rumex crispus littoreus, Dicranum scoparium community which, Potentilla anserina and Beta vulgaris while Rubus dominated, often supports a maritima, thus reflecting influences both varied grass and herb content in particular from the shingle and marsh substrates. A Geranium robertianum, Plantago further pioneer community which displays lanceolata and Hieracium pilosella. a major marsh influence is found where shingle from the current storm ridge, i.e. The second scrub community may be the youngest ridge, has overtopped the silt described as an open Prunus spinosa, behind such that bare shingle is clearly Geranium robertianum community with visible in the quadrats, while it is clear that prostrate and dwarfed Prunus found in the vegetation is rooted in silt and can association with scattered plants of therefore be considered as relict vegetation. Geranium robertianum and Hypnum This community comprises a Phragmites cupressiforme. This community is found at australis, Tripleurospermum maritimum, the edge of the scrub communities, furthest Rumex crispus littoreus association. from the marsh sediments which may act as a nutrient source, and may be indicative A more mixed grassland community is of a nutrient-poor environment. characteristic of the older shingle at the rear of the site. This community is best These represent two ends of a continuum described as a Festuca rubra, and, not surprisingly, in places where the Anthoxanthum odoratum, Cerastium pure Rubus scrub grades into the Prunus semidecandrum mixed grassland with a scrub, the community definition becomes high herb content including Achillea unclear and an additional community may millefoliuni) Plantago lanceolata, be defined. This third scrub community Ranunculus bulbosus, Galium verum and comprises fully developed Prunus spinosa, Sanguisorba minor minor. Despite the Rubus fruticosus scrub with various herb continued presence of Festuca rubra the and grass species, in this case Agrostis major and minor associates found in this capillaris, Festuca rubra, Senecio community are very different. jacobaea, Cirsium arvense and Rumex crispus littoreus. Additional woody A very open community, which is found associates include Crataegus monogyna or on the older ridges, is unique to Pwll Du. Fraxinus excelsior. This is an open Geranium robertianum, Epilobium parviflorum association with Community key Hieracium pilosella as an occasional SH121 Rubus fruticosus - Prunus spinosa - associate. This keys out to SH2. Arrhenatherum elatius scrub; The remaining communities are all scrub SH119 Rubus fruticosus - Arrhenatherum communities, which occupy areas of older, elatius scrub. stable shingle, often found at the shingle/marsh transition. The level of SH103 Phragmites australis - scrub development seems to be out of Tripleurospermum maritimum reed proportion with the scale of the site which bed; is, on a national scale, very small. However, it appears that the combination SH63 Festuca rubra - Plantago lanceolata of a source of freshwater and of a seed - Dicranum scoparium - source (from the Bishopstone valley Anthoxanthum odoratum grassland; woodlands) has led to its development. Clearly, the lack of human disturbance is SH49 Festuca rubra - Lotus corniculatus - also a contributory factor. Thymus polytrichus britannicus - Cladonia furcata grassland; The major distinction between the different scrub communities is made on the presence SH46 Festuca rubra - Ceratodon of Prunus spinosa. The first community is purpureus - Sedum spp. grassland;

SH16 Beta vulgaris maritima - Festuca rubra - Tripleurospermum maritimum grassland; SH2 Geranium robertianum - Prunus spinosa community.

Figure 19 Pwll du

50 East Aberthaw

S. Glamorgan SS 033657 The secondary ridge in turn gives way to Conservation status: SSSI the marsh behind. Area: 10.4 ha Fieldwork date: 25/5/89 At the eastern end of the site there is a ridge running along the base of the cliff. Introduction This has a sand capping of approximately This relatively small site comprises a 5cm and the vegetation reflects the sandy shingle spit growing out from the Lias nature of the substrate. cliffs to the east of the estuary trapping a small saltmarsh behind. In addition, there is Threats/management much intertidal shingle within the old Despite its proximity to the caravan park estuary and a narrow strip of permanent on top of the cliffs, this site appears to sandy shingle trapped by groynes on the suffer little disturbance from recreational western side of the site. pressure. The groynes are the only form of stabilisation work at this site. The spit is highly dynamic being frequently breached and rebuilt at its western end. Access to the site is restricted to This results in an impermanent flora on the pedestrians, so there is no vehicular western hook of the spit where it comes damage. close to the sea inlet to the marsh. This is presumably due to increased exposure, as There is no evidence of grazing at this site. there is the reappearance of a more permanent vegetation on the stable recurve Vegetation of the spit which is protected from such This site offers examples of shingle direct maritime influences. communities which display saltmarsh influences and of sandy shingle It is an example of a predominantly sandy communities. shingle site with small areas of silty shingle at the marsh edge. The site appears On the western side of the bay there is a to be suffering active erosion witnessed by narrow strip of sandy shingle which the need for groynes at the western end of supports relatively closed grassland the site and the obvious landward communities. At the far western end of this movement of the spit over marsh strip there is a small patch of Festuca sediments. This is evident in the shingle rubra, Plantago lanceolata, Lotus fans and lobes seen spreading out over the corniculatus grassland found on the less marsh and in the fact that old marsh disturbed area. This contrasts with the sediments are appearing along the Elymus pycnanthus, Dactylis glomerata, foreshore as the shingle is driven Plantago lanceolata mixed grassland found backwards. on the rest of this area. The herb associates in this community include Anthyllis The foreshore and storm crest are devoid of vulneraria, Raphanus raphanistrum vegetation, perhaps because of the active maritimus, Crepis capillaris and Trifolium nature of the site which precludes the dubium. establishment of pioneer communities more typical of this area on a shingle beach. Further down the foreshore, immediately above the driftline, the grassland The structure of the spit consists of a community gives way to a more open current storm crest which is separated from Festuca grassland with pioneer species as a secondary ridge by a small depression. additional constants such as Rumex crispus littoreus and Tripleurospermum maritimum. This keys out to a Festuca rubra, Silene uniflora, Lotus corniculatus community.

51 This community is also found on the main The herb rich Festuca, Plantago, Lotus spit. community occurs also on the very sandy ridge which runs along the base of the An additional pioneer community found cliffs. on the spit, but very localised is a Crambe maritima, Rumex crispus Community key littoreus, Tripleurospermum maritimum SH68 Festuca rubra - Plantago lanceolata community typical of many shingle sites. - Poa pratensis grassland; Much of the spit is occupied by a SH65 Festuca rubra - Achillea millefolia - shingle/saltmarsh community which is Lotus corniculatus grassland; found commonly at the edge of the lee slope of the shingle and may be SH63 Festuca rubra - Plantago lanceolata described as a Atriplex portulacoides, - Dicranum scoparium grassland; Cochlearia officinalis community with Spergularia media and Plantago SH54 Festuca rubra - Plantago lanceolata maritima as frequent associates, although in places Beta vulgaris maritima becomes - Lotus corniculatus grassland; important. SH53 Festuca rubra - Ononis repens - A second community found along much Anthyllis vulneraria community; of the spit is, however, an example of a Festuca rubra, Elymus pycnanthus SH46 Festuca rubra - Ceratodon grassland with other marsh associates purpureus - Sedum spp. grassland; including Armeria maritima and Plantago maritima. This is clearly a SH36 Elymus pycnanthus - Festuca rubra - mature Festuca grassland typical of a Atriplex portulacoides grassland; shingle substrate which is subject to marsh influences. In places which have SH16 Beta vulgaris maritima - Festuca been particularly stable this community rubra - Tripleurospermum maritimum appears to be developing into a closed community. community with the Festuca rubra and Elymus found in association with moss and lichen species indicative of stability such as Ceratodon purpureus, Eurynchium praelongum and Cladonia rangiformis.

Figure 20 East Aberthaw 53 Porthkerry

S. Glamorgan ST 091670 Management Conservation status: none, but close There has been no loss of vegetated to SSSI and LNR shingle to any form of development Area: 1.9 ha and there is no need for stabilisation Fieldwork date: 24/5/89 works as the site is in dynamic equilibrium, although there is some evidence of a minor landward Introduction movement of the shingle with marsh Porthkerry pebble ridge is a shingle sediments reappearing on the bar which has diverted the flow of the foreshore. stream. The bar comprises a steep foreshore which is largely bare giving There is no evidence of grazing on way to an extensive area of intertidal this site. shingle and a wave cut platform. The pebbles, which are derived from the Community key local limestone, are large, disc shaped T1 Narrow strip of discontinuous and, particularly at the top of the strip of vegetation comprising slope, are highly imbricate which Rubus fruticosus, could clearly have important Arrhenatherum elatius, Rumex implications for seed germination. crispus littoreus, Dactylis This pebble structure may also help to glomerata and Lolium perenne. explain the steep angle associated with This closely resembles SH119 the foreshore. Rubus fruticosus - Arrhenatherum elatius scrub. The vegetation is largely limited to the ends of the ridge close to the T2 A muddy matrix has led to the limestone cliffs with the main central development of Festuca rubra, section of the bar supporting no Lolium perenne, Dactylis vegetation. The vegetation has been glomerata, Cirsium arvense and mapped largely using target notes. Geranium robertianum. Threats T3 Mixed vegetation comprising There is a golf course on the alluvial patches of Geranium plain which is behind the shingle and robertianum, Dicranum this forms part of the Porthkerry scoparium, Senecio jacobaea Country Park. Clearly, this heightens and Potentilla erecta with the level of recreational use of the site occasional Rubus fruticosus which may, in part, account for the plants. general lack of vegetation. However, despite widespread public access there is little evidence of damage to the site by trampling.

54 Figure 21 Porthkerry

55 References

For all key references relating to Fuller, R.M., 1987. Vegetation shingle vegetation see: establishment on shingle beaches. Journal of Ecology 75, 1077-1089. Sneddon, P. & Randall, R.E. 1989. Vegetated shingle structures survey of Randall, R.E., 1977. Shingle formations. Great Britain; Bibliography. In Barnes, R.S.K., ed. The Coastline. Peterborough, Nature Conservancy London, Wiley. Council. (Research & survey in nature conservation, No 20.) Randall, R.E., Sneddon, P. & Doody, J.P., 1990. Coastal shingle in Great Britain: a preliminary review. Peterborough, Nature Conservancy Council. (Contract surveys Additional references cited in this text No. 85.) are: Scott, G.A.M., 1963. The ecology of Chapman, V.J., 1976. Coastal shingle beach plants. Journal of Ecology Vegetation. Oxford, Pergamon Press. 51, 733-742.. Clapham, A.R., Tutin, T.G. & Moore, Sparks, B., 1972. Geomorphology. London, D.M. 1987. Flora of the British Isles. Longman. Third edition. Cambridge, Cambridge University Press. Sneddon, P. 1992. Variations in shingle vegetation around the British coastline. Ferry, B. & Waters, S., eds. 1985. PhD. Thesis, University of Cambridge. Dungeness ecology and conservation. Peterborough, Nature Conservancy Sneddon, P. & Randall, R.E. 1993. Council. (Focus on Nature Vegetated shingle structures of Great Conservation, No 12.) Britain. Main report. Peterborough, Joint Nature Conservation Committee. Ferry, B., Lodge, N. & Waters, S. 1990. Dungeness: a vegetation survey of a Steers, J.A., 1964. The coastline of shingle beach. Peterborough, Nature England and Wales. Cambridge, Conservancy Council. (Research & Cambridge University Press. survey in nature conservation, No 26.)