Fixed dune vegetation occurs mainly on the largest dune systems, being those that have the width to allow it to develop. It typically occurs inland of the zone dominated by marram Ammophila arenaria on coastal dunes, and represents the vegetation that replaces marram as the dune stabilises and the organic content of the sand increases. In the UK the vegetation corresponds to the following NVC types:
SD7 Ammophila arenaria – Festuca rubra semi-fixed dune community
SD8 Festuca rubra – Galium verum fixed dune grassland
Some examples of SD9a Ammophila arenaria – Arrhenatherum elatius dune grassland, typical sub-community, can also be referable to this vegetation type. Inland stands of SD11 Carex – Cornicularia community and SD12 Carex – Festuca – Agrostis dune grassland are referable to Annex I type 2330 Inland dunes with open Corynephorus and Agrostis grasslands.
Fixed dunes are an extremely complex habitat type. For the purposes of the Habitats Directive, Fixed dunes with herbaceous vegetation ("grey dunes") has been divided into a series of sub-types (European Commission DG Environment 1999). The UK is particularly important for Atlantic dune (Mesobromion) grasslands.
The herbaceous vegetation of fixed dunes in the UK exhibits considerable variation. The most widespread type is Atlantic dune grassland, consisting of a short sward characterised by red fescue Festuca rubra and lady’s bedstraw Galium verum and typically rich in species of calcareous substrates. The vegetation shows considerable variation both from north to south and from east to west. In northern Scotland, Scottish primrose Primula scotica can occur in this community; in the south, several orchid species are found, including pyramidal orchid Anacamptis pyramidalis, and a rich variety of other species. In south-west England and in Wales wild thyme Thymus polytrichus often dominates this type of vegetation. A taller type of dune grassland vegetation, in which bloody crane’s-bill Geranium sanguineum is prominent, is particularly characteristic of north-east England. In areas with a drier and more continental climate, such as Norfolk, and where the substrate is at the acidic end of the spectrum, the fixed dune vegetation is rich in lichens.
Where ‘climbing dunes’ have developed over bedrock, grasslands similar to inland calcicolous types may occur, notably in the Western Isles where forms of NVC type CG10 Festuca ovina – Agrostis capillaris – Thymus praecox grassland are widespread on fixed dunes. Herb-rich transitions to CG13 Dryas octopetala – Carex flacca heath (6170 Alpine and subalpine calcareous grasslands) on wind-blown sand occur very locally in the north and west.
European status and distribution
As with 2110 Embryonic shifting dunes and 2120 Shifting dunes along the shoreline with Ammophila arenaria, this Annex I type is widely distributed throughout the EU.
Bann Estuary in Northern Ireland contains a series of three sand dune systems, which are part of the same physiographic unit. The most morphologically diverse are at Portstewart, where transverse dune ridges are up to 30 m high. ‘Grey dune’ is the most extensive vegetation community and is dominated by marram Ammophila arenaria and red fescue Festuca rubra. Short sward communities within this are characterised by a floristically diverse range of herbs and in places lower plants. Lady’s bedstraw Galium verum, wild thyme Thymus polytrichus and wild pansy Viola tricolor are widespread.
Barry Links is one of the largest dune systems in eastern Scotland. The site is known for its very fine parabolic dunes but these and the system as a whole are now quite stable. Most of the area is occupied by acid fixed dune grassland, though there is heather Calluna heath locally, some of it rich in Cladonia lichens. Such extensive areas of comparatively unmodified fixed dune are now rare in eastern Scotland.
Braunton Burrows, in south-west England, is one of the largest dune sites in the UK and is of particular importance because it is virtually intact and still active. There are very extensive areas of species-rich calcareous dune grassland with good examples of a variety of important communities. The short turf areas are extremely rich in herbs and lichens, including a number of nationally rare species. Flowering herbs such as large thyme Thymus pulegioides, common restharrow Ononis repens and common bird’s-foot-trefoil Lotus corniculatus are locally dominant.
Important dune systems with actively-forming spits and well-conserved structure and function occur within the Carmarthen Bay Dunes complex at Whiteford, Pembrey Coast and Laugharne and Pendine Burrows. The vegetation includes extensive areas of fixed dune grassland with red fescue Festuca rubra and lady’s bedstraw Galium verum and semi-fixed dune grassland with marram Ammophila arenaria and red fescue.
Coll Machair features the highest proportion of semi-fixed dune in western Scotland, which extends as much as 600 m inland, reflecting a combination of high exposure and high moisture levels. Blowout activity is high, perhaps linked to high rabbit Oryctolagus cuniculus numbers; this has given rise to a highly varied dune and 21A0 machair landscape with blowouts in various stages of development and restabilisation, and with the floors of some blowout scars having a high water table. The semi-fixed dune often has a high cover of mosses, mainly Tortula ruralis ssp. ruraliformis.
This extensive complex dune system lies in the inner Moray Firth in north-east Scotland. It consists of a low dune plain which is still developing in its outer part. The dune system consists of a series of ridges with heath and juniper scrub on the older ridges which grade into the fixed dune vegetation of maritime grassland in the mid and outer parts.
Durness contains one of the largest sand dune systems in the north of Scotland. It is an example of an extreme northern variant of fixed dunes with herbaceous vegetation. The site is maintained by very active physical and biological processes. Fixed dune vegetation at this site occurs on an extensive and diverse sequence of dunes and on soils covered with blown sand. A rich variety of calcareous dune grassland species grow here in association with arctic-alpine plants such as mountain avens Dryas octopetala.
Invernaver is one of the two largest dune sites in north Scotland, and it is actively accreting owing to its exposed location. Dunes merge into areas of sand that have been blown up and over the cliffs by strong winds as so-called ‘climbing dunes’, giving mosaics of fixed dune with grassland or heathland communities. Transitions from calcareous grassland to heath are well-developed. The presence of a number of arctic-alpine species such as mountain avens Dryas octopetala and purple oxytropis Oxytropis halleri, as part of the fixed dune vegetation, is particularly important. The nationally scarce endemic Scottish primrose Primula scotica is also present.
Kenfig is a largely intact dune system in south Wales with extensive areas of fixed dune vegetation with red fescue Festuca rubra and lady’s bedstraw Galium verum and semi-fixed dune grassland with marram Ammophila arenaria and red fescue. There is also a relatively large area of more acidic vegetation dominated by sand sedge Carex arenaria, sheep’s-fescue Festuca ovina and common bent Agrostis capillaris.
The sand dunes within this site are confined to the Castlemartin Peninsula in Pembrokeshire and include Broomhill, Brownslade, Kilpaison, Linney and Stackpole Burrows. The area includes extensive stands of short, species-rich, fixed dune grassland, which is being maintained by populations of rabbits Oryctolagus cuniculus, aided by sheep and cattle. Deposited on limestone, these dunes are extremely base-rich, and the fixed dune grasslands have much in common with calcicolous grasslands. They therefore support a number of ‘lime-loving’ species including the rare lichen Fulgensia fulgens.
This large, acidic dune system in south-west Scotland lies on the north side of the Solway Firth. There are a range of dune types, providing considerable diversity and complexity along with associated dune slack, fen and heath habitats. The area contains a wide range of flowering plants and invertebrates typical of fixed dunes with herbaceous vegetation.
Magilligan in Northern Ireland is one of the largest calcareous dune systems in the UK, with a well-developed and largely undisturbed system of ridges and slacks. Fixed dune vegetation with red fescue Festuca rubra and lady’s bedstraw Galium verum is very extensive and dominates most of the site. Much of the grassland is tall, with downy oat-grass Helictotrichon pubescens prominent, but the more open areas have wild thyme Thymus polytrichus and are notable for an abundance of the moss Rhytidium rugosum.
Sandscale Haws at the entrance to the Duddon Estuary supports the largest area of calcareous fixed dunes in Cumbria, which contrast with the acidic dunes at the adjacent North End Haws on Walney Island. South End Haws on Walney Island supports a smaller area of fixed dunes. North Walney and Sandscale in particular show well-conserved structure and function. The fixed dunes support a rich plant diversity including wild pansy Viola tricolor, lady’s bedstraw Galium verum, common restharrow Ononis repens and the uncommon dune fescue Vulpia membranacea and dune helleborine Epipactis dunensis.
Murlough is one of the most diverse and natural dune systems in Northern Ireland. The site is an ancient system with acidic sands and a long history of traditional management. A complex mosaic of different communities, some of which are very species-rich, covers the ‘grey dunes’. Marram Ammophila arenaria and red fescue Festuca rubra are dominant over much of the area, while species such as common restharrow Ononis repens and wild thyme Thymus polytrichus are prevalent where the sward is shorter and more herb-rich. These grey dunes form part of a well-developed natural succession from 2110 Embryonic shifting dunes and 2120 Shifting dunes along the shoreline on the seaward side, to areas of dune heath and gorse Ulex europaeus scrub on the landward side.
North Norfolk Coast on the east coast of England contains a large, active series of dunes on shingle barrier islands and spits and is little affected by development. The fixed dunes with herbaceous vegetation represents one of the principal variants of this vegetation type in the UK, as many of the swards are rich in lichens and drought-avoiding winter annuals such as common whitlowgrass Erophila verna, early forget-me-not Myosotis ramosissima and common cornsalad Valerianella locusta. The main communities represented are marram Ammophila arenaria with red fescue Festuca rubra and sand sedge Carex arenaria, with lichens such as Cornicularia aculeata.
North Northumberland Dunes represents fixed dunes with herbaceous vegetation in north-east England. It is an active site with extensive calcareous fixed dunes locally grading into more acidic fixed dune vegetation and dune heath. The site has been selected particularly as a representative of the north-eastern variant, in which bloody crane’s-bill Geranium sanguineum is prominent.
The sands of the three small bay dune systems at Oldshoremore and its neighbouring beaches are calcareous, forming 21A0 Machair, in contrast to the acid sands of Sandwood. The three small systems display a range of dune types, principally fixed dunes with herbaceous vegetation and 2120 Shifting dunes along the shoreline, with notable species-rich climbing machair at Oldshoremore and Oldshorebeg. Sandwood is very exposed and has a good sand supply, and the margins of the site have unusual climbing dunes with mountain avens Dryas octopetala. All the systems at this site are rich in bryophytes.
Penhale Dunes, like Braunton Burrows, is in south-west England and also has a large area of fixed dunes with herbaceous vegetation on an extensive and exposed calcareous dune system where active geomorphological and successional processes occur. However, of particular interest are the communities developing on sand overlying the adjacent hillsides, which has been blown inland by strong winds. In this respect the site is functionally similar to Invernaver, on the north coast of Scotland, though the vegetation is very different owing to climatic differences.
Within this dune complex on the east coast of England there are extensive areas of fixed dune vegetation within largely intact geomorphologically-active systems, with representation of early successional stages on the seaward side, and more stable areas. The lime-rich dunes support a rich and diverse flora, dominated in places by red fescue Festuca rubra and with unusual species including pyramidal orchid Anacamptis pyramidalis, bee orchid Orchis apifera, sea-holly Eryngium maritimum, lesser meadow-rue Thalictrum minus and sea campion Silene maritima. The fixed dunes are part of a successional transition, and the rapidly-accreting dunes on the seaward sand bars and shingle banks make this an important site for research into the processes of coastal development.
Sandwich Bay is a largely inactive dune system with a particularly extensive representation of fixed dune grassland, the only large area of this habitat in the extreme south-east of England. The vegetation is extremely species-rich and the site has been selected because it includes a number of rare and scarce species, such as fragrant evening-primrose Oenothera stricta, bedstraw broomrape Orobanche caryophyllacea and sand catchfly Silene conica, as well as the UK’s largest population of lizard orchid Himantoglossum hircinum.
Sefton Coast is a large area of predominantly calcareous dune vegetation in north-west England. The sequence of habitats from foredunes to dune grassland and dune slack is extensive, and substantial areas of open dune vegetation remain. There are large areas of semi-fixed and fixed dunes with herbaceous vegetation exhibiting considerable variation from calcareous to acidic. In the calcareous areas common restharrow Ononis repens is prominent. There are small but significant areas of decalcified sand with grey hair-grass Corynephorus canescens, a species more characteristic of decalcified fixed dunes in the east of England and around the Baltic.
The 21A0 Machair on Tiree features similar vegetation to Coll, but the sand is more stable, and rabbits Oryctolagus cuniculus are absent. Calcareous fixed dunes are extensive, with a wide range of these represented, including large areas of lightly grazed fixed dune, relatively uncommon in northern Scotland.
Within this dune complex in north Wales are extensive areas of both fixed dune vegetation with red fescue Festuca rubra and lady’s bedstraw Galium verum and semi-fixed dune grassland with marram Ammophila arenaria and red fescue. Despite the fact that a large proportion of the open vegetation has been afforested, the remaining communities retain considerable interest. Notable species of the site include early sand-grass Mibora minima. On the south side of Menai Strait, the dunes at Morfa Dinlle include a lichen-rich community with Coelocaulon aculeatum (SD11), a type of vegetation which is very rare in Wales.
SACs where this Annex I habitat is a qualifying feature, but not a primary reason for site selection