COASTAL SAND DUNES (UK BAP PRIORITY HABITAT)

Summary

Coastal sand dunes occur where sand is blown inland from beaches and deposited above the high water mark where it typically builds up into a series of low hillocks or ridges. They are widespread along the Scottish coast.

Near their seaward edges, sand dunes are relatively young and ‘mobile’, with much bare, unstable sand and just a patchy cover of pioneer plants. Further inland are older, more stable ‘fixed’ dunes where the vegetation is more continuous and varies from species-rich grassland to species-poor coarse grassland and sea buckthorn Hippophae rhamnoides scrub. The hollows in between the ridges or hillocks are wetter ‘dune slacks’ with wetland vegetation. Coastal sand dunes provide a rich habitat for birds, reptiles, insects, vascular plants, bryophytes, lichens and fungi.

Coastal sand dunes are affected by grazing, encroachment by sea buckthorn, afforestation (especially with pines and sycamores) and golf course development.

Grazing can be beneficial in maintaining species-rich fixed dune grassland. Control of sea buckthorn, an introduced species, is undertaken in many places as a means of maintaining the ecological interest of the open dunes. Afforestation of Coastal sand dunes should be avoided. Golf course development should be planned sensitively so as to minimise disturbance to this priority habitat.

What is it?

Coastal sand dunes occur along coastlines with extensive beaches of sand which dries out when exposed at low tide, allowing loose sand to be blown inland by onshore winds and deposited onto adjacent land above the high water mark. This deposited sand forms the dune habitat. The sand typically builds up into a series of low hillocks or ridges interspersed by hollows, so the topography can be complex on a small scale.

Near the seaward edge the dunes typically have a patchy vegetation cover and extensive areas of bare, unstable sand. These are relatively young, ‘mobile’ dunes in the early stages of formation and colonisation by vegetation. Typical plant species here are sand couch Elytrigia juncea which commonly forms open pioneer vegetation in a narrow zone of ‘foredune’ at the extreme seaward edge, lyme grass Leymus arenarius which is common generally along the seaward edge, and marram Ammophila arenaria which extends further inland and dominates much of the mobile dune vegetation. The abundant tall tufts of greyish-green leaves of marram give dune vegetation it’s most characteristic and familiar appearance, but along the seaward edge L. arenarius is equally distinctive and eye-catching because of its very broad bluish-green leaves.

Further inland the dunes become progressively older, more thickly vegetated and more stable. Their vegetation consists of varied mixtures of species such as Ammophila arenaria, sand sedge Carex arenaria, red fescue Festuca rubra and the moss Syntrichia ruralis ssp. ruraliformis. The oldest and most stable dunes are referred to as ‘fixed’ dunes. Their vegetation can resemble that of a neutral grassland with an abundance of species such as F. rubra, lady’s bedstraw Galium verum, ribwort plantain Plantago lanceolata, bird’s-foot trefoil Lotus corniculatus and white clover Trifolium repens, but also including some A. arenaria or C. arenaria or both. Some fixed dunes have coarser, less botanically diverse grassland of A. arenaria, F. rubra, false oat-grass Arrhenatherum elatius and cock’s foot Dactylis glomerata. Others have scrub of sea buckthorn Hippophae rhamnoides which is introduced in Scotland and most of the UK but native along much of the coast of eastern England. The pH of the soils of fixed dunes varies from calcareous with herb-rich grassland to more leached and acidic with dwarf shrub heath or mossy grassland.

The hollows within complexes of sand dunes are relatively poorly drained, so they commonly support wetland vegetation and can even be flooded for much of the time in winter. They are called dune slacks and their vegetation typically has some resemblance to an inland neutral mire. Typical species include common sedge Carex nigra, silverweed Potentilla anserina, marsh pennywort Hydrocotyle vulgaris, Yorkshire fog Holcus lanatus, Festuca rubra, creeping bent Agrostis stolonifera, glaucous sedge Carex flacca, creeping buttercup Ranunculus repens and the moss Calliergonella cuspidata. However, the presence of creeping willow Salix repens in many dune slacks is a point of difference from a typical inland mire.

How do I recognise it?

Coastal sand dunes account for most of the habitat in which coastal sand has been blown and deposited onto adjacent land above the high water mark. The remainder belongs to the Machair priority habitat (see notes below).

Differentiation from other Priority Habitats

The most similar priority habitats are Coastal vegetated shingle and Machair. Coastal vegetated shingle is made up of a different set of NVC communities except for SD2 which overlaps both priority habitats. Examples of SD2 on sand belong in the Coastal sand dunes priority habitat; those on stony shingle are in the Coastal vegetated shingle habitat.

The separation from Machair is less straightforward owing to the more complex definition of the Machair priority habitat. Amongst the areas of coastal wind-blown sand above the high water mark, those belonging in the Coastal sand dunes priority habitat are those which do not conform to the summarised definition of the Machair priority habitat given below the table of NVC communities. The Coastal sand dunes priority habitat overlaps with the Lowland calcareous grassland priority habitat, but this is only in the case of the CG2 grassland community which is rare in Scotland, and quite simply, examples on coastal sand belong in the Coastal sand dunes habitat.

In summary, in Scotland Coastal sand dunes priority habitat includes all examples of sand dune NVC communities except SD1, SD3, examples of SD2 on stony or shingly ground, and examples of SD7x and SD8a/c/d/e/x (as described by Dargie, 2000) which, for various reasons (see below), may be assigned to the Machair priority habitat. Also included are all examples of H11 Calluna-Carex arenaria heath in Scotland, and examples of CG2 calcicolous grassland and juniper scrub which are on coastal sand. Dargie (2000) describes a range of other vegetation types that sometimes occur on sand dunes.

Definition in relation to other habitat classifications

Classification Habitat types belonging to this UK BAP priority habitat H11(all examples), SD2 (on sand; not on shingle strandlines), SD4-19 (all examples except SD7x and SD8a/c/d/e in transitions to machair priority habitat – see below), CG2 (on coastal dunes), Juniper scrub on Coastal sand dunes (provisional NVC types NVC described by Dargie (2000)) and a range of other types in Dargie (2000). H11, S2, S4-19 and CG2 are included in the Scottish Biodiversity List. In England this priority habitat also includes examples of H1 heath on sand dunes. The Coastal sand dunes priority habitat includes two Phase 1 Phase 1 habitat types: B3 (example on coastal sand dunes) and H6 (all examples). UK BAP broad All examples of the Coastal sand dunes priority habitat in Britain habitat belong in the UK BAP broad habitat - Supralittoral sediment.

Machair priority habitat = sites with the following characteristics: soil = blown sand with significant % of shell- derived material, so lime-rich with pH >7; topography = flat or gently sloping ground at mature stage of geomorphological evolution; marshy or flooded in winter; climate = cool, moist and oceanic; management = influenced by grazing, cultivation, trampling or drainage within recent historical period; vegetation = SD8a/c/d/e/x*, SD17, MG11 or Arable and fallow, with transitional areas characteristically including SD7x*, SD8z*, Mx*, SxTHF*, SHv* or S19x* (* = provisional NVC types described by Dargie 2000).

Definition in relation to legislative classifications

Classification Habitat types belonging to this UK BAP priority habitat This priority habitat includes all examples of Annex I types H2110, H2120, H2130, H2140, H2150, H2160, H2170, H2190 Annex I and H2250, and dunes bordering H21A0.

SSSI habitat The Coastal sand dunes priority habitat includes all examples of features one SSSI Habitat Feature: Sand dune.

Where is it?

Coastal sand dunes occur where coastal sand has been blown and deposited onto adjacent land above the high water mark. These occurrences are mostly along ‘soft’ coasts with sandy beaches rather than rocks and cliffs, but some dunes can occur where sand has been blown some distance up rocky slopes or even steep cliffs. To the seaward side they typically adjoin sandy beaches, though there can be a narrow zone of sandy or shingly strandline in between the outer edge of the dunes and the upper edge of the sandy beach. In an inland direction the sand dunes most commonly pass into various types of grassland, bracken, scrub or woodland.

Coastal sand dunes are widespread along most parts of the Scottish coast. Information from the Sand Dune Survey of Scotland indicates that there are at least 33,000 hectares of this habitat in Scotland.

What is special about it?

As this priority habitat includes such a wide range of smaller-scale habitats ranging from dry to wet and from almost bare sand to near-continuous vegetation, it is not surprising that in total it includes much ecological interest in the way of birds, reptiles, insects, vascular plants, bryophytes, lichens and fungi. Some species of special conservation status recorded in this priority habitat in Scotland are listed below.

Wildlife EC Scottish and UK BAP Habitats Bio- Red Country- Common priority Directive diversity Data side Act Group name Latin name list Annex II List List (1981) natterjack amphibians Epidalea calamita y y y y toad bees, moss carder- wasps and Bombus muscorum y y bee ants bees, red-shanked wasps and Bombus ruderarius y y carder-bee ants bees, wall mason wasps and Osmia parietina y y bee ants Greenland Anser albifrons subsp. birds white-fronted y y flavirostris goose barnacle birds Branta leucopsis y goose birds curlew Numenius arquata y y birds lapwing Vanellus vanellus y y y Larus argentatus herring gull y y y subsp. argenteus birds skylark Alauda arvensis y y y birds linnet Carduelis cannabina y y y birds twite Carduelis flavirostris y y birds corn bunting Emberiza calandra y y y birds roseate tern Sterna dougallii y y y y northern butterflies Aricia artaxerxes y y y brown argus butterflies small blue Cupido minimus y y y butterflies grayling Hipparchia semele y butterflies wall Lasiommata megera y Fonseca's flies Botanophila fonsecai y dune fly flowering purple milk- Astragalus danicus y y plants vetch flowering curved Carex maritima y y y plants sedge flowering caraway Carum carvi y y y plants flowering stinking Chenopodium y y y plants goosefoot vulvaria flowering frog orchid Coeloglossum viride y y plants flowering Gentianella field gentian y y plants campestris Wildlife EC Scottish and UK BAP Habitats Bio- Red Country- Common priority Directive diversity Data side Act Group name Latin name list Annex II List List (1981) flowering juniper Juniperus communis y y plants flowering yellow bird`s- Monotropa hypopitys y y y plants nest flowering prickly Salsola kali subsp. y y y plants saltwort kali dark-purple Geoglossum fungi y earthtongue atropurpureum date- fungi coloured Hygrocybe spadicea y y waxcap matt felt lichens Peltigera malacea y y y lichen lichens a lichen Toninia sedifolia y liverworts petalwort Petalophyllum ralfsii y y y y y cylindrical Truncatellina molluscs y y whorl snail cylindrica matted mosses Bryum calophyllum y y y bryum Knowlton`s mosses Bryum knowltonii y y y thread-moss mosses Baltic bryum Bryum marratii y y y saltmarsh mosses Bryum salinum y y y thread-moss mosses sea bryum Bryum warneum y y y moths rosy minor Mesoligia literosa y lunar yellow moths Noctua orbona y y underwing Perizoma albulata moths grass rivulet y y subsp. albulata reptiles slow-worm Anguis fragilis y y reptiles sand lizard Lacerta agilis y y y y common reptiles Zootoca vivipara y y lizard a foliage spiders Agroeca cuprea y spider a money- spiders Mecopisthes peusi y spider a money- Silometopus spiders y spider incurvatus baltic stoneworts Chara baltica y y y stonewort

How do we manage it?

Coastal sand dunes can be affected directly or indirectly by various forms of human activity.

Many dunes are grazed by stock such as sheep or cattle, and many are also accessible to deer. Rabbits are also very common in this habitat. The vegetation of the more mobile dunes tends to be little-grazed because the main species here are unpalatable to large herbivores. On fixed dunes the vegetation typically includes some more palatable species and is grazed at many sites. In such places grazing can be beneficial in maintaining species-rich grassland of high botanical interest. In such places the removal of grazing can lead to the development of taller, coarser, species-poor vegetation of lower botanical interest, such as coarse grassland, bramble underscrub or sea buckthorn scrub.

Sea buckthorn, which is an introduced species in Scotland/much of Britain, can be very invasive at the expense of other types of dune vegetation, thereby causing a reduction in ecological interest and diversity. In many areas management is undertaken to cut back encroaching sea buckthorn and keep other habitats open, especially where those open habitats are of interest for uncommon small plants or for birds or invertebrates. This scrub can, however, provide shelter and feeding habitat for birds such as wintering and migrating passerines.

Areas of this priority habitat are best kept open and not planted with trees. Pines, sycamore and various other trees and shrubs are able to grow successfully on the more stable parts of sand dunes but they convert the open dunes into a habitat of lower ecological interest.

Some areas of sand dune have been affected by development as golf courses either within or adjacent to the dune systems. Golf course development should be planned sensitively where it comes close to this priority habitat. It can cause direct loss of dune habitat if dunes are smoothed out or flattened, reseeded and converted into golf course greens and fairways. There can also be losses or degradation of dune habitat as a result of paths or tracks created for access to different parts of a golf course. Partial development of a dune complex, as in scattered intensively managed greens and fairways surrounded by unmanaged dunes, can break up the natural mosaic of small scale habitats within a dune complex and thereby reduce the total ecological diversity.

References, links and further reading

Angus, S. 2004. De tha machair? Towards a machair definition. Scottish Natural Heritage. https://www.nature.scot/information-library-data-and-research/information-library

Dargie, T.C.D. 2000. Sand Dune Vegetation Survey of Scotland: national report (2 vols). Perth, Scottish Natural Heritage, (Contract No. SNH/032/95/AEB).

Ellis, N.E. and Munro, K. 2004. A preliminary review of the distribution and extent of BAP priority habitats across Scotland. Scottish Natural Heritage Commissioned Report No.044 (ROAME No. F00NA02). https://www.nature.scot/information-library-data-and-research/information-library

Rodwell, J.S., ed. 2000. British plant communities Volume 5: Maritime cliffs, Sand dunes, Saltmarshes and Other vegetation. Cambridge, Cambridge University Press.

Rodwell, J.S., Dring, J.C., Averis, A.B.G., Proctor, M.C.F., Malloch, A.J.C., Schaminee, J.H.J. & Dargie, T.C.D. 1998. Review of coverage of the National Vegetation Classification. Joint Nature Conservation Committee contract report F76-01-170. Coordinated by the Unit of Vegetation Science, Lancaster University.

UK BAP 2008. http://jncc.defra.gov.uk/pdf/UKBAP_BAPHabitats-09-CoastSandDunes.pdf

Usher, M.B., Bain, C. and Kerr, A. eds. 2000. Action for Scotland's Biodiversity. Scottish Biodiversity Group. Edinburgh, The Scottish Executive and The Stationery Office.

Common Standards Monitoring guidance: documents (pdf files) available to download from http://www.jncc.gov.uk/page-2199

National Biodiversity Network (NBN) Gateway https://data.nbn.org.uk/

Scottish Government website – information about agricultural grants, subsidies and services: http://www.scotland.gov.uk/Topics/farmingrural/Agriculture/grants/A-Z/Intro

Scottish Natural Heritage website: http://www.nature.scot

UKBAP information on JNCC website: http://jncc.defra.gov.uk/default.aspx?page=5155