Habitat account - Coastal sand dunes and continental dunes
2170 Dunes with Salix repens ssp. argentea (Salicion arenariae)
Background to selection
|Distribution of SACs/SCIs/cSACs with habitat 2170 Dunes with Salix repens ssp. argentea (Salicion arenariae). Click image for enlarged map.|
Description and ecological characteristics
This habitat type comprises dunes or parts of dunes where creeping willow Salix repens ssp. argentea is dominant, forming prominent, low scrubby growth. Creeping willow is found on dunes throughout the UK. It grows predominantly in and around dune slacks, though on some sites it may spread up the drier ridges.
This type of vegetation marks the mature phase in the life cycle of calcareous dune slacks. When found with other wetland and dry dune vegetation it indicates that successional processes are still active and that the structure and function of the dune system are well-conserved. On most of the highest-quality sites this habitat type occurs alongside a number of others, particularly 2190 Humid dune slacks, calcareous and acidic fixed dune vegetation and, locally, dune heath.
Creeping willow is often found in dune slack vegetation, and the boundaries between Dunes with Salix repens ssp. argentea and 2190 Humid dune slacks are often diffuse and difficult to define on the ground. The examples which have been selected to represent the former habitat type in the UK sites series are those where creeping willow is dominant and forming prominent, low, scrubby growth, sometimes referred to as ‘hedgehog dunes’. Much of this habitat corresponds to NVC type SD16 Salix repens – Holcus lanatus dune slack community, although not all examples of SD16 are referable to this Annex I type. This type of vegetation tends to occur in and around mature slacks where there has been little or no sand movement for some time and where grazing is light. Creeping willow tends to grow most vigorously at the drier end of the spectrum of slack vegetation types and it is also mainly associated with calcareous dune sites. Most occurrences of S. repens ssp. argentea on dunes in Scotland have been allocated to 2190 Humid dune slacks. Only one site in Scotland, Invernaver, can be confidently allocated to Dunes with Salix repens ssp. argentea, because of the abundance of Salix. Elsewhere in the UK, this habitat type is of only local occurrence on most sites, Sefton Coast being exceptional in supporting a substantial area, with S. repens ssp. argentea extending out of the slacks onto the adjoining dry dunes.
European status and distribution
Dunes with Salix repens ssp. argentea are widespread on the coasts of northern and western Europe.
UK status and distribution Click to view UK distribution of this habitat
In the UK dunes with Salix repens ssp. argentea are widespread but rare, being estimated to cover much less than 1,000 ha. The habitat type is best-developed in the southern half of the UK.
Site selection rationale
Sites have been selected to take account of the rarity of this habitat type in the UK. The largest examples have generally been treated as priorities for selection, and the SAC series contains a high proportion of the total UK resource. Site selection has also taken account of the habitat’s wide geographical range.
|Braunton Burrows is one of the largest virtually intact dune sites in the UK and is representative of dunes with Salix repens ssp. argentea in south-west England. The habitat is scattered across the site and form part of a complex mosaic of vegetation containing creeping willow, including early and mature successional stages of dune slack vegetation. There are transitional stages between this type and more mature scrub vegetation.|
|Carmarthen Bay Dunes/ Twyni Bae Caerfyrddin||East Wales, West Wales and The Valleys|
|Carmarthen Bay Dunes is representative of dunes with Salix repens ssp. argentea in the south Wales part of its range. Three dune systems associated with the Burry Inlet – Whiteford and Pembrey Dunes, Laugharne and Pendine Burrows – contain examples of the habitat type, part of a range of dune habitats on the site.|
|Drigg contains a number of dunes with Salix repens ssp. argentea. These span a range of hydrological conditions from very wet to relatively dry. The slacks also grade into more acidic 2190 Humid dune slacks with some interesting intermediate types. This site is representative of dunes with Salix repens ssp. argentea in north-west England.|
|Invernaver||Highlands and Islands|
|Invernaver is the only Scottish site that can be confidently allocated to dunes with Salix repens ssp. argentea, because of the relative density of creeping willow. The site is an extreme northern variant of the habitat type and contains a wide range of sand dune habitats. Dunes with Salix repens ssp. argentea occurs in hollows among hummocky dunes and within narrow blow outs in two main areas and extends into areas of ‘climbing dunes’ where sand has been blown up onto cliffs.|
|Kenfig/ Cynffig||East Wales|
|Kenfig contains one of the largest series of dune slacks in Wales. The dune slacks are species-rich and there are extensive areas of dunes with Salix repens ssp. argentea, which represent a mature phase in dune slack development. This site is in the central part of the range of this community on the west coast and is a highly representative example of this habitat type.|
|Magilligan is one of the largest calcareous dune systems in the UK. It has an extensive and well-developed series of dune slacks which contain virtually all of the dune slack vegetation in Northern Ireland. Most of the slack vegetation is dominated by creeping willow Salix repens ssp. argentea, although more open humid slacks and older hollows filled with mire vegetation also occur.|
|Morfa Harlech a Morfa Dyffryn||West Wales and The Valleys|
|Both Morfa Harlech and Morfa Dyffryn have comparatively large areas of dunes with Salix repens ssp. argentea and Yorkshire-fog Holcus lanatus, especially in some of the older, more inland parts of the system. In addition, there are two other dune slack communities that support creeping willow.|
|North Northumberland Dunes||Northumberland and Tyne and Wear|
|The dunes of Holy Island and Ross Links are calcareous and represent dunes with Salix repens ssp. argentea on the north-east coast of England. Creeping willow Salix repens ssp. argentea dominates the more mature dune slacks and a number of rare plant species are associated with this type of vegetation. The mature slacks contribute to the wide range of habitats found on this site and form part of a well-developed successional series.|
|The small area of dunes with Salix repens ssp. argentea found at Sandwich Bay is of interest as it is the only example found in the dry south-east of England and is representative of this habitat type in a near-continental climate.|
|At Sefton Coast on the north-west coast of England there are extensive dune slacks dominated by creeping willow Salix repens ssp. argentea, making this site particularly important for dunes with Salix repens ssp. argentea. Radley (1994) estimated that 99 ha, or 43% of the total English resource of the main dune slack community dominated by creeping willow occurred here. The species also dominates areas of free-draining dune grassland to a much greater extent than at most other UK sites. Despite some urban and recreational development, both successional and geomorphological processes are still active and the structure and function of the site as a whole is still well-conserved. Management, including partial removal of planted conifers, has taken place in recent years to maintain and enhance these processes.|
|Y Twyni o Abermenai i Aberffraw/ Abermenai to Aberffraw Dunes||West Wales and The Valleys|
|Abermenai to Aberffraw Dunes in north Wales comprises an extensive area of dunes with a complete range of dune vegetation, including substantial areas of slack vegetation dominated by creeping willow Salix repens ssp. argentea. Despite the extent of afforestation, the dune aquifer retains its overall integrity, although changes in water table, partly attributable to the growth of the forest, have influenced the development of the dune slacks. There is long-term potential for further improvement.|
SACs/SCIs/cSACs where this Annex I habitat is a qualifying feature, but not a primary reason for site selection
|Morecambe Bay||Cumbria, Extra-Regio, Lancashire|
|Murlough||Extra-Regio, Northern Ireland|
|Penhale Dunes||Cornwall and Isles of Scilly|
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