Invernaver

General site character

• Tidal rivers, Estuaries, Mud flats, Sand flats, Lagoons (including saltwork basins) (37.2%)
  
• Coastal sand dunes, Sand beaches, Machair (20.2%)
  
• Inland water bodies (Standing water, Running water) (0.5%)
  
• Bogs, Marshes, Water fringed vegetation, Fens (2%)
  
• Heath, Scrub, Maquis and Garrigue, Phygrana (17.9%)
  
• Dry grassland, Steppes (3.2%)
  
• Alpine and sub-Alpine grassland (9.8%)
  
• Broad-leaved deciduous woodland (0.3%)
  
• Inland rocks, Screes, Sands, Permanent Snow and ice (8.9%)
  

Annex I habitats that are a primary reason for selection of this site

• 2130 "Fixed coastal dunes with herbaceous vegetation (""grey dunes"")"  * Priority feature

  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.

• 2150 Atlantic decalcified fixed dunes (Calluno-Ulicetea)  * Priority feature

  This very exposed and active dune system is an extensive representative of Atlantic decalcified fixed dunes (Calluno-Ulicetea) on the north coast of Scotland and is an extreme northern variant of the habitat type. Areas of sand have been blown up and over cliffs by strong winds to form ‘climbing dunes’. This situation is functionally similar to the blown sand of Penhale Dunes, although the communities present are very different because of climate and location. These dunes support a highly complex mosaic of fixed dune grassland and heathland communities. Atlantic decalcified fixed dunes exist in a matrix of other dune heath communities that include a number of arctic-alpine species. This is the largest example of an extreme northern variant of this vegetation type and is of interest because it forms a transition between the typical northern acidic dune heath vegetation and the arctic vegetation that is widespread further north. It is therefore considered to be particularly important in the European range of ecological variation of dune vegetation.

• 2170 Dunes with Salix repens ssp. argentea (Salicion arenariae)

  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.

• 2250 Coastal dunes with Juniperus spp.  * Priority feature

  Invernaver contains a high density of dune habitats in a relatively small area, with an extensive transition zone to non-dune conditions. Dune juniper thickets occur in their more dispersed form, with scattered individuals occurring relatively widely. Of particular interest is the occurrence of the scattered form of Coastal dunes with Juniperus spp. on ‘climbing dunes’ found where sand has been blown onto cliff slopes, giving complex transitions from dune to cliff habitats and mountain avens Dryas octopetala heath. Juniper is also found as more discrete areas of low scrub in the dunes, extending as more scattered individuals into the non-dune habitats of this site.

• 4060 Alpine and Boreal heaths

  Invernaver represents a form of Alpine and Boreal heaths that is, as far as is known, floristically unique in the UK. The site is complementary to Ronas Hill in representing altitudinal descent of the habitat type to near sea level on the exposed north coast of Scotland. The heath consists of a mix of short heather Calluna vulgaris, juniper Juniperus communis, crowberry Empetrum nigrum, bearberry Arctostaphylos uva-ursi and bell heather Erica cinerea, similar to mixed heaths developed in coastal districts in Norway, but practically unknown in the UK outside Invernaver. This may be related to H16 Calluna vulgaris – Arctostaphylos uva-ursi heath, but its NVC status is uncertain at present. This is the only site in the series where there are widely-developed transitions to 6170 Alpine and subalpine calcareous grasslands, for which the site is also selected. There are also transitions to oceanic H10 Calluna vulgaris – Erica cinerea heath and to coastal communities.

• 6170 Alpine and subalpine calcareous grasslands

  Invernaver is one of five sites representing low altitude CG13 Dryas octopetala – Carex flacca heath, and this is the only site with extensive development of Alpine and subalpine calcareous grasslands on wind-blown calcareous shell-sand, from near sea level to about 100 m. On the other four low-altitude examples, the heath is developed chiefly on limestone outcrops. The site has an unusually extensive representation of a sub-type of Dryas heath in which the Dryas is mixed with ericaceous and other woody plants, including crowberry Empetrum nigrum, bearberry Arctostaphylos uva-ursi, creeping willow Salix repens ssp. argentea and juniper Juniperus communis. This sub-type is better represented here than on any other site selected. The abundance of woody plants may be partly attributable to lower grazing pressure. The diversity of arctic-alpine species is relatively low compared with high-altitude sites, but mountain avens, crowberry Empetrum nigrum ssp. hermaphroditum and bearberry Arctostaphylos uva-ursi are abundant, and other species, such as purple saxifrage Saxifraga oppositifolia, yellow saxifrage S. aizoides and hair sedge Carex capillaris, are frequent. The site is unusually exposed for a low-altitude site, and this is reflected by the occurrence of dwarf juniper Juniperus communis ssp. nana. There are transitions to calcareous coastal habitats to seaward, while inland there are transitions to a unique form of mixed Calluna – Juniperus – Arctostaphylos heath on more acid soils, and to oceanic Calluna – Erica cinerea heath, calcareous grassland and base-rich mires.

Annex I habitats present as a qualifying feature, but not a primary reason for selection of this site

• 2120 "Shifting dunes along the shoreline with Ammophila arenaria (""white dunes"")"
• 7230 Alkaline fens

Annex II species that are a primary reason for selection of this site

• Not Applicable

Annex II species present as a qualifying feature, but not a primary reason for site selection

• Not Applicable