Red List habitat classification > RLB - Coastal habitats > RLB1.8a Atlantic and Baltic moist and wet dune slack

Atlantic and Baltic moist and wet dune slack

Quick facts

Red List habitat type code RLB1.8a
Threat status
Europe Vulnerable
EU Vulnerable
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)

Summary

This is a very broad habitat, comprising all open and closed, low to tall, aquatic, marsh and helophyte vegetation of moist to wet depressions in coastal dunes of the Atlantic and Baltic coasts. It comprises dune lakes and ponds with open water and floating or submerged vegetation, pioneer communities on bare shores, calcareous and acidic fen communities, as well as beds of helophytic reeds and sedges. Within the communities of the hygrosere (the succession series in dune slacks) the late succession stages (scrub, forests) and wet heathlands are considered under other habitats (respectively  B1.6a, B1.7a and B1.5a). Also mesic grasslands in coastal dunes are not included in the dune slack habitat, although they may in some cases grow in mosaic with this habitat. On a higher level EUNIS makes a distinction between coastal and inland habitats, but mesic freshwater grasslands in coastal areas are included under inland types, for example grasslands of the Calthion palustris, Nardo-Juncion squarrosi, Cynosurion cristati or Molinion caeruleae. In coastal areas such grasslands are often associated with old, traditionally managed meadows or pastures, and are less characteristic for dynamic dune slacks. In many cases they are found on the transition from dunes towards the inland, in other situations they are part of old, traditional mosaic landscapes (like machairs, see B1.9).

Dune slacks may develop in two ways. In the first place wind activity may blow out sand, resulting in depressions up to the depth level of groundwater. These depressions are known as secondary dune slacks. Primary dune slacks are the result of new formed fore-dunes, which isolate a beach from the influence of the sea and thus create a depression with groundwater influence within two ridges. In the Wadden Sea area a rare, third situation occurs on so-called green beaches, found on the head or tail of barrier islands. Such beaches are irregularly flooded both from the North Sea and from the Wadden Sea direction, and have complex gradients of dune slack, salt marsh and dry dune communities.

The water table in dune slacks fluctuates strongly during the year, with relatively wet conditions in winter and spring, and sometimes extreme dry conditions in summer. Because of these fluctuations peat layers rarely develop. In the Baltic coast the water table of dune slacks fluctuates less, and here in some cases acidic mire communities or even bogs develop in dune slacks.

In very wet conditions the dune slack communities of this habitat may form azonal climax communities, but in most slacks the pioneer and mire communities, as well as sedge and reed beds show succession towards scrub (Salix) and forest (Salix, Betula, Alnus). Mowing or grazing is practiced to conserve species rich, intermediate and young succession stages, for example communities of the alliances Caricion davallianae and Caricion nigrae. However, although such management may slow down succession, due to other changes in this dynamic landscape species composition changes in time. For example coastal erosion or sedimentation will change the size and place of freshwater lenses, and in this way affect the vegetation of dune slacks. In calcareous dune slacks, due to high precipitation rates, decalcification takes places, leading to changes in species composition. For this reason, the species rich calcareous fen communities of the Caricion davallianae are best preserved in dynamic landscapes, where now and then new primary dune slacks are formed. They may survive in older dune slacks, but only in places with a high rate of seepage of calcareous groundwater.

As many of the vegetation types of dune slacks are also found inland, in similar or other habitats, few plant species are restricted to the Atlantic and Baltic dune slacks. Some coastal species have been described as different ecotypes (Parnassia palustris), others have relatively larger populations in coastal areas (Liparis loeselii, Sagina nodosa, Centaurium littorale, Potamogeton coloratus). Only a few species are mainly restricted to coastal areas, like Carex trinervis.

Along the Atlantic coast these dune slacks are found from Norway to northern Spain, with relatively large areas in the broad dunes of Jutland, the Wadden Sea, mainland Netherlands, northern France and southwestern France. In Ireland, England and the Baltic coasts the dune slacks are relatively rare and more widespread. In Spain their occurrences are marginal, while the dune slacks along the Portuguese Atlantic coast belong to the Mediterranean habitat B1.8b.

Indicators of good quality:

  • No anthropogenic changes in water table
  • Species richness
  • Occurrence of rare and endangered species
  • Broad diversity in different types of dune slacks and related plant communities
  • Forming intact landscape mosaics with and transitions towards dry dune habitats

Characteristic species
For full habitat description, please download the habitat factsheet.

Threat status

Synthesis of Red List assessment

Large reductions in quantity over the last 50 years (criterion A1) and over a longer time frame (A3) lead to the Red List category Vulnerable (VU). A large part of the remaining area declined in quality, with values just below the threshold for Vulnerable, resulting in a Near Threatened (NT) status for criterion C/D1.
EU
Red List Category Red List Criteria
Vulnerable A1, A3
Europe
Red List Category Red List Criteria
Vulnerable A1, A3

Confidence in the assessment

medium
Red List of habitat categories and criteria descriptions

Pressures and threats

  • Agriculture
    • Intensive grazing
  • Human intrusions and disturbances
    • Outdoor sports and leisure activities, recreational activities
  • Pollution
    • Nitrogen-input
  • Natural System modifications
    • Human induced changes in hydraulic conditions
  • Natural biotic and abiotic processes (without catastrophes)
    • Biocenotic evolution, succession

Habitat restoration potential

When severely damaged restoration is possible by restoring hydrological functioning, in combination with creating young pioneer stages of dune slacks.

Trends in extent

Average current trend in quantity

Decreasing Decreasing
EU28 EU28+

Trends in quality

Average current trend in quality

Decreasing Decreasing
EU28 EU28+

Conservation and management needs

Management should focus on maintaining or restoring dynamics in hydrology of the dune systems, resulting in yearly fluctuating levels of ground water. Besides, to prevent quick succession towards higher vegetation, mowing or extensive grazing may be applied as a management practice.

List of conservation and management needs

  • Measures related to agriculture and open habitats
    • Maintaining grasslands and other open habitats
  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving the hydrological regime
    • Restoring coastal areas
  • Measures related to spatial planning
    • Establish protected areas/sites

Distribution

For each habitat a distribution map was produced from a wide variety of sources indicating known and potential occurrences of the habitat in 10x10 km grids within Europe. Occurrences in grid cells were given in two classes: actual distribution from relatively reliable sources (surveys, expert knowledge), and potential distribution based on models or less reliable indicators. Please download the fact sheet to see the map.

Geographic occurrence and trends

EU28 Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Belgium Present 0.5 Decreasing Decreasing
Denmark Present 76 Decreasing Decreasing
Estonia Present 1.6 Unknown Stable
Finland mainland Present 0.1 Decreasing Decreasing
France mainland Present 75 - Decreasing
Ireland Present 2.8 Unknown Unknown
Latvia Present 14 Decreasing Decreasing
Lithuania Uncertain unknown Unknown Unknown
Netherlands Present 27 Decreasing Decreasing
Poland Present 0.9 Decreasing Decreasing
Spain mainland Present 0.1 Decreasing Decreasing
United Kingdom Present 18 Decreasing Decreasing
Northern Island Uncertain 18 Decreasing Decreasing
Aland Islands Uncertain 0.1 Decreasing Decreasing
Germany Present 8 Decreasing Decreasing
Sweden Present Unknown Unknown Unknown
Portugal mainland Present marginal Unknown Unknown
EU28 + Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Kaliningrad Uncertain - -
Norway Mainland Present Unknown Unknown Unknown
Iceland Uncertain Unknown Unknown
Svalbard Uncertain Unknown Unknown Unknown
Jan Mayen Uncertain Unknown Unknown Unknown

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 3042100 568 225
EU28+ 568 225
AOO = the area occupied by a habitat measured in number of 10x10 km grid cells.
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).

Characteristic species

The full list of characteristic species and genus are available above from the Summary. The species available in the EUNIS database are shown here.
Amphibians Bufo calamita
Ferns Equisetum variegatum
Ferns Ophioglossum vulgatum
Ferns Pilularia globulifera
Flowering Plants Agrostis canina
Flowering Plants Agrostis stolonifera
Flowering Plants Anagallis tenella
Flowering Plants Apium inundatum
Flowering Plants Blackstonia perfoliata
Flowering Plants Bolboschoenus maritimus
Flowering Plants Calamagrostis canescens
Flowering Plants Calamagrostis epigejos
Flowering Plants Calamagrostis stricta
Flowering Plants Carex demissa
Flowering Plants Carex flacca
Flowering Plants Carex hartmanii
Flowering Plants Carex nigra
Flowering Plants Carex oederi
Flowering Plants Carex punctata
Flowering Plants Carex trinervis
Flowering Plants Centaurium erythraea
Flowering Plants Centaurium littorale
Flowering Plants Centaurium pulchellum
Flowering Plants Centunculus minimus
Flowering Plants Cicendia filiformis
Flowering Plants Cladium mariscus
Flowering Plants Dactylorhiza incarnata
Flowering Plants Dactylorhiza majalis subsp. purpurella
Flowering Plants Eleocharis palustris
Flowering Plants Eleocharis quinqueflora
Flowering Plants Eleocharis uniglumis
Flowering Plants Epilobium palustre
Flowering Plants Epipactis palustris
Flowering Plants Erica tetralix
Flowering Plants Gentianella amarella
Flowering Plants Herminium monorchis
Flowering Plants Hippuris vulgaris
Flowering Plants Holoschoenus romanus
Flowering Plants Hydrocotyle vulgaris
Flowering Plants Juncus acutus
Flowering Plants Juncus alpinoarticulatus
Flowering Plants Juncus arcticus
Flowering Plants Juncus articulatus
Flowering Plants Juncus bufonius
Flowering Plants Juncus maritimus
Flowering Plants Juncus subnodulosus
Flowering Plants Liparis loeselii
Flowering Plants Littorella uniflora
Flowering Plants Lythrum salicaria
Flowering Plants Mentha aquatica
Flowering Plants Myrica gale
Flowering Plants Oenanthe lachenalii
Flowering Plants Orchis palustris
Flowering Plants Parnassia palustris
Flowering Plants Phragmites australis
Flowering Plants Platanthera bifolia
Flowering Plants Potamogeton coloratus
Flowering Plants Potamogeton gramineus
Flowering Plants Potamogeton pectinatus
Flowering Plants Potentilla erecta
Flowering Plants Pyrola rotundifolia
Flowering Plants Radiola linoides
Flowering Plants Ranunculus baudotii
Flowering Plants Ranunculus flammula
Flowering Plants Sagina nodosa
Flowering Plants Salix repens
Flowering Plants Samolus valerandi
Flowering Plants Schoenus nigricans
Flowering Plants Teucrium scordium
Flowering Plants Vaccinium macrocarpon
Mosses & Liverworts Bryum pseudotriquetrum
Mosses & Liverworts Calliergonella cuspidata
Mosses & Liverworts Campylium stellatum
Mosses & Liverworts Drepanocladus aduncus
Mosses & Liverworts Pellia endiviifolia
Species scientific name English common name Species group
Bufo calamita Natterjack Amphibians
Equisetum variegatum Ferns
Ophioglossum vulgatum Ferns
Pilularia globulifera Ferns
Agrostis canina Flowering Plants
Agrostis stolonifera Flowering Plants
Anagallis tenella Flowering Plants
Apium inundatum Flowering Plants
Blackstonia perfoliata Flowering Plants
Bolboschoenus maritimus Flowering Plants
Calamagrostis canescens Flowering Plants
Calamagrostis epigejos Flowering Plants
Calamagrostis stricta Flowering Plants
Carex demissa Flowering Plants
Carex flacca Flowering Plants
Carex hartmanii Flowering Plants
Carex nigra Flowering Plants
Carex oederi Flowering Plants
Carex punctata Flowering Plants
Carex trinervis Flowering Plants
Centaurium erythraea Flowering Plants
Centaurium littorale Flowering Plants
Centaurium pulchellum Flowering Plants
Centunculus minimus Flowering Plants
Cicendia filiformis Flowering Plants
Cladium mariscus Flowering Plants
Dactylorhiza incarnata Flowering Plants
Dactylorhiza majalis subsp. purpurella Flowering Plants
Eleocharis palustris Flowering Plants
Eleocharis quinqueflora Flowering Plants
Eleocharis uniglumis Flowering Plants
Epilobium palustre Flowering Plants
Epipactis palustris Flowering Plants
Erica tetralix Flowering Plants
Gentianella amarella Flowering Plants
Herminium monorchis Flowering Plants
Hippuris vulgaris Flowering Plants
Holoschoenus romanus Flowering Plants
Hydrocotyle vulgaris Flowering Plants
Juncus acutus Flowering Plants
Juncus alpinoarticulatus Flowering Plants
Juncus arcticus Flowering Plants
Juncus articulatus Flowering Plants
Juncus bufonius Flowering Plants
Juncus maritimus Flowering Plants
Juncus subnodulosus Flowering Plants
Liparis loeselii Flowering Plants
Littorella uniflora Flowering Plants
Lythrum salicaria Flowering Plants
Mentha aquatica Flowering Plants
Myrica gale Flowering Plants
Oenanthe lachenalii Flowering Plants
Orchis palustris Flowering Plants
Parnassia palustris Flowering Plants
Phragmites australis Flowering Plants
Platanthera bifolia Flowering Plants
Potamogeton coloratus Flowering Plants
Potamogeton gramineus Flowering Plants
Potamogeton pectinatus Flowering Plants
Potentilla erecta Flowering Plants
Pyrola rotundifolia Flowering Plants
Radiola linoides Flowering Plants
Ranunculus baudotii Flowering Plants
Ranunculus flammula Flowering Plants
Sagina nodosa Flowering Plants
Salix repens Flowering Plants
Samolus valerandi Flowering Plants
Schoenus nigricans Flowering Plants
Teucrium scordium Flowering Plants
Vaccinium macrocarpon Flowering Plants
Bryum pseudotriquetrum Mosses & Liverworts
Calliergonella cuspidata Mosses & Liverworts
Campylium stellatum Mosses & Liverworts
Drepanocladus aduncus Mosses & Liverworts
Pellia endiviifolia Mosses & Liverworts

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

This habitat may be equivalent to, or broather than, or narrower than the habitats or ecosystems in the following typologies.
Classification Code Habitat type name Relationship type
EUNIS Habitat Classification 200711 B1.8 Moist and wet dune slacks narrower
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