Atlantic and Baltic coastal dune grassland (grey dune)

Stabilized or semi-stabilized dune grasslands or chamaephytic vegetations (grey dunes) of the Atlantic and Baltic coasts, dominated by grasses, herbs, mosses and/or lichens. This habitat is usually dominated by perennial species, with a certain proportion of therophytes. The type is distributed along the Baltic coast and the Atlantic coast, from southern Norway to halfway Portugal, including the British Islands, Ireland and (marginal) Iceland.

It is a grassland type of dry dune sands that has a broad diversity in species composition. Species composition changes over the climatic north-south and west-east gradients, but differs also within one site on different soils (acid to slightly calcareous sands) and under different microclimates (especially north versus south exposition). Most species of the European temperate coastal grasslands are also found in inland sand grasslands, but several dune chamephytic species have their optimum in the coast. Especially in the south (Southwest-France to Portugal) communities of the order Crucianelletalia contain several coastal dune restricted  and endemic species.

The occupied area of the type depends on the size of the dunes, which is relatively large along shallow, sandy seas with relatively large tidal differences. In stretches of rocky coast dunes and the associated grasslands are limited to small parts in the estuaries of rivers. In dynamic dune landscapes these grasslands may form temporary natural succession stages, which could be overgrown with shrubs, overblown with sand, or washed away during severe storms. Such situations are rare, however. In more stabilized dunes these grasslands are maintained by natural dynamics like wind, salt spray, drought and grazing (rabbits), in combination with semi-natural management by cattle and sheep grazing (decreasing drastically or abandoned in certain areas) or rarely by mowing.

Indicators of good quality:

In good conditions these grasslands are rich in forbs, mosses and lichens. They are threatened by natural succession towards shrubland (a.o. Hippophae rhamnoides, Salix repens subsp. arenaria) and forest (Quercus spp, Pinus spp),  and by encroachment of tall or dense grasses (a.o. Calamagrostis epigejos, Ammophila arenaria, Festuca rubra), herbs and shrubs (incl. non-native species like Prunus serotina) under suboptimal conditions (for instance high atmospheric deposition, low dynamics, no grazing, eutrophication linked to human frequentation). The habitat is also locally threatened by trampling. Also the non-native moss Campylopus introflexus behaves as an invasive species. In cases of overgrowth with grasses, shrubs and trees, more intensive management may help maintenance of species diversity. A patchy pattern of grassland and shrubs on a landscape scale is, on the other hand, of importance for several typical bird species of coastal dune complexes.

The following characteristics may be considered as indicators of good quality, but these indicators differ in different regions:

·     High species richness

·     Presence of rare and/or threatened species (characteristic communities species)

·     Absence or low presence of invasive or nitrophilous species

·     Diversity within the type within an area and over the whole range

·     High cover of lichens (in some varieties)

·     Low vegetation structure

·     Low cover of encroaching tall grasses, tall herbs and shrubs

·     Low cover of alien and ruderal species

·     Presence of typical fauna (birds, lizards, butterflies, other invertebrates)

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats