Atlantic and Baltic soft sea cliff

The habitat refers to coastal loamy cliffs, with a bedrock of clays, shales or loamy sands, sometimes mixed with layers of pebbles, peat or gravel, which erode much quicker than cliffs with a hard bedrock. Erosion may be caused by storms, rain, waves and seepage from the inland, causing landslides, resulting in many sites in less steep cliffs than hard cliffs. The vegetation cover is low, with pioneer species prevailing, but sometimes with more closed grassland, shrubs and trees on the highest and less eroded parts, and also on parts of the cliff that have shifted downward by landslides. Because of soil movements and water streaming down the rock, many micro-habitats exist. Differences in bedrock layers, sediment size, soil chemistry, water flow and erosion patterns result in a widely varied habitat, with different species composition in different places.

In general, most species on the Atlantic and Baltic soft sea cliffs are common, widely spread ruderal species, that have adaptations to survive the turbulent conditions, for example deep rooting systems, broad spreading rhizomes or stolones, or a short life cycle. Examples of such common pioneers are Tussilago farfara, Calamagrostis epigejos, Petasites spurius, Petasites hybridus, Hieracium umbellatum, Equeisetum arvense and Arabidopsis thaliana. Where grasslands succeed to develop Cynosurus cristatus, Dactylis glomerata, Daucus carota subsp gummifer, Agrostis spp and Festuca spp are found. Several salt-tolerant species may be found, like Plantago coronopus, Armeria maritima and Plantago maritima. A rather characteristic species combination on soft cliffs along the Channel is Brassica oleracea and Silene maritima. Several rare species may be found on Baltic soft cliffs, like Linaria loeselii, Tragopogon heterospermus and Alyssum gmelinii. Scrub communities with Rubus sp., Ulex sp., Prunus spinosa can develop op long-time stable parts of the cliffs. On seepage areas Phragmites australis, Salix ssp and Alnus glutinosa may settle. Rumex rupestris, Apium graveolens, Sonchus maritimus and Sonchus arvensis grow together on soft cliffs of the western most coasts of the UK, France and Spain.

Coastal soft cliffs are a much rarer habitat than hard cliffs along the Atlantic coasts and in the northern and Baltic coast, but are relatively common on the southern and eastern shores of the Baltic Sea, with some large examples in the Wolinski National Park in Poland. More rarely soft cliffs are found in the Wadden Sea (for example the red cliffs of Sylt) and along the Channel coasts.

Indicators of good quality:

• diversity in micro-habitats, resulting in rich structural diversity
• diversity between cliffs in different localities and along the altitudinal gradient
• absence of invasive species

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats