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The Seashore

Sand Dunes

Embryo Dunes

SAND COUCH HABITAT

Sand grains move up the beach (when prevailing wind conditions allow) until they hit an obstacle. An embryo dune forms which is characterised by pioneer plants such as sand couch (Elytrigia juncea) and/or lyme grass (Leymus arenarius) and strandline plants including sea sandwort (Honckenya peploides), sea rocket (Cakile maritima), prickly saltwort (Salsola kali), sea mayweed (Tripleurospermum maritimum) and various orache (Atriplex) species.

Occasional but periodic immersion by spring tides stops marram grass (Ammophila arenaria) from dominating here, as it is intolerant of inundation.

Plants stabilise the embryo dune with their roots and encourage accretion (sediment build-up) with their aerial parts (the bodies of the plants act like barriers to the movement of sand). In time the sand will build up to above the height of EHWS and a mobile dune, dominated by marram will take the embryo dune’s place.

This is an extreme environment where colonising plants have to tolerate or avoid extremes of temperature; sand burial and scouring; lack of water and nutrient stress.

See species page for adaptations to this habitat.

 


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