Summary of succession on sand dunes

The vegetation succession in sand dunes is often described in a sequence from open mobile dunes to more stable types as the growing vegetation traps sand. This is true for sand dunes in temperate regions, but not those of drier desert lands which are not the subject of this guidance. The zonation which develops reflects the physical characteristics affecting sand transport rates and deposition acting in concert with the vegetation and other biological factors (many references describe this but see Packham & Willis 1997 pp. 153-169).

The development of strandline depends on the presence of debris and plants on the beach which help trap sand. Foredune development in north west Europe is directly related to the ability of plants such as Elytrigia juncea and Ammophila arenaria to withstand burial by sand together with the other stresses, such as water availability, in what is an inhospitable environment. [Similar species occupy the same niche in America, where Ammophila breviligulata replaces the ubiquitous Ammophila arenaria of Europe.]

Once the main body of the dune is formed other processes come into play and initiate a sequence from mobile foredunes and 'yellow dunes' to 'grey' semi-fixed dunes with grassland, heath, scrub and woodland. A typical sequence can be established which helps form the basis for considering management and restoration. The original calcium content of the sand, and the age of the dune soil (including the degree of leaching) helps to determine whether succession is to calcareous dune grassland or dune heath. This sequence rarely occurs in a straightforward progression from one stage to the next as depicted. Blow-outs occur with or without the intervention of man and can be the precursors of dune slacks. Similarly the re-profiling of dune ridges under the influence of changing wind patterns brings an infinitely variable topography, the origins of which may be difficult or impossible to unravel. The complex topography, spatial and temporal variation helps to sustain a particularly diverse flora which includes many rare species and fauna.

References

Packham, J.R. & Willis, A.J. 1997. Ecology of Dunes, Salt Marsh and Shingle. Chapman & Hall, London, 335 pp.