DUNES

The Dune System

Sand dune systems are sand gravel deposits within a marine beach system, which are in permanent dynamic equilibrium. Coastal dunes are highly sensitive. 

They are formed by the combined action of the wind on the sand and some type of obstacle, vegetation being the most common, allowing the blown sand to accumulate. Dunes are covered with coastal vegetation particularly tolerant to harsh environmental conditions such as wind, salinity, high insulation, dryness and lack of nutrientes.

After reaching the state of dynamic equilibrium, the dune system constitutes the border between the terrestrial and marine environments, playing a fundamental role in the protection and conservation of the coast.

The Dune system consists of:

• Beach Sand - The beach sand corresponds to the strip of sand, located next to the sea, where the first plants, cakile maritima, polygonum maritimum and elymus farctus spp. boreoatlantica grow and are particularly tolerant to submersion and salinity in water

• Primary Dune or Embryo Dune - The primary dune (or embryo dune) corresponds to the transition band between the beach sand and the mobile dunes, where vegetation such as elymus farctus, euphorbia paralias, eryngium maritimum and the otanthus maritimus, play a major role in the development of the dune, capable of withstanding temporary immersion in sea water

• Mobile Dune (dune ridges) - The dunes are formed up to the dune ridges, or mobile dune, the sand being essentially fixed by the ammophila australis together with calystegia soldanella and lotus creticus

• Interdune Zone - The mobile dune is followed by a flattened area called the interdune zone which is sheltered from the action of winds and the sea. This zone has the greatest diversity and abundance of plants. Noteworthy are the artemisia crithmifolia, helichrysum italicum ssp. picardii, pancratium maritimum, sedum sediforme, anagallis monelli ssp. microphylla and seseli tortuosum

• Secondary or Fixed Dune - This zone is limited to the interior by a new elevation, more or less parallel to the primary dune, integrating the secondary dune, which comprises several depressions and elevations. In this area junipers turbinate, corema albu and malcolmia littorea stand out