Sand dune - Country Report, France
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This article on the sand dunes of France, is a revised country report from the 'Sand Dune Inventory of Europe' (Doody ed. 1991) [1]. The 1991 inventory was prepared under the umbrella of the European Union for Dune Conservation [EUDC]. The original inventory was presented to the European Coastal Conservation Conference, held in the Netherlands in November 1991. It attempted to provide a description of the sand dune vegetation, sites and conservation issues throughout Europe including Scandinavia, the Atlantic coast and in the Mediterranean.
An overview article on the distribution of European sand dunes provides links to the other European country reports. These represent chapters from updated individual country reports included in the revised, 2nd Edition of the 'Sand Dune Inventory of Europe' prepared for the International Sand Dune Conference “Changing Perspectives in Coastal Dune Management”, held from the 31st March - 3rd April 2008, in Liverpool, UK (Doody ed. 2008)[2].
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Contents
Introduction
At the time of the original inventory, little information was available about the sand dunes of France and there was no synthesis of the sand dune habitat. Inspection of the vegetation maps of France published by The Centre National de la Recherche Scientifique over a period of 15 years, mostly in the 1960s provided the first assessment of the distribution of dunes in France. Prof. Géhu provided more detailed information in general and Brabant (Espace Naturel Régional) for the Pas de Calais region. The current report is augmented with information derived from studies, especially those of the Aquitaine coast.
Distribution and type of dune
France contains some of the most extensive dune landscapes in Europe. The original total area of blown sand was estimated at 250,000ha (Council of Europe 1984). Dunes or dune remnants occupy long stretches of the coastline. On much of the coast dunes occur behind beaches, and in places have moved in over rocky coasts, as in Cotentin and Brittany. On the Channel (Manche) coast of France, the wide intertidal beach at Bray has much eroded grassy dunes. The coastline has receded, as indicated by the ruins of blockhouses built in 1940 on the dune fringe, which are now on the shore. The bay of Wissant west of Calais is also backed by the dunes of Aval and Chatelet, fronting peaty marshland. Dunes extend across the mouth of the valley of the River Slack, which is constricted by a spit of sand and shingle.
South from Boulogne the coast of Picardie has sandy beaches, wide at low tide, and dunes that extend inland under pine forest behind Hardelot Plage. The sand has come mainly from the extensive Palaeocene and Eocene deposits on the sea floor to the west, rather than from the rivers, which have Chalk catchments and deliver little sand. Similar dunes are seen beside the Canche estuary near Le Touquet and along the coast southward past Berck to the Somme estuary and Cayeux (Briquet 1930).
Dunes occur locally on the Côte Fleurie, notably alongside the Grand Vey, a wide shoaly inlet to the west. On the western side of the Cotentin Peninsula, long gently curved beaches front the dunes of Vauville and Biville, and there are dunes at Cap Carteret. The sand has come mainly from the Eocene sediments extensive on the sea floor around the Channel Islands to the west. In the Baie de Saint Michel, there are dunes behind a beach of shelly sand south of Granville. On the north coast of Brittany, the wider bays generally have almost flat sandy beaches, some backed by dunes often damaged by vehicle traffic and camping. The dunes of Keremma back a bay adjacent to the Greve de Goulven. On the west coast of Brittany the wide Plage des Blancs Sablons, backed by grassy dunes, faces northwest on the northern side of the Kermorvan Peninsula. On the south coast, the rocky Presqu'ile de Quiberon is attached to the mainland by the dune-capped tombola of Penthièvre.
On the Vendée coast, Les Sables de l’Olonne is a seaside resort at the southern end of a lagoon separated from the sea by a forested dune barrier. To the south, the Pointe d’Arcay has multiple dune ridges and ends in eastward recurves. Offshore the Ile de Ré is low-lying with sandy beaches, particularly on the exposed SW shore, which has dunes up to 20m high and the west coast of the Ile d’Oléron has a sandy foreland with dune ridges. There are extensive dunes on the Pointe de la Coubre on the northern side of the Gironde estuary (Facon 1965). South of the Gironde mouth a long sandy coastline borders the Bay of Biscay. The sand has come largely from the Gironde, and drifted southward, but there is also calcareous sand, sometimes shelly, swept in from the sea floor. South of Soulac the Médoc beaches are backed by afforested dunes on a wide barrier that encloses several lakes. The sandy beach ends southward in the recurved spit at Cap Ferret, beside the Bassin d’Arcachon.
South of Arcachon the Landes of Gascony coast behind the foredune is a fringe of formerly transgressive dune ridges 60-70m high and up to 6km wide. The ridges have been stabilised by pine plantations (introduced from 1801 onwards by Nicolas Brémontier) except for the still-active Dune of Pilat (Pyla), a ridge of bare sand 118m high, with an escarpment spilling on to forested dunes. The coastal dune fringe has a sparse grassy and shrubby cover, but to landward, the dunes are under pine forest. They backed by a hinterland sandy plain that rises gradually inland to more than 40m above sea level, and bears heath and pine plantations. Pinchemel (1980) commented, “…the vast sand covering of the Landes is believed to be an Aeolian deposit laid down during a Quaternary [Pleistocene] cold spell. The material probably came from the continental shelf, where Pliocene sands extensive on the sea floor, were uncovered by the sea during a phase of marine regression”. At Biarritz the dunes come to an end as bluffs and cliffs rise behind the beach.
The map (Figure opposite) gives an indication of the maximum extent of dune present in France and may be an over-representation of the position today, since many of the open dune landscapes have been developed for forestry and other damaging activities. In the north, some of the botanically richer areas on the Atlantic coast occur where dunes are composed of calcareous sand or lie against chalk cliffs as at le Nord de la Baie de Canche. Further south, they are more acid in character and under the influence of the prevailing strong westerly winds stretch many kilometres inland, especially on the Aquitaine coast. On the Mediterranean coast, dunes are narrower and often found in association with deltas.
Vegetation - Atlantic Coast
A number of different dune types occur along the Atlantic coast. These include the narrow shore parallel dunes of Flanders and Picardy. The former protect low-lying land, the latter occur as dunes with slacks between extensive dune ridges. Further south the Normandy coast has a narrow, almost continuous line of vegetated dunes. These extend landward as an extensively cultivated plain (mielles) similar in type to the machair of Ireland and western Scotland. Brittany has a rocky coast interspersed with small and scattered sand dunes. South of Nante dunes occur as a narrow belt with extensive areas of woodland, though not as extensive as along the coast of Aquitaine. Here the system is approximately 124,000ha, up to 8km wide and 30-70m high (Favennec 1998).
The sequence of vegetation on the Atlantic coast of France is similar to that occurring in the rest of North West Europe. This typically involves the progressive stabilisation of dune forms as vegetation helps trap sand blown inland from the beach. Southern floral elements begin to appear the further south the dunes are formed. These may include species more typical of the Mediterranean. The following list provides a summary of the main vegetation types.
Strandline
The ephemeral beach vegetation has typical nitrophilous and salt tolerant species. These include Cakile maritima, Atriplex arenaria and Salsola kal.
Foredune
Elytrigia juncea dominates the earliest stages of dune growth.
Yellow dune
Ammophila arenaria is the main dune-forming species, occasionally together with Leymus arenarius. In this zone, other important plants typically include Eryngium maritimum, Euphorbia paralias and Calystegia soldanella.
Dune grassland
In the northern part of the coast where the dunes rest against chalk cliffs or are derived from calcareous sediment, rich dune grassland occurs.
Dune slack
Dune slack vegetation includes Schoenus nigricans, which can be common. The richer calcareous dunes may include Liparis loeselii, Spiranthes aestivalis and Serpia lingua.
Dune heath
Most of the dune areas are composed of silica sand and where these are not planted with pine forest the vegetation is rich in lichens and bryophytes.
Scrub
Scrub typically includes Hippophae rhamnoides, Sambucus nigra and Ulex europaeas.
Woodland
Natural woodland is scarce on the French coast. Primary birch forest does occur in the north and east. Further south on the wider dunes of Les Landes (Aquitaine) oak forest with Quercus ilex is the probable natural climax vegetation.
Afforested areas. Planted maritime pines (Pinus maritima, P. pinaster and P. pinea) cover much of the dune landscape of France, particularly on the large expanses of dune, which face the exposed Atlantic coast. In places, these include underplanting with oak, which on the acid sands of Les Landes includes Quercus ilex and Q. suber.
Vegetation of the Mediterranean coast
The typical sequence of zonation shown on the Atlantic coast is less obvious here. However, mobile dunes still have Ammophila arenaria and Elytricia juncea (sand couch), which includes abundant Medicago maritima. The more open natural dune is rich in species with Pancratium maritimum. Stands of stone pine (Pinus pinea) occur and in the Camargue have an undergrowth of species such as Daphne gnidium, Cistus solvifolius and Rosmarinus officinalis. Additional information Corre (1991).
Important sites
The original list of sand dunes in France is shown in the table below. These were mainly derived from an Atlas published by des Espaces Naturels du Littoral in 1991.
[[Image: Table.jpeg|thumb|right|350px|Figure: List of important sand dunes sites in Finland.
Conservation
Additional information
Web sites:
References
- ↑ Doody, J.P., ed., 1991. Sand Dune Inventory of Europe. Peterborough, Joint Nature Conservation Committee/European Union for Coastal Conservation.
- ↑ Doody, J.P., ed. 2008. Sand Dune Inventory of Europe, 2nd Edition. National Coastal Consultants and EUCC - The Coastal Union, in association with the IGU Coastal Commission.
See also
- Sand Dunes in Europe
- Articles on sand dunes on Wikpedia
- European Sand Dune Distribution
- Sand dune types - Europe
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