Sand dunes

According to the Larousse dictionary, a dune is “a hill made up of a mass of sand accumulated by the wind”. In France, the most famous is obviously that of Pilat, located on the Silver Coast, at the entrance to the Arcachon basin. It is the highest in Europe (nearly 106 meters) and therefore a popular tourist spot. Unfortunately, the French dunes seem more and more threatened. Why ? And what to do to protect them?

The finding is alarming. In fact, the dunes of France, in particular along the Atlantic coast, are tending to decrease, or even disappear. There are two reasons for this: first, the excessive urbanization of the coasts which tends to destroy the ecosystem favorable to the maintenance of these sandy hills. Then, global warming, causing the rise in sea level and the proliferation of storms. However, the dunes are a natural protection for the population living on the coast against the elements. So what solutions should be adopted to protect these fragile French dunes?

The first would be to promote the presence of ponds. Indeed, these are essential to an amphibian, the pelobate. However, the latter is, according to specialists, an excellent barometer of the ecosystem of a dune. If the pelobate is present, it is because the dune and its immediate ecological environment are "in good health".

The second solution to protect the ecosystem around a dune will be to mark out - strictly - the places accessible to walkers. More generally, the information and awareness of people wishing to access the beach via the dune or simply to climb it will be essential for the preservation of the flora and fauna within and around the dune. Because it should be known, it is not necessarily the wind and the waves which are the main cause of erosion of the dunes but also the trampling of walkers. Indeed, the latter slowly destroys the vegetation that retains the sand.

Finally, according to a study carried out as part of the French assessment of ecosystems and ecosystem services (Efese), the protection and reinforcement of dunes would be much more effective, while being much less costly, to protect the coast and its homes. . Indeed, the cost of recharging a beach with sand is 100 times higher than priority management of dune ecosystems. In short, the protection and management of French dunes are of both economic interest and above all an absolute ecological necessity.

Thomas Rouquette

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