An initiative that takes root. For the third year in a row, the town of La Teste-de-Buch, in the Arcachon basin, has renewed its “Sapins for our dunes” operation.
After the end-of-year celebrations, she collected the Christmas trees of the inhabitants of several municipalities in the southern Bassin, and the town of Saint-Aubin-de-Médoc, to entrust them to the National Forestry Office (ONF ) which uses it as ramparts against the erosion of the dunes. This year, some 1,600 fir trees have been placed at La Salie Nord beach, near the Pilat dune. “It is a doubly virtuous operation, welcomes the mayor of La Teste Patrick Davet, since it avoids throwing the trees anyhow, and it serves to stabilize the dunes. And a popular success, since “we filled 19 dumpsters this year, compared to five the first year. The city also involves the children of its schools in the operation, to raise their awareness of the environment.
“We use fir trees as windbreaks”
Adèle, in CM1 class, came to lend a hand with enthusiasm. And she understood perfectly the meaning of her action. “You have to arrange the trees in a line so that the sand blocks during storms or gusts of wind, she explains, so the dune can go up a little in height for this summer. And she is also aware that “we must act to protect our environment. »
“We give a second life to these trees, and in addition we interact with the children,” rejoices Cédric Bouchet, technician at the ONF, who oversees the operation. The ONF intervenes on the coastal dunes to protect them from wind erosion. “We use fir trees as windbreaks, explains Cédric Bouchet: we install them in places where we need to capitalize on sand, which makes it possible to catch up with the profiles of the dune where it is needed. »
“The objective is to keep the sediment on the white dune”
The operation is not done just anyhow, and “an individual cannot come and place his tree himself on the dune, it must be supervised” warns the ONF technician. “We study each area before determining the places where we will place the trees on the dune. Our interventions are carried out in sectors where there are respites from marine erosion, to capture the sand in the places that interest us, and accelerate the natural dynamics. The objective is to keep the sediment on the white dune, and prevent the sand from crossing the dune rim to congeal in the gray dune, or even in the forest, which could create losses of diversity with buried plants. »
On this beach in La Salie, the approach is thus to consolidate a dune which is still well preserved, “since we have 200 meters of white dune, and varied environments, with forest, pre-forest hems, sand dune grey…” This is not the case for all the beaches on the coast. “A little further north, at the Lagoon, the entire dune system has disappeared, it has gone into the ocean” notes Cédric Bouchet.
“Last year at La Lagune, we lost almost fifty meters of coastline, confirms the mayor of La Teste. This is considerable, especially since we have five campsites along the beaches, two of which are directly impacted by coastal erosion, and a road that runs along the coast. We say be careful, it happens, and now is the time to anticipate a phenomenon that could strike us in ten years. We take up this subject that concerns us. »