Under the sun, facing the Mediterranean, about fifteen people are busy replanting astragalus shoots. This emblematic bush of Marseille creeks, trampled by hikers, pushed back by urbanization, attacked by laundry that pollute the sea, is threatened with extinction.
Away from the city, near the creek of Marseilleveyre accessible after 45 minutes of walking on rocks made slippery by the passage of walkers, defenders of the astragalus participating in a reintroduction program dig methodically this morning. reddish earth.
In the summer, thousands of visitors seek in the hollow of the coves and coves that succeed between Marseille and Cassis a peaceful place to swim. But in the heart of the late season, gardeners of the day enjoy the quiet to plant off the path some of the 3,000 plants cultivated for almost a year in the nurseries of Marseilles.
In four or five years, when only 20% to 50% of them should have survived, they will give rise to small verdigris thorn bushes, nicknamed "mother-in-law's cushion".
In this "ecological niche between the sea and the scrubland, plants should find the resources to develop and reconnect with existing astragalus populations," Laureen Keller, ecologist at the Calanques National Park, hopes.
Their reintroduction, in which the University Aix-Marseille, the city, the national park and the region participate in the European project Life Habitat Calanques, financed mainly by Europe, represents a major challenge.
Rare endemic plant whose oldest specimens on the site of its reintroduction are estimated at 40 or 50 years, "astragalus tragacantha" is concentrated at 90% on the Marseille coast, the Var, Spain and Portugal sheltering the rest of its population.
"If we lose it here, it is the French population of astragalus that disappears," said the head of the scientific knowledge center of the Calanques National Park, Lidwine Le Mire Pecheux, looking at the tiny plants.
- "Ecological solidarity" -
The plant, listed on the Red List of Threatened Species in France by the International Union for the Conservation of Nature (IUCN), entered in 2019 the category of species "endangered". The UN estimates that of the 8 million animal and plant species living on Earth, one million are threatened with extinction.
In the forefront of risks for astragalus, urbanization, which has driven the plant from its natural environment, and hikers, who leave the trails and crush without even realizing it.
Exposed to the Mistral, the plant is also among its enemies sea spray polluted by discharges into the sea of wastewater treatment plants, which contain surfactants contained in particular in shower gels or laundry residues.
"These products are intended to remove fat: the problem is that the leaves of the astragalus are covered with a greasy film intended to protect them from sea salt, but with the spray this protection disappears and the plants do not resist more salt, "says Laureen Keller.
The species, which has not changed for 2.6 million years, is yet an example of adaptation to the Mediterranean environment, including its very long roots that will draw water in depth.
"Protecting astragalus is also protecting all of its environment, it is an example of ecological solidarity," insists Lidwine Le Mire Pecheux.
A chance for these coves located near old lead, soda or sulfur plants, the last of which closed in 2009.
"When the environment is good, it is the health of the man who is better," enthuses the manager. In the distance, some hikers, polar on their back and sticks in hand, advance on the path along the coast.
© 2019 AFP