Science

A year after the megafire, the resilience of the Mediterranean forest is being tested – Science et Avenir

In the Maures mountain range in southeastern France, the hills are starting to turn green again after a fire last summer that burned some 7,000 hectares of vegetation. But the restoration of fire-adapted Mediterranean forests may have limits.

“It was the fourth since 1979,” Michel Mondani, mayor of Mayon, says with some fatalism, listing the fires that devastated his village, the last of which, in August 2021, claimed the lives of two people in the nearby town of Grimaud, over the Gulf of Saint-Tropez.

Thousands of vacationers had to be evacuated due to the spread of fire in this wooded area.

A year later, arbutus, thyme and other shrubs are slowly coming back to life amid the still-blackened cork oaks and Aleppo pines that loom over the ridges, notes this former volunteer firefighter.

“Nature takes its rights, but we see that regular fires exhaust it,” continues the former head of the fire and rescue department of this village of 630 inhabitants.

A very thick bark that protects the cork oak from the damaging effects of temperatures during the passage of a flame, pines, the cones of which release a jar of seeds, which, when in contact with the ashes, give rise to new trees, shrubs, the recovery nodes of which are underground …

In the Mediterranean region, “most species are fire-adapted,” Anne Ganto, a fire risk assessment specialist at the National Research Institute for Agriculture, Food and the Environment (Inrae) in Aix-en-Provence, explains to AFP.

– Lark –

Forest fires in Grimaud, Var department, August 17, 2021 (AFP/Archive – Valery ASCHE)

“If the frequency of fires is moderate, this is not a serious problem. Fire allows you to regulate some invasive plants. It may come as a surprise, but without fire, some birds, such as larks, sparrows, may disappear because their habitat will be confused, ”also recalls Roger Prodon, emeritus professor at the Practical School for Advanced Study, specializing in “fire ecology”.

However, scientists warn of the limitations of this “natural resilience” of Mediterranean flora in the face of climate change and the recurring heatwaves that are one of its symptoms.

If the number of hectares burned in France as a whole has fallen from an average of 45,000 hectares per year in 1970-1980 to 12,000 hectares since 2006, the fire that devastated 21,000 hectares in the Gironde and the frequency of fires require vigilance.

“If the frequency of fires increases, which is expected in the future, the interval will become too short for, for example, Aleppo pine to mature and release its seeds before another fire burns it,” warns Ms Gantome.

In France, “(fire) activity will increase in areas where it is already strong in the southeast, and also spread to the mountainous fringes of this southern region,” as well as “in the half of the north, where temperatures and drought will increase,” notes Jean- Luc Dupuis, fire safety specialist for Inrae in Avignon. Like a fire in July at Mont-d’Arret in Brittany.

“We should not expect species to adapt to the advent of a new fire regime (the natural frequency of fires that an ecosystem can sustain without irreversible long-term effects, editor’s note) in a few decades,” Dupuy warns.

“It takes several thousand years to adapt,” insists the researcher, who is especially concerned about “new territories” whose vegetation is less adapted to fires than in the Mediterranean.

In the Provence-Alpes-Côte d’Azur region, for the first time, public and private funds were allocated at the initiative of the region through its Respir program to help forest areas and prevent new natural disasters.

The side effects of recurring fires are indeed numerous: the lack of rainwater-retaining vegetation increases the risk of flooding, and ash runoff into ditches can also disrupt the quality of water needed by animals.

Thus, about 468,000 euros were allocated for priority works, such as the “charm”, which consists of strengthening the banks of the rivers with pieces of wood and slowing down the water gully on the steepest slopes.

Previously, about 200,000 euros of emergency work has already been done (cutting down burnt trees that threaten to collapse, pruning).

“We have to make the forest as resilient as possible for the next fire,” concedes Julie Mariton of the More Mountains Mixed Syndicate, “we have to be humble, we know it will happen again.”

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