Gironde’s 2022 Fire Aftermath: Witnessing Nature’s Remarkable Resilience

Hostens (Gironde), report

« It used to be a forest »: Elsa Barré, the Forest Project Manager for the Gironde department, points out a large 60-hectare plain brightened by yellow gorse flowers, patches of heather, and a few charred tree trunks. Located a few kilometers east of the town of Hostens in southern Gironde, the 2022 fires did more than just shock the local residents—they dramatically transformed the landscape, while the recovery of wildlife and plant life has been notably varied.

In 2022, two wildfires scorched 32,000 hectares of the Landes de Gascogne forest, an unprecedented event since 1949. « Back then, there was no monitoring of post-fire biodiversity, Jean-Luc Gleyze, the president of the Gironde department (Socialist Party), told Decatur Metro. So now is the time to start this effort, to understand how nature reclaims burned areas. »

On March 12, the department officially launched a post-fire biological inventory of the Landes de Gascogne massif. This initiative, in collaboration with a consortium of associations and the National Botanical Conservatory of South Atlantic (CBNSA), covers Hostens and the Gât Mort lagoons, totaling 482 hectares. In 2022, 71 % of this area was affected by the fires. Owned by the department since 1967, the zone featured a diverse range of habitats: lake areas with aquatic or amphibious vegetation, moist heaths, meadows, reed beds, peat bogs, forests…

At the Fosse des demoiselles, in the heart of the reserve, Anthony Le Fouler is busy cataloging flora. Within a seven-meter by seven-meter plot marked by a white rope, the CBNSA botanist records and counts all plant species growing on the dark soil. Located in a peat bog, this area had already been monitored by ecologists before the fire due to its multiple ecological benefits.

« Peat bogs are carbon sinks, flood regulators, and botanical treasures, the scientist explains, holding a GPS device that helps relocate the plot year after year. In the Landes de Gascogne, this habitat has become particularly rare due to hydraulic developments initiated under Napoleon III in the late XIX^th century to « sanitise » the region.

The moist heaths and heather areas, once prevalent and which gave the region its name of « landes », were considered unhealthy as they were thought to propagate malaria. Once drained, they were extensively planted with maritime pines, creating Europe’s largest artificial forest covering a million hectares.

The peat bog monitored by Anthony Le Fouler is also not natural. In its place was a former lignite quarry, which ceased operations in 1964. The flooded pit gradually reverted to nature, and a peat bog ecosystem established itself. Lignite in the soil, however, prolonged the presence of underground fires, with the last hotspots only extinguished in November 2024.

The scientist’s findings at this site are encouraging. The presence of inundated clubmoss, a small fern listed as a nationally protected species, and papillose sphagnum, a clumping moss, indicates a resurgence of typical peat bog flora. « These are healing plants for peat bogs, the scientist notes. Their return was expected following the passage of fire. Fires have existed since time immemorial, just like pioneer plants. »

Some plants, such as purple moor-grass growing in clumps with straw-colored stems, are even considered pyrophilic. « It’s not that purple moor-grass loves fire, explains Anthony Le Fouler. But because of its clumping structure, its core remains unscathed by a swiftly moving fire. Thus, it is among the first plants to regenerate after a fire. »

The biological recovery at the Fosse des demoiselles, however, carries uncertainties. The normally highly acidic soil may have been altered by the fires. The ashes, rich in potassium, and the phosphorous-laden fire retardants used by firefighters could have « enriched » it with more basic components. The population of viviparous lizards, a species emblematic of wet areas, seems to have been particularly affected: only one specimen has been observed since 2024.

A more thorough study of how the fire spread is also crucial for understanding the biological resurgence. « Fires that rapidly move across the surface have different effects from those that penetrate the soil and linger, » says Anthony Le Fouler. The summer spiranthe, an orchid species with bulbs deep in the soil, seems to have survived the fires that swept through the peat bog. However, other species, like the dwarf plantain with oval leaves, have not been spotted since 2022.

The potential disappearance of certain species in the biological reserve could prompt the department to take a more proactive approach. Since March 12, its management strategy has been updated, leaving 10 % of its area—primarily deciduous forest zones—to evolve naturally. The remaining 90 % is classified as a managed biological reserve, allowing interventions to facilitate public access, species reintroduction, or grazing.

One goal of this hands-on management is to maintain open spaces. « The heathlands are recognized as a habitat of community interest at the European level, explains Elsa Barré. The intention to restore these areas by converting existing pine forests existed before the fires. The fires have accelerated this process. »

The former forest east of Hostens, now a meadow, will for instance be kept as an open space through grazing with marine cows native to the Landes de Gascogne. « Biodiversity is often richer in open environments than in closed environments composed of maritime pine monocultures, » says Anthony Le Fouler. According to early scientific observations, these new meadows have facilitated the settlement of birds such as the tawny pipit, the skylark, and the woodlark.

« However, without human intervention, these spaces will close up due to the natural progression of forests, » estimates Elsa Barré. The scrutiny of scientists on these fire-remodeled habitats is especially crucial as they remain conducive to the establishment of invasive exotic species, such as Canadian fleabane, with its lantern-shaped flowers, which is taking hold among the flowering gorse.

This new management approach for the reserve aims to balance the preservation of biological and landscape heritage and the prevention of fire risk. « In the Landes de Gascogne massif, we know that the monoculture of maritime pines presents a higher fire risk than open habitats, clarifies Elsa Barré. There are clear convergences between biodiversity objectives and fire prevention. »