“Release” publishes throughout the summer a series of reports, in partnership with the French Committee of the IUCN (International Union for the Conservation of Nature) devoted to the major issues related to biodiversity, on the occasion of the World Conservation Congress of IUCN, organized from September 3 to 11, 2021 in Marseille.
Equipped with boots and waterproof pants, Geneviève Magnon crouched down on the spongy ground, pointed to a tuft of grasses perched on a small hillock and pouted. “When the molinia settles, it is a bad sign, it is typical of a peat bog which dries up and releases carbon”, sighs the biologist. Lots and lots of carbon. “A dried-up peat bog releases 25 tonnes of CO2 per hectare and per year, as much as 25 return trips from Paris to New York by plane, explains our guide. If it is transformed into a cornfield, it is even worse, 75 tonnes of CO2 per hectare, a real climate bomb. It is therefore urgent to restore them. ” This is exactly what Geneviève Magnon, self-proclaimed with humor “Bog plumber”, more meaningful than his official title (in charge of mission at the Public Establishment of Water Development and Management of Haut Doubs and Haute-Loire).
Or noir local
We are at the heart of the small regional nature reserve of Seigne des Barbouillons. That is to say 34 hectares located in the town of Mignovillard, in the Jura, about twenty kilometers from the Swiss border. Like most peat bogs in the Jura massif, the place, which designates a marsh in local dialect, has been exploited since the 18th century for its peat. It took more than eight thousand years to form, with the accumulation of plants (especially sphagnum moss, a kind of moss) little or badly decomposed because they were covered with stagnant water. A local black gold, used for domestic heating until the 1960s. In addition to this artisanal but systematic extraction, the peat bogs were drained to evacuate their water, backfilled, planted, wooded, the meanders of the streams which were in them were rectified cross, we dumped garbage … Add to that the effect of climate change and its procession of droughts and heat waves, and these so-called “wet” environments are less and less so.
Long unloved, evil in tales and legends, considered unhealthy mosquito nests and dangerous areas where we risk sinking to the bust, peat bogs have been massively destroyed, here as elsewhere. Half of them have disappeared in France over the past fifty years.
Carbon sink
However, these are real natural treasures, of which homo sapiens began to grasp the invaluable value about thirty years ago. So judge the thousand and one services they render. They regulate water by playing a sponge role, limiting floods and droughts, they filter and purify water. They are home to rare and endangered flora and fauna. Offer splendid and exotic landscapes: the Seigne des Barbouillons looks like Canada, Scandinavia or the Siberian tundra. Keep objects, plant, animal or human remains intact and thus serve as scientific and historical archives …
And, therefore, trap a quantity of carbon: while they represent only 3% of the land surface in the world, peatlands alone store a third of all the carbon trapped in the soil. Their peat stores twice as much carbon as all forests and contains as much as the earth’s atmosphere. Alas, if we mistreat them and dry them out, as is the case almost everywhere in the world, they no longer behave as carbon sinks, but as emitters, with a devastating effect on the climate.
Hence the launch in 2014 of the Jura “Life peat bogs” program, aiming to rehabilitate some fifty peat bogs spread over 500 hectares of Natura 2000 sites in Doubs and Jura. That is to say about 35% of the peaty surfaces of the Jura massif, one of the richest areas in peat bogs in Western Europe. The 8 million euro project, one of the most ambitious of its kind in Europe, was mainly funded by the European Union and the Rhône Méditerranée Corse Water Agency. The ecological engineering work, mainly consisting in restoring the hydrological functioning of the peatlands, must be completed in November. In all, they will have made it possible to “neutralize” (that is to say butcher) “About twenty km of drains and to restore 13 to 14 km of watercourses, by recreating meanders so that the water flows more gently and permeates the bog instead of spinning. It is more than the objectives set at the start ”, says Emilie Calvar, from the Conservatory of Natural Areas (CEN) in Franche-Comté, the program coordinator.
“Natural monument”
At the Seigne des Barbouillons, this May, Geneviève Magnon, who supervises the work, gives the final instructions to the workers handling an excavator. The machine is placed on wooden trays, in order not to sink into the peat and not to further damage this fragile ecosystem, where a butterfly threatened with extinction in the Jura, the pearly of the cranberry, takes refuge.. “We tried to heal the two parts of the bog, so that the water returned to the dry part., explains the “plumber of the peatlands”. It is three weeks of work, but two to three years of preliminary studies and two to three months of administrative procedures. The goal, once the work is finished, is to leave it alone and leave the bog to fend for itself. ” After cutting the spruces that colonized space when they have nothing to do in a bog and even help to dry it out further, we have to take care of the 600-meter drain dug in the 1960s. that to fill it entirely, it is a question of installing small wooden dams covered with peat to slow the flow of water, raise the level, and make so that it goes again towards the water. dried up part.
In the area, land belonging to the municipality, graze Bertrand Rousseaux’s heifers. The farmer, producer of morbier, welcomes the return of the water, which is already forming beautiful puddles. “In summer, in case of drought, the grass will stay green here while it will be roasted elsewhere, said the quadra. And then, I learn to observe small spiders and amphibians. Whereas when I was a kid, we weren’t interested in peatlands and their inhabitants. ”
Local pride
The times have changed. The peatlands have become a local pride. “We don’t have the Eiffel Tower or Mont Saint-Michel, but we have this natural monument, this gem that we must take care of”, smiles Florent Serrette, the mayor of Mignovillard, which has 880 inhabitants. Here, one of the streets of the last subdivision to emerge from the ground was not given a writer’s or poet’s name, but a small carnivorous bog plant, the sundew, which must trap insects to find the nutrients it needs because they are missing from this acidic soil.
Since 2015, following a vote of the population, the school has been baptized “École des Barbouillons”. “We take the students to see the bog, they work on the subject, the school logo has a sundew, a dragonfly and rushes, and each class has a name of these species of the bogs: orchid, green frog, clover. ‘water, or even farlouse pipit, a little bird with a funny name, chosen by the kindergartens ”, says the director, Mélanie Bourgeois.
La Seigne des Barbouillons is not fitted out with wooden pontoons to allow visitors to walk there, unlike the peat bog in the neighboring town of Frasne, which has become so popular that newlyweds have their picture taken. “We do not try to attract too many people, because it is a fragile environment and which can be dangerous, explains Florent Serrette. But we organize one or two guided tours there per year so that the local population is aware of this exceptional wealth. We are also going to do it in September for heritage days, a great opportunity to say that this is not only cultural, it is also natural. ”
Concertation
About fifteen kilometers from Mignovillard, in Mouthe, in the Doubs, restoration work on the Moutat peat bog took place in 2017. The main aim was to restore water to the old meander of the Doubs, from which the source springs up. a few dozen meters upstream, by filling in the 80 meters of “rectified” artificial bed and removing the “plug” of earth and pebbles that had been erected to prevent water from flowing over the 230 meters of the natural route . “Technically, it was quite simple, but it required a lot of consultation upstream, it was necessary to explain to the elders that no, it was not“ always been like that ”, that the meander was“ rectified ”by man, probably at the very beginning of the 20th century ”, confides Pierre Durlet, project manager at the Haut-Jura Regional Natural Park. In the distance, we can also see old plugged drains. Review of operations? “We have given back three times the length of streams to trout to reproduce and live. But aquatic insects such as mayflies have not yet completely reinvested in the “new” bed, because their larval phase lasts three years, explains Pierre Durlet. It takes five to ten years for the populations of insects and fish in a stream to recover. Nature takes time to find a balance, it must be accepted. “
In the meantime, the CEN of Franche-Comté intends to apply for a second “Life” program, because there are still many peatlands to be restored in the region. “If the project is selected, it will be necessary to find how to measure the quantity of carbon not destocked thanks to the works, admits Emilie Calvar. But one thing is already visible and measurable: just a few days after the work, the groundwater level rises, the water remains in the bog, which again makes it possible to block the process of peat decomposition and better resist drought. ” Or how healthy nature can both mitigate and adapt to climate change.
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