Climate: the forest, a threatened French passion

How long will the respite last? In the Rambouillet forest that he has been surveying for more than thirty years, forester Laurent Tillon holds his breath. After two years of terrible drought, which emptied the ponds and made the trees thirsty, the vegetation has regained some color in recent months. “However, it is difficult to be completely reassured, because we do not yet know whether the torrential rains of recent months will not lead to rotting phenomena,” underlines the expert from the National Forestry Office (ONF).

It was during the great heatwave of summer 2003 that this forest enthusiast, who recounted in a book in 2021 his “friendship” with an oak tree (1), feels the first concerns linked to climate change. “At the time, we still imagined that warming would contribute to the growth of trees, by increasing the level of carbon in the atmosphere. For my part, I understood that year that without water, there would be no photosynthesis, and that the trees would just die. he remembers.

All signals are red

Twenty years later, there is no longer any doubt: the French forest, which structures landscapes, fixes carbon, refreshes water, and shelters most of France’s biodiversity, is in bad shape. Whether it is the tree mortality rate, which has more than doubled in ten years, the number of hectares in decline (5% of the forest according to the forest health department attached to the Ministry of Agriculture ), or even the productivity rate of the forest (the cubic meter of wood per hectare is falling by 10 to 20% depending on the species): all the signals are red.

Result, while it has doubled in surface area in two hundred years due to the abandonment of agriculture and today covers a third of the French territory, the forest plays less and less its role as a carbon sink: this This has been divided by three in twenty years, reaching 20 million tonnes of CO2 sequestered per year in the recent period. The cause therefore is climate change with its successions of droughts, heatwaves, but also floods. This weakens the species and increases the risk of fires and the development of diseases.

“To give you an example, now a quarter of the wood harvested in public forests is dying wood, whereas before 2018, this represented less than 5% of our harvests,” underlines François Bonnet, deputy director general of the ONF. In certain regions of France, such as in the Grand Est, particularly affected by the bark beetle crisis – these tiny insects which proliferate during very mild winters – certain forest areas have even become net emitters of carbon. That is to say, the carbon emitted by trees when they burn or decompose is greater than that captured during photosynthesis.

Carbon sinks in danger

Enough to worry even in the highest echelons of the State, who were banking on these forest sinks to achieve the objective of carbon neutrality by 2050. “From now on, the challenge is no longer to increase forest sinks, but to manage to limit their decline,” explains Antoine Colin, head of the analysis department of the IGN (National Institute of Geographic and Forestry Information), who however warns against exploiting the subject: “Everyone has an interest in saying that the forest is doing badly to avoid calling into question. Except that forests are not intended, and no longer have the capacity, to offset the emissions of other sectors. »

Enough to also explain the passionate turn that the subject has taken in recent years. All over France, mobilizations are breaking out to oppose the felling of this plane tree or that oak, to protest against this clear-cutting project or this “mega wood factory”. “Machine damage has never been so significant, observes, irritated, Antoine d’Amécourt, the president of Fransylva, the national federation of private foresters. It seems that people love solid oak furniture and walking in open forests, but cutting down a tree has become a crime of lèse majesté. »

Proof of the growing tension between foresters and environmental defense associations: the France Bois Forêt inter-professional association, which brings together all the players in the sector, recently demanded the legal annulment of the ministerial approval for the protection of the environment obtained by the Canopée association, known for its fight against clear felling. “This shows to what extent the forestry world remains dominated by very strong conservatism,” deplores forestry expert Philippe Gourmain on this subject, who himself was head of the inter-profession until 2021.

Adaptation, a complicated science

From a scientific point of view, the few main principles of more sustainable forest management are known: avoiding large monocultures by diversifying species; limit clearcutting to plots that are dying; and keep those that continue to grow and capture carbon for as long as possible. “The problem is that these main principles do not fit well with the industrial exploitation of the forest, which rather needs homogeneous, single-species forests to be efficient,” specifies Philippe Gourmain.

“Beyond the old antagonisms opposing forest operators to defenders of free evolution, we must understand that the adaptation of the forest is a complex subject which requires experimenting with the planting of new species, but also implementing very careful monitoring of existing populations”, underlines Laurent Tillon.

According to a recent study in the journal Naturea third of European species will not survive the climate in effect by 2100. Specialist on the subject within the NGO WWF, Daniel Vallauri agrees: “The forestry world, accustomed to working over the long term, has reason to be destabilized. Unlike agriculture, which can rotate its crops, the choices made today will be structuring for the next fifty or seventy years. » Especially since it is not because a species is adapted to temperatures of +4 degrees that it is necessarily adapted today…

And then, as ecologists point out, what is good for carbon is not necessarily good for biodiversity. For example, a forest that reaches a certain age will sequester less carbon, but will be excellent for the preservation of ecosystems… “Basically, the mistake would be to reduce the forest to its simple role as a carbon sink when it fulfills many other invaluable services for society, believes Antoine Colin. At a time of energy transition, it is also crucial to ask ourselves how to better connect upstream and downstream. »

A wood-intensive energy transition

This is in fact one of the other issues highlighted by the sector, which employs 400,000 people: the need for wood is likely to increase significantly in the years to come due to the use of biomass as energy for industry and as fuel for transport. According to calculations by the SGPE, the interministerial body responsible for establishing France’s emissions reduction trajectory, biomass production should increase by 15% by 2030 to meet these new uses.

For several years, the ministries of agriculture, pushed by large forestry cooperatives, have been looking for ways to encourage millions of small forest owners to manage their woods to produce more, while better preserving the forest.

“The French forest has the particularity of being very fragmented with more than 3 million owners who own less than four hectares. By increasing the share of this forest under management, we could finance an adaptation which will be very expensive,” says Stéphane Viéban, at the head of the largest French cooperative, Alliance Forêt Bois. Attempts which never succeeded, due to lack of real tax or heritage interest to activate.

Subsidies promoting clear felling

Contrary to these considerations, NGOs believe that it is urgent to question the sustainability of the levies. They accuse public policies of favoring a model of intensive exploitation, based on reforestation rather than conservation. Since 2020, all forest recovery plans have resulted in massive aid for replanting, with the ambition now supported by Emmanuel Macron to plant a billion trees by 2030.

“Under the pretext that they have dying populations, we continue to subsidize the big players, when we should be supporting all these owners who are more interested in heritage than in wood management,” regret Daniel Vallauri. “The forest is not managed by planting trees but by promoting improvement work, such as thinning or enriching existing stands”agrees Sylvain Angerand, at Canopée.

In 2023, the association revealed that more than 85% of the aid granted to the sector since Covid (i.e. a little more than 200 million euros) had made it possible to finance clear cuts, of which at least a third were not justified by real decline. “There were some very unfortunate windfall effects, confirms a member of the government team in place at the time. The worst thing is that a significant part of these plantations did not survive because of climate change…”