An adaptation strategy for forests

Forests are essential ecosystems for the balance of climate and human societies. By hosting 80% of terrestrial biodiversity, by contributing to the mitigation of greenhouse gas emissions, by providing numerous natural resources, ecosystem services that create millions of jobs, they are essential for the survival of human beings, both individually and socially. However, like every living entity, they are greatly threatened by climate change, which increases the risks of fires, droughts, storms and the development of diseases. Faced with this challenge, the National Forestry Office (ONF), in charge of the sustainable management of public forests since 1964, decided to launch an adaptation plan, including, among other actions, the establishment of new species and the adaptation of silvicultural practices in French public forests.

French forests cover nearly a third of the national territory and constitute an exceptional natural heritage, which is home to great biodiversity, stores carbon, produces wood, provides recreation and protects against natural risks. But these forests are also vulnerable to climate change, which is accelerating and intensifying. According to projections by the Intergovernmental Panel on Climate Change (IPCC), the average temperature in France could increase by 2 to 4°C by the end of the century, depending on greenhouse gas emissions scenarios. Rainfall could decrease by 10 to 30% in the south of the country, while extreme events, such as heatwaves, droughts or storms, could increase.

These climate changes are already having visible impacts on forest health. Since 2018, more than 300,000 hectares of public forests have suffered an unprecedented mortality rate, the equivalent of 30 times the size of Paris. All regions and all species are concerned, but some are more sensitive than others, such as beech, fir or spruce, which need water and freshness.

Faced with this assessment, in September 2021, the ONF presented its national strategy for the adaptation of public forests, whose importance Erwin Ulrich, pilot of this mission, explains to us. “We have to act, and relatively quickly” he says “The climate of French forests evolves very quickly, with, in the case of a disease for example, effects that are sometimes only noticeable several months after infection, when it is too late to act. [...] To take effective action, you have to set a budget, and be particularly agile.”

As part of the France Relance plan, the ONF was able to benefit from an envelope of 200 million euros specifically dedicated to the adaptation of forests to climate change and to the initiation of their renewal in order to protect biodiversity and meet the needs of society in wood products. According to Erwin Ulrich, this unprecedented envelope is “An encouraging signal sent by the State to the forest sector”. A good start, which allowed the ONF to present its adaptation program, which is based on three main axes.

First part, The diversification of forest species, which consists in introducing species that are more adapted to the future climate or in promoting the coexistence of several species within the same population. “With the aim of increasing the resilience of forests in the face of climatic hazards and parasitic attacks, and maintaining wood production and biodiversity.” Declares the pilot of the operation. Second part: the adaptation of methods for the renewal of forest stands, which consists in modifying silviculture techniques (cutting, planting, thinning, etc.) according to climatic conditions and management objectives. The objective is to promote the natural renewal of trees, to reduce wood losses and to preserve soil and water. And finally, the monitoring and evaluation of adaptation actions, which consists in setting up mechanisms to measure and observe the effects of climate change on forests and the results of adaptation actions. “Here, the objective is to have reliable and up-to-date data” says Erwin Ulrich, “To share knowledge and feedback, and to adjust practices according to changes.”

To implement this strategy, the ONF relies on scientific and technical tools, such as the Aforce joint technological network, which brings together 15 forest research and development organizations, of which the ONF is one of the structuring partners. The mission of this network is to support foresters in adapting forests to climate change, by producing knowledge, methods and training.

The ONF aims to make the public forests it manages a model for adapting to climate change, by reconciling environmental, economic and social challenges. To do this, he has set himself short and medium term numerical goals.

Diversify 20% of forest populations sensitive to climate change by 2026, or around 400,000 hectares. Adapt the renewal of 50% of forest stands sensitive to climate change by 2030, i.e. around 1 million hectares. Monitor the evolution of forest health on 100% of public forest land by 2026, thanks to a national observation system. Evaluate the effectiveness of adaptation actions on 10% of public forest land by 2030, thanks to a network of islands of the future.

Through this mission, the ONF hopes to contribute to the preservation of French forest heritage, and to the fight against global warming. Erwin Ulrich recalls: “If the forest is threatened by global warming, we must not forget that it remains a powerful tool in the fight against it. We will therefore have to continue this work of adaptation and preservation even at the end of this program, in the hope that budgets will continue to be released.”