C1-C2 : Preserving sensitive ecosystems

Can we maintain natural forest habitats in a context of climate change?

The territory of the park includes many local tree species emblematic: beech, oak, chestnut, oak ... These species are structuring for several natural habitats whose ecological value is recognized by Europe under the Habitats Directive and by the network of Natura 2000 sites in France. The objective of Natura 2000 sites is to maintain both human and economic activities while preserving these environments in the long term. The issue of climate change adds a layer of complexity to this balance. Will future generations still be able to admire these habitats on the territory and benefit from their services?

To respond to this, the Foreccast project aims to assess the vulnerability of natural habitats on the Park's territory. The challenge is significant because it would be necessary to know both the extent of climate change in relation to the ecological niche of species and their response capacity, particularly by genetic adaptation and phenotypic plasticity.

As a pilot project, the FORECCAST project is trying to provide answers on the acidiphile beech forest in hut, habitat Natura 2000 also known under the code 9120. This rather rare beech facies at the European scale is characterized by an acidophilic flora and a presence marked with holly. It is one of the main Natura 2000 habitats with a management stake in the territory. The developed method will be transposable to other forest habitats.

The first step is to assess the presence of habitat on the territory. A state of knowledge is based on inventories on Natura 2000 sites and supplemented by the presence of this habitat on the plots of the national forest inventory, thanks to a partnership with the IGN. Future climate scenarios will need to be applied to measure the extent of climate niche movements where habitat is present.

Concerning the in situ genetic adaptation capacity of trees, scientific knowledge is unfortunately insufficient to accurately model the speed and extent of genetic adaptation. It seems, however, that beech could be much better armed than originally thought to cope with climate change. Indeed, there has been relatively little decline observed for beech despite the extreme climatic events of recent decades. It is also known that the beech populations present on the territory of the Park come from a more southern genetic lineage (Catalonia, Eastern Pyrenees, Black Mountain, South Massif Central and Southern Alps), so a priori better suited to drought. . This particular genetic resource could therefore play a very useful role in national or European strategies to promote the adaptation of beech.

Preserve habitats of community interest

The studied habitat is the Atlantic acidophilous beech holly, present in a rather rainy Atlantic climate and at an altitude higher than 500 m. There are several indicator species of this habitat type, such as blueberry (Vaccinium myrtillus) and rocky clover (Galium saxatile).

The Acidiphile Atlantic beech forest is represented by a beech dominated stratum, accompanied by wart birch and fowl ash, where holly is very present, and a covering herbaceous carpet.

This habitat often takes its place after the abandonment of agropastoral surfaces. It can also be linked to silvicultural management with coppice under beech trees. These beech forests are often transformed into softwood stands, which poses a significant threat. (Source: "Cahiers d'Habitats" Natura 2000. Knowledge and Management of Habitats and Species of Community Interest Volume 1 - Forest Habitats Bensettiti F., Rameau J.-C. & Chevallier H. (coord.), 2001. MATE / MAP / MNHN, The French Documentation) .https: //inpn.mnhn.fr/docs/cahab/tome1.pdf

Vigilance maps for this habitat in the Natura 2000 zone are produced and make it possible to propose new silvicultural management routes in a context of climate change.