Assessing the potential effects of climate change on future forest composition in France

Climate change is already affecting French forests: rising temperatures, altered precipitation, and more frequent extreme events are driving shifts in species distributions, reduced productivity, and increased tree mortality. Anticipating future forest composition requires understanding species' exposure to future climatic conditions, their sensitivity to these conditions, and their capacity to adapt or migrate. Regional contrasts are marked, with stronger warming and drying in northeastern and Mediterranean regions, while parts of western France are comparatively less affected. Observations show high vulnerability of temperate species such as Fagus sylvatica and Picea abies, whereas Mediterranean species (e.g. Pinus pinaster, P. halepensis) appear more resistant at present.Future changes will depend on climate change evolution intensity, site and stand characteristics, species composition, and adaptive capacity. Initially, adaptive management-adjusting stand structure, promoting diversity, and managing density, water, and species selection-can mitigate impacts and buy time. Under higher vulnerability, species replacement may become necessary-ideally by favoring drought-tolerant species already present through natural regeneration, or otherwise through assisted migration using drought-adapted provenances of native species or non-native species with suitable traits. Uncertainties about ecosystem resilience and the effectiveness of management measures underline the need for integrative, site-specific strategies to sustain ecosystem services and effectively guide future forest composition under ongoing climate change.