In the face of predicted climate change, a forest species can be considered resistant if it is adapted to the climatic conditions it will encounter throughout its life. A team of researchers has modelled the distribution of climatically adapted European species throughout the 21st century, making up the species pool on which management can rely today to build the future forest. The pace of climate change can make a site unsuitable for a species over its lifetime.
The addition of new species, which would be adapted to future conditions, could increase the current pool of adapted species to an average of 85% by the end of the 21st century. But the majority of these species are not adapted to current conditions, so are not a short-term solution. As a result, the average pool of continuously adapted tree species over the century is smaller than under current and end-of-century climatic conditions, creating a bottleneck. Taking into account the need for continuous climatic suitability throughout the lifetime of a tree planted today, climate change reduces the pool of tree species available for management by 33% to 49% of its current values, in the event of both moderate and severe climate change respectively.
On the European average, according to average climate change scenarios, only 9.4 tree species per square kilometre can be adapted to a changing climate throughout the 21st century. This could have a significant negative impact on wood production, carbon storage and biodiversity conservation. This effect is particularly problematic in Europe, where species diversity has already been reduced since the Pleistocene. According to this study, only 56% of Europe remains suitable for mixtures of at least two species with high multifunctional potential. Strategies for adapting silviculture by producing mixed forests could therefore be limited by the reduction in mixing potential.
However, these results could underestimate the climatic tolerances of species that are currently of little importance in forestry and are therefore less well known. Non-native tree species were also excluded from the analysis and could mitigate the reduction in the pool of adapted species, but the advantages and disadvantages of introducing non-native species (invasiveness, threat to native biodiversity, reduction in the provision of ecosystem services, etc.) should be carefully considered.
This study highlights the need for effective climate change mitigation in all areas to maintain the integrity and potential of forest ecosystem services.