Natura 2000 areas under climate change: Effects of tree species distribution shifts

The climate crisis leads to a change in forest tree species distributions, favouring most likely heat and drought tolerant species. As a consequence, many forest sites across Europe will become unsuitable for drought sensitive species. The combination of climate change and conservation goals of Natura2000 forest habitat types will lead to severe conflicts in conservation and forestry. The concept of “no deterioration” in article 6 of the Habitats Directive supports a static conservation of the prevalent flora and fauna. In those areas forestry is oriented towards conservation of natural forest habitat types. Especially areas with reduced silvicultural activities or strict silvicultural requirements, such as Natura 2000 sites, are prone to a long forest conversion process towards more suitable tree species. As forestry is based on long-term life cycles, this development will impact forest condition, forest cover, silviculture and conservation negatively. The Natura2000 legislation is under pressure.

This study aims at analysing (1) the changes of future tree species ranges in Europe, (2) how severe changes will impact current natural forest habitat types of Natura 2000 sites and (3) which new tree species might be present in future climate scenarios. We selected a combination of generalised additive models, generalised linear models and boosted regression trees for the modelling process. As model input serve four preselected bio-climatic variables from a total of 26 bio-climatic variables, derived from EURO-CORDEX CMIP5 climate simulations for 1971-2098 for IPCC’s representative concentration pathways 2.6, 4.5 and 8.5. JRC soil characteristics and JRC European tree species data serve as additional input variables. Potential tree species ranges with 1km spatial resolution as model outcome is compared to current definition of natural forest habitat types of Natura 2000 sites. This allows conclusions about their potential future occurrence and endangered static protection state. Most tree species reveals a severe decline of suitable ranges in all RCP scenarios and range shift towards polwards regions and higher elevations. As a consequence protection goals of forest Natura 2000 areas are at stake.