Laurent BERGÈS, Univ. Grenoble Alpes, INRAE, LESSEM, France
Aim
Bird and tree species distributions will shift along with future climatic conditions. Tree species composition changes indirectly drive changes in forest bird habitats, but these indirect effects are poorly known. In this study, we investigated the effects of climate changes and forest management on the amount of reachable habitat for forest birds and teased apart the role of climate-driven tree species composition change.
Methods
We used general additive models to project tree and bird species distributions (2020 and 2050) while accounting for their response to climatic conditions at a large scale (France) and to local environmental conditions at a regional scale. The future projections combined two scenarios of climate changes (RCP 2.6 and 8.5) and two scenarios of forest management (increase in either deciduous or coniferous stands). We modelled the amount of reachable habitat with landscape graphs and the equivalent connectivity index (EC) for five birds associated to the main stands in terms of area.
Results
For birds with low and intermediate thermal maxima, climate-based distributions were nearly stable over time and the change in EC was explained by climate-driven changes in tree species composition. For the other bird species (high thermal maximum), the change in EC was mostly driven by more favorable climatic conditions and less by changes in tree species composition.
Main conclusions
Using an innovative modelling framework that bind species distribution and connectivity models with climate and land use changes in forest, we showed that EC dynamics could be completely due to climate-driven changes in tree species composition. Our results highlight the importance of accounting for the indirect effects of climate changes for species conservation, especially in forests where major shifts in tree species composition are expected.
Mots clés : Ecological niche modelling |Multiscale |Landscape dynamics |landscape connectivity |Forest management
A103850EL