Effects of barriers on functional connectivity of riparian plant habitats under climate change

Alterations of riparian areas of running waters resulted in fragmentation of the riverscape. The possible impact of climate change additionally stresses the importance for conservation planning for riparian habitats, especially for sessile plant species. The survival of species under changing habitat availability can be counteracted by ensuring functional connectivity of riparian plant species. This study applies a coupled modelling framework using species distribution models and dispersal simulations, which allow to analyze the potential future distribution of species in relation to their ecological niche, life history traits including dispersal abilities as well as barriers to dispersal such as dams. Modelled suitable habitats for six riparian plant species characteristic for the olive willow plant community (Salicion elaeagni) showed dramatic changes under the impact of two climate change scenarios. While habitat suitability remained low for species with a narrow ecological niche, it increased under climate change scenarios for species which are also found in secondary habitat outside riparian areas. Simulations of dispersal to the potential future habitat revealed nevertheless high numbers of decolonized cells after 80 years of dispersal for species with high future habitat suitability. This stresses the importance of a joint investigation of the habitat suitability under climate change scenarios, dispersal parameters as well as life history traits for conservation planning of riparian species. The simulated future distribution revealed that barriers along rivers have a significant negative effect on the spread of the studied plant species. Our results suggest that conservation management should focus on providing connected stepping stone habitats for riparian plant species along rivers, as current species occurrences are not persistent over time.