Biotic interactions of alien species with native competitors and antagonists are crucial for invasion success, yet it has rarely been considered that these interactions may change with residence time of a species in the new range. To investigate such potential long-term changes in biotic interactions, this project builds on a previous project in which I demonstrated that plant performance and range sizes depend on residence time. This project will now focus on the actual mechanisms and specific biotic interactions associated with the changes in performance over long timescales. In particular, the project will test whether biotic resistance of native communities to novel species increases over time. To test this hypothesis, I use an ‘alien-native species continuum’, including 30 Asteraceae species of increasing residence times from ca. 10-10,000 years in Germany (i.e. from novel to native). A workshop will be held aiming to conceptually synthesize the theoretical mechanisms of biotic resistance by native communities to novel species and how they change over time, and review the research findings on this topic so far. A pairwise competition experiment across the 30 Asteraceae and three native phytometer species will investigate changes in plant interactions depending on length of coexistence time, quantify niche and fitness differences, and make predictions on coexistence. A plant-soil feedback experiment will test how belowground interactions influence long-term invasion success. Finally, an enemy exclusion experiment will investigate aboveground antagonistic interactions, assessing the potential effects of enemy release and accumulation over time. To obtain a better mechanistic understanding of biotic interactions, all three experiments will also investigate how variation in biotic interactions across the alien-native species continuum is determined by functional traits. The project will thus greatly advance the understanding of the long-term dynamics of biotic interactions in novel biotic contexts, making important contributions to invasion biology, community ecology, population biology and conservation biology.
Project start 01/05/2022
Project end 30/04/2025
Sponsor mark (sponsor) DFG Project SH 924/1-2
