Multigenerational invasive exposure leads to divergent native plant root allocation response to differing resource availability

Background Invasive plant species strongly affect native plant communities, often with strong influences belowground. Some native plants respond with rapid trait change from multigenerational interactions with invasives, including via root biomass allocation. Native plant root allocation responses to multigenerational invasive exposure are poorly typified, and researchers have yet to summarise whether resource availability mediates the responses of native plants that have co-occurred with invasive plant species (invader-experienced) and those that have not (invader-experienced).Aims Evaluate root partitioning from invader-experienced and invader-naïve native plant populations, in experiments in which native plants were grown alone or with the co-occurring invasive species at varying resource levels.Methods Use 242 effect sizes on 17 native species in meta-analysis models to compare root allocation between invader-experienced and invader-naïve and under varying resource levels.Results I found that differences in response to the presence or absence of multigenerational invasive exposure were only apparent when testing different resource levels. Specifically, when grown alone, invader-experienced plants had greater root allocation under stress, whereas invader-naïve plants had lower root allocation under resource limitation.Conclusion Interactions with invasive plant species produced adaptive responses in native plant species to resources which are observed even without interactions with invasives. This indicates a significant effect of invasive species below-ground and calls for more research assessing eco-evolutionary root trait responses to coexistence by native species with invasive species.