Introduced plant species can become locally dominant and threaten native flora and fauna. This dominance is often thought to be a result of release from specialist enemies in the invaded range, or the evolution of increased competitive ability. Soil borne microorganisms have often been overlooked as enemies in this context, but a less deleterious plant soil interaction in the invaded range could explain local dominance. Two plant species, Carpobrotus edulis and the hybrid Carpobrotus X cf. acinaciformis, are considered major pests in the Mediterranean basin. We tested if release from soil-borne enemies and/or evolution of increased competitive ability could explain this dominance. Comparing biomass production in non-sterile soil with that in sterilized soil, we found that inoculation with rhizosphere soil from the native range reduced biomass production by 32% while inoculation with rhizosphere soil from the invaded range did not have a significant effect on plant biomass. Genotypes from the invaded range, including a hybrid, did not perform better than plants from the native range in sterile soil. Hence evolution of increased competitive ability and hybridization do not seem to play a major role. We conclude that the reduced negative net impact of the soil community in the invaded range may contribute to the success of Carpobrotus species in the Mediterranean basin.
- aizoaceae taxa
- enemy release
- hybrid vigor
van Grunsven, R. H. A., Bos, F., Ripley, B. S., Suehs, C. M., & Veenendaal, E. M. (2009). Release from soil pathogens plays an important role in the success of invasive Carpobrotus in the Mediterranean. South African Journal of Botany, 75(1), 172-175. https://doi.org/10.1016/j.sajb.2008.09.003