Allelopathic effects of invasive alien plants on native Mediterranean plant species
Acacia dealbata (Fabaceae, EPPO List of Invasive Alien Plants) and Hakea decurrens subsp. physocarpa (Proteaceae, EPPO A2 list) are both native to Australia and are invasive alien plants in south-western Europe, where they have colonized Mediterranean habitats and displaced native flora. Both species can have negative impacts on biodiversity and ecosystem services changing the structural diversity of the habitats they invade. The potential allelopathic effects of A. dealbata and H. decurrens subsp. physocarpa was studied on two common Mediterranean native species; Cistus ladanifer (Cistaceae) and Lavandula stoechas (Lamiaceae). Leaf extracts from each invasive alien plant were formulated into aqueous solutions at varying concentrations and applied to petri dishes which contained seeds of each native species. The results showed that A. dealbata and H. decurrens subsp. physocarpa exert significant allelopathic effects on C. ladanifer and L. stoechas at various early stages of development including germination, hypocotyl emergence and root growth when the aqueous extracts were at high concentrations. However, even at low concentrations, negative effects were still seen. The study shows that these two invasive alien plants can have allelopathic impacts on native plant species which promote their establishment at the detriment of the native plant community.
Sources
Nogales L, Chaves N, Blanco-Salas J, Mateos L, Rubio LV, Alías JC (2025) Allelopathic effect of the invasive species Acacia dealbata Link and Hakea decurrens R.Br., subsp. physocarpa on native Mediterranean scrub species. Plants 14, 3685. https://doi.org/10.3390/plants14233685