Effects Of Invasive Cape Ivy On The Mycorrhizal Presence In California Native Plants

Invasive plants change a biological community leading to a decrease of biodiversity amongst native plant species, however our understanding of the mechanisms underlying the adverse effects on native species is limited. Mycorrhizal fungi are an important component of terrestrial ecosystems that can affect the growth performance of native plants. The disruption of mutualisms between plants and mycorrhizal fungi is a potentially powerful mechanism by which invasive plants can negatively impact native plants. We investigated the effect of Cape Ivy (Delairea odorata: Asteraceae), an invasive evergreen vine native to South Africa, on the mycorrhizal associations of native plants in the coastal scrub plant community in northern California. We collected root and soil samples from areas invaded by cape ivy and from non-invaded areas. Samples were examined microscopically for mycorrhizae. The presence of ectomycorrhizae and endomycorrhizae in soil and roots were compared. Results obtained show that fewer mycorrhizae were associated with dicot shrubs in the cape ivy invaded areas compared to that same plant species growing in non-invaded areas. Our results demonstrate that invasive species may reduce the competitive ability of some native plants by interfering with mycorrhizal associations. The results highlight the role of mycorrhizal symbionts and that soil microbiota should be considered in ecosystem management and restoration programs.