Seed biology of a recently introduced species, Myoporum laetum in comparison to a successful invasive alien, Acacia cyclops, in the southwestern Cape, South Africa
The invasive potential of Myoporum laetum, a tree recently introduced into the southwestern Cape, South Africa, was evaluated, by comparing various aspects of its seed biology with those of another bird-dispersed alien, Acacia cyclops which is a successful invader in this region. M. laetum has higher annual seed production, but lower soil-stored seed banks than A. cyclops. Both experience high seed predation, especially under parent canopies. M. laetum has a more persistant seed store and is able to germinate and establish in shade. Germination of untreated A. cyclops seeds was 23.3% and this increased to 47.4% after mild heat treatment. Untreated M. laetum seeds were completely dormant, but 3.3% germinated after acid treatment. The high seed production, bird dispersal, persistant seed banks and ability to establish in shade, suggest that M. laetum could become invasive in thickets, such as existing acacia stands.
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