Melaleuca parvistaminea Hons LJacobs
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This project assesses the first invasion of Melaleuca parvistaminea Byrnes (Rough-barked Honey myrtle) anywhere in the world. Initially this serotinous reseeder was identified as Melaleuca ericifolia Sm. (Swamp paperbark), a sister taxon, but examination of morphology and reproductive characters led to revision during this study. While not all areas were searched exhaustively, approximately 13 000 plants were found to be spread over 372 ha (condensed canopy area of ~0.73 ha) at 3 sites between Tulbagh and Wolsley, in the Western Cape. I estimated a further 1334 ha of the Kluitjieskraal plantation and 318 ha of the Kluitjieskraal wetland needs to be surveyed to determine the full extent of the infestation. The population structure indicates considerable spread by seed with at least 63 % of plants being seedling or juvenile. Clearing and fire trigger seed release causing prolific recruitment (up to ~18 000 seedlings/m2) after winter rain. No evidence for a soil stored seed bank was found. Risk assessment shows significant invasive potential, while bioclimatic niche modelling indicates high suitability in the southern Cape region. Plants however only reproduce at 5 years. This water-dispersed species is situated less than 2 km from major river systems, and given its potential to spread, clearing effectiveness thus far and limited distribution I consider eradication a reachable goal that should be desired to maximise time-cost benefits of early eradication. ZAR 1 639 000 is needed for eradication, which can potentially be declared in 2019. I propose listing the species under category 1a in the National Environmental Management: Biodiversity Act and suggest that a detailed assessment of alien Myrtaceae be undertaken in South Africa.