Evaluating the status of Acacia species in South Africa
For effective management, it is imperative to know the status and extent of the spread of particular invasive alien plants. Australian Acacia species have been introduced into South Africa since the early 18th century and as a result the country has the largest diversity of Australian Acacia introductions anywhere in the world. Even though this group of species has been managed in South Africa, little is known about species other than those with substantial commercial value. The last detailed inventory of Australian Acacia in South Africa was based on data collated 40 years ago where it was estimated that there were 70 Australian Acacia species known to be introduced into South Africa and of these 14 species are considered invasive. The present study aimed to update the inventory in order to create a new list of Australian Acacia species present in the country. Literature sources, student theses and unpublished records documenting these species were reviewed. In addition, local herbarium data were compared with records from the literature. Following this review, field surveys were conducted from a list of introduction sites compiled during the review. During these surveys, samples were taken for molecular analysis when species identification through morphological means was not possible (some of the species are very difficult to identify using morphological methods). During the study, evidence was found on the introduction of 141 Australian Acacia species, which was double the previous estimate but through field surveys and molecular research only the presence of 33 species was confirmed. The authors highlight reasons for the discrepancy between those species recorded as being introduced compared to those species confirmed as still present may include the fact that Acacia species from historic forestry trials were detailed from the literature reviews though none of these species subsequently naturalized. In addition, some species may not have survived at sites of initial introduction due to unfavorable climatic conditions.
Sources
Magona N, Richardson DM, Le Roux JJ, Kritzinger-Klopper S, Wilson JRU (2018) Even well-studied groups of alien species might be poorly inventoried: Australian Acacia species in South Africa as a case study, NeoBiota 39, 1-29.