Search

A key global change challenge is to significantly reduce the risks of alien taxa causing harmful impacts without compromising the rights of citizens. As part of efforts to address this challenge, South Africa promulgated comprehensive regulations and lists of alien taxa in 2014. In this paper, we review how the lists developed, changed over time, and how they have been implemented. As of March 2021, 560 taxa were listed under four broad regulatory categories, and between 2014 and 2020, almost 3000 permits were issued to regulate the continued use of listed taxa. The full lists of regulated taxa, permits issued, and corresponding regulations are available in the Supplementary material. A proposed standardised, transparent, and science-informed process to revise the regulatory lists is also presented – as of 30 April 2024, risk analyses have been developed for 140 taxa using the Risk Analysis for Alien Taxa (RAAT) framework and reviewed by an independent scientific body [the Alien Species Risk Analysis Review Panel (ASRARP)] with input from taxon-specific experts. These recommendations are being considered by an interdepartmental governmental decision-making body established in March 2023 [the Risk Analysis Review Committee (RARC)]. Finally, key issues with the listing of alien taxa in South Africa that remain to be resolved are presented. As South Africa’s regulatory framework continues to develop, the process of listing and regulating alien taxa will, we believe, become more transparent, consistent, and acceptable to stakeholders, and ultimately facilitate efforts to reduce the harmful impacts of alien taxa. Significance: The regulation of alien species is a major part of how South Africa addresses biological invasions. For this process to be effective, relevant stakeholders need to be engaged and involved. This paper outlines how species have been regulated in the past, provides regulatory lists in accessible formats, and analyses how the lists have changed over time. A transparent, science-informed process to update the regulatory lists is presented and progress to date reviewed. This process aims to engage interested and affected parties in efforts to preserve the benefits of alien species while reducing the harmful impacts of invasions. [ABSTRACT FROM AUTHOR]

It is important for regulators and managers to effectively distinguish native from alien taxa. However, a taxon can have both native and alien populations within the same country as biogeographic and administrative boundaries do not always align. Here we propose a protocol for classifying populations as native, alien, cryptogenic, or native-alien, and describe the evidence required. This protocol comprises of three questions: (1) is the population outside the historic native range of the taxon, (2) is/was natural dispersal from the native range unlikely, and (3) is the taxon native to a part of the administrative region where the population is found. If information on introduction pathways, genetics, and biogeographical barriers is available, we propose an alternative process to answer question 2. The protocol was applied to 176 suspected native-alien populations in South Africa. A total of 132 populations from 77 native taxa were classified as native-alien, 13 as cryptogenic, 13 as alien (native-alien status uncertain), and 18 as native. We believe the protocol provides a transparent and standardised method for categorising native-alien populations and thereby facilitates the appropriate regulation and management of this type of biological invasion. [ABSTRACT FROM AUTHOR]

Global change is driving a massive rearrangement of the world's biota. Trajectories of distributional shifts are shaped by species traits, the recipient environment and driving forces with many of the driving forces directly due to human activities. The relative importance of each in determining the distributions of introduced species is poorly understood. We consider 11 Australian Acacia species introduced to South Africa for different reasons (commercial forestry, dune stabilization and ornamentation) to determine how features of the introduction pathway have shaped their invasion history. Projections from species distribution models ( SDMs) were developed to assess how the reason for introduction influences the similarity between climatic envelopes in native and alien ranges. A lattice model for an idealized invasion was developed to assess the relative contribution of intrinsic traits and introduction dynamics on the abundance and extent over the course of simulated invasions. SDMs show that alien populations of ornamental species in South Africa occupy substantially different climate space from their native ranges, whereas species introduced for forestry occupy a similar climate space in native and introduced ranges. This may partly explain the slow spread rates observed for some alien ornamental plants. Such mismatches are likely to become less pronounced with the current drive towards 'eco gardens' resulting in more introductions of ornamental species with a close climate match between native and newly introduced regions. The results from the lattice model showed that the conditions associated with the introduction pathway (especially introduction pressure) dominate early invasion dynamics. The placement of introduction foci in urban areas limited the extent and abundance of invasive populations. Features of introduction events appear to initially mask the influence of intrinsic species traits on invasions and help to explain the relative success of species introduced for different purposes. Introduction dynamics therefore can have long-lasting influences on the outcomes of species redistributions, and must be explicitly considered in management plans. [ABSTRACT FROM AUTHOR]

The pet trade has been a major pathway for the introduction of vertebrate invaders, but little is known about its role in invertebrate invasions. Here we assess the trade in terrestrial invertebrates (excluding spiders) in South Africa and the potential of this trade to result in biological invasions and impacts. Pet stores, websites, and expositions were visited, and a list of the taxa traded was compiled. DNA barcoding was used to determine if the species were correctly identified in the trade. Information on invasion history and impact elsewhere was used to assess the potential for species to become invasive and have impact in South Africa. We found 53 alien terrestrial invertebrate taxa that were traded, although only 36 of these matched a valid species name. Of 11 species tested using DNA barcoding nine were correctly identified. Species accumulation curves were produced, but did not reach an asymptote, suggesting there are many species in the trade that were not recorded. The most common species were used as food for pets, rather than as pets themselves. None of the species were reported to be invasive elsewhere, and few had records of causing negative impacts (the exception being moderate impacts to human health caused by venomous scorpions). Therefore, there is little evidence that the invertebrates traded pose a significant threat to South Africa. However, given uncertainties in which taxa are traded and the lack of data on invasiveness and impact, there might be a significant invasion debt. We recommend continued monitoring and engagement with the industry. [ABSTRACT FROM AUTHOR]

Biological invasions severely impact on marine ecosystems around the world, but to date management is rare and has not previously been attempted in Africa. This study documents a trial management programme aimed at informing a national management strategy for the invasive European shore crab, Carcinus maenas , in South Africa. The approach involved testing control methods used elsewhere (baited traps, crab condos, diver collections and sediment dredging) and adapting these to the local context. Following these trials, baited traps were deployed over the course of the year, and the catch per unit effort (CPUE) tracked. A total of 36,244 crabs were collected during the management period, six times more than a pre-management population estimate. The population was not extirpated and CPUE increased once trapping ceased. The cost of attempting nationwide eradication is prohibitive, particularly given the lack of current impacts by this crab in this region and the possibility of reintroduction. We highlight key administrative challenges encountered, and the importance of such pilot trials in setting long-term goals when attempting alien species management interventions. • This study presents the first management of a marine alien species in Africa. • Control methods used elsewhere were tested for local applicability. • Trapping was used to remove the European shore crab Carcinus maenas. • Despite removal of >36,000 crabs over a year, extirpation was not achieved. • Key administrative considerations in alien species management are highlighted. [ABSTRACT FROM AUTHOR]

• Detailed current and potential distribution of Psidium cattleyanum in South Africa is presented. • The species is self-sustaining with evidence of spread. • The population in the Western Cape is the first substantial invasive population reported from a temperate winter-rainfall region globally. • Recommendations for regulating P. cattleyanum in South Africa are provided. Psidium cattleyanum (Myrtaceae) is a widespread invasive species in several countries, particularly on oceanic islands. The species was first recorded in South Africa in 1948 and has since established self-sustaining populations. We present the first comprehensive evaluation of the invasiveness of P. cattleyanum in South Africa by: 1) mapping the current distribution of the species; 2) estimating its potential range using species distribution models in MaxEnt; 3) analysing the risk posed to South Africa using the risk analysis for alien taxa framework; and 4) developing recommendations for regulation. Psidium cattleyanum was recorded at 52 sites in four provinces across South Africa, with the population in the Western Cape being the first substantial invasive population reported from a temperate winter-rainfall region globally. Invasive populations were assessed in detail at four sites: Newlands Forest (Western Cape; n=2193 plants; covering ∼12 ha), Eshowe (KwaZulu-Natal; n=1561, ∼7.6 ha), Southbroom (KwaZulu-Natal; n = 449, ∼2.9 ha), and George (Western Cape; n=214, ∼2.4 ha). At all four sites the species is self-sustaining and there is evidence of spread. In South Africa, the east coast is climatically suitable for the species to expand its range. Although damaging invasions of P. cattleyanum have only been recorded on several islands to date, we find no reason to suggest that climatically suitable continental regions (including parts of South Africa) will not suffer harmful impacts if invasions progress unmanaged. As such, we support the current regulation of P. cattleyanum in South Africa, whereby the species must be controlled as part of a national management plan (category 1b) noting that while it is advisable to ban cultivation, the forcible removal of plants from people's gardens should perhaps only be prioritised if such plantings clearly pose a high risk (i.e., in climatically suitable regions near to riparian areas or natural areas). [ABSTRACT FROM AUTHOR]

Large sums of money are spent globally on invasive alien plant control projects, but their effectiveness in the medium to long term is seldom reported. Here we review the cost, extent and effectiveness of the management of plant invasions by South Africa's "Working for Water" program between 1998 and 2020. We use a broad framework of indicators for assessing the inputs, outputs, and outcomes of alien plant control interventions at a national level. Our study is based on (1) spatially explicit data on efforts that targeted selected sites and species for control; (2) surveys of the extent of invasion; and (3) case studies of control effectiveness. An average of ZAR310 million (adjusted to 2020 values) was spent annually, creating the equivalent of 8113 full-time jobs, with expenditure rising rapidly between 1998 and 2003 and again between 2009 and 2015, dropping more recently. Control efforts were directed at 178 species, with 15 taxa receiving two thirds of the total expenditure. Control was conducted on ~76,000 sites covering 2.7 million ha, which is ~14 % of the estimated invaded area. Over a quarter of the control was not in priority areas for biodiversity and/or water conservation. The effectiveness of control operations has not been monitored regularly, but a few studies at local scales have found reductions in alien plant cover, and it is likely that "Working for Water" has had a role in limiting invasion. Nonetheless, national surveys suggest that plant invasions have continued to grow—the problem is too large to expect that control can be achieved everywhere. We recommend that, to bring plant invasions under control at priority sites, a national strategy should be based on conservation triage, focussing on clearly defined priority sites, improving planning and monitoring, and increasing operational efficiency. [ABSTRACT FROM AUTHOR]

• 28 species of bamboo have been introduced to South Africa. • Only 8 species could be confirmed as currently present. • No evidence that naturalised bamboos were spreading along the Nonoti river in Kwazulu-Natal. • There is a need to update current legislation to include invasive bamboo species. The growing interest in commercial cultivation of bamboos (Poaceae subfamily Bambusoideae) has led to the introduction of new alien species into South Africa. The rate at which bamboos are being planted in South Africa is a cause for concern because of the impacts of bamboo invasions in other parts of the world. To understand the risks associated with new introductions and new plantings, we assess the outcomes of past introductions of bamboos into South Africa. To this end we: (1) produce an inventory of alien bamboo taxa; (2) assess the distribution of bamboos; (3) determine the rate of spread of bamboo at a site with a high density of naturalised stands; and (4) evaluate the current regulatory status of alien bamboos in South Africa. We used a combination of expert opinion, literature, historical records of populations, and public participation to produce a species list and locate populations of alien bamboos. We also attempted to confirm species identities using DNA barcoding. We found that 28 currently-accepted species of bamboo have been recorded in South Africa. However, we have little confidence in this estimate, as 20 of the species could not be confirmed or identified as present in the country. Bamboos are an inherently challenging group to identify using vegetative material, and DNA barcoding was inconclusive. The distribution of bamboos across the country varied with the type or lineage (e.g. herbaceous, tropical or temperate) and the source of information (e.g. herbarium records, in-field observation or public contribution). Although alien bamboos are naturalised at several sites, we found no large invasive stands nor evidence of widespread negative environmental impacts. Nonetheless, we recommend caution regarding future introductions of bamboos for commercial cultivation, as the nature of the plantings will likely differ from the historical situation in both the location, configuration, and the scale of cultivation, and as new species are likely to be introduced. We propose several changes to the current listing of bamboo taxa in national legislation pertaining to alien and invasive species. [ABSTRACT FROM AUTHOR]

Abstract: The legumes (Fabaceae) Genista monspessulana and Spartium junceum are major invaders in several other parts of the world, but not yet so in South Africa. We determine their current distributions in South Africa at different spatial scales, assess population structure (soil seed banks and size at reproduction) evaluate current management activities, and provide recommendations for control (including assessing the feasibility of nation-wide eradication). G. monspessulana occurs at nine localities in three quarter-degree cells, covering a total of 22.7ha. S. junceum is much more widespread, occurring in 33 quarter-degree cells and is frequently cultivated in private gardens. All naturalised or invasive populations are in disturbed areas, mostly along roadsides. Once established, G. monspessulana and S. junceum accumulate large, persistent soil-stored seed banks, ranging in size between 909 and 22,727 (median 1970)seeds/m2 and 0 and 21,364 (median 455)seeds/m2 for the two species respectively. Both species resprout vigorously after cutting and stump herbicide application (60% of G. monspessulana and 43% of S. junceum plants resprouted) which necessitates regular follow-ups. We estimate that over 10years, at a cost of about ZAR 81,000 (1 ZAR=0.114 US$ as on 6 October 2012), G. monspessulana could be extirpated from South Africa. S. junceum is far more widespread and coupled with low effectiveness of control, abundance of seeds and seed longevity, eradication is unfeasible. We recommend that control methods used for S. junceum be improved to prevent resprouting, and that areas are managed to limit the movement of seeds and avoid further spread and establishment. Further studies are required to understand why these two species have failed to replicate the invasiveness shown in other parts of the world. [Copyright &y& Elsevier]