Supplementary Material to 'A South African perspective on the 2023 IPBES Thematic Assessment Report on Invasive Alien Species and their control'

Supplementary Material to ‘A South African perspective on the 2023 IPBES Thematic Assessment Report on Invasive Alien Species and their control’ Citation of the original article: Wilson JRU, Faulkner KT, Fernández Winzer L, McCulloch-Jones EJ, van Wilgen BW, Blanchard R, Carbutt C, Dechoum MS, Foxcroft LC, Greve M, Hui C, Ivey P, Kgope B, Kumschick S, le Roux PC, Masehela TS, Measey J, Miza S, Mogapi T, Mpikanisi F, Mulaudzi L, Nelukalo K, Nnzeru L, Nsikani MM, Pattison Z, Rahlao SJ, Richardson DM, Robinson TB, Shackleton RT, Tererai F, Tshidada N, Tshikhudo PP, Tshivhandekano I, Wanjau K, Ziller SR, Zengeya TA (2025) A South African perspective on the 2023 IPBES Thematic Assessment Report on Invasive Alien Species and their control. African Biodiversity & Conservation 55. doi:10.38201/abc.v55.9 The article and this supplementary material can be found at: https://www.abcjournal.org/index.php/abc/article/view/531 This supplementary material is archived at: http://dx.doi.org/10.5281/zenodo.17543246 Copyright: © 2025. The Authors. Licensee: SANBI. This work is licensed under the Creative Commons Attribution 4.0 International License Supplementary Table S1. IPBES IAS Assessment experts and countries of affiliation ............... 2 Supplementary Table S2. The key message paragraphs from the IPBES IAS Assessment and the corresponding South African situation ................................................................................ 3 Supplementary Table S3. Objectives and actions for managing biological invasions with details of the South African situation ...................................................................................... 27 Supplement Table S4. Knowledge and data gaps identified in the IPBES IAS Assessment in the context of South Africa ............................................................................................................ 35 Supplementary References ...................................................................................................... 49 2/57 Supplementary Table S1. IPBES IAS Assessment experts and countries of affiliation As experts1 can have multiple countries of affiliation, the total in the table is greater than the total number of experts. 25 experts listed South Africa as an affiliation: co-chairs (0/3); coordinating lead authors (2/14): Melodie A. McGeoch, Sebataolo J. Rahlao; lead authors (3/69): Ryan Blanchard, Llewellyn C. Foxcroft, Olaf L.F. Weyl; contributing authors (17/199 + 3 also listed under other roles): Bianca Hagen, Bruce R. Ellender, Cang Hui, Clinton Carbutt, Colleen T. Downs, David M. Richardson, Johannes J. le Roux, John Measey, Julie A. Coetzee, Llewellyn C. Foxcroft, Luis R. Pertierra, Ndivhuwo Shivambu, Philip Ivey, Ross T. Shackleton, Ryan Wasserman, Sabrina Kumschick, Sean M. Marr, Tinyiko Cavin Shivambu, Tsungai A. Zengeya, Zarah Pattison; and review editors (3/12): Cang Hui, David M. Richardson, John R. Wilson. By comparison, 9 experts listed other African countries as an affiliation. Country Number of experts with that affiliation UK 39 USA 35 Australia 28 Germany 25 South Africa 25 Argentina 18 Italy 17 Switzerland 15 New Zealand 13 Canada 12 Ecuador 11 Spain 11 Brazil 9 Portugal 9 France 8 Netherlands 8 India 7 Austria 6 Chile 6 Czech Republic 5 Japan 5 China 4 Cyprus 4 Norway 4 Denmark 3 Estonia 3 Greece 3 Iran 3 Mexico 3 Turkey 3 1 IPBES does not call contributing authors ‘experts’ and the term ‘authors’ is preferred to describe all roles (though review editors are of course not authors). For simplicity we use the term expert to refer to all those involved and authors to refer to those responsible for content. Members of the Technical Support Unit (based in Japan) were not included here, though they all played critical roles in the production of the IPBES IAS Assessment Country Number of experts with that affiliation Armenia 2 Belgium 2 Fiji 2 Finland 2 Ghana 2 Kenya 2 Nepal 2 Panama 2 Tanzania 2 Venezuela 2 Belarus 1 Bolivia 1 Cameroon 1 Canada 1 Colombia 1 Costa Rica 1 Ireland 1 Israel 1 Lesotho 1 Poland 1 Republic of Korea 1 Romania 1 Russian Federation 1 Senegal 1 Slovenia 1 Sri Lanka 1 Uganda 1 Uruguay 1 Zimbabwe 1 3/57 Supplementary Table S2. The key message paragraphs from the IPBES IAS Assessment and the corresponding South African situation The key message paragraphs are taken verbatim from the IAS Assessment (IPBES 2023) and split into sections that warrant separate responses. The degree of resonance for South Africa was evaluated as one of five values (completely agree, largely agree, somewhat similar, different and not applicable) with one of four levels of confidence [well established, established but incomplete, unresolved and inconclusive (IPBES 2018)]. See Table 1 in the paper for further details of the method of scoring. See Table 2 in the paper for the scoring of the key messages themselves. The focus is on mainland South Africa and the immediate offshore environment (including islands). Paragraph Available information for RSA RSA References A1 More than 37 000 established alien species have been introduced by human activities across all regions and biomes of Earth … Over 3 500 alien species are present outside of captivity or cultivation. Alien taxa have been recorded in all biomes, all but one water management area, and in all in-shore marine ecoregions. No alien taxa have been recorded in offshore marine ecoregions. The degree of establishment for these taxa is not systematically recorded yet. Zengeya et al. (2023) A1 …, with new alien species presently being recorded at an unprecedented rate of approximately 200 annually. Three new alien species have been recorded per year, but this is likely an underestimate of the number of introductions. This number does not include those legally introduced for which the risk has been assessed and found to be acceptably low. The global figure used in the IPBES IAS Assessment (200 per year) is across all combinations of countries and alien species. As such it is hard to directly compare this to the rate for South Africa. Faulkner (2023) A1 Studies with evidence of negative impacts exist for more than 3 500 of these species, which are categorized as invasive alien species. Over 1 000 taxa are categorised as invasive, but only 36 taxa have been formally evaluated for their environmental impact (using the IUCN’s Environmental Impact Classification for Alien Taxa methodology). The economic impact for only 71 taxa has been documented. Van Wilgen et al. (2022b), Zengeya et al. (2023) A1 The proportion of established alien species known to be invasive varies among taxonomic groups, ranging from 6 per cent of all alien plants to 22 per cent of all alien invertebrates. About a third of the alien species found outside cultivation or captivity in South Africa are invasive and these are mostly plants (74%) and terrestrial invertebrates (14%). Estimates are likely to be lower if we also consider all alien species only found in captivity or cultivation. Note the definitions for established and invasive differ between the South African status report and the IPBES IAS Assessment (cf. Box 1 in the paper). Zengeya et al. (2023) 4/57 Paragraph Available information for RSA RSA References A1 Twenty per cent of all impacts are reported from islands. Major impacts have been observed on South Africa’s offshore and inshore islands. For example, Robben Island has many invasives, which have transformed the habitat (e.g., cats have impacted penguins and wattles transformed the landscape). Other islands have rabbits and mice, but these have not been formally assessed for impact. South Africa has few islands, and most offshore islands are only recently separated from the mainland and so few carry unique species. The situation on the Prince Edward Islands is distinct. Fernández Winzer et al. (2023, 2025), Weller et al. (2014) A1 A disproportionate number of documented negative impacts have been reported in terrestrial realms, especially in temperate and boreal forests and woodlands and cultivated areas (including agricultural land). & About one quarter of documented negative impacts have been reported from aquatic realms, especially from inland surface waters/waterbodies and shelf ecosystems. Trees and freshwater fishes, in particular, have ‘Major’ negative impacts on people and nature across the country. Significant impacts are also seen along the coast, particularly in the intertidal zone. No alien species were recorded on shelf ecosystems and so no impacts were recorded. Almost all monetary costs are noted for the terrestrial environment, with only 1% of costs reported for the aquatic realm. McCulloch-Jones et al. (2024), Robinson et al. (2020), Zengeya and Wilson (2023) A1 In addition to their impacts on nature, about 16 per cent of invasive alien species have negative impacts on nature’s contributions to people, and about 7 per cent on good quality of life. Impacts have not been evaluated as per the IPBES framing of impacts on ‘nature’s contributions to people’ and ‘good quality of life’. Moreover, the impacts of invasions on agricultural and human health have not been systematically collated to date and lists of invasive taxa in such ecosystems are not as yet integrated with lists of species that pose threats to the environment, biodiversity or ecosystem services. None A2 Invasive alien species have contributed solely or alongside other drivers to 60 per cent of recorded global extinctions, and are the only driver in 16 per cent of the documented global animal and plant extinctions. Invasive plants have been implicated in ~20% of plant extinctions in South Africa (7 out of 33) (although not as the main driver). Invasive fishes have been implicated in the extirpation of several freshwater fishes. Chakona et al. (2022), Van der Colff et al. (2023) 5/57 Paragraph Available information for RSA RSA References A2 Biotic homogenization, whereby biological communities around the world become more similar, is a major negative impact of invasive alien species, with consequences for the structure and functioning of ecosystems. With the global movement of alien species, many previously unique ecosystems in South Africa now have similar species compositions to analogous climatic regions elsewhere in the world (e.g., Mediterranean-type ecosystems). Some alien plant species occur across the country, but different assemblages of alien plants occur in different parts of the country: fynbos-specific invaders, grassland-specific invaders, moist-subtropical invaders and semi-arid invaders. Richardson et al. (2020b) A2 Changes in the properties of ecosystems, such as soil and water characteristics, account for more than a quarter of documented impacts. Not evaluated as a percentage of documented impacts. There have been notable impacts on nutrient cycling, significant changes to hydrology, and effects recorded on the intensity and frequency of wildfires. Van Wilgen et al. (2022b), Zengeya and Wilson (2023) A2 The magnitude and types of impacts vary for different invasive alien species and across ecosystems and regions. The impacts of only 36 alien species have been assessed formally, but these species have impacts that vary in their magnitude (‘Minimal Concern’ to ‘Massive’) and mechanism (including competition, disease transmission, changes to ecosystem functioning, and parasitism). Zengeya and Wilson (2023) A2 The majority of documented global extinctions attributed mainly to invasive alien species have occurred on islands (90 per cent), and local extinctions account for 9 per cent of documented impacts of invasive alien species on islands. With few islands, impacts are much more prominent on the mainland. The situation on the Prince Edward Islands is distinct. Fernández Winzer et al. (2023, 2025) A2 Some areas, despite being protected for nature conservation or being remote, are also vulnerable to the negative impacts of invasive alien species. All protected areas for which there are data have alien species, with the area invaded ranging from minor to extensive. Zengeya and Wilson (2023) A3 In 2019, global annual costs of biological invasions were estimated to exceed US$ 423 billion. The IPBES IAS Assessment global estimate incorporates both damage and management costs, which comprise modelled (historical or current cost projections) and observed estimates (actual incurred costs). These costs have been separately reported for South Africa. The observed annual cost of management is ZAR 150M (2022 values); the modelled annual cost of management is ZAR 3.6B; and the modelled annual cost of damage is: ZAR 1–10B. There was insufficient data to get an estimate of the observed annual cost of damage. McCulloch-Jones et al. (2024) 6/57 Paragraph Available information for RSA RSA References A3 The vast majority of global costs (92%) accrue from the negative impacts of invasive alien species on nature’s contributions to people or on good quality of life, while only 8 per cent of that sum is related to management expenditures of biological invasions. Of the total observed costs, 85% were due to negative impacts and 15% related to management expenditure. McCulloch-Jones et al. (2024) A3 The benefits to people that some invasive alien species provide do not mitigate or undo their negative impacts, which include harm to human health (such as disease transmission), livelihoods, water security and food security … For many species, benefits are seen in the short term, but negative impacts are felt elsewhere and later in time; with invasions often becoming a net negative. Shackleton et al. (2007), Van Wilgen and Richardson (2014), Weyl et al. (2017), Zengeya et al. (2017) A3 … with reduction in food supply being by far the most frequently reported impact (more than 66%). Invasive plants can reduce the carrying capacity of rangelands for livestock production at a farm scale by 75%. In South Africa, invasive plants are estimated to reduce the value of livestock production by ZAR 340M, this could increase as the invasions spread. The overall cost to agriculture has not been estimated. O’Connor and Van Wilgen (2020), Yapi et al. (2018) A4 People with the greatest direct dependence on nature, including those involved in genderand age-specific activities, such as fishing or weeding, may be disproportionately affected by invasive alien species. Although a spatial correlation has been shown between income levels and the presence of invasive plants, there is no clear evidence for disproportionate impacts. By contrast, there is clear evidence that those who directly depend on nature in South Africa often utilise invasive species. Ellender and Weyl (2014), Reynolds et al. (2020), Shackleton et al. (2007) A4 More than 2 300 invasive alien species are found on lands managed, used and/or owned by Indigenous Peoples across all regions of Earth, threatening their quality of life and often leading to general feelings of despair, sadness and stress. The number of invasive species found on ‘lands managed, used and/or owned by Indigenous Peoples’ has not been specifically evaluated. Research on the impacts of invasions in communal land areas in South Africa has found that people benefit (in the short term) from some invasive species; this has not yet been mapped. Please note that the terminology used in South Africa is often different from the IPBES terminology (cf. Box 4 in the paper). De Neergaard et al. (2005), Shackleton et al. (2007), Shackleton and Shackleton (2018), Wootton and Shackleton (2023), Yapi et al. (2018) 7/57 Paragraph Available information for RSA RSA References A4 Indigenous Peoples and local communities, ethnic minorities, migrants, and poor rural and urban communities are disproportionately impacted by invasive alien vector-borne diseases. Relatively high densities of alien disease vectors (e.g., rodents) in rural areas and urban informal settlements put people in these areas at risk of contracting zoonotic diseases. The Department of Health and various municipalities have initiated vector control, especially relating to rodents and mosquitoes. Most of this research, however, is from the perspective of health rather than the environment or social science. Bastos et al. (2011), Jassat et al. (2013), Lebelo (2020) A4 Biological invasions negatively affect the autonomy, rights and cultural identities of Indigenous Peoples and local communities through the loss of traditional livelihoods and knowledge, reduced mobility and access to land, and increased labour to manage the invasive alien species. The definitions used in South Africa are not always the same as those used by IPBES (Box 4). Nonetheless comparable issues have been evaluated in some cases. Evidence of such negative impacts are available from across Africa, particularly for subsistence agriculture. Yapi et al. (2018) A4 Impact reports by some Indigenous Peoples and local communities document 92 per cent negative impacts and 8 per cent positive impacts on nature caused by invasive alien species. There are examples of both positive and negative impacts, but the relative proportion has not been estimated. Current information is rather patchy. Both are needed to increase the number of studies and for a method to summarise information. See references in other sections. A5 Up to 2020, only partial progress was made towards international goals and targets (e.g., Aichi Biodiversity Target 9 and Sustainable Development Goal Target 15.8). South Africa has made significant progress towards reporting on biological invasions, as well as developing the indicators needed to do so. Wilson et al. (2018), Zengeya and Wilson (2023) A5 While most countries have targets related to the management of biological invasions within their national biodiversity strategies and action plans, effective policies are often lacking or inadequately implemented. A national strategy and action plan is under development. A national target for 2030 to respond to our obligations under the KM-GBF of the CBD is also under development. The National Environmental Management: Biodiversity Act of 2004 and the Alien and Invasive Species Regulations along with other legislation guide management activities, as does South Africa’s National Biodiversity Strategy and Action Plan 2014–2025. However, coordination is lacking and the extent of interventions vary. Lukey and Hall (2020), Wilson and Kumschick (2024) 8/57 Paragraph Available information for RSA RSA References A5 Eighty-three per cent of countries do not have national legislation or regulations directed specifically toward the prevention and control of invasive alien species. National legislation addressing alien plants has been in place since 1983, and since 2014 addressing all alien taxa. Regulatory lists are in place and have been updated every few years. Different legislation is in place to address different aspects of the problem (e.g., agriculture and biodiversity); these aspects are not well aligned. Kumschick et al. (2020a), Lukey and Hall (2020), Wilson and Kumschick (2024) A5 Policy relevant to biological invasions is also fragmented within countries and across sectors. Various national policies address biodiversity and plant health, but there is no integrated single policy on biological invasions. Lukey and Hall (2020) A5 To date, capacity to respond to biological invasions has varied widely across regions, with nearly half of all countries (45%) not investing in management of invasive alien species (SDG indicator 15.8.1). Approximately ZAR 320 million (adjusted to 2020 values) has been spent by the government annually (1998–2020), largely on managing plant invasions, although the annual expenditure has declined recently. This figure does not include biosecurity and investment by private companies, though other evidence shows that significant interventions are in place (notably the Cape Town Water Fund). Volunteer groups are making substantial inputs. Jubase et al. (2021a), Stafford et al. (2019), Turpie et al. (2019), Van Rensburg et al. (2017), Van Wilgen et al. (2022a) A5 Differences in perception, including conflicting interests and values, of the importance and urgency of the threat of invasive alien species, coupled with lack of awareness of the need for a collective and coordinated response, as well as gaps in data and knowledge, can hinder the management of invasive alien species. The management of conflict-generating species has been particularly challenging and management interventions have often required trade-offs that aim to preserve benefits while limiting negative impacts. Stakeholder engagement around the management of cacti invasions has helped build shared understanding in South Africa. Novoa et al. (2017), Zengeya et al. (2017) A5 Economic development policies and those aiming to manage other drivers of change sometimes facilitate biological invasions. Actions to improve water security have resulted in biological invasions through inter-basin water transfer schemes. Relatively new policies such as the promotion of aquaculture as a source of food and South Africa as a destination for the maintenance of oil and gas infrastructure could facilitate new introductions, while future climate change mitigation and adaptation strategies (e.g., carbon sequestration projects) similarly pose a threat. Biofuels/biomass to stimulate rural development could also create invasions (e.g., Jatropha and bamboo). Faulkner et al. (2020), Richardson and Blanchard (2011), Van Wilgen et al. (2023b) 9/57 Paragraph Available information for RSA RSA References A5 Demographic drivers also facilitate the introduction and spread of invasive alien species while acknowledging that drivers differ across regions and level of impact. People have immigrated to South Africa from different regions at different times bringing plants and animals from their home regions to serve various purposes. Trade in alien species (such as pets) is focused in highly populated areas, and alien species richness (at least for birds and plants) is highest around urban areas. Faulkner et al. (2020), Mantintsilili et al. (2022), Measey et al. (2020), Shivambu et al. (2021), Shivambu et al. (2022), Zengeya and Wilson (2023) A5 The lack of border biosecurity (such as inspections undertaken by quarantine officers of commodities, goods and people) in one country weakens the efficacy of such measures in other countries. Most African countries have a low capacity to prevent the introduction of alien species. The spread of alien species between African countries represents an important and possibly increasing threat to South Africa’s biosecurity. Agreements such as the African Continental Free Trade Agreement will facilitate biological invasions especially considering that neighbouring jurisdictions do not apply biosecurity interventions pre-port and at-port to the same extent as South Africa. Early et al. (2016), Faulkner et al. (2017) B1 Many invasive alien species have been intentionally introduced outside their natural range around the world for their perceived benefits without consideration or knowledge of their negative impacts … Most terrestrial and freshwater alien species introduced to South Africa have been intentionally introduced. These include hundreds of plant taxa for ornamental/horticultural, forestry and agricultural purposes, and animals for fishing or as pets. Faulkner et al. (2016), Faulkner et al. (2020) B1 …, but there have also been many unintentional introductions, including as contaminants of traded goods and stowaways in shipments. Many alien organisms have been accidentally introduced, particularly with imported plants, animals or their products, and through shipping. The relative importance of accidental introductions has increased over time. Faulkner et al. (2020), Faulkner et al. (2016) B1 Indirect drivers of change, particularly those associated with economic activities, of which international trade is the most important, are increasingly facilitating transport and introduction, the early stages of biological invasion. The first known introductions were intentional, with plants and animals being introduced to serve specific purposes (economic, aesthetic, resource related), but as South Africa’s trade and transport increased and expanded geographically, and technologies changed, introduction pathways became diverse, with accidental introductions beginning to play a more important role. Faulkner et al. (2020) 16/57 Paragraph Available information for RSA RSA References C3 Over the last 100 years, 88 per cent of eradication attempts on 998 islands have proven successful, especially for invasive alien vertebrates. There are a few examples of extirpation of invasive vertebrates from in-shore islands, including rabbits from Robben Island. Davies et al. (2020b) C3 Large-scale eradications have been achieved but in many cases are likely to be infeasible. No examples from South Africa. As a highly connected continental system, large-scale eradications would often require regional collaboration. In general, these are only possible on islands. None C3 There are also examples of eradication of invasive alien plants and invertebrates, particularly for those with limited distribution. A snail species was eradicated from mainland South Africa, several ongoing programmes are underway for plants, and possibly several undocumented cases exist. There are no marine examples. Wilson et al. (2013) C3 Adoption of appropriate tools and technologies and involvement of relevant stakeholders underpin and improve the success of eradication programmes. Several alien fish species have been extirpated from discrete water catchments using either mechanical methods (gill nets, electrofishing and seine netting) or chemical control (use of piscicides such as rotenone). Davies et al. (2020b), Zengeya and Wilson (2020) C3 Sustained investment is required for eradication programmes but they are generally more cost-effective than long term and permanent control or the costs incurred through inaction. ZAR 183 million has been invested between 2006 and 2020 on alien plants that are potential targets for eradication. Additional resources have been invested to eradicate alien pests of agricultural crops. The cost effectiveness of these investments has not been estimated. Van Wilgen et al. (2020) C4 Physical control alongside chemical control options in terrestrial and closed water systems are generally only effective at a local scale and can have non-target effects. The broad-scale impact of herbicide usage in efforts to control invasive plants in South Africa has not been fully evaluated. Working for Water has, however, had projects covering 2.7 million ha, which is ~ 14 % of the estimated invaded area, with some cases demonstrating effective control at landscape scales. Van Wilgen et al. (2023a), Van Wilgen et al. (2022a) C4 Biological control can be applied for widely distributed invasive alien species and has been successful in managing some invasive alien plants, invertebrates and, to a lesser extent, plant pathogenic microbes and vertebrates, … At least 17 species have been brought under permanent control through biological control and reductions in many other invasions exist. Biological control can also be effectively deployed against invasive plant species with limited distributions. Olckers (2004), Van Wilgen et al. (2023a), Zachariades et al. (2017) 17/57 Paragraph Available information for RSA RSA References C4 … but it may also have non-target effects if not well regulated. International standards and risk-based regulatory frameworks for biological control have been used in many countries to manage risks, and continue to be successfully applied. In over a century of classical biological control in South Africa there has been no significant nontarget damage. South Africa has processes in place to adhere to international best practice in the field. Hill et al. (2020), Ivey et al. (2021) C4 Integrated management, where more than one containment or control option are used, can improve outcomes. Integrated management has shown positive results; for example, the use of biological control in the landscape in combination with site-based control. Nsikani et al. (2018), Van Wilgen et al. (2001) C5 Management outcomes can be improved by the integration of siteand/or ecosystembased management options that enhance ecosystem function and resilience. See C4. See C4 C5 Frequent long-term monitoring of sites ensures early detection of invasive alien species, including re-invasions, and can inform further management actions. Monitoring is crucial to the management of biological invasions; hence clearing efforts are often accompanied by follow-up treatments aimed at reducing re-invasions. Nsikani et al. (2017) C5 In marine and connected water systems, ecosystem restoration has so far proved to be largely ineffective. No restoration has been attempted in marine or connected water systems in South Africa. There is no evidence that it would be successful. None C5 Adaptive management, possibly combining multiple options, will improve management of biological invasions under ongoing climate and land-use change. There are cases of restoration efforts in the country that have combined multiple options (e.g. biological control, manual removal of target invaders, follow-ups and seed application) leading to enhanced ecosystem recovery through the management of barriers to ecological restoration. Frameworks for adaptive management have been developed. Foxcroft (2004), Nsikani et al. (2018) C5 Integrating site and/or ecosystem-based approaches can improve management outcomes of biological invasions and also enhance ecosystem functioning under ongoing climate and land-use change. The application of biological control in the landscape reduces the reproductive output of invaders and slows their spread. When combined with site-based clearing that is followed-up by restoration, management outcomes have been improved. Similarly, in aquatic environments, biological control of floating aquatic invasive plants promotes ecosystem recovery. Coetzee et al. (2020), Motitsoe et al. (2020), Nsikani et al. (2018) 18/57 Paragraph Available information for RSA RSA References C6 Engaging stakeholders, including the private sector, and Indigenous Peoples and local communities in the collaborative management of biological invasions is important for social acceptability and improving environmental, social and economic outcomes, particularly where there are conflicting perceptions of the value of invasive alien species and the ethics of management options. Specific approaches and frameworks to engage with stakeholders on the issue of biological invasions were developed by South African stakeholders at a workshop in Cape Town. Collaborative engagement across sectors (including academics, government institutions and private stakeholders) is being undertaken to support the sustainability of biological control programmes in the country. Ivey et al. (2024), Jubase et al. (2021a), Novoa et al. (2018) C6 Management actions also benefit from sharing and collaboration across knowledge systems. There are a variety of active working groups and an annual national symposium on biological invasions and their management. In addition, building collaborative governance initiatives can help to ensure sufficient funding for research and management that is relevant to stakeholders’ needs. However, more can be done in South Africa to promote this both within and outside of academia. Abrahams et al. (2019), Foxcroft et al. (2020), Ivey et al. (2024) C6 Recognizing Indigenous Peoples’ and local communities’ knowledge, rights and customary governance systems in accordance with national legislation also helps to improve long-term management. Management of biological invasions, particularly in communal areas, often takes place in consultation with traditional leadership and authorities. These have not, however, been well documented as far as we are aware. Understanding local perspectives and needs is being considered increasingly by managers and decision-makers and has helped to shape discourses on management and governance [for example, justifying the support for the introduction of more damaging biological control agents for managing invasive Neltuma (prosopis) in the Northern Cape]. In addition, in some areas, local communities are very active in managing their local environments to prevent or limit invasions, this could be a useful leverage point to build collaborative governance moving forward. Ivey et al. (2024), Jubase et al. (2021a), Shackleton et al. (2007), Shackleton et al. (2015) 19/57 Paragraph Available information for RSA RSA References D1 Strategic actions to prevent the introduction and impact of invasive alien species include: enhancing coordination and collaboration across international and regional mechanisms; developing and adopting effective and achievable national strategies; sharing efforts and commitment and understanding the specific role of all actors; improving policy coherence; broad engagement across all stakeholders and Indigenous Peoples and local communities; resourcing innovation, research and technology; and supporting information systems, infrastructures and data sharing. These are discussed in turn in Table 3 in the paper. A ‘participatory futuring process’ has been applied with a view to scaling up a range of already successful or promising interventions to transform and improve invasive species management in South Africa. Van Velden et al. (2023) D2 International, national and local agencies involved in developing policies for the environment, agriculture, aquaculture, fishing, forestry, horticulture, border control, shipping (including biofouling), tourism, trade (including online trade in animals, plants, and other organisms), community and regional development (including infrastructure), transportation and the health sector can all play a role in developing a coherent approach to managing biological invasions and preventing and controlling invasive alien species. Various policies and legislation exist, but these are not completely aligned. Other actions (i.e., those not at the border) are not coherent (e.g., different risk analyses systems for different threats). A newly created intra-departmental Alien and Invasive Species Forum was established by the DFFE to facilitate integrated governance across all aspects of biological invasions. The intention is for it to become interdepartmental. There are various provincial working groups and partnerships with various sectors (e.g., the horticultural and forestry industries). These facilitate discussions around regulatory lists published for public consultation, in a few cases while lists are being implemented. There are, however, several unresolved issues (e.g., how to address the risks of horticultural cultivars). The Border Management Authority (BMA) was established as a schedule 3(A) public entity and the third law enforcement agency on 1 April 2023. The BMA is the single authority for the management of South Africa’s borders. The BMA integrates and facilitates the implementation of biosecurity interventions at ports of entry and the Border Law Enforcement area under a single command and control. Chetty et al. (2024), Wilson and Kumschick (2024), Zengeya and Wilson (2023) 20/57 Paragraph Available information for RSA RSA References D2 Enhancing coordination and collaboration across international and regional mechanisms is one of the key strategic actions for rapid and transformative progress. International and regional partnerships can improve management of biological invasions. There are partnerships between African countries to monitor for new alien species, these partnerships tend to be industry specific (e.g., the Forest Invasive Species Network for Africa monitors for forestry pests). There are increasing initiatives at the level of the Southern African Development Community (SADC) and there is the potential for an Africa-wide strategy to address biological invasions. However, there is little evidence of on-ground implementation of such initiatives. A greater focus on bottom-up approaches (e.g., through research and management collaboration) might lead to tangible improvements. To our knowledge there has been no general perspective paper on this topic for RSA D2 Collaboration and co-development with Indigenous Peoples and local communities can increase the effectiveness of implemented strategies. The IPBES definitions do not always correspond to definitions used in South Africa, but the sentiment does (cf. Box 4 in the paper). There are various hack groups, spotter networks and farmer groups. Some efforts have gone into translating into local languages. There are also land user incentive programmes. Recently, farm-level management strategies to improve the control of Neltuma invasions in the Northern Cape were co-developed by multiple local and national stakeholders. This drew heavily on co-developed national strategy suggestions. Similarly, co-development actions for strategic planning have been developed for other taxa, such as invasive cactus species. Ivey et al. (2024), Jubase et al. (2021a), Kaplan et al. (2017), Novoa et al. (2016), Nxele et al. (unpublished), Shackleton et al. (2017) D3 Implementation-focused national biodiversity strategies and action plans can help to spur strategic actions and establish the properties of the governance systems required for the successful prevention and control of invasive alien species and the management of biological invasions, and work towards delivering Target 6. South Africa’s National Biodiversity Strategy and Action Plans (NBSAPs) included activities to address biological invasions. The Convention on Biological Diversity’s programme of work provides an obligation for South Africa to develop a national strategy (which is under development). Under development 21/57 Paragraph Available information for RSA RSA References D3 Coordinated efforts to strengthen national regulatory instruments are also priorities, including those for online trading and the creation of appropriate policies for the development and use of environmentally sound technologies, as well as making available data and information accessible. National regulatory instruments: the management of biological invasions is mainly informed by the NEM:BA A&IS Regulations of 2014 and as revised in 2016 and 2020. These regulations provide a list of taxa that require management. Inclusion of taxa in these lists was initially largely informed by expert opinion; however, risk analyses are increasingly being relied upon to inform the list of species targeted for management. I mprovements to the regulations have been made, e.g., amendments to The National Environmental Laws Amendment Act, 2022 (NEMLAA) which came into effect on 30 June 2023. Online trading: some studies have looked at this, though there is not a specific policy. Development and use of environmentally sound technologies: biological control is well regulated. Making available data and information accessible: the South African status report provides a crucial function in this regard. Risk analyses are not in public domain yet, but the plan is for them to be published in concert with revisions to regulatory lists. However, much more needs to be done. For example, the current biosecurity landscape is fragmented and characterised by several databases and inventories that are managed by various entities, including government departments and entities, non-profit organisations and research institutions. While there has been some cooperation between these entities, the varying format, content and completeness of these databases make it difficult to fully define the scope of biosecurity. There are significant gaps in the available information on pathways of introduction and dispersal, making it difficult to develop effective biosecurity measures. A centralised and comprehensive system for managing biosecurity, which integrates the existing databases and inventories into a unified system, is in development. Ivey et al. (2021), Mantintsilili et al. (2022), Nelufule et al. (2020), Shivambu et al. (2020), Wilson and Kumschick (2024) D3 Market-based instruments such as tax relief and subsidization can be used to incentivize action and spur relevant investment. Payments for ecosystem services have been proposed, but not yet implemented. Value-added industries that utilise alien biomass have been shown in theory to be beneficial but have not been successful in practice. Pirard (2023), Turpie et al. (2008) D3 Sharing efforts and commitment, understanding the specific roles of all actors and encouraging engagement across sectors on prevention, control and environmental liability are integral to the effective management of biological invasions. The draft National Invasive Alien Species Strategy and Action Plan promises to see a stepchange in the coordination of South Africa’s response to the issues of biological invasions. Under development 22/57 Paragraph Available information for RSA RSA References D4 Awareness of the risks of biological invasions will contribute to the effective delivery of several of the Sustainable Development Goals, especially those addressing the conservation of marine biodiversity (Goal 14) and terrestrial biodiversity (Goal 15, including but not restricted to Target 15.8) … Acknowledging and managing the threat of biological invasions to South Africa contributes to progress both towards SDG Goals 14 and 15 and to many other goals as well. For example, the large-scale Working for Water Programme, which focuses on clearing invasive plants, contributes to the provision of water (addressing Goals 6, 13) and employment and upskilling/education of poor rural communities in the country (addressing Goals 1, 2, 4, 8, 10). Cumming et al. (2017), Van Wilgen and Wannenburgh (2016) D4 … food security (Goal 2) … Management of pests and diseases for major crop species, e.g. fall army worm, is critical to ensure food security. Employment has been created through Working for Water’s focus on clearing invasive plants, this has aided household food security of the rural poor. Cumming et al. (2017), Mendesil et al. (2023), Van Wilgen and Wannenburgh (2016) D4 … sustainable economic growth (Goal 8) … Responsible use of invasive tree biomass can aid sustainable economic growth at local scales. Ivey et al. (2024) D4 … and sustainable cities (Goal 11) … Some municipalities (e.g., City of Cape Town and eThekwini) have units devoted to working on biological invasions. There is also a large body of work done on municipalities by environmental health practitioners under the framework of the Health Professions Act of 1974. Gaertner et al. (2016) D4 … as well as climate change (Goal 13) … Managing invasive species will help mitigate climate-related effects and stressors. For example, climate change is expected to impact water security in southern Africa. The Working for Water Programme, which clears invasive trees that use up excess water, thus contributes to climate change mitigation. Le Maitre et al. (2016), Van Wilgen and Wannenburgh (2016) D4 … and health and well-being (Goal 3). Many invasive species in South Africa have direct impacts on the health and well-being of people, e.g., by causing allergies and asthma. In addition, invasive species can hinder well-being by reducing economic options. Managing and reducing these impacts directly aids progress toward Goal 3. Job creation through large-scale invasive species control (e.g., the Working for Water Programme) provides income and education to poor rural communities, contributing to livelihoods and well-being. Magadlela and Mdzeke (2004), Shackleton and Shackleton (2018), Van Wilgen and Wannenburgh (2016) 23/57 Paragraph Available information for RSA RSA References D4 Existing collaborative and multisectoral approaches (e.g., One Health) could provide frameworks for cross-disciplinary thinking and could contribute to the management of biological invasions. There have been academic discussions on the similarities between emerging infectious diseases, forestry health and pathogens and biological invasions. In terms of actual implementation there is little direct output. The University of Pretoria has a One Health network that is a multisectoral community of practice, this offers the opportunity for more engagement on work on biological invasions. Ogden et al. (2019), Paap et al. (2020) D5 By delivering current data to relevant actors, information systems can facilitate the prioritization of actions and allow for early detection and rapid response. The South African Emergency Plant Pest Response Plan (SAEPPRP) outlines a response strategy for detecting, identifying and mitigating an emergency plant pest incursion in South Africa. South Africa has an incursion response unit that is part of SANBI and the unit has been active for more than 16 years. Over 80 taxa have been managed by this unit to varying degrees. The NEM:BA A&IS Regulations list taxa that require management and those that are specifically eradication targets. The incursion response unit selects targets from this list, collects data on incursion response targets while managing the taxa. Targets that are not listed in the NEMBA A&IS Regulations are also selected if there is sufficient documented evidence to show the potential for eradication, which warrants in-depth investigation and incursion response. In both cases a clear flow of data from observation to action and suitable data pipelines and workflows are needed. Wilson et al. (2013) D5 Information systems can also support improved governance … The Water Information Management System (WIMS) was developed to track clearing efforts and improve governance. It has, however, been quite difficult to use. In the absence of quality information, tracking the efficacy of control is difficult. Kraaij et al. (2017), Marais et al. (2004), Zengeya and Wilson (2023) D5 … and help develop indicators of biological invasions, which in turn feed into policy support tools. South Africa has pioneered the development of indicators to track the status of biological invasions. National level indicators have been developed and are implemented in the South African status reports. These initiatives link to international processes including the development of indicators to track progress towards Target 6 of the KM-GBF. McGeoch et al. (2006), McGeoch et al. (2010), McGeoch et al. (2023), Wilson et al. (2018), Zengeya and Wilson (2023) 24/57 Paragraph Available information for RSA RSA References D5 Collaboration between biological invasion experts and across knowledge systems in all regions, and enhancement of research capacity where needed, can improve data and information availability and the understanding of the context-specific features of biological invasions and their impacts. The inter-institutional Centres for Invasion Biology and for Biological Control have been highly successful in building research networks across the country and with international partners. Various meetings address biological invasions including the Conservation Symposium in KZN and the National Biological Invasions Symposium. There are also some fora that have ceased to meet, e.g., the Management, Research and Planning (MAREP) meetings. There are also farmers days, integrated working groups, online and in-print pamphlets, popular books and various short courses. Byrne et al. (2020), Richardson et al. (2020a) D6 Advances can be achieved through adequately and sustainably resourced public awareness campaigns … The Working for Water Programme funded a significant public awareness campaign for many years. Byrne et al. (2020) D6 … education … Various awareness campaigns are run and popular articles published about biological invasions, with the focus on educating different people (including school children) on what biological invasions are, their impacts and management. Studies in South Africa have shown that improving public awareness promotes acceptance of the management of biological invasions. Byrne et al. (2020), Novoa et al. (2017) D6 … citizen science … There are numerous citizen science and volunteering initiatives in South Africa such as iNaturalist, SAPIA, SABAAP2, Bird Atlas, society programs (Botanical Society of South Africa) and others (e.g., local hack groups). D6 … and targeted investment in research innovation … Two large inter-institutional research institutes (the Centres for Invasion Biology and Biological Control) received significant governmental funding for many years, although this funding has dramatically declined in the past few years. Richardson et al. (2020a) D6 … and environmentally sound technology. Biological control of invasive plants has a substantial record with no major direct negative nontarget impacts recorded in South Africa. There has been no evaluation of the environmental impact of herbicides to date. Under some conditions, using helicopters to apply herbicides may be cost-effective. De Lange et al. (2022), Hill et al. (2020) 25/57 Paragraph Available information for RSA RSA References D6 Public engagement with citizen science platforms and community-driven eradication campaigns can raise awareness and contribute to actions that reduce the threat of invasive alien species. This can also be aligned with efforts to share efforts and commitment and understand the specific roles of all actors. There are numerous avenues to promote awareness and engagement such as the ARC Newsletter, information sheets, and the Invasives South Africa website (https://invasives.org.za/). iNaturalist and other online reporting programmes have grown in usage and South Africa has a relatively large global presence (e.g., in the BioBlitz and City Challenge). Hack groups are spreading awareness and promoting IAS control. From our experience, when people know that taxa are being controlled (e.g., as part of an eradication), people are very willing to help identify new infestations. Byrne et al. (2020), Jubase et al. (2021a) D6 Communication strategies based on evidence can help to bring about community action on biological invasions by supporting the codesign of management actions, knowledge exchange and enhanced partnerships among stakeholders. Various working groups are in place based on particular taxa or regions (e.g., invasive animals and Cactaceae). The link between research and communication projects could, nonetheless, be improved. Developing a comprehensive integrated communication strategy and facilitating comanagement should be included in the national strategy. Byrne et al. (2020), Davies et al. (2020a), Foxcroft et al. (2020), Novoa et al. (2016) D7 With sufficient resources, political will and long-term commitment, preventing and controlling invasive alien species are attainable goals that will yield significant long-term benefits for people and nature. The Working for Water Programme has been active since 1995. The funding has not been sufficient to bring plant invasions in South Africa down to maintenance levels, but nonetheless substantial progress has been made, without which the situation would undoubtedly be much worse. Monetary estimates suggest control is feasible, and in a few cases of biological control extremely financially attractive. McConnachie et al. (2003), McCullochJones et al. (2024), Van Wilgen et al. (2022a) D7 Increasing the availability and accessibility of information and means of implementation and addressing major knowledge gaps on biological invasions, particularly in developing countries, would result in more robust and effective policy instruments and management actions. There is often a close working relationship between scientific and governmental institutions in South Africa. Knowledge can be critical to inform effective policy although issues with researchimplementation gaps still exist. There is a need to mobilise various information sources making them broadly available, including risk analyses, factsheets on invasive species, supporting the website ‘Invasive Species South Africa’ and various pamphlets and out-reach material. Various initiatives are underway to develop data pipelines including through the South African status report. Esler et al. (2010), Zengeya and Wilson (2023) 32/57 Objective Management action Availability Ease of use Effectiveness Notes References RSA Global RSA Global RSA Global Containment and control Chemical control ** *–*** ** ** *–*** ** Effective registered herbicides are available for many but not all invasive plants. Piscicides (Rotenone) have been effectively used locally. Insecticides are often used to control agricultural pests and manage household pests such as ants, cockroaches , and houseflies. Competency requires training and experience. The registration of herbicides for a particular target can be very cumbersome and there is often no commercial incentive to acquire registration. The Biodiversity Stewardship Programme (national and provincial) sometimes offer complimentary herbicides to participating landowners as an incentive to engage with the programme and secure properties for conservation. Effective control has been achieved in some places, but the cost of widespread application of chemicals is high and can have significant non -target impacts. A better system for accounting of chemical usage and impacts is needed. Bellingan et al. (2019), Prinsloo and Uys (2015), Weyl et al. (2013) Containment and control Biological control *** *** *–*** ** *** *** South Africa is a world-leader in biocontrol. Various quarantine, research and mass -rearing facilities are in place. There is a well-regulated system to review proposed biological control releases. Already released agents often self -disperse and form self-sustaining populations (requiring no additional intervention). In other situations, periodic re -introductions might require mass rearing (requiring some technical expertise). Developing and testing new biological control agents, however, requires substantial technical and research expertise and facilities. 46 alien plant species are under effective or permanent biological control. Many agricultural pests are also effectively managed using biological control. Hill et al. (2020), Ivey et al. (2021) 33/57 Objective Management action Availability Ease of use Effectiveness Notes References RSA Global RSA Global RSA Global Containment and control Adaptive management * *–** *–** * * *–*** Adaptive management is only really practised in some protected areas as it r equires capacity, monitoring, and that organisations can be responsive (e.g., by having flexible budgets). More adaptative management could lead to significant improvements if more widely used in South Africa. Foxcroft and McGeoch (2011) Ecosystem restoration Adaptive management *–** *–*** *–*** * *–*** *–*** Significant contributions through research have been made to the theory and practice of restoration ecology and local guidelines for ecological restoration have been developed for numerous situations. Restoration often requires careful planning, goal setting and monitoring to be effective. There are few qualified restoration ecologists and certified practitioners relative to the demand. There has been limited uptake in implementing active restoration projects at larger scales. Restoration efforts, particularly active restoration, remain limited to local scales (often localised to some protected areas), i.e., the scale of restoration is low compared to the scale of the problem. Effectiveness is reliant on capacity, cost and scale. In some cases, few interventions are needed – the system recovers with passive restoration – in other cases even drastic action would be unlikely to bring about recovery to a pre -invaded state. In cases where active restoration is effective and financially feasible compared to passive restoration, the costs are sometimes deemed prohibitive, and co ntrol programmes rely on passive restoration even if it is inappropriate to do so. Gaertner et al. (2011, 2012a,b,c), Holmes et al. (2020) 34/57 Objective Management action Availability Ease of use Effectiveness Notes References RSA Global RSA Global RSA Global Public understanding Public engagement ** *** *–** *–** ? *** There are numerous educational campaigns (e.g., ‘Alien busters’), ‘ hacking days’ through volunteers that require minimal funding, and education through Working for Water that is increasingly drawing on co - developed management initiatives including various stakeholders. Various on -line resources are available (see above). Resources and capacity are needed, as well as translation into othe r languages. Outcomes have rarely if ever been monitored so it is unclear what works. Byrne et al. (2020), Ivey et al. (2024), Murray (2005) 35/57 Supplement Table S4. Knowledge and data gaps identified in the IPBES IAS Assessment in the context of South Africa This is based on Table SPM.A1 of the IPBES IAS Assessment (IPBES 2023). Five categories were considered: very low, low, medium/intermediate, high, and very high. Seven types of gaps were identified (the following wording is taken verbatim from the IPBES IAS Assessment): 1. Gaps in biomes, units of analysis and species groups; 2. Regional gaps in data and knowledge; 3. Interoperable data for monitoring invasive alien species and effects of drivers of biodiversity change; 4. Gaps in how invasive alien species affect nature’s contributions to people; 5. Management and policy approaches; 6. Gaps to fill to support the implementation of policy and management; and 7. Gaps in knowledge on invasive alien species of particular relevance to Indigenous Peoples and local communities. The focus is on mainland South Africa and the immediate offshore environment (including islands). Some gaps were combined where the responses were the same. At least during the plenary sessions, it was often found to be difficult to score the potential management gain and potential understanding gain, so we have little confidence that these are reliable estimates. Type Gap(s) Situation in South Africa and notes on value of improved knowledge Proposed actions for strategy Management gain Understanding gain 1 Incomplete or lack of inventories of invasive alien species in marine, tropical and Arctic ecosystems Marine surveys have taken place, but these are primarily in harbours, with less known about natural habitats. Tropical areas (a relatively small area of the country) are not specifically under-sampled in South Africa, in fact the alien taxa in the Kruger National Park are regularly inventoried. Arctic ecosystems are not found in mainland South Africa, though see Box 3 on the Prince Edward Islands. • Integrate data from citizen science into inventories for marine protected areas and other relevant databases. • Coordinate long-term monitoring and data curation concurrently with detection activities. High (marine) Low (tropical) NA (Arctic) Very High (marine) Low (tropical) NA (Arctic) 36/57 Type Gap(s) Situation in South Africa and notes on value of improved knowledge Proposed actions for strategy Management gain Understanding gain 1 Incomplete or lack of inventories of invasive alien microorganisms and invertebrates No systematic inventory of micro-organisms in part due to issues with biogeographic knowledge, but also as existing information has not been collated within the framework on biological invasions. There are various invertebrate lists, but there is significant under-sampling. The completeness of particular lists depends on the availability of relevant taxonomists and sampling. Biocontrol introductions are well documented and inventoried. Better knowledge would provide opportunities for eradication or control. • Integrate current data sources and database into current species list (e.g., the Foundational Biodiversity Information Programme). • Ensure molecular data and eDNA surveys are linked to ground truthing surveys and conventional sampling (in particular for studies on microorganisms). • Link foundational biodiversity data to lists of aliens. • Support foundational work by taxonomists. • Support general surveys targeting invertebrates and microorganisms. High Very High 1 Lack of understanding of the drivers of change that facilitate biological invasion for some animal groups (notably invertebrates), fungi and microbes Drivers of ecosystem change in terrestrial, freshwater and marine ecosystems are fairly well studied for some taxa (plants and vertebrates) but less so for fungi, microbes and invertebrates. There are gaps in our understanding of pathways for invertebrates, fungi and microbes; particularly accidental introductions. Deliberate introductions are much better understood. Better knowledge would enable risks to be estimated and mapped, and interventions to be targeted and become pro-active. • Map the drivers facilitating invasions and look at scenarios for how they might change in future, particularly around accidental introductions. • Explore how organisms move around the country (deliberately and accidentally). Very High Very High 37/57 Type Gap(s) Situation in South Africa and notes on value of improved knowledge Proposed actions for strategy Management gain Understanding gain 1 & 2 Lack of understanding and synthesis of the impacts of invasive alien microbes (1) & Incomplete data on the impacts of invasive alien species across Africa and Central Asia (2) There are few limited studies on the impacts of alien microbes. For example, recent studies have highlighted the impact of the polyphagous shot hole borer and its fungal symbiont, Fusarium euwallaceae. In general calls for greater interaction between microbiologists and invasion scientists have not been met. Improved impact assessment methodologies have aided in identifying highly impactful species in South Africa. There is ongoing development of frameworks and models assessing potential impacts and risks posed. Better knowledge would assist management but only if effective interventions are feasible. • Promote and fund studies that formally assess the impacts of alien species, especially underrepresented taxa such as microbes. • Test existing risk analysis and impact frameworks for their applicability to microbes (and develop new tools as needed). • Create working groups or points of interaction between pathologists, fungal biologists and those working on biological invasions. • Collate existing information in terms of biological invasions. • Develop pathway management strategies relating to high-risk microbes or implementation of contingency plans. • Institutionalise alerts through surveillance mechanisms. Very High Very High 38/57 Type Gap(s) Situation in South Africa and notes on value of improved knowledge Proposed actions for strategy Management gain Understanding gain 1 & 2 Poor understanding of drivers of change that facilitate biological invasions in aquatic and marine systems (1) & Comparative lack of understanding of the drivers of change that facilitate biological invasions in developing economies (2) & Lack of data and knowledge of the drivers of biological invasions in subSaharan Africa, tropical Asia and South America (2) Drivers of ecosystem change in terrestrial, freshwater, and marine ecosystems are fairly well studied but there are some gaps. Eutrophication and variation in water flow are well known to have impacts on aquatic weeds. The impact of plastic pollution on the marine environment (South Africa is a collector of plastics) is not known. Elevated dissolved CO2 levels is likely to affect aquatic plant growth. FBIS (https://freshwaterbiodiversity.org/) provides a baseline of species distribution, richness and abundance to enable an understanding of drivers in freshwater ecosystems. Better knowledge would enable risks to be estimated and mapped, and interventions to be targeted and become pro-active. • Fund research into how the impacts of biological invasions interact with other drivers of global change. Very High Very High 39/57 Type Gap(s) Situation in South Africa and notes on value of improved knowledge Proposed actions for strategy Management gain Understanding gain 1 Lack of data on successful restoration attempts in terrestrial and marine systems South Africa has been a leading country in the science of restoration of invaded habitats in riparian and terrestrial ecosystems. Such studies need long-term monitoring of restoration success post invader removal. Some specific active restoration projects have been well documented. The Working for Water Programme has substantial clearing activities, but it is not designed specifically for restoration (largely relying on passive restoration). Nothing has been done in marine systems as uncertainties are too high. As eradication is not feasible, removal and ensuing restoration would need to be ongoing, making it costly. Better knowledge would allow for adaptive management. • Develop tools [e.g., the ‘Management Unit Clear Plan’ (MUCP)] to track clearing activities and expand these to explicitly include restoration. • Ensure data on the costs, the spatial coverage of work, and volunteer and paid work hours are captured and made available, so methods are transferable. • Upscale the restoration component of management projects. • Develop indicators to track ecosystem recovery and incorporate those into evaluations of the outcome of interventions. High High 2 Comparatively incomplete inventories of invasive alien species in Africa and Central Asia South Africa has reliable estimates of invasive mammals, plants, birds, and freshwater fishes but not of other taxa. Knowledge in neighbouring countries tends to be a lot less than in South Africa. Better knowledge is foundational for regulations and the prioritisation of interventions. • Curate and regularly update inventories. • Formalise processes and workflows for adding or removing species from national inventories. • Collaborate with neighbouring countries to improve data flow. Very High Very High 40/57 Type Gap(s) Situation in South Africa and notes on value of improved knowledge Proposed actions for strategy Management gain Understanding gain 3 Lack of standardization of terminology for invasive alien species monitoring South Africa has terminology set out in regulations and national syntheses (see Box 1 of the paper). The understanding of mandates can be affected by views on terminology belonging to a particular discipline (e.g., pests are agriculture, invasives are biodiversity, emerging infectious diseases are health), potentially leading to a disconnect. • Align regulatory terms with terms used in the glossary in the South African status report and to those used in practice. • Where possible and desirable align terms to international standards. • Curate terms used in a single place. • Ensure terms are defined wherever used Medium Medium 3 Lack of information on the role of indirect drivers, especially governance and sociocultural drivers, in affecting biological invasions Various conflicts have arisen when all stakeholders are not considered, including through perverse incentives (e.g., a narrow focus on increasing tree cover can lead to the planting and spread of invasive trees). Better knowledge would allow for more integrated governance and likely facilitate management. • Incentivise interdisciplinary research (e.g., looking at causal loops and feedbacks). • Conduct a stakeholder mapping exercise. • Evaluate information on social media culture and ‘fashions’ as an indirect driver to assist with evaluating the degree to which alien species have been incorporated into tradition and culture. High High 3 Lack of understanding of the net effects of multiple interacting drivers in shaping and promoting biological invasions & Lack of knowledge on interactions and feedback across drivers in promoting invasions There is a realisation that interactions between drivers can be important, but few studies explicitly look at them (given how difficult such studies often are). Different governmental departments with different mandates and performance measures are not conducive to looking at interacting drivers. • Set up mechanisms to allow for crossdepartmental and cross-provincial alignment of strategies and monitoring efforts (integrated governance). • Utilise symposia to exchange ideas and promote cross-sectoral collaboration. Unknown (potentially very high if effective) Unknown 41/57 Type Gap(s) Situation in South Africa and notes on value of improved knowledge Proposed actions for strategy Management gain Understanding gain 4 Incomplete data on impacts on nature’s contributions to people and good quality of life While arguably South Africa is a leader in research on the topic, much more is needed. All impacts have been understudied. A handful of preliminary studies have evaluated impacts using the SEICAT framework. There are historical studies on the impact of invasions on ecosystems services, economics, and livelihoods. There are few collaborations between invasion scientists, social scientists, and economists in South Africa. Where this has happened, the papers have been highly cited and the research very impactful. Better knowledge would help demonstrate the impacts on nature’s contributions to people and good quality of life and likely be highly effective for prompting action. • Synthesise studies on the impact of biological invasions on South Africa and update the estimates where possible. • Set up methods to collect data & systematically monitor impacts on nature’s contribution to people and good quality of life. Very High Unknown 5 Lack of control options for marine invasive alien species and invasive alien microbial fungal pathogens of plants and animals There are very few control options in marine systems in South Africa (as globally), almost all are mechanical, very difficult, and often very dangerous. Some control techniques have been developed for fungal pathogens of plants, but only in a few cases. It seems unlikely that game-changing technologies will come along soon. • Piggyback on the development of novel technologies as they become available. • Interact with plant pathologists to explore control options. Very High Low 48/57 Type Gap(s) Situation in South Africa and notes on value of improved knowledge Proposed actions for strategy Management gain Understanding gain 7 Lack of consideration of the knowledge and perceptions of Indigenous Peoples and local communities in scenarios and models The ASSET project aimed to be inclusive in their approach to clearing and beneficiation exercises to support restoration activities (https://assetresearch.org.za/interactive-restorationmodels/). • Combine participatory mapping exercises to improve the inclusion of local communities in scenario planning and modelling exercises. 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