South Africa has over 3 500 alien species present outside of captivity or cultivation, at least a third of which are invasive (established but incomplete). New alien species arrive every year and those present in the country continue to spread and cause negative impacts. Better planning and monitoring are required to ensure effectiveness of interventions aimed at managing biological invasions for the benefit of biodiversity, people and the economy.
Since 2018, South Africa has detected around three new alien species per year. Invasive species continue to spread and are found throughout the country. The national survey of invasive plants showed that coverage of selected invasive species increased by 10.6% between 2008 and 2023. Recent estimates indicate that 17% of terrestrial ecosystem types show greater than 10% cover by invasive alien plants. Biological invasions contribute to the listing of 31% of threatened terrestrial ecosystems, and 36% of all threatened species.
Invasive alien species are having increasing impacts on nature, water security, people and the economy. Studies show that biological invasions use 3–5% of South Africa’s precious surface water runoff each year, which is a direct threat to water security in a water-scarce country. They also reduce the value of livestock production from natural rangelands by R340 million per year, impacting both food security and livelihoods.
Tsamaelo Malebu.png)
Knowledge of the distributions of alien plants has increased through the national survey, as well as through citizen science and the digitisation of historical records. Biological invasions have also been successfully managed in some cases, including through biological control, with positive returns on investment. Successful eradication includes the estuarine cordgrass (Sporobolus alterniflorus) from the Great Brak Estuary and the smallmouth bass (Micropterus dolomieu) from the Rondegat River. Prevention is crucial, through management of introduction pathways, particularly in marine systems where eradication is often unfeasible. Finalisation of the Ballast Water Management Bill is essential to preventing marine introductions. The establishment of the Border Management Authority aims to improve the prevention of illegal and accidental introductions. Management plans with clear goals and consistent monitoring will improve the effectiveness of invasive species control. Several global and national initiatives provide a framework for managing invasive species. These include the Kunming-Montreal Global Biodiversity Framework (Target 6) and the Invasive Alien Species Assessment of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. At a national level, South Africa is guided by the White Paper on the Conservation and Sustainable Use of South Africa’s Biodiversity and the draft National Invasive Species Strategy and Action Plan. With judicious investment and integrated governance, the impact of biological invasions on South African society can be reduced and any potential benefits researched and optimised.