Acting Minister of Environmental Affairs, Minister Derek Hanekom announces the release of the Status Report on Biological Invasions in South Africa

The Acting Minister of Environmental Affairs, Mr Derek Hanekom, has announced the release of the National Status Report on Biological Invasions in South Africa. He noted that “this report represents a milestone for the Republic of South Africa as it is the first comprehensive national-scale assessment of the status of biological invasions and their management anywhere in the world”.

The report will be followed by repeat assessments every three years.

The Status of Biological Invasions and their Management 2017, was compiled by a team of 37 editors and authors from 14 organisations, led by the South African National Biodiversity Institute (SANBI) in collaboration with the Department: Science and Technology (DST)National Research Foundation (NRF) Centre of Excellence for Invasion Biology (CIB) at Stellenbosch University.

The report is one of SANBI’s outputs for assessing the state of biodiversity in South Africa, says the Chair of the SANBI Board, Mrs Beryl Ferguson. It fulfils the legal requirement of the National Environmental Management: Biodiversity Act (NEM:BA, Act 10 of 2004), which stipulates that SANBI has to submit a report on the status of biological invasions, and the effectiveness of control measures and regulations, to the Minister of Environmental Affairs every three years.

Biological invasions pose an enormous threat to South Africa’s ecosystems and the services they deliver, such as clean water and air, and biodiversity. South Africa is among the few countries that have legislation specifically aimed at managing this problem. Dr Moshibudi Rampedi, the Chief Executive Officer (CEO) of SANBI noted further that “The economic damage caused by biological invasions has been estimated at billions of Rands per year, and the problem is growing rapidly as more alien species are introduced”.

The status report provides a framework for reporting on the status of biological invasions at a national level using a set of indicators. These indicators will serve as a baseline for assessing trends and for setting realistic management targets. They also highlight several important gaps in our ability to provide evidence to support decision-making.

The purpose of this Status Report

Policy and Strategy: The assessment should be used to inform policy and strategies relating to the management of biological invasions nationwide. Although this is obviously relevant to the biodiversity sector, other sectors are also impacted by biological invasions and this assessment should inform policies and strategies in sectors such as water, agriculture, health and social development.

Planning: This first report provides an assessment of the available information on biological invasions and should be used to prioritise the often limited resources for managing biological invasions, especially actions aimed at preventing their introduction and spread, managing established populations, and mitigating their impacts on ecosystems and people. It should be recognised that this first assessment has focused on identifying indicators and datasets that can inform planning initiatives while recognising that many of these datasets are currently not available or need to be strengthened for future assessments.

Research: the report should be used to identify research priorities. The assessment guides this in two ways, first by identifying those areas where critical questions remain to be answered and, second, by showing where data gaps exist in the evidence base required to inform planning and actions for the management of biological invasions.

Education: The assessment should be a key reference and educational product that can be used to build capacity regarding the understanding and management of biological invasions in South Africa.

Among the key findings on the status of Biological Invasions in South Africa are: 

  • 2 034 alien species have established populations outside of cultivation or captivity in South Africa. Most of these were deliberately introduced for agriculture, forestry, horticulture, mariculture, aquaculture and the pet trade. Other alien species arrived accidentally, as stowaways on ships and aircraft, or as contaminants in traded goods.
  • 775 of the 2 034 alien species with established populations are invasive. More than a hundred of these invasive species (107) have caused large negative impacts on the environment: they have reduced rangeland condition and carrying capacity, reduced surface water runoff and groundwater recharge, increased fire hazards, and eroded biodiversity.
  • 80 of the invasive species that cause severe impacts are terrestrial or freshwater plants, the worst culprits being black wattle, lantana, pine trees, gum trees, Port Jackson, rooikrans, hakea, mesquite, bugweed, cacti, syringa trees, triffid weed, poplar trees and weeping willow.
  • The remaining high impact invasive species comprise 8 mammals, 5 freshwater vertebrates (e.g. small-mouth bass), 5 terrestrial invertebrates (e.g. the common garden snail), one marine species (Mediterranean mussel), 2 amphibians and one bird (common myna).
  • Alien plants are the most diverse, widespread and damaging group of invaders in South Africa. Well over 100 new species have been recorded as naturalized or escaped from cultivation over the past decade, and the recorded ranges of almost all invasive plants has increased significantly over the past decade. A relatively small subset of these species has become particularly widespread and often problematic, and hundreds of millions of rands have been spent annually on attempts to control them. The main culprits are mesquite trees, several cacti, lantana, famine weed, triffid weed, Australian wattles, and pine trees.
  • The rate of introduction of species is increasing, in line with increases in travel and trade – the estimated rate of introduction currently stands at seven new species per year.
  • The Western Cape is the most invaded province, followed by Mpumalanga, Northern Cape and KwaZulu-Natal (KZN). Approximately 28% of the Western Cape was invaded by alien plants, with the most important being wattles, pines, and hakeas. Approximately 16% of the area of Mpumalanga was invaded by alien plants such as wattles, lantana and bugweed. Invasion in the Northern Cape is dominated by mesquite trees (14%). Nine percent of KZN is invaded by wattles, triffid weed, cacti and bugweed. Other provinces are estimated to have less than 3% cover by invasive alien plants. However, these estimates are more than 20 years out of date, and both the extent of invasions and the relative dominance of species have changed considerably since then.

Some of the main impacts of biological invasions include:

  • Invasive alien plants reduce surface water runoff by between 1 500 to 2 500 million cubic metres per year. This is equivalent to the capacity of the Jozini dam in KwaZulu-Natal. Primary catchments most affected are in the Western and Eastern Cape, and KwaZulu-Natal.
  • The reductions in water resources, if no remedial action is taken, are estimated to be between 2 600 million and 3 200 million cubic metres per year, about 50% higher than estimated current reductions.
  • The productivity of rangelands is under serious threat from a large number of invasive plants that could potentially halve the production of livestock from natural rangeland areas.
  • Alien plant invasions can change the structure and biomass of vegetation, adding fuel and increasing the severity of wildfires, making them more difficult to control and more destructive.
  • The unique plant biodiversity of the Fynbos biome is particularly at risk from invasive pines, hakeas and wattles.

The report notes that control measures introduced by government have been effective in some areas. Responding effectively to biological invasions requires integrated interventions that focus on different aspects of the invasions process, from steps to prevent the introduction of high risk species, to the detection and eradication of early phase invasives, and management of those that have spread. Government efforts have focused on biosecurity, early detection of emerging invasions, and programmes such as Working for Water (WfW), which have the dual objectives of job creation and the control of biological invasions. These programmes provide significant socio-economic benefits, while also managing invasive species.  Government efforts need to be strengthened in order to focus resources where they are most needed to deal with the growing problem of biological invasions.

Amongst the successes has been a programme of biological control research and implementation that has resulted in 15 of the 60 invasive plant species or taxa targeted for biological control thus far in South Africa now being under complete biological control. A further 19 species are under a substantial degree of biological control.

By combining biological and mechanical and chemical control, it has been possible to effectively reduce the populations of some of the most damaging invasive species, such as Hakea and Acacia species in the Western Cape, and for Lantana and Opuntia species in the Kruger National Park. The economic benefits of these interventions have been substantial, with estimated cost to benefit ratios indicating that, for every one rand invested into biological control, economic losses due to invasive alien plant invasions of between R8 and over R3000 have been avoided.

In savanna ecosystems, ongoing control has reduced the degree of invasion by a number of species in the Kruger National Park, and that of triffid weed in the Hluhluwe-iMfolozi Park in KZN.

While attempts to control invasive alien animals have been limited, feral cats have been eradicated from Marion Island, and potentially damaging house crows have been reduced to very low numbers in Cape Town and Durban.

The assessment concludes that it should be imperative to improve the management of biological invasions given the substantial economic and social consequences that would be associated with a failure to adequately address the problem.

See the key findings and main impacts of biological invasions.

Download the Report below:

Watch Dr Rahlao talking about the release of the National Status Report on Biological Invasions.

Video credit: eNCA

Dr Sebataolo Rahlao
Director: Invasive Monitoring and Reporting
Cell: 073 221 2379
Tel.: +27 21 799 8805

Professor John Donaldson
Chief Director: Biodiversity Research, Assessment and Monitoring
Cell: 082 718 3253
Tel.: +27 21 799 8672

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