The Department of Environmental Affairs recently published an updated National List of Alien and Invasive Species that includes 383 plants, 15 fish, 35 reptiles, 24 birds, seven amphibians (frogs and toads) and 41 mammals.

“The department has budgeted R200-million over the next three years to build up its capacity to regulate invasive alien species,” says Environmental Affairs Minister Edna Molewa.

“This is in addition to a R4.2-billion budget to control these species through the internationally renowned Working for Water Programme over the same period.

“The costs of controlling invasive alien species are very high. We need to prioritise our efforts to secure the greatest returns on investment. An obvious example would be the pine trees from Europe, Asia and North America that are invading our mountain catchments, and could have unaffordable consequences for water security, as they use far more water than the indigenous plants they displace,” she explains.

The new regulations are aimed at preventing the introduction of more species that may be potentially invasive into the country, as a first priority. This will entail monitoring of deliberate and accidental introduction of species through the airports, harbours, land borders and through the mail.

“Those wishing to bring species into the country will be required to have a risk assessment undertaken, to establish the potential harm from introducing the species into the country,” Molewa says.

Invasive alien species are species that have been introduced into an area, and are able to out-compete and displace indigenous or useful alien species. They may be plants, animals or microbes, including diseases, and are widely regarded as among the biggest threats to the productive use of land and water, to the ecological functioning of natural systems, to health and to the economy.

One of the worst 559 invasive species listed is famine weed (Parthenium hysterophorus), an inconspicuous plant from South America that has a small white flower that resembles florist’s gypsophila (Gypsophila paniculata), otherwise known as babies’ breath.

Famine weed has spread across northern KwaZulu-Natal and is now invading areas around Mbombela, Barberton and even Brits in Gauteng.

Seed is carried in the soil of trucks, and famine weed has the potential to invade all but the driest parts of South Africa, and most of Africa. Fields of famine weed, as the name implies, will wreak economic, ecological and health havoc.

“Neither South Africa’s stock nor game species can survive in these invaded areas. Crop production will be unaffordable. Allergies and skin lesions in humans will abound, and respiratory diseases will worsen. It is truly a Frankenstein plant, an unwanted and relentless gatecrasher in our country,” explains Dr Guy Preston, head of environmental programmes in the Environmental Affairs department.

South Africa has tens of thousands of alien species, most of which are not necessarily a problem. However, a relatively small percentage of these have become invasive.

The impact on biological diversity, while difficult to quantify in monetary terms, can be devastating. A research study by Professor Michael Samways of Stellenbosch University showed that the shading of water bodies by just one invasive alien plant, the black wattle (Acacia mearnsii), could cause the extinction of more than half of the dragonfly and damselfly species found only in South Africa.

Molewa says the most difficult category is the Category 2 species. A balanced approach has therefore been taken for species that have value. For example, many invasive gum (Eucalyptus) species from Australia have a very negative impact on water, biological diversity and in terms of wild fires. But they are also an excellent source of wood, shade, beauty and food for bees.

Another example would be the much-loved jacaranda tree (Jacaranda mimosifolia), from South America. While invasive in Mpumalanga, the tree is not listed in urban areas, and large specimens can be grown within 50 metres of farm homesteads.

“Jacarandas can continue to be grown as street trees and ornamental garden trees,” Molewa says.

She warns that invasive species rival climate change in terms of the potential consequences of their destructive tendencies.

“This is not a battle that government can win on its own. We need to work together with all stakeholders to combat the scourge of invasive species. These regulations, coupled with the investments made through the Working for Water programme, have the potential to reverse the cancer of invasions in our country,” she explains.

According to the International Union for the Conservation of Nature, invasive species are regarded as the second biggest cause of species extinction worldwide after habitat destruction. On islands such as Madagascar and the Hawaii group, they are by far the biggest cause of species extinction.