What are invasive alien species?

An invasive alien invader species is a species that is not from our country. They are called exotic, non-native or of foreign origin. This refers to any plant or animal species that has been introduced to South Africa from a different country.

The introduction of exotic species to countries or new areas has been happening for millenia. With the advent of global travel, ships carrying animals, food and people to different parts of the world have accelerated this. Over the past 500 years, there has been an explosion of Invasive Alien Species across the globe. A well documented consequence of this is the Small Pox pandemic that began spreading in the 6th century when increased trade with China and Korea took Smallpox to Japan. Historians have been able to trace the global spread of Smallpox to the growth of civilizations and exploration.

The rapid spread of COVId-19 and resulting global pandemic can be attributed to the planet being a GLobal Village with the movement of people across the globe nowadays being more than ever.

Invasive Alien plants and animals reach our shores from foreign countries through several mechanisms

• Some”hitch a ride”. The invasive alien species is present in food, other organic materials and the the clothing of people. These are unsuspectingly brought to a new country by a visitor. The TV series “Border Control” shows how serious countries like Australia are about keeping Invasive Aliens out of their country.
• People also “import” aliens on purpose. It is said that the weed Lantana was brought to South Africa and Kei Country by ladies who thought it was a pretty plant and cultivated it in their gardens.
• Many Alien Invasive plants have been introduced to countries on purpose for commercial use. A prominent example of this in South Africa is the deliberate introduction of pine and black wattle for commercial use.
• Some plants were introduced because they were erroneously thought to do a better job than the indigenous species. An example of this in the Eastern Cape is the introduction of Port Jackson to stabilise coastal dunes.

Why are Invasive Alien Species a problem?

Many Invasive Alien Species were introduced to South Africa for a purpose. These plants and animals were introduced without their natural predators, and when they ‘escaped’ into our natural habitats they began to threaten the natural plant and animal species.

According to Clive Brimelow, author of Problem plants and alien weeds in South Africa, “The spread of exotics or biological pollution, is one of the greatest threats to the earth’s biological diversity, and as a threat of extinction, bio-invasion may rank just behind habitat loss, which covers almost any physical disruption of existing habitats.

Invasive alien plants compete with natural vegetation for water and space, often out-competing natural vegetation. Without natural predators to keep their numbers in check, they reproduce and spread quickly. They often take up more water than the surroudning natural vegetation. The result of this is that more alien plants grow, and fewer indigenous plants are able to to grow. This results in a disrution and weakening of the ecosystem, with the indigenous animals no longer being able to rely on the plants they have evolve with over millenia for food also disappearing. The final result of this is a loss of biodiversity and a depletion of water resources.

The invasive plants often form dense stands of the same species,representing a high fuel load for veld fires. This unnaturally high fuel load leads to extremely hot veld fires, that in turn damage the structure of the soil.

What is being done about the problem?

The first efforts to control and eradicate invasive alien species in South Africa began with the fight to bring the prickly pear’s “scourge to agriculture” under control in the Eastern Cape, way back in 1906. Efforts to eradicate and control invasive alien species have been ongoing ever since. It is estimated that Invasive Alien Plants have become established in over 10 million hectares of land in South Africa, and control efforts cost the country more than R 600 million a year.

There is now legislation governing the introduction and control of invasive species in South Africa. The Department of Environmental Affairs manages Invasive Alien Species under the National Environment Biodiversity Act (NEMBA) 10 of 2004. This Act aims to provide the framework, norms and standards for the conservation, sustainable use, and equitable benefit-sharing of South Africa’s biological resources. Alien plants and animals are placed into three categories depending on the severity of their effect on the natural environment.