Invasives, aliens, exotics, indigenous – so what is all the fuss about?

2016-03-01 06:00
Marge Mitchell of Keep Hillcrest Beautiful.

Marge Mitchell of Keep Hillcrest Beautiful.

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THERE are 27 000 indigenous plant species in the country, and 9 000 exotic or alien species in South Africa.

Only 517 (some 6 percent) of the 9000 foreign plant species, in South Africa are deemed to be problem invader alien plants. (Ref. National Environmental Management: Biodiversity Act, 2004, NEM:BA).

Why they are a problem?

· Invasive Alien Plants (IAPs) are plants that have been introduced from other countries and which out-compete the indigenous species, and thereby threaten the biodiversity which attracts tourists to our country.

· IAPs have invaded 10 million hectares of South Africa or an area the size of KwaZulu-Natal. This is 10% of our available land.

· They are highly adaptable and don’t have the natural enemies, and therefore easily invade many ecological niches in their new homes, from rivers to mountain kloofs.

· IAPs reduce our ability to farm and they intensify flooding and fires.

· They cause erosion, destruction of rivers, siltation of dams and estuaries, and poor water quality.

· Aquatic invaders cover dams and lakes and block rivers.

· IAPs in South Africa use 7 percent of our water - which is about the same amount of water needed by humans to survive in South Africa.

· They grow fast and produce enormous amounts of seed, and they have deep or spreading root systems that are difficult to remove. This helps them to multiply quickly and makes them difficult and expensive to eradicate.

· Many are toxic to humans, birds and animals.

The laws against invasive alien plants

The National Environmental Management: Biodiversity Act [NEM:BA], [2004] has declared 379 plant species as being invasive, and 238 plants as being prohibited.

This list can be found in Government Gazette 37886 [August 2014.], and also at

Due to the problems caused by IAPs it makes sense that these destructive plants have been declared illegal.


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