Invasive alien plant species (IAP)

April 2017

A great deal of South Africa's water is used by plants that do not belong here. They are called invasive alien plants. These plants are invasive because they spread and displace our natural trees and plants.

Invasive alien plant species (IAP) are species whose introduction and/or spread outside their natural distribution threaten biological diversity. They are non-native to an ecosystem, and may cause economic or environmental harm. They impact negatively on biodiversity, including decline or elimination of indigenous species – through competition for water and the disruption of local ecosystems and ecosystem functions. IAPs, introduced and/or spread outside their natural habitats, have affected natural biodiversity in almost every ecosystem type on earth and are one of the greatest threats to biodiversity.

Without natural enemies, these plants reproduce and spread quickly, taking valuable water and space from our indigenous plants. Many alien plants consume more water than local plants, depleting our valuable water resources. Thick alien vegetation can also provide fuel for veldfires, making them exceptionally hot, which damages the burnt areas soil structure. IAPs cost South Africa tens of billions of rand annually in lost agricultural productivity and resources spent on removing or managing them. IAPs are a major threat to biodiversity in catchment areas, potentially disrupting the delicate natural balance in ecosystems. As we depend on biodiversity for water, food, wood, clean air, medicine and much more, it is vitally important that we protect this resource.

The regulations identify a total of 559 alien species, including 383 plant species as invasive in four different categories, and a further 560 species listed as prohibited and may not be introduced into the country. Visit https:// www.environment.co.za for a list of AIPs and their categories.

AIP categories

• Category 1a and 1b: Must be removed and destroyed immediately.
• Category 2: May be grown if a permit is obtained and the land owner ensures that the invasive species do not spread beyond his/ her property.
• Category 3: May not be planted.

It is interesting to note that some invasive plants are categorised differently in different provinces.

Alien vegetation management
There are a number of ways to control the growth and spread of alien invasive plants. The ‘treatment’ would depend on the species being controlled.

Biological
Some alien plants have natural enemies, such as insects and diseases that only affect a specific species. The controlling agents (beetles, viruses) are sourced from the country of origin and released here among an invasive species to control it.

Manual
Young or small invaders can be manually removed from the soil. The plants should be stacked and disposed of responsibly to prevent regrowth.

Mechanical
Larger plants and trees can be chopped or cut down. Trees can also be killed by removing a 30 cm - 40 cm strip of bark around their trunks (known as ‘ring-barking’). This prevents food going to the leaves and kills the tree.

Chemical
Two or more methods can be used at the same time e.g. ring-barking and then spraying herbicides on the stump.

How can you help?

• Learn how to identify, control and remove invasive alien plants.
• Educate others.
• Join or form a hacking team to control alien plants in your area.
• Remove the IAPs when they are still small.
• Replace alien plants with indigenous ones.
• Plant indigenous, water-wise plants in your garden.

IAPs and the law
The task of managing alien vegetation lies mainly with landowners. In August 2014, the Minister of Environmental Affairs published the ‘Alien and Invasive Species Regulations’ to limit the negative effects of IAPs. The regulations call on landowners and sellers of land to assist the Department of Environmental Affairs to conserve our indigenous fauna and to foster sustainable use of our land.

Non adherence can result in a criminal offence punishable by a fine of up to five million rand (ten million if a second offense) and or a period of imprisonment of up to ten years.

Top 5 IAPs per province

• Gauteng: Balloon vine, Black wattle, Bloodberry, Bugweed, Castor oil plant.
• KwaZulu-Natal: African tulip tree, Ash leafed maple, Baloon vine, Bloodberry, Bugweed.
• Limpopo: Black locust, Bugweed, Butterfly orchid tree, Castor oil plant, Kudzu vine.
• Mpumalanga: Coral creeper, Moth catcher, Yellow flowered Mexican poppy, Butterfly orchid tree, Camphor tree.
• Northern Cape: Blue leaf cactus, Castor oil plant, Chinese tamarisk, Common thorn apple, Giant reed.
• North West: Bird of paradise flower, Boxing glove cactus, Canary bird bush, Common dodder, Four o’clock.
• Western Cape: Rooikrans, Black wattle, Port Jackson, Silky hakea, Long leafed wattle.

Related websites

• Working for Water www.wfw.org.za.
• Environment www.environment.co.za.
• Invasive species South Africa www.invasives.org.za.

Article submitted by Ingrid Marti,Freelance Journalist. For more information, send an email to ingridmarti7@gmail.com.

Publication: April 2017

Section: Pula/Imvula