Alien Invasive Plants: Impacting on South Africa’s biodiversity

Posted on 7 Sep 2021

The Department of Forestry, Fisheries and Environmental Affairs (DFFE) define Alien Invasive Plant species (AIPs) as plant species that are exotic, non-indigenous or non-native to an ecosystem that are either purposefully or accidentally brought into a country through anthropogenic means. Due to the absence of natural predators, these species are able to spread rapidly and outcompete native species for resources resulting in the population decline of native species.

 

According to the DFFE minister Barbara Creecy, AIPs are the third-largest threat to biodiversity in South Africa with only cultivation and land degradation being more devastating. An estimated yearly ecological loss of R6.5 billion is as a result of Alien invasive plants and animals in South Africa. This value was calculated by the effects alien invasive plants and animals have on ecosystem services and thereby affecting Water resources, grazing and agriculture. Furthermore, over R600 million is spent annually to clear over 10 million hectares.

 

In South Africa, the Alien and Invasive Species Regulations of the National Environmental Management: Biodiversity Act 10 of 2004 (NEMBA) regulates all invasive organisms in South Africa and categorizes them into four (4) categories:

 

CATEGORY 1A:

Invasive species requiring compulsory control. Any specimens of Category 1a listed species need, by law, to be controlled and maintained. No permits are required for having in possession or to exercise control over the species. No permit will be issued for restricted activities.

 

CATEGORY 1B:

 

Invasive species that are compulsory to contain the specimen, keeping it from spreading, if an Invasive Species Management Programme has been developed, a landowner must control it in accordance with it. No permits are required for having in possession or to exercise control over the species. No permit will be issued for restricted activities.

 

CATEGORY 2:

 

Invasive species requiring a permit to carry out restricted activities and is regulated by activities. A permit is required to import, possess, grow, breed, move/ relocate, sell, buy, or accept as a gift of any plants listed as Category 2 plants. No permits will be issued for Category 2 plants to exist outside of the specified land as indicated in the permit and will be treated as Category 1b.

 

CATEGORY 3:

 

Invasive species regulated by are or occurrence. Specimens are subject to exemptions and prohibitions. Species found in riparian areas will be considered Category 1b Listed Species. No permits are required for having in possession or to exercise control over the species. No permit will be issued for restricted activities.

 

A total of 383 plants species are considered to be Alien Invasive species in South Africa with some of the most threatening species being Acacia cyclops (Rooikrans), Acacia mearnsii (Black Wattle), and Acacia saligna (Port Jackson tree) (CapeNature, 2016).

 

AIPs not only change the species composition of an area but also affect the soil chemistry, alter surface roughness which can lead to flooding and erosion, as well as altering fire regimes. As a result of these secondary impacts, further biodiversity is lost. Therefore early detection and eradication of AIPs are of the utmost importance before significant damage to the native biodiversity takes place.

 

Control strategies for AIPs include Biological (the use of natural predators from the species’ country of origin), Manual (The physical removal of the individuals), and chemical (the use of pesticides and herbicides) however the application differ depending on the species being eradicated as well as budget.

 

ENVASS has a holistic approach to all matters pertaining to the environment and consequently, we ensure that every aspect impacting on the environment is taken into account. As part of our scientific approach to alien invasive species identification, mapping, control, and eradication – we include a biodiversity assessment on indigenous vegetation. Our clients are not charged extra for this as it can be done simultaneously with alien invasive surveying. Biodiversity assessments are important as part of an alien invasive management plan due to the threat posed by aliens to biodiversity. By knowing how species-diverse a particular site is, one can determine the significance of the threat by aliens and act accordingly.

 

CapeNature. (2016). Alien Vegetation Management. [online] Available at: http://www.capenature.co.za/care-for-nature/conservation-in-action/integrated-catchment-management/alien-vegetation-management/ [Accessed 6 September 2021].