Invasive alien species (IAS) are recognised as one of the greatest threats to the ecological and economic wellbeing of the planet and are therefore a matter of global concern. Most of these plants and animals do not naturally belong in Cape Town.
Invasive species pose a very real threat to the economy and the unique biodiversity (variety of plant and animal life) in the city of Cape Town. The Cape metropole is located in the heart of the Cape Floristic Region – the smallest and most threatened of the world’s six plant kingdoms and also one of the world’s 34 biodiversity ‘hot spots’ (an area with a high number of indigenous species threatened with extinction). Six of the 19 vegetation types found within the City’s boundary are found nowhere else on earth and as such can only be conserved within the city of Cape Town. This makes Cape Town unique in comparison with many other cities of the world.
What are invasive alien species?
To understand the term invasive alien species, one needs to recognise that firstly, not all alien species are invasive and secondly, species indigenous to an area may also become invasive under suitable conditions. Invasive species refer to those organisms causing harm to or having a negative impact on the economy, environment or health in the area where they have been introduced.
The problem
Organisms from all taxonomic groups - animals (vertebrates and invertebrates), plants, viruses, micro-organisms and microbes have been moved around the world by human activities. It is sometimes better to refer to ‘introduced’ species for species occurring in areas outside their natural range. Species are either intentionally or unintentionally introduced to areas around the world. Species are intentionally introduced for specific purposes such as economic, aesthetic, agricultural or as pets. Examples of unintentional introductions are species that are translocated in packaging material, timber, produce, soil and plants.
Harmful invasive alien species compete with indigenous species for resources (i.e. water, food, space), or cause genetic contamination through interbreeding. Dense stands of invasive alien plants pose a fire risk and thereby threaten properties and livelihoods. The Conservation of Agricultural Resources Act, Act 43 of 1983 and the National Environmental Management: Biodiversity Act, Act 10 of 2004 places the onus on landowners to control invasive alien species on their land.
Strategies to manage invasive alien species
Invasive species are combated by a combination of strategies such as preventing introduction, detecting invasive species at an early stage and eradicating them before they become established, using a range of internationally accepted best practice methods. IAS management is complex and conflicts of interest exist in almost every case where alien species are deemed problematic. This complexity increases in an urban environment, requiring innovative approaches to ensure the threat of invasive species is managed in a sustainable manner.
Human activities, the availability of financial resources and biodiversity concerns are some of the complicating factors influencing the way in which IAS management is approached by the City of Cape Town. In 2008 the City of Cape Town adopted a strategic framework for combating invasive alien species within its boundary. This framework is aligned with the Cape Action for People and the Environment (C.A.P.E.) programme’s Invasive Alien Species Strategy and implementation occurs within the ambit of the C.A.P.E. programme.
Successful implementation of the City of Cape Town’s Invasive Alien Species Strategy will require co-operation between all stakeholders within the City’s boundary – government (national, provincial and local), NGOs, private landowners, residents and visitors.
Please explore the rest of our invasive species web pages:
For further information on the City's invasive species management, contact:
Ms Louise Stafford (Invasive Alien Species Co-ordinator)
Tel: +27 (0)21 712 1944 /1434
Fax: 086 578 0410 (RSA only)
E-mail: louise.stafford@capetown.gov.za
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