Chapter 17
An Evaluation of the Impacts of Alien
Species on Biodiversity in South Africa
Using Different Assessment Methods
Tsungai A. Zengeya , Sabrina Kumschick , Olaf L. F. Weyl ,
and Brian W. van Wilgen
Abstract Studies of the impact of alien species on the environment are increasingly
being carried out, and there has been ongoing debate about how to standardise the
description of these impacts. This chapter evaluates the state of knowledge on the
impacts of alien species on biodiversity in South Africa based on different assessment methods. Despite South Africa being one of the most biologically diverse
countries in the world, there have been very few studies that formally document the
impacts of alien species on biodiversity. Most of what is known is based on expert
opinion, and consequently the level of confidence in the estimates of the magnitude
of these impacts is low. However, it is clear that a significant number of alien species
cause major negative impacts, and that there is cause for serious concern. There is a
T. A. Zengeya (*)
South African National Biodiversity Institute, Kirstenbosch Research Centre, Cape Town,
South Africa
Centre for Invasion Biology, Department of Zoology and Entomology, University of Pretoria,
Pretoria, South Africa
e-mail: t.zengeya@sanbi.org.za
S. Kumschick
South African National Biodiversity Institute, Kirstenbosch Research Centre, Cape Town,
South Africa
Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University,
Stellenbosch, South Africa
O. L. F. Weyl
DSI-NRF South African Research Chair in Inland Fisheries and Freshwater Ecology,
South African Institute for Aquatic Biodiversity, Makhanda, South Africa
Centre for Invasion Biology, South African Institute for Aquatic Biodiversity, Makhanda,
South Africa
B. W. van Wilgen
Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University,
Stellenbosch, South Africa
© The Author(s) 2020
B. W. van Wilgen et al. (eds.), Biological Invasions in South Africa, Invading
Nature - Springer Series in Invasion Ecology 14,
https://doi.org/10.1007/978-3-030-32394-3_17
489
An Evaluation of the Impacts of Alien
Species on Biodiversity in South Africa
Using Different Assessment Methods
Tsungai A. Zengeya , Sabrina Kumschick , Olaf L. F. Weyl ,
and Brian W. van Wilgen
Abstract Studies of the impact of alien species on the environment are increasingly
being carried out, and there has been ongoing debate about how to standardise the
description of these impacts. This chapter evaluates the state of knowledge on the
impacts of alien species on biodiversity in South Africa based on different assessment methods. Despite South Africa being one of the most biologically diverse
countries in the world, there have been very few studies that formally document the
impacts of alien species on biodiversity. Most of what is known is based on expert
opinion, and consequently the level of confidence in the estimates of the magnitude
of these impacts is low. However, it is clear that a significant number of alien species
cause major negative impacts, and that there is cause for serious concern. There is a
T. A. Zengeya (*)
South African National Biodiversity Institute, Kirstenbosch Research Centre, Cape Town,
South Africa
Centre for Invasion Biology, Department of Zoology and Entomology, University of Pretoria,
Pretoria, South Africa
e-mail: t.zengeya@sanbi.org.za
S. Kumschick
South African National Biodiversity Institute, Kirstenbosch Research Centre, Cape Town,
South Africa
Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University,
Stellenbosch, South Africa
O. L. F. Weyl
DSI-NRF South African Research Chair in Inland Fisheries and Freshwater Ecology,
South African Institute for Aquatic Biodiversity, Makhanda, South Africa
Centre for Invasion Biology, South African Institute for Aquatic Biodiversity, Makhanda,
South Africa
B. W. van Wilgen
Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University,
Stellenbosch, South Africa
© The Author(s) 2020
B. W. van Wilgen et al. (eds.), Biological Invasions in South Africa, Invading
Nature - Springer Series in Invasion Ecology 14,
https://doi.org/10.1007/978-3-030-32394-3_17
489