In 2017, the Centre for Biological Control (CBC) was established at Rhodes
University. The Centre builds on existing research collaborations and seeks to
sustainably control environmental and agricultural pests for the protection of ecosystems and the societies that depend on them, and to ensure that the maximum
benefits of biological control are realised through excellence in research, implementation and community engagement (van Wilgen 2020, Chap. 2).
Finally, in anticipation of the legal requirement to prepare a status report on
biological invasions in South Africa in 2017 (Box 1.2), the CÁIÁB and the
South African National Biodiversity Institute convened a 3-day symposium (at the
43rd National Symposium on Biological Invasions) to assemble information that
could be used in the status report. It was the first meeting to consider the full
spectrum of issues pertaining to the research and management of biological invasions across all taxa. This culminated in a special issue of a local journal (Wilson
et al. 2017) in which the status of introduction pathways, the status of taxa (plants
and animals) and their impacts, and the effectiveness of management were reviewed.
1.2 How Many Alien Species Are There in South Africa?
It is important to have an accurate picture of how many alien species have
established in the country, to know their status (sensu Richardson et al. 2011a;
Blackburn et al. 2011; Wilson et al. 2018), and to understand where they occur. Such
knowledge is necessary to underpin effective regulation, to prioritise species for
management, and to monitor their status. Lists are dynamic, subject to regular
change, and can differ greatly between curators. For example, Picker and Griffiths
(2017) documented that South Africa had 41 naturalised alien vertebrate species that
had their origins outside the geopolitical borders of the country. Van Wilgen and
Wilson (2018) included all alien vertebrate species, and so had a much higher
number (283), although they also provided a number of naturalised species as 45;
and in this book, Measey et al. (2020a) lists 30 terrestrial vertebrate species in
Chap. 5, and Weyl et al. 2020 lists 21 fish species in Chap. 6 (i.e. 51 naturalised
alien vertebrate species). These differences are partly attributable to differences in
definitions. In this book, we follow the scheme of Blackburn et al. (2011), and apply
the definitions of Richardson et al. (2011a). In brief, alien species are those that have
been moved over a natural geographic barrier, naturalised species are alien species
that have self-sustaining populations outside of captivity or cultivation over several
life-cycles, and invasive species are naturalised species that have dispersed and
formed new populations a considerable distance from the initial point of introduction. In large countries such as South Africa which have many biomes and a diversity
of climates, species can be both native and alien within the borders of the same
country. These species have been called “domestic exotics” (Guo and Ricklefs
2010), or “extra-limital species” (Foxcroft et al. 2017). Because they are shown as
native species in local guidebooks, they are sometimes ignored or not given the same
level of attention as species from other countries or regions. The number of species
for different taxonomic groups or habitats covered in this book are listed in Table 1.1;
1 Biological Invasions in South Africa: An Overview
19
University. The Centre builds on existing research collaborations and seeks to
sustainably control environmental and agricultural pests for the protection of ecosystems and the societies that depend on them, and to ensure that the maximum
benefits of biological control are realised through excellence in research, implementation and community engagement (van Wilgen 2020, Chap. 2).
Finally, in anticipation of the legal requirement to prepare a status report on
biological invasions in South Africa in 2017 (Box 1.2), the CÁIÁB and the
South African National Biodiversity Institute convened a 3-day symposium (at the
43rd National Symposium on Biological Invasions) to assemble information that
could be used in the status report. It was the first meeting to consider the full
spectrum of issues pertaining to the research and management of biological invasions across all taxa. This culminated in a special issue of a local journal (Wilson
et al. 2017) in which the status of introduction pathways, the status of taxa (plants
and animals) and their impacts, and the effectiveness of management were reviewed.
1.2 How Many Alien Species Are There in South Africa?
It is important to have an accurate picture of how many alien species have
established in the country, to know their status (sensu Richardson et al. 2011a;
Blackburn et al. 2011; Wilson et al. 2018), and to understand where they occur. Such
knowledge is necessary to underpin effective regulation, to prioritise species for
management, and to monitor their status. Lists are dynamic, subject to regular
change, and can differ greatly between curators. For example, Picker and Griffiths
(2017) documented that South Africa had 41 naturalised alien vertebrate species that
had their origins outside the geopolitical borders of the country. Van Wilgen and
Wilson (2018) included all alien vertebrate species, and so had a much higher
number (283), although they also provided a number of naturalised species as 45;
and in this book, Measey et al. (2020a) lists 30 terrestrial vertebrate species in
Chap. 5, and Weyl et al. 2020 lists 21 fish species in Chap. 6 (i.e. 51 naturalised
alien vertebrate species). These differences are partly attributable to differences in
definitions. In this book, we follow the scheme of Blackburn et al. (2011), and apply
the definitions of Richardson et al. (2011a). In brief, alien species are those that have
been moved over a natural geographic barrier, naturalised species are alien species
that have self-sustaining populations outside of captivity or cultivation over several
life-cycles, and invasive species are naturalised species that have dispersed and
formed new populations a considerable distance from the initial point of introduction. In large countries such as South Africa which have many biomes and a diversity
of climates, species can be both native and alien within the borders of the same
country. These species have been called “domestic exotics” (Guo and Ricklefs
2010), or “extra-limital species” (Foxcroft et al. 2017). Because they are shown as
native species in local guidebooks, they are sometimes ignored or not given the same
level of attention as species from other countries or regions. The number of species
for different taxonomic groups or habitats covered in this book are listed in Table 1.1;
1 Biological Invasions in South Africa: An Overview
19