country has had such a deluge of alien tree species, and South Africa can surely
claim the title of “tree invasion capital of the world” (Richardson et al. 2020b,
Chap. 3). But there is also a demand for South African species from other parts of the
world, as discussed by Pyšek et al. (2020), Chap. 26; and Measey et al. (2020b),
Chap. 27. Many South African grasses, which evolved adaptations to deal with
frequent fires and intense pressure from a diverse fauna of large mammals, have been
disseminated across the planet to create or supplement pastures and rangelands for
growing populations of domestic livestock (Driscoll et al. 2014). Many of these
grass species have become aggressive invaders with the capacity to transform
ecosystems (Visser et al. 2016; Linder et al. 2018).
1.1.4 A Rich and Varied Socio-political History
South Africa also has a unique socio-political landscape—the legacy of waves of
colonisation and migration, and decades of enforced separation of races during the
apartheid era. South Africa has eleven official languages (ten of which originated in
the country), and a range of other native languages spoken by the Khoisan. None of
these languages is spoken by more than a quarter of the population as a home
language (Fig. 1.1d), just one measure of the social diversity. There also has been,
and remains, a high degree of inequality between different segments of
South African society, often resulting in very different perceptions regarding the
relative value of, or harm done by, particular invasive species. As we were finalising
this chapter, in May 2019, the cover story of Time proclaimed South Africa “The
world’s most unequal country” (Baker 2019; see also Fig. 1.1d). Sharp gradients
between affluence and abject poverty in many parts of the country pose major sociopolitical and environmental challenges. The rich tapestry of biodiversity, a long
history of species introductions and invasions, and the complex social issues have
created a unique natural laboratory in which to study perceptions relating to benefits
and negative impacts due to alien species across diverse gradients (e.g. Kull et al.
2011 for Australian Acacia species).
1.1.5 A Long History of Managing and Regulating Biological
Invasions
For more than a century, considerable effort has gone into managing and regulating
invasive species in South Africa (Fig. 1.4), with varying degrees of success. This has
meant that the management of invasions has been relatively well studied, because
efforts to manage invasive species in natural areas began earlier than in most other
parts of the world. Where invasive species are clearly harmful, there has been general
agreement that they should be controlled, but in several cases the situation has not
been clear-cut. Species introduced for commercial or amenity value, (e.g. trees for
12
B. W. van Wilgen et al.
claim the title of “tree invasion capital of the world” (Richardson et al. 2020b,
Chap. 3). But there is also a demand for South African species from other parts of the
world, as discussed by Pyšek et al. (2020), Chap. 26; and Measey et al. (2020b),
Chap. 27. Many South African grasses, which evolved adaptations to deal with
frequent fires and intense pressure from a diverse fauna of large mammals, have been
disseminated across the planet to create or supplement pastures and rangelands for
growing populations of domestic livestock (Driscoll et al. 2014). Many of these
grass species have become aggressive invaders with the capacity to transform
ecosystems (Visser et al. 2016; Linder et al. 2018).
1.1.4 A Rich and Varied Socio-political History
South Africa also has a unique socio-political landscape—the legacy of waves of
colonisation and migration, and decades of enforced separation of races during the
apartheid era. South Africa has eleven official languages (ten of which originated in
the country), and a range of other native languages spoken by the Khoisan. None of
these languages is spoken by more than a quarter of the population as a home
language (Fig. 1.1d), just one measure of the social diversity. There also has been,
and remains, a high degree of inequality between different segments of
South African society, often resulting in very different perceptions regarding the
relative value of, or harm done by, particular invasive species. As we were finalising
this chapter, in May 2019, the cover story of Time proclaimed South Africa “The
world’s most unequal country” (Baker 2019; see also Fig. 1.1d). Sharp gradients
between affluence and abject poverty in many parts of the country pose major sociopolitical and environmental challenges. The rich tapestry of biodiversity, a long
history of species introductions and invasions, and the complex social issues have
created a unique natural laboratory in which to study perceptions relating to benefits
and negative impacts due to alien species across diverse gradients (e.g. Kull et al.
2011 for Australian Acacia species).
1.1.5 A Long History of Managing and Regulating Biological
Invasions
For more than a century, considerable effort has gone into managing and regulating
invasive species in South Africa (Fig. 1.4), with varying degrees of success. This has
meant that the management of invasions has been relatively well studied, because
efforts to manage invasive species in natural areas began earlier than in most other
parts of the world. Where invasive species are clearly harmful, there has been general
agreement that they should be controlled, but in several cases the situation has not
been clear-cut. Species introduced for commercial or amenity value, (e.g. trees for
12
B. W. van Wilgen et al.