and low biological diversity, reducing the number of potential competitors for space
and resources (Catford et al. 2012).
In this chapter, we focus on the role of terrestrial transportation systems, particularly railways, in dispersing stowaway fauna and flora and in facilitating the
natural dispersal of non-native species, i.e. the second and third mechanisms identified above. We start by providing a contextual overview of the impacts of invasive
species in a global context, in order to better familiarize readers with the significance
of the problem. We then focus on the role of railway traffic in transporting non-native
stowaway species and describe some of the best-known examples. Finally, we
discuss and provide examples of natural dispersal of non-native species along
transportation corridors and conclude by discussing some of the management actions
that could be taken to help reducing the spread of those species in railways.
Why Care about Invasive Species? An Overview
of Their Global-Scale Relevance
In natural environments, invasive species compete, predate and hybridize with
native species, and alter community structure and ecosystem processes, ultimately
leading to irreversible changes on the diversity and distribution of life on earth
(Simberloff et al. 2013; Capinha et al. 2015). Examples of mass extinctions precipitated by the introduction of non-native species include nearly every native bird
species on the Pacific island of Guam after the arrival of the invasive brown tree
snake (Boiga irregularis) (Wiles et al. 2003), or the extinction of more than 100
terrestrial gastropods due to the introduction of the predatory rosy wolf snail
(Euglandina rosea) in tropical oceanic islands worldwide (Régnier et al. 2009). The
Nile perch (Lates niloticus) is another paradigmatic example of the negative
impacts of invasive species on native species. In the 1950s, this predatory freshwater fish was intentionally introduced in Lake Victoria, Africa, to boost the lake’s
fish stocks, which were becoming severely overfished. In the decades after its
introduction, the Nile perch density grew massively leading to the extinction of
nearly 200 endemic species of cichlid fishes (Craig 1992).
The economic costs of invasive species can be striking. It is estimated that
invasive species can cost many billions of dollars in the USA and in Europe alone
(Pimentel et al. 2005; Davis 2009; Hulme 2009; Marbuah et al. 2014). For example,
Bradshaw et al. (2016) recently compiled a comprehensive database of economic
costs of invasive insects. Taking all reported goods and service estimates, according
to the authors’ study, invasive insects cost a minimum of US$70.0 billion per year
globally and the associated health costs exceed US$6.9 billion per year. These
values mainly reflect observable damages, such as those caused on other economically important species, e.g. the cinnamon fungus (Phytophthora cinnamomi)
on the sweet chestnut (Castanea sativa in Europe, and Castanea dentata in North
America) (Vettraino et al. 2005), or on man-made infrastructures and equipment,
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F. Ascensão and C. Capinha
and resources (Catford et al. 2012).
In this chapter, we focus on the role of terrestrial transportation systems, particularly railways, in dispersing stowaway fauna and flora and in facilitating the
natural dispersal of non-native species, i.e. the second and third mechanisms identified above. We start by providing a contextual overview of the impacts of invasive
species in a global context, in order to better familiarize readers with the significance
of the problem. We then focus on the role of railway traffic in transporting non-native
stowaway species and describe some of the best-known examples. Finally, we
discuss and provide examples of natural dispersal of non-native species along
transportation corridors and conclude by discussing some of the management actions
that could be taken to help reducing the spread of those species in railways.
Why Care about Invasive Species? An Overview
of Their Global-Scale Relevance
In natural environments, invasive species compete, predate and hybridize with
native species, and alter community structure and ecosystem processes, ultimately
leading to irreversible changes on the diversity and distribution of life on earth
(Simberloff et al. 2013; Capinha et al. 2015). Examples of mass extinctions precipitated by the introduction of non-native species include nearly every native bird
species on the Pacific island of Guam after the arrival of the invasive brown tree
snake (Boiga irregularis) (Wiles et al. 2003), or the extinction of more than 100
terrestrial gastropods due to the introduction of the predatory rosy wolf snail
(Euglandina rosea) in tropical oceanic islands worldwide (Régnier et al. 2009). The
Nile perch (Lates niloticus) is another paradigmatic example of the negative
impacts of invasive species on native species. In the 1950s, this predatory freshwater fish was intentionally introduced in Lake Victoria, Africa, to boost the lake’s
fish stocks, which were becoming severely overfished. In the decades after its
introduction, the Nile perch density grew massively leading to the extinction of
nearly 200 endemic species of cichlid fishes (Craig 1992).
The economic costs of invasive species can be striking. It is estimated that
invasive species can cost many billions of dollars in the USA and in Europe alone
(Pimentel et al. 2005; Davis 2009; Hulme 2009; Marbuah et al. 2014). For example,
Bradshaw et al. (2016) recently compiled a comprehensive database of economic
costs of invasive insects. Taking all reported goods and service estimates, according
to the authors’ study, invasive insects cost a minimum of US$70.0 billion per year
globally and the associated health costs exceed US$6.9 billion per year. These
values mainly reflect observable damages, such as those caused on other economically important species, e.g. the cinnamon fungus (Phytophthora cinnamomi)
on the sweet chestnut (Castanea sativa in Europe, and Castanea dentata in North
America) (Vettraino et al. 2005), or on man-made infrastructures and equipment,
68
F. Ascensão and C. Capinha