economically viable, whereas the costs of fully restoring ecosystem structure,
functioning and composition in highly degraded ecosystems are rarely deemed
economically justifiable. Valuations of specific biodiversity components, such as
threatened ecosystems and species, remain problematic to assess, and these components could be under-valued in such studies. South African researchers have made
significant contributions to the theory and practice of restoration ecology globally
and have produced local guidelines for ecological restoration. However, there has
been limited uptake in implementing active restoration projects at larger scales. This
apparent knowing-doing gap may have three causes: firstly, insufficient
co-production by all stakeholders in planning restoration projects, including
prioritisation and goal setting; secondly, shifting beyond clearing invasive alien
species to restoring ecosystems; and thirdly, insufficient resources to implement
active restoration projects at the necessary scale. To achieve Convention on Biological Diversity and the UN Sustainable Development Goals, interventions must shift
from controlling invasive alien species alone to restoring native ecosystem structure
and functioning.
23.1 Introduction
Many invasive alien plant species in South Africa cause substantial ecosystem
changes, and are the focus of expensive management operations due to the perceived
negative impacts on ecosystem services and biodiversity (Richardson and van
Wilgen 2004; Gaertner et al. 2011; Le Maitre et al. 2011). Other main causes of
ecosystem degradation include over-grazing by livestock (Carrick and Krüger 2007)
and inappropriate fire regimes (Kraaij and van Wilgen 2014). These degrading
forces sometimes act synergistically, since alien plants may exploit recruitment
opportunities created by other drivers of vegetation change (Sher and Hyatt 1999).
Invasive alien plants may also disrupt ecological processes, for example resulting in
reduced palatable forage or altered fire regimes (Brooks et al. 2004). Such synergistic forces may further accelerate the loss of biodiversity and ecosystem services.
To reverse ecosystem degradation and control invasions, it is sometimes necessary to not only optimise control of the invasive alien species, but also to actively
restore the altered ecosystem. According to the Society for Ecological Restoration,
“Ecological restoration is the process of assisting the recovery of an ecosystem that
has been degraded, damaged or destroyed” (Clewell et al. 2004). This is generally
interpreted to mean implementing actions that will set an ecosystem on a trajectory
towards recovery. Managers therefore require a deep understanding of the ecosystems they manage, including the extent and intensity of change that has occurred, the
recovery potential of the native ecosystem and the interventions required to promote
recovery. Key questions include: “Will the ecosystem self-repair following removal
of the invasive alien species?”; “Which removal method best promotes natural
ecosystem recovery?” and, if the ecosystem is degraded beyond a state where selfrepair is likely, “Is active restoration feasible and affordable?”
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functioning and composition in highly degraded ecosystems are rarely deemed
economically justifiable. Valuations of specific biodiversity components, such as
threatened ecosystems and species, remain problematic to assess, and these components could be under-valued in such studies. South African researchers have made
significant contributions to the theory and practice of restoration ecology globally
and have produced local guidelines for ecological restoration. However, there has
been limited uptake in implementing active restoration projects at larger scales. This
apparent knowing-doing gap may have three causes: firstly, insufficient
co-production by all stakeholders in planning restoration projects, including
prioritisation and goal setting; secondly, shifting beyond clearing invasive alien
species to restoring ecosystems; and thirdly, insufficient resources to implement
active restoration projects at the necessary scale. To achieve Convention on Biological Diversity and the UN Sustainable Development Goals, interventions must shift
from controlling invasive alien species alone to restoring native ecosystem structure
and functioning.
23.1 Introduction
Many invasive alien plant species in South Africa cause substantial ecosystem
changes, and are the focus of expensive management operations due to the perceived
negative impacts on ecosystem services and biodiversity (Richardson and van
Wilgen 2004; Gaertner et al. 2011; Le Maitre et al. 2011). Other main causes of
ecosystem degradation include over-grazing by livestock (Carrick and Krüger 2007)
and inappropriate fire regimes (Kraaij and van Wilgen 2014). These degrading
forces sometimes act synergistically, since alien plants may exploit recruitment
opportunities created by other drivers of vegetation change (Sher and Hyatt 1999).
Invasive alien plants may also disrupt ecological processes, for example resulting in
reduced palatable forage or altered fire regimes (Brooks et al. 2004). Such synergistic forces may further accelerate the loss of biodiversity and ecosystem services.
To reverse ecosystem degradation and control invasions, it is sometimes necessary to not only optimise control of the invasive alien species, but also to actively
restore the altered ecosystem. According to the Society for Ecological Restoration,
“Ecological restoration is the process of assisting the recovery of an ecosystem that
has been degraded, damaged or destroyed” (Clewell et al. 2004). This is generally
interpreted to mean implementing actions that will set an ecosystem on a trajectory
towards recovery. Managers therefore require a deep understanding of the ecosystems they manage, including the extent and intensity of change that has occurred, the
recovery potential of the native ecosystem and the interventions required to promote
recovery. Key questions include: “Will the ecosystem self-repair following removal
of the invasive alien species?”; “Which removal method best promotes natural
ecosystem recovery?” and, if the ecosystem is degraded beyond a state where selfrepair is likely, “Is active restoration feasible and affordable?”
666
P. M. Holmes et al.