Reduction Activity measures, to limit impacts on mean annual runoff, but this has
never been used to regulate invasions. Despite this limitation, invaded land in the
strategic surface water source areas can be made a priority for enforcement and for
investment aimed at maximising the water benefits. Prioritisation of areas where the
water gains are greatest (Forsyth et al. 2012) is being implemented by the Department of Environment, Forestry and Fisheries, with a new focus on strategic water
source areas (Nel et al. 2013; Le Maitre et al. 2018). The importance of prioritising
areas to optimise the gains from clearing, including water has been emphasised in a
recent assessment of the state of invasions, but there is still a legacy of projects that
were initiated in areas which were not optimal (van Wilgen and Wilson 2018). The
recently launched Cape Town Water Fund is targeting such areas (Stafford et al.
2019), but the Natural Resource Management programmes need to more actively
target such areas.
Recent work has found that public and private sector collaboration in the control
of invasive alien plants, and the productive use of the biomass could potentially
realise considerable benefits (Mudavanhu et al. 2017b). Clearing of Acacia saligna
(Port Jackson) for the production of wood polymer composites could potentially
more than offset the costs, while increasing runoff and/or groundwater recharge.
Similarly, a public-private partnership and cost-sharing model for the use of biomass
for bio-energy production on the Agulhas Plain could result in a net benefit (Stafford
and Blignaut 2017). The feasibility of this enterprise depends on the willingness of
participants to share the cost for invasive alien plant biomass supply; in this case the
bioenergy entrepreneur would invest ZAR154/green tonne and the government
ZAR246/green tonne. In both instances, the benefits reported exclude further downstream benefits such as that of the contribution to job creation, Gross Domestic
Product (GDP), and the benefits of skills development, the stimulation of rural
development, and helping to steer South Africa towards a more sustainable development path. If the potential water flow gains are used to guide the location of these
investments, factored in and realised, then such programmes could make a substantial contribution to water security.
15.9 Financial and Economic Impacts of Water Lost
Through Invasions
From a financial perspective, the opportunity cost of invasive alien plants are: (a) the
lost value of production due to a reduction in water resources, and (b) the increased
requirement for water supply augmentation schemes, and the earlier development of
such schemes. Economically speaking, the impacts of invasive alien plants are much
broader because they have an impact on ecosystem functioning, processes, biodiversity, and every aspect of human life and livelihood that depends on them and is
affected by them.
448
D. C. Le Maitre et al.
never been used to regulate invasions. Despite this limitation, invaded land in the
strategic surface water source areas can be made a priority for enforcement and for
investment aimed at maximising the water benefits. Prioritisation of areas where the
water gains are greatest (Forsyth et al. 2012) is being implemented by the Department of Environment, Forestry and Fisheries, with a new focus on strategic water
source areas (Nel et al. 2013; Le Maitre et al. 2018). The importance of prioritising
areas to optimise the gains from clearing, including water has been emphasised in a
recent assessment of the state of invasions, but there is still a legacy of projects that
were initiated in areas which were not optimal (van Wilgen and Wilson 2018). The
recently launched Cape Town Water Fund is targeting such areas (Stafford et al.
2019), but the Natural Resource Management programmes need to more actively
target such areas.
Recent work has found that public and private sector collaboration in the control
of invasive alien plants, and the productive use of the biomass could potentially
realise considerable benefits (Mudavanhu et al. 2017b). Clearing of Acacia saligna
(Port Jackson) for the production of wood polymer composites could potentially
more than offset the costs, while increasing runoff and/or groundwater recharge.
Similarly, a public-private partnership and cost-sharing model for the use of biomass
for bio-energy production on the Agulhas Plain could result in a net benefit (Stafford
and Blignaut 2017). The feasibility of this enterprise depends on the willingness of
participants to share the cost for invasive alien plant biomass supply; in this case the
bioenergy entrepreneur would invest ZAR154/green tonne and the government
ZAR246/green tonne. In both instances, the benefits reported exclude further downstream benefits such as that of the contribution to job creation, Gross Domestic
Product (GDP), and the benefits of skills development, the stimulation of rural
development, and helping to steer South Africa towards a more sustainable development path. If the potential water flow gains are used to guide the location of these
investments, factored in and realised, then such programmes could make a substantial contribution to water security.
15.9 Financial and Economic Impacts of Water Lost
Through Invasions
From a financial perspective, the opportunity cost of invasive alien plants are: (a) the
lost value of production due to a reduction in water resources, and (b) the increased
requirement for water supply augmentation schemes, and the earlier development of
such schemes. Economically speaking, the impacts of invasive alien plants are much
broader because they have an impact on ecosystem functioning, processes, biodiversity, and every aspect of human life and livelihood that depends on them and is
affected by them.
448
D. C. Le Maitre et al.