21.2 Alien Plant Control Projects
Many conservation agencies at national and provincial level, private landowners,
volunteer “hack” groups, and NGOs have implemented alien plant control projects
(Fenn 1980; Attwell 1985; Macdonald et al. 1985; van Wilgen et al. 2017; van
Rensburg et al. 2017). However, monitoring data for these efforts were either not
available to us, or were never collected in the first place. This section therefore
provides a brief summary of the extent of alien plant control projects funded by the
WfW programme between 1995 and 2017, both because data are available, and
because WfW has provided the bulk of funding for alien plant control projects over
the past two decades.
Since 1995, WfW has spent ZAR 15 billion (unadjusted for inflation) on alien
plant control operations across South Africa. The amount spent per year has risen
exponentially since 2010, reaching around ZAR 2 billion per year in 2017
(Fig. 21.1a). During this time, WfW has cleared an average of about 200,000
condensed ha (Fig. 21.1c) per year, and conducted follow-up operations on about
600,000 ha per year (cleared areas are subjected to an average of three follow-up
operations over time). The apparent decrease in area treated since 2014 is due to a
relaxation of the requirement to record areas treated. This essentially means that
recent figures are underestimates. In terms of the species targeted, wattles received
more than three times the funding (ZAR 3.5 billion) than any other taxon
(Table 21.1). The other groups on which large amounts have been spent include
Lantana camara (Lantana), trees in the genera Prosopis and Eucalyptus, and
Chromolaena odorata (Triffid Weed) (Table 21.1). WfW has dual goals, which
require it to create employment and to clear invasive alien plants (van Wilgen and
Wannenburgh 2016); the programme has created between 2000 and 23,000 fulltime equivalent jobs per year.
Alien plant control operations funded by WfW are carried out by implementing
agents who often operate on adjacent land parcels owned or managed by different
agencies. Plant invasions, however, do not respect jurisdictional boundaries. To gain
control over invasions in any given area, it would therefore be necessary for
neighbouring landowners to collaborate closely with each other, and to co-ordinate
control efforts, which brings additional challenges. Box 21.1 profiles case studies
where alien plants are managed in large areas across several jurisdictions to illustrate
challenges and achievements.
21 The Extent and Effectiveness of Alien Plant Control Projects in South Africa
599
Many conservation agencies at national and provincial level, private landowners,
volunteer “hack” groups, and NGOs have implemented alien plant control projects
(Fenn 1980; Attwell 1985; Macdonald et al. 1985; van Wilgen et al. 2017; van
Rensburg et al. 2017). However, monitoring data for these efforts were either not
available to us, or were never collected in the first place. This section therefore
provides a brief summary of the extent of alien plant control projects funded by the
WfW programme between 1995 and 2017, both because data are available, and
because WfW has provided the bulk of funding for alien plant control projects over
the past two decades.
Since 1995, WfW has spent ZAR 15 billion (unadjusted for inflation) on alien
plant control operations across South Africa. The amount spent per year has risen
exponentially since 2010, reaching around ZAR 2 billion per year in 2017
(Fig. 21.1a). During this time, WfW has cleared an average of about 200,000
condensed ha (Fig. 21.1c) per year, and conducted follow-up operations on about
600,000 ha per year (cleared areas are subjected to an average of three follow-up
operations over time). The apparent decrease in area treated since 2014 is due to a
relaxation of the requirement to record areas treated. This essentially means that
recent figures are underestimates. In terms of the species targeted, wattles received
more than three times the funding (ZAR 3.5 billion) than any other taxon
(Table 21.1). The other groups on which large amounts have been spent include
Lantana camara (Lantana), trees in the genera Prosopis and Eucalyptus, and
Chromolaena odorata (Triffid Weed) (Table 21.1). WfW has dual goals, which
require it to create employment and to clear invasive alien plants (van Wilgen and
Wannenburgh 2016); the programme has created between 2000 and 23,000 fulltime equivalent jobs per year.
Alien plant control operations funded by WfW are carried out by implementing
agents who often operate on adjacent land parcels owned or managed by different
agencies. Plant invasions, however, do not respect jurisdictional boundaries. To gain
control over invasions in any given area, it would therefore be necessary for
neighbouring landowners to collaborate closely with each other, and to co-ordinate
control efforts, which brings additional challenges. Box 21.1 profiles case studies
where alien plants are managed in large areas across several jurisdictions to illustrate
challenges and achievements.
21 The Extent and Effectiveness of Alien Plant Control Projects in South Africa
599