the animals they support have been complicit in the success of many alien species.
Refinement of rangeland management in order to suppress or contain invasive alien
plants deserves closer attention. Withdrawal of fire, or an increase in fire-return
interval, appears to have been an important management action promoting woody
alien species in the fire-dependent Grassland and Savanna Biomes. The effect of
chronic grazing on the availability of fuel, especially in communal areas, has
contributed to increased fire-return intervals. Appropriate resting and burning
programmes should be adopted, which would further serve to suppress native bush
(O’Connor et al. 2014). Fire exclusion, not uncommon with commercial producers,
will lead to invasion by alien woody species into savanna and grassland. Management options in the Karoo biomes, Albany Thicket, or riparian habitats, which are
not prone to fire, are limited because grazing management has less of an effect on the
success of alien species, although critical study awaits. Heavy grazing intensity
apparently promotes invasive alien plants. Effective seed dispersal of certain
woody species by livestock can be reduced by appropriate management of their
movement; palatable alien species may be contained by stocking with additional
herbivore species. Rangelands, on account of covering >70% of South Africa and
influencing the delivery of the bulk of the country’s ecosystem services, warrant
closer investigation of the manner in which management can be refined in order to
contain invasive alien plants.
The large archive of phytosociological data in South Africa awaits analysis for
defining the effect of land tenure and environment on the richness and abundance of
alien plants.
No panacea for preventing further increases in invasive alien plants has been
unearthed. Rather, a diversity of alien species displaying a wide range in their
invasion dynamics demands further innovative response to identify economically
sustainable means of preventing or limiting their increase. Biocontrol has been
successful in some cases, but the sheer number of invasive alien species militates
against this avenue providing overall success. Achievements realised through
government-sponsored clearing have been noteworthy, but this approach will
require additional funding in order to maintain the current level of threat of treated
species.
Acknowledgements BvW acknowledges support from the DSI-NRF Centre for Invasion Biology
and the South African National Research Foundation (Grant 109467).
Electronic Supplementary Material
The online version of this chapter (https://doi.org/10.5281/zenodo.3560669) contains supplementary material, which is available to authorised users.
482
T. G. O’Connor and B. W. van Wilgen
Refinement of rangeland management in order to suppress or contain invasive alien
plants deserves closer attention. Withdrawal of fire, or an increase in fire-return
interval, appears to have been an important management action promoting woody
alien species in the fire-dependent Grassland and Savanna Biomes. The effect of
chronic grazing on the availability of fuel, especially in communal areas, has
contributed to increased fire-return intervals. Appropriate resting and burning
programmes should be adopted, which would further serve to suppress native bush
(O’Connor et al. 2014). Fire exclusion, not uncommon with commercial producers,
will lead to invasion by alien woody species into savanna and grassland. Management options in the Karoo biomes, Albany Thicket, or riparian habitats, which are
not prone to fire, are limited because grazing management has less of an effect on the
success of alien species, although critical study awaits. Heavy grazing intensity
apparently promotes invasive alien plants. Effective seed dispersal of certain
woody species by livestock can be reduced by appropriate management of their
movement; palatable alien species may be contained by stocking with additional
herbivore species. Rangelands, on account of covering >70% of South Africa and
influencing the delivery of the bulk of the country’s ecosystem services, warrant
closer investigation of the manner in which management can be refined in order to
contain invasive alien plants.
The large archive of phytosociological data in South Africa awaits analysis for
defining the effect of land tenure and environment on the richness and abundance of
alien plants.
No panacea for preventing further increases in invasive alien plants has been
unearthed. Rather, a diversity of alien species displaying a wide range in their
invasion dynamics demands further innovative response to identify economically
sustainable means of preventing or limiting their increase. Biocontrol has been
successful in some cases, but the sheer number of invasive alien species militates
against this avenue providing overall success. Achievements realised through
government-sponsored clearing have been noteworthy, but this approach will
require additional funding in order to maintain the current level of threat of treated
species.
Acknowledgements BvW acknowledges support from the DSI-NRF Centre for Invasion Biology
and the South African National Research Foundation (Grant 109467).
Electronic Supplementary Material
The online version of this chapter (https://doi.org/10.5281/zenodo.3560669) contains supplementary material, which is available to authorised users.
482
T. G. O’Connor and B. W. van Wilgen