Terrestrial invasive plants refer to plants that invade terrestrial ecosystems such as mountains forests, or landscapes. These plants are found in different growth forms - trees (pine, hakea, port jackson); shrubs (yellow bells, castor-oil plant, American bramble); herbs (spear thistle, Patterson’s curse, canna); spreading or flat-growing herbs (madagascar periwinkle, nasturtium, false strawberry); creepers or climbers (morning glory, english ivy, moth catcher) and succulents (prickly pear, sisal, torch cactus).
Terrestrial invasive plants have detrimental impacts on the areas they invade. Compared to other threats to biodiversity, invasive plants rank second only to habitat destruction. In fact, invasive species are a greater threat to native biodiversity than the combined effect of pollution, harvesting, and disease.
Landowners, including local municipalities such as the City of Cape Town are legally obliged to have control programmes in place to address the impacts caused by invasive species.
Different methods are used to control terrestrial invasive plants
The best results are obtained through a combination of two or more of the following control methods, generally referred to as "integrated control".
- Mechanical – using chainsaws or other machines to fell and cut down invader plants.
- Manual – hand-pulling of seedlings or cutting down smaller plants with hand tools.
- Herbicides – applying registered herbicides according to label instructions by suitably qualified herbicide applicators.
- Biological control – using natural enemies (herbivorous insects, mites or plant pathogens).
- Fire – this method can be used in two ways, either by burning an entire area or by burning stacks after an initial clearing.