- They crowd out local species. They can be trees, shrubs or understory plants. Alien ginger lilies, for example, can invade undisturbed forest floors. Their dense network of rhizomes suppresses other growth.
- Aliens have unexpected and worrying effects on local fauna. One example: The sprawling shrub Lantana camara is spread in part by frugivorous birds. But a secretion from young lantana stems dries into sticky, hard deposits on bird’s feet, sometimes making the foot unusable. White-bellied sunbirds, Tawny-flanked prinias and Spectacled weavers are just a few species affected. In Kenya, the same plant threatens sable antelope habitat!
- Invasive tree species such as bugweed, wattle and gum are enormously thirsty and significantly decrease water run-off from catchment areas – a serious concern in a water-scarce country such as South Africa. In KwaZulu-Natal, alien invader plants use approximately 576 million m3 of water per annum more than the natural vegetation they have invaded and replaced.
Botanist Michele Hofmeyr and others are advising us as to what area-appropriate species to replant.
Researchers at the University of KwaZulu-Natal’s Forest Biodiversity Research Unit, School of Life Sciences are experimenting with alternative alien clearing methods at Ferncliffe Nature Reserve. For bugweed, a particular scourge, it appears that thinning the infestation (to allow the remaining canopy to protect any emerging indigenous trees) may be more effective than clear-cutting. Thinned bugweed provides a sheltering canopy below which indigenous trees can re-establish themselves – unlike sun-baked earth, or within the scrum of creepers and vegetation that swamps disturbed earth. Bugweed also doesn’t live very long, and indigenous forest trees will overtake them within 20-odd years. This theory, first suggested by respected forest ecologist Coert Geldenhuys, is now being tested in a long-term study in the Reserve.
We hand-pull or dig up smaller plants wherever possible, and ringbark larger trees, with continuous follow-up to strip new growth.
Different plants require different clearing methods (just as plants in different biomes may require different techniques). Many creeper and rhizome species require complete removal of the roots and tubers. We will adjust methods to species, and use advice and proven best practice methods – but remain open to new rewilding techniques and methodology.
We avoid chemicals. If forced to, we’ll use herbicides recommended by environmental scientists and local conservation organisations.
In South Africa, yes. We are registered as a Public Benefit Organisation, number 93 007 2645, and can issue Section 18A tax certificates on request. (As of 30 September 2021.)
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