Invasive weeds are one of the biggest threats to biodiversity in South Australia, and tackling weeds impacting native habitat is a vital part of our work at Trees For Life.
Preventing their spread is crucial, and requires coordinated efforts. Last year, Trees For Life lent our support to a nomination to list wild olives and buffel grass as Weeds of National Significance (WoNS). We are pleased that both these weeds have passed the initial review phase.
Listing as a Weed of National Significance helps deliver a nationally coordinated approach and improved research and resourcing to tackle their spread and impact. There are currently 32 WoNS, including African boxthorn and blackberry.
It is anticipated that new national weed priorities will be announced in late 2025.
So why are these weeds a problem?
Olives smother and compete with native species for space, water and nutrients, completely dominating the lower canopy and changing the vegetation structure. Its seed can be spread great distances by wildlife and it is a particular problem in our open grassy woodlands, including nationally threatened Grey Box (Eucalyptus microcarpa) Grassy Woodlands and Peppermint Box (Eucalyptus odorata) Grassy Woodlands.
Buffel grass poses extreme risks to habitat across most of South Australia if it is not contained. It is already recognised as the greatest invasive species threat to ecosystems and First Nations cultures across Australia’s arid lands, and is heading South – already spreading to semi-arid areas within South Australia. This highly invasive weed totally transforms landscapes, destroying habitats and dramatically increasing the intensity and frequency of fire.