Invasive Weed Threatens Australia’s Northern Territory

Spread of gamba grass fuels massive wildfires—and need for government action

Invasive Weed Threatens Australia’s Northern Territory
Gamba grass
Gamba Grass can grow to 4 metres in height and replaces native vegetation across savanna landscapes.
John Woinarski

The extensive savanna woodlands of Australia’s Northern Territory are prime habitat for an array of native wildlife and a place of beauty and solitude for locals and visitors alike. But the region faces a severe threat: the spread of gamba grass—an invasive species that is fuelling intense bushfires and destroying natural habitats in the north of the territory, known locally as the Top End.

Gamba grass, native to African savannas, was introduced to the Top End in 1942 to feed cattle. But it wasn’t until the early 1980s that it was planted on a large scale to feed a growing number of livestock. The Territory Government initially hailed the grass as a huge success, but soon the invasive plant’s dangers came to light, and by the late 1990s it was clear that gamba grass was a major threat.

This highly invasive weed destroys and replaces savanna woodlands and has the potential to spread across millions of hectares of Northern Australia. Working with partners to prevent the spread of gamba forms part of The Pew Charitable Trusts’ efforts to secure a sustainable future for people and nature in Outback Australia.

Gamba grass is a declared weed under the Northern Territory Weeds Management Act, and Top End landholders like Andrew Spiers are working hard to eradicate it from their properties. Getting rid of these dangerous grasses has cost Spiers time, labour, and a great deal of money—and he’s not alone.

The NT Government has started to invest in efforts to stop the spread of this grass and reduce risks to life and property across the Top End by providing free herbicide to rural landholders. The government has also stepped up efforts to ensure compliance with weed management laws, working in partnership with local firefighters, but much more is needed. Without urgent action, experts predict that the landscapes of the Top End will be irreversibly changed within a few decades.

Following consultation with local stakeholders and experts, Pew has identified five priorities for action: increasing investment in community outreach; maintaining support for private landholders to manage the weed; improving gamba management on public land, including national parks; enhancing compliance and enforcement; and fostering collaboration between key agencies and stakeholders.

For these efforts to succeed, the scale of investment by the NT Government must be proportionate to the threat. Failure to contain the spread of gamba will result in ever increasing costs for fire control and weed management, accompanied by unacceptable threats to life and property and the loss of natural savanna landscapes across the Top End.

Pepe Clarke is a deputy director with The Pew Charitable Trusts’ Outback to Oceans program, and Mitch Hart is Pew’s Northern Territory manager working with the Gamba Grass Roots alliance.