Biodiversity threat spreading at record rate 

Gamba grass is one of the fastest moving plant invasions ever recorded 

An invasive species is moving across northern Australia at an unprecedented rate, carrying a fuel load that could cause catastrophic fires and pose a significant threat to the biodiversity of the NT.

New research has mapped the extent of the highly invasive gamba grass across the Top End and found the grass is one of the fastest moving plant invasions ever recorded. 

Charles Darwin University Research Institute for the Environment and Livelihoods research fellow Aaron Petty said the grass originally from Africa, was spreading across northern Australia at an alarming rate.

“The grass grows up to four metres high and produces large amounts of fuel that results in catastrophic fires,” Dr Petty said. “It threatens an irreversible decline in tree cover in tropical savannas, resulting in increases in carbon emissions and losses in biodiversity.

“We have mapped the extent of gamba grass in the NT, predicting the main pathways of its spread across the landscape and compared its current extent with historical records to show that it has spread across the landscape at a rate of over 500 metres per year.

“The grass is spreading predominantly along creek lines, where the soil is moister and has higher nutrients. In more established areas it has moved away from creeks and is spreading upland,” he said.

Dr Petty said in northern Australia gamba grass was currently limited in its extent to a relatively small proportion of the otherwise pristine tropical savannas. “However, given its speed and ability to spread virtually everywhere in the savanna, gamba grass poses a significant threat. We recommend careful monitoring and control along creeks to contain its further spread.”

This was a collaborative project between CDU and the Weed Management Branch of the Northern Territory Department of Natural Resources, the Environment, Arts and Sport.