Research Projects Risk On Prized National Park From Invasive Weed
New research from The University of Western Australia and Charles Darwin University (CDU) has shown that the Top End’s iconic Litchfield National Park is under significant threat by the invasive weed gamba grass.
“We propose a new scenario where gamba grass is eradicated over a much larger area to better protect the significant values of the park.”
The research, published in the Journal of Environmental Management and funded by the National Environmental Science Program and the Northern Territory Government, predicts the invasive weed could cover almost a third of Litchfield National Park and threaten all popular visitor sites within a decade unless a major investment is made to control it.
Tackling gamba grass is identified as a priority in the federal government’s Threatened Species Action Plan. New Australian Government funding of $9.8 million is being directed to strategic gamba grass control in locations where it can be eradicated and contained, such as Kakadu National Park and Arnhem Land.
Given the outcomes of this new research, significant investments are also needed to address catastrophic and established infestations in areas managed by states and territories, such as Litchfield National Park.
Professor Samantha Setterfield, from UWA’s School of Agriculture and Environment, and CDU’s Dr Natalie Rossiter-Rachor conducted helicopter surveys of the park in 2014 and again in 2021–22.
These surveys showed the invasive weed had spread rapidly, covering 30,000 hectares of the 144,000-hectare park, making it the largest gamba grass infestation in a national park in Australia.
Without intervention, the researchers’ modelling showed that gamba grass would continue to rapidly spread in the park to more than 42,000 hectares, impacting all popular visitor sites, degrading habitats for threatened species and posing extreme risks for bushfires.
“We propose a new scenario where gamba grass is eradicated over a much larger area to better protect the significant values of the park, which is predicted to cost $6.6 million over five years,” Professor Setterfield said.
“Under this scenario, gamba would be kept away from most major visitor attractions.
“Litchfield contains significant environmental, cultural and social values and our research shows this it is at risk unless a major investment is made in weed control,” Dr Rossiter-Rachor said.
“The longer we wait to fund intensive management action, the more expensive it will become and the more impacts we’ll see to the park’s incredible biodiversity and stunning natural areas.”