Priority threat management in the Lake Eyre Basin

Endemic Mitchell grasslands are being converted to shrubland by the invasion of exotic invasive species like prickly acacia. (Photo by Jennifer Firn.)

Endemic Mitchell grasslands are being converted to shrubland by the invasion of exotic invasive species like prickly acacia. (Photo by Jennifer Firn.)

The Lake Eyre Basin in Central Australia is under pressure from multiple sources. Something needs to be done quickly but, as is often the case, environmental managers are operating under severe time and resource limitations, and are attempting to make decisions surrounded by enormous uncertainty. The threat that is really scaring environmental managers is the establishment and spread of exotic plants (as identified by the Lake Eyre Basin Rivers Assessment implementation plan).

Given that there are insufficient resources to manage all invasive plants species across this vast area, information on the ecological cost-effectiveness of different management strategies is critical. To help assemble this information, 22 experts in weed management, policy making, community engagement, biodiversity and natural values were brought together to prioritise invasive plant management strategies across the Lake Eyre Basin. The project resulted from a collaboration between the Queensland University of Technology and CSIRO (involving several NERP ED researchers) and was funded as a NERP emerging priorities project.

The experts identified the key invasive plants species threatening the natural values of ecosystems across the bioregions of the Lake Eyre Basin. They estimated the level of investment required and the likely benefit gained per dollar for each strategy. The expected biodiversity benefit of each strategy was estimated as the reduction in area that an invasive plant species is likely to dominate over a 50-year period, where dominance was defined as more than 30% coverage at a site.

Twelve strategies to manage invasive plants were agreed upon by the experts at a four-day workshop held in Brisbane in May, 2013. The strategies focused primarily on ten weeds which were considered to have a high potential for broad, significant impacts on natural ecosystems in the next 50 years and for which feasible management strategies could be defined. The total cost of the 12 strategies over the next 50 years was estimated at $1.7 billion. If implemented, it was estimated that these strategies would result in a reduction of invasive plant dominance by 17 million ha; representing a 32% reduction. That’s an area covering roughly 14% of the Lake Eyre Basin.

The risks of not undertaking these management strategies include the likely conversion of 14% of the entire basin to weed domination, and a high likelihood of the mound springs ecosystems being lost.

The top five most cost-effective strategies for the entire Lake Eyre Basin were for the management of: 1) Parkinsonia, 2) Chinee apple, 3) Mesquite, 4) rubber vine and 5) bellyache bush.


Reference

Firn J, TG Martin, B Walters, J Hayes, S Nicol, I Chades & J Carwardine (2013). Priority Threat Management of invasive plants species in the Lake Eyre Basin. CSIRO Climate Adaptation Flagship Working paper No. 17 (CSIRO and QUT).

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