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Posted 25 February 2009

A Federal Government report released late last year has warned Australia needs to invest far more research, funding and public debate into the effects climate change will have on the country’s invasive species.

Written by Tim Low in his former role as a member of the Biological Diversity Advisory Committee, the report Climate Change & Invasive Species: A Review of Interactions warns that invasive species have received too little recognition in climate change discussions.

“They deserve more publicity, research effort, policy development and management, backed by more funding,” the report says.

Droughts, fires, cyclones and floods are well known to benefit weeds, which means that the predicted increases in extreme weather events will lead to a weedier world.

The report notes that extreme weather events promote invasions by “killing or weakening native species over vast areas, by aiding dispersal of pests, and often by providing a pulse of nutrients”.

One of the more obvious impacts is that many invasive species will increase their range or population densities – cane toads hopping further south, for example.

One of the country’s worst weeds, prickly acacia (Acacia nilotica), is likely to invade vast areas of inland Australia. Foxes, mice and weeds are already invading higher in the Australian Alps, where the foxes are endangering the mountain pygmy-possum.

Pathogens will thrive

Diseases are another concern. Higher temperatures or other climatic changes will increase the virulence and range of some pathogens.

Already chytrid fungus, an exotic pathogen, has been implicated in the first postulated climate change extinctions – 70 frog species wiped out in Central and South America. In Australia the pathogen may already be responsible for the extinction of eight frog species.

Weeds love carbon dioxide

Increased levels of carbon dioxide will benefit many weeds. More CO2 will increase the water efficiency of prickly acacia and rubber vine, allowing them to invade drier habitats.

Of major concern is that rising CO2 significantly reduces the effectiveness of glyphosate, the main herbicide used to control environmental weeds.

The report also documents how some native species will benefit from climate change and in turn harm other native species. For example, an invasive sea urchin (Centrostephanus rodgersi) has moved into Tasmanian waters and is creating vast barrens where kelp beds once flourished.

Download report
The full report Climate Change & Invasive Species: A Review of Interactions, can be downloaded from the Australian Government’s Department of the Environment, Water, Heritage and the Arts.