Ants act as bioindicators in Australian land project

Mining companies use ants to assess the health of their sites. For rehabilitated sites, changes in ant species on the treated sites are compared with those on undisturbed sites over a period of time. Rehabilitation is successful when there is no distinction between the ant communities of natural and treated sites.

At the Australian research institute CSIRO Dr Hoffmann also studies how ants respond to land disturbance. “We sample ant communities and compare the total species richness, abundance of key species and community structures. There is no one simple thing to look for, rather a whole series of interrelated parts that tell a collective story about the health of the landscape.”

Healthy signs include normal proportions of ant types within a community. “A healthy ant community will have a full suite of ants from all functional groups,” Hoffmann explains. “A healthy environment will have many ant species, often over a hundred, with no overabundance of opportunistic or dominant species that are known to increase with disturbance. We also look for rare or specialised species.”

But when “weedy species” start to dominate the colonies, or there is a loss of species diversity or specialised groups, it’s time to re-assess the state of the land.

Dr Hoffmann is currently working with mining and grazing industries, studying ant communities on sites with specific management regimes. His work will cover rangeland management practices in northern Australia, where cattle grazing predominates. “Ants are rapidly being integrated into monitoring regimes throughout Australia,” says Hoffmann. “The work is now slowly extending into the US and Europe.”

Up to 20 million ants from 100 species live in any single hectare of the Australian bush, says Hoffmann. So will ants take over the planet one day? “Ants took over the planet millions of years ago,” laughs Hoffmann. “They’ll still be here long after we’ve gone. If anyone disputes their dominance, just check how many Australians don’t have ants in their house – the answer is none!”