THE ability of microscopic plants to increase soil carbon and nitrogen levels may hold the secret for land managers in Australia’s arid landscape to benefit from bio-sequestration, according to rangeland ecologist Wendy Williams of the University of Queensland.

It is good news for producers who graze livestock on the arid or semi arid rangelands – regions with less than 500mm of rainfall – which form more than 70 percent of Australia’s landscape.

“Simple, microscopic plants grow on the soil surface of these areas, generally forming large masses or colonies which are visible on bare soil between plants or on rocks,” Ms Williams said.

“These single-celled micro-organisms were once called ‘terrestrial blue green algae’ and are now more correctly known as cyanobacteria, and well-managed grazing practices can encourage cyanobacterial soil crusts to thrive within their natural environment.”

Ms Williams explained that through the process of photosynthesis, cyanobacteria utilises carbon dioxide and converts it into biomass while replacing oxygen back into the atmosphere.

They thrive in harsh environments ranging from the Antarctic to hot deserts and rock surfaces where temperatures exceed 70 deg C.

“Ancient cyanobacteria were so productive that they changed earth’s atmosphere from a CO2-rich state to the oxygenated atmosphere that supports life as we know it today,” she said.

“Recent research on a global scale shows cyanobacterial soil and rock crusts account for significant amounts of net terrestrial carbon and more than 40 percent of biologically fixed nitrogen.

“This nitrogen is in a form immediately available to plants and is crucial to carbon capture.

“Increasing the terrestrial carbon sink can be tricky, as Australia has limited water and nutrients, however, place cyanobacteria in the picture and the situation appears much more favourable.

“Cyanobacteria are a natural asset in the Australian landscape and in that context are freely available to be used for our benefit – for example, Queensland has abundant cyanobacterial crusts on soil and rocks across the Mulga lands, Channel Country, Gulf Plains and Cape York.


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