DR Roger Lawes, a CSIRO scientist working with the CRC for
Australian Weed Management, and Dr Jeremy Wallace of CSIRO are
using images provided by the IKONOS satellite to map the spread of
prickly acacia ( Acacia nilotica ) across Australia’s
northern grasslands. From space, prickly acacia has a recognisable
‘signature’ that is picked up in satellite images.
“The images are so precise we can see the advance of prickly
acacias into the Mitchell grass country,” Dr Lawes said.
“This gives us a reliable indication of what is happening
over large areas. It can be used as an early warning system to
detect new invasions. If we detect a change in the index, we can
have a look on the ground and take the necessary steps to control
The technique can also be used to monitor other changes in
perennial vegetation across the landscape. The technology was
developed using a combination of remote sensing, ground surveys and
detailed data analysis. Ikonos has a one-metre pixel resolution and
anything larger than one square metre can be detected. Acacia trees
have a canopy of up to five metres, so individual trees are easy to
“This means that we can accurately count the number of
trees in a given paddock,” Dr Lawes said. For broader-scale
work, Landsat images are used with a 25 m pixel resolution. While
the project results are yet to be published, the software behind
the technique is available to interested parties.
Dr Roger Lawes, Weeds CRC, CSIRO SE
Tel: (07) 4753 8537, (07) 4753 8600
Peter Martin, Weeds CRC, Tel: (08) 8303 6693
CRC for Australian Weed Management
The Weeds CRC which closed its doors on June 30, 2008, and will be replaced by a $15 million National Weeds and Productivity Research Program. The website will no longer be updated after September 30, 2008. However, all of the Weeds CRC's resources are available for download and the site will remain online until approximately June 2010.