Australian scientists are developing a revolutionary way to
monitor changes in biodiversity across vast tracts of the continent
using satellites.
In research for the Desert Knowledge CRC, Dr Ken Clarke of the
University of Adelaide has helped pioneer a new way to watch over
biodiversity in the deserts – where some of the
nation’s gravest extinction rates occur – and study
what happens to it as the impacts of pests, human activity and
climate change build up.
“The first big challenge is that we don’t even know
what species we have in Australia; on-ground surveys are still
finding new plants and animals whose existence we never suspected.
If we don’t know what we have, how can we save it?” Ken
asks.
“I believe we have a duty to conserve our nation’s
biodiversity – including that which we don’t yet know
about. However, till now, this has been an unrealistic goal for the
rangelands, which cover 70 per cent of the continent. They are
simply too vast and there are too few people to cover them by
surveying small plots on the ground.”
One possible answer was to explore the use of satellites to
monitor not so much individual species but rather the overall
health and variety of desert ecosystems and vegetation, Ken
says.
“You can’t measure biodiversity as such from outer
space – but you can measure primary productivity (or plant
growth), which we know is dependent on the amount of water and
energy available to sustain species. We felt that if we could
understand what generates biodiversity in the first place, we could
then look for what was putting the sort of pressures on it that
cause extinction.”
Using the driest of the Australian deserts, the Stony Plains
country extending over 400,000 square kilometres between Spencer
Gulf in South Australia and the NT border as their
‘laboratory’, Ken and his colleagues began to amass
satellite data and link it to field observations of vegetation
condition to build up a picture of the primary productivity of the
region.
“Where you see vegetation failing to grow to the potential
which the local climate affords it, then you know it must be under
some sort of stress – for example from overgrazing by feral
or domesticated animals.”
The team has been using imagery from the MODIS sensor, flying on
two satellites called Terra and Aqua, which pass above Australia
every day. By monitoring the same areas of vegetation every two
weeks, Ken and colleagues have assembled an understanding of how
stressed the plants are, or how well they are doing on the energy
and water available to them.
“Our aim is to build a picture of where the pressure on
native Australian biodiversity is greatest. Then on-ground
investigation can establish the causes, so that the responsible
managers can take action.”
For example, it may be possible for pastoralists to reduce stock
numbers and restrict access to watering points to reduce grazing
pressure from both domestic and feral animals, so allowing
vegetation and other biodiversity to recover.
“Manipulating access to water is a powerful technique used
by pastoralists in desert regions to manage grazing pressure and
there is evidence pastoralism can help to improve biodiversity
values by grazing more strategically,” he adds.
Conservation and natural resources managers can also respond
with programs to control the large numbers of feral camels, goats,
rabbits and other introduced species threatening the desert
regions.
The use of satellites to monitor biodiversity is not without
scientific controversy. “Obviously you can’t see small
endangered animals from space – but there is quite good
evidence that the abundance of native animals is linked to the
health and diversity of the vegetation and, at a landscape scale,
that’s what you want.”
In one way, however, satellites have an advantage, Ken adds.
Even experienced biologists miss some of our more cryptic plants
and animals when they carry out a survey – so an on-ground
survey does not provide a true picture of local biodiversity.
However, ensuring the overall health of the vegetation at a
regional scale can go a long way towards protecting species we do
not even know are there, he says.
“Although we have only tested the concept in the Stony
Plains region, the initial results give confidence that we will be
able to develop satellite monitoring into a useful technique for
monitoring the health of Australian biodiversity, especially in the
desert regions.
“Given the major pressures which these regions face from
climate change, human activity, grazing and feral animals, it is
vital that we develop some sort of early warning system that will
enable us to take timely action if we see part of the landscape
suffering and signs of the loss of species richness.
“The Holy Grail of using satellites to do this isn’t
quite there yet, but we have made promising progress in developing
it to work as a new tool to help us better care for the enormous
expanse of the deserts which occupy almost three quarters of the
Australian landmass.”
More information:
Dr Ken Clarke, DKCRC and University of Adelaide, ph 08 8303 8112 or
0422 137 759
Kenneth.clarke@adelaide.edu.au
Jan Ferguson, Managing Director, DKCRC, 08 8959 6041 or 0401 719
882
Prof. Julian Cribb, DKCRC media, 0418 639 245
Images: http://www.desertknowledgecrc.com.au/news/media.html
