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What is it that makes Australian deserts so different?
Rather than being consistently dry, our arid regions receive
highly variable and irregular annual rainfall. Droughts and
sudden rain events are a normal part of the climatic cycle.
Rain can occur anywhere on the continent in response to rain-bearing
depressions generated by tropical cyclones or by deep lows centred
in the Southern Ocean. As a consequence, the Australian deserts
are relatively well vegetated and support sizeable populations
of animals compared to many other deserts around the world.
Our unique animals and plants are well adapted to this highly
variable rainfall regime. The key to their success is their
ability to survive in the generally hot, dry conditions and
their capacity to respond rapidly following rain. Many desert
plants tend to be woody, long-lived and slow-growing. Many have
only a small number of leathery or fleshy leaves, which helps
them to retain moisture. Most are capable of rapid growth when
enough moisture is available, flowering and setting seed in
the space of a few weeks. Short-lived annuals are also common.
They survive from generation to generation by producing large
quantities of seed that can lie dormant in the soil for many
years.
These growth strategies ensure that the plant species survive.
The plants then provide a food resource for the highly adapted
desert animals during the often lengthy dry times. Many of the
less conspicuous animals in the food chain, such as termites,
are adapted to a diet of woody plant material rather than leaves
and, in turn, many of the mammals and reptiles are insectivorous.
Seed eating is also common amongst insects, mammals and birds.
Many species do not require drinking water but gain enough moisture
from what they eat. ‘Boom and bust’ breeding strategies
among animals, and their ability to disperse widely throughout
the landscape to take advantage of localised good conditions,
also help them survive.
A lot of what we understand about the desert ecosystems of arid
Australia comes from the studies of Sydney researcher Dr Chris
Dickman and his research team, who have been working on Ethabuka
for more than ten years. Over this period Ethabuka has been
a cattle station and we now have the opportunity to watch how
the landscape and its wildlife responds without the influence
of cattle grazing.
Matt Dell, Murray Haseler and I recently spent three weeks installing
a series of monitoring sites across the property to document
the expected recovery following rain. At present animal populations
are very low in response to the drought and a period of severe
overgrazing and wildfires that occurred before we purchased
the property. In many places vegetation is now extremely sparse
to almost non-existent.
During our research we were thrilled to discover areas where
localised thunderstorms had already begun the process of recovery.
The dune fields and the Field River in the far west are now
carpeted in wildflowers and abuzz with insects and birds. We
glimpsed the dormant vibrancy of the desert when Ethabuka received
about
10 mm of rain while we were there. Within a week, areas that
had been devoid of living vegetation were a carpet of sprouting
grasses and copper burrs. We can only speculate on the response
following drenching summer rains, which will return sooner or
later.
Our monitoring sites and the work of Chris Dickman and his team
will now document this exciting story of renewal. One thing
is certain! The resources created by this next good season will
remain in the desert and not be trucked away on the rumps of
fat cattle. Populations of native animals will explode and the
natural desert cycles will return to Ethabuka.
From top: Sunset over Pulchera Waterhole. Out
in the grassland.
Galahs and wildflowers return to the Field River after rain.
Murray Haseler with a centralian blue-tongue. Phil Cullen setting
up a monitoring point. Phil Cullen in a sea of grass on the
Field River. Wildflowers soon emerge after rain. PHOTOS:
MATT DELL
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