Pulchera Waterhole. Photo Matt Dell.
Bush Heritage Landscape Ecologist Phil Cullen explores the arid-zone ecology of the plants and animals of Ethabuka Reserve, Queensland.
Australia is often referred to as the driest continent on Earth. This is somewhat misleading. Antarctica actually receives the least amount of precipitation of any continent but, as run-off proceeds at a glacially slow pace, water is very evident in the landscape.
Galahs and wildflowers return to the Field River after rain. Photo Matt Dell.
Moreover, Australia has vast areas of arid lands and deserts but they're not as dry nor as barren as the Namib, Atacarma or parts of the Saharan deserts.
In fact, Australian deserts are some of the richest landscapes in the country for their diversity of animals and plants. Our recently acquired Ethabuka Reserve in far-western Queensland is a classic example of this.
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.
Murray Haseler with a centralian blue-tongue. Photo Matt Dell.
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.
Out in the grassland. Photo Matt Dell.
Many species don't 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've 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.
Sunset over Pulchera Waterhole. Photo Matt Dell.