Nature Notes - Sand Country
Australian deserts are surprisingly well vegetated despite the low, and highly unpredictable, rainfall. There are majestic Desert Oak (Allocasuarina decaisneana) trees, a wide range of wattles and other shrubs, and spectacular wildflowers. However, it is the spinifex (Triodia species) that dominates this habitat.
In fact, Spinifex grasslands are the single most extensive vegetation type in Australia, covering 22% of the continent. Spinifex thrives on the poorest, most arid soils Australia has to offer. It is Spinifex that has prevented our deserts from becoming a Sahara-like world of bare, shifting sand.
Spinifex roots go down a long way: approximately 3 meters. The roots develop from the same nodes as the shoots so each shoot has its own personal water supply. The spiky leaves contain a lot of silica which makes them stiff and rigid.
They’re tough and indigestible to all animals except termites. These tiny grazers are Australia’s equivalent of the Bison of North America. They thrive on the Spinifex litter. A grass that’s very poor in nitrogen and phosphorus poses no problems for them.
While nothing else seems to eat it, lots of things hide in it, especially lizards. The sand country is the land of lizards. Lizards reign supreme here and an abundance of termite prey is one of the reasons why. Lizards are Australia’s equivalent of the leopards, lions and cheetahs of Africa. Scientists have found that as you move to more fertile parts of the country, where other detritus feeders compete, termite abundance and diversity declines and so does the diversity of lizards.
After heavy rain this land of scurrying lizards can turn into a frenzy of leaping frogs. The same moisture that brings forth thousands of winged termites on their marriage flights causes’ small, but fat, burrowing frogs to emerge from their underground sleeping spots.
A food-web dominated by invertebrates has also encouraged the evolution of small insectivorous marsupials such as dunnarts, the mulgara and marsupial mole.
Compared to other habitats of Australia’s deserts, there has been very little non-Aboriginal settlement in the sand country. However, feral animals are now a significant problem. European rabbits, feral cats and red foxes have a devastating effect on native wildlife and the full impact of Arabian camels on the vegetation has yet to be determined. A century ago the Burrowing Bettong and Golden Bandicoot were very common mammals in the sand country. Both have now gone.
Another significant problem is the breakdown of traditional Aboriginal fire management. Long established patch burning in the cooler times of the year had produced a diverse habitat sustaining populations of marsupials such as mala, bandicoots and quolls that are now rare. Burning the Spinifex also encouraged the growth of a number of valued food plants such as the bush tomato (Solanum centrale).
Traditional fire management is now being reintroduced in some areas. However, unless it’s done on a more widespread basis and effective feral animal control programs are put in place, then biodiversity will continue to decline.
Compare with a Sonoran Desert habitat.
