Nature Notes - Ranges and Gorges

Central Australian ranges lie in some of the world’s driest country and yet their rugged scenery holds many glistening waterholes and a rich assortment of native plants and animals.

The few waterholes that are permanent are very special. They become the drought-time life-support for millions of desert-ranging animals such as pigeons, finches, and parrots, and they are the last drought refuges for central Australian fish and other aquatic creatures.

Permanent underground water has also helped the isolated palms (Livistona mariae) of Palm Valley to survive through thousands of years. Breaks in the ranges (chasms, gaps & gorges) form cool shady retreats, where the water held in gravel-beds, rock-holes and crevices is slow to evaporate.

These special places are home to a community of animals and plants including cycads, ferns and lilies which survive nowhere else in central Australia. The main threats to such areas come from excessive tourist traffic and the risk of runaway summer fires.

Black-footed Rock-wallabies find daytime shelter in the ranges’ caves and rocky slopes, but move down onto the foothills at night to feed on grasses and herbs. Unlike their bigger relatives, the Euros, Rock-wallabies rarely venture onto the valley floors but stay on rocky foothills where their sure-footed agility can be used to outrun hunting dingos.

The foothills and floodplains gather the rainfall that runs off the rocky ridges. They may in one year receive the equivalent of 500mm of rain when only 250mm actually fell. This results in a richer growth of natural pasture which indirectly supports most of the range’s wildlife and also accounts for 80 per cent of the range’s cattle production. These areas are threatened by over-grazing which accelerates erosion; and by the shrubs which will replace pasture if fire is excluded.

Compare with a Sonoran Desert habitat.