Nature Notes - Desert Rivers

The desert rivers and the nutrient-rich areas that run alongside them are ribbons of favourable habitat in the Australian Deserts. Conditions here are relatively stable though still subject to the vagaries of the unpredictable climate. The rivers may only flow for short periods of time after rain but there’s usually no shortage of water beneath the sand.  Plant life is most abundant in this habitat, with permanent pools being the most biologically significant places.

Pulses of activity are a feature of life here. Floods bring change and rebirth for many aquatic animals. Spencer’s Burrowing Frog, for example, digs down under the sand in times of drought. Its life comprises long periods of suspended animation followed by bursts of accelerated activity. Fish, such as the hardy Spangled Grunter, will die if the waters dry up but their eggs survive in the mud until next heavy rain fills the waterholes again.

The desert rivers habitat is the land of the birds. The River Red Gums lining the banks are like multistory, high density housing developments for a large range of birds and other animals. Prominent residents include brightly coloured parrots and cockatoos, honeyeaters, kingfishers, pardalotes, butcherbirds and owls.

The rivers have been intensively utilised by the cattle industry since the 1870s and so they are not nearly as rich floristically as they used to be. Wildlife has also been affected. Golden Bandicoots and bilbies were common in the country adjoining the rivers but have now disappeared. Until the 1930s, Brushtail Possums were abundant in the trees lining the rivers but only survive now in a few isolated localities in the MacDonnell and Petermann Ranges.

Weed infestation is another problem. Imported Couch Grass Cynodon dactylon, for example, is an aggressive colonizer of the riverbeds, displacing native grasses and sedges. It grows vigorously after rain, adding a significant amount of  inflammable material. This can subsequently fuel very hot fires which damage River Red Gums and other trees. Prior to the introduction of Couch, rivers were effective firebreaks but infested watercourses can now provide a channel for spreading fires rather than limiting them.

Compare with the Riparian Communities of the Sonoran Desert.