Landscape and Wetlands

Ethabuka is a landscape that receives only 100-200mm of rain per year and that rainfall is extremely patchy with huge variations from year to year. Some of the plant communities would rather rely on a 5 –10 year regional flood cycle than wait for rain. The smallest rainfall brings great change here as the desert absorbs each drop. Flowers bloom, frogs come out of the once hard clay to spawn and baby mammals and birds are born.

The clay and gibber plains are exposed in the east as extensive floodplains or broad swales between dunes. Pulchera waterhole, a wetland of national significance, lies on the edge of the channel country and is fed by the Mulligan River in the Georgina Diamantina catchment. Its extremely flat riverbed can hold water for several kilometres though most of the time it is a parched white plain. Pulchera waterhole provides an important refuge for the birds and animals of the desert and is a stop in Australia’s migratory bird’s journey. Between the flood-out country of the east and the extensive deep red dunefields of the west lie gigdee woodlands, tall shrubland communities and shallow waterbodies. The deep red colour of the dunes is common only to the northern part of the Simpson Desert and is caused by a coating of laterite on each grain of sand.

Ethabuka and Alnagatta Springs are 2 free flowing artesian springs which emerge in wide dune swales near the edge of the dune fields. They also provide an important refuge. Both are shallow depressions of water which each species takes its turn to drink. In the past the springs have been modified by machinery and the vegetation consumed and trampled.
The vegetation on Ethabuka is diverse, with eighteen major plant communities and 200 species identified so far. 

Around 36 200 ha of the property is on or adjacent to the flood plains, the type of country that is prized for cattle production and thus unreserved or poorly reserved. Most importantly, the property extends along a major environmental gradient and incorporates country from the heart of the Simpson Desert to permanent or semi-permanent waterholes on the flood plain. This gradient is not represented in the Simpson Desert National Park.

The ephemeral wetlands and the semi-permanent Pulchera Waterhole on Ethabuka are part of a complex of features on the junction of the Mulligan River and Wheeler Creek that have earned the area listing as a wetland system of national significance. The wetlands spring to life after big rains or with floods coming down from higher in the catchment. They provide habitat for large numbers of waterfowl. The Pulchera Waterhole dries up only during the most severe droughts, so remains a focus for cattle grazing.

Equally important is the Field River, a normally dry watercourse that on rare occasions flows down from higher country to the north-west and out into the heart of the Simpson Desert. It delivers lifegiving water to a string of waterholes, stands of red gums and coolibahs and extensive grassy flats.This ecosystem extends many kilometres into the Simpson Desert dune field, creating an oasis for a suite of arid woodland species. Again, cattle concentrate here when water is available.

Photos Wayne Lawler / Ecopix