The Mulga-Eucalypt line

Charles Darwin Reserve lies across a junction of major landforms, ecosystems and climates, known as the Mulga-Eucalypt Line. This is where the south-west meets the desert and the characteristic species of each intermingle, providing a rich biological frontier.

The Mulga-Eucalypt line can be drawn as a line on a map: it is a real phenomenon on the ground. It is possible to see the change from dense shrublands on yellow sandplain and York gum woodlands on red loamy soils, to the stony red earths with their covering of open acacia shrubland as one moves into the north-eastern end of Charles Darwin Reserve, from Seven Mile Well to Christmas Bore.

The Mulga-Eucalypt line coincides roughly with the 250mm (10 inch) isohyt. It marks the boundary of the Mediterranean climate of the south-west with its wet winters and dry summers, and the arid zone of the north-east with its erratic rainfall, whether in summer or winter, and long dry spells.

First postulated by the botanist von Mueller in 1883, the concept of the Mulga-Eucalypt line and its mapping has been refined by a succession of eminent geographers and botanists including Woodward, Diels, Clarke, Gardner, Burbidge and Beard, culminating in the currently accepted maps of the Biological Regions of Australia.