Southern Frome Basin (Environmental Region 5.3)
This region consists of seven environmental associations. It lies to the north of the Olary Spur and is part of a large internal drainage basin, probably of structural origin, the centre of which is occupied by Lake Frome. The plain, which is mainly covered with shallow calcareous earths, has a low shrubland of saltbush and bluebush, often with low open woodland or tall shrubland overstory. It is nearly featureless except in the north near Lake Frome where sand dunes occur more frequently. These dunes support a low woodland or tall shrubland with an understory of bluebush and ephemeral herbs. Streams from the Olary Spur do not reach the lake but flood out at a short distance from the upland, however some larger streams from the Flinders Ranges to the west intermittently reach the salt lake. The region has a warm climate with high evaporation and very low and unreliable rainfall throughout the year. Temperatures range from warm to hot in summer to cool to cold in winter. Mean annual Class A pan evaporation ranges from about 2700 mm in the south-west to about 3200 mm in the extreme north-east of the region. Mean monthly evaporation exceeds the 90th percentile of monthly rainfall throughout the year. Mean annual rainfall is generally less than 200 mm and may fall as low as 150 mm in the north of the region. Background panoramic views dominate in the region, the Flinders Ranges and the Olary Spur form a backdrop to the views in the far southern and western parts of the region. Dunes and, to a lesser extent, stream channels lined with red gums form local features. Differences in the vegetation composition afford ephemeral views through wind and light effects, especially at lower sun-angles.
