Northern Arid (Province 8)
This province comprises northern South Australia from the N.S.W. and Queensland borders to the Western Australian border. Its southern limit extends from Lake Frome and the northern Flinders Ranges westward to the northern margin of the Nullarbor Plain.
The province has a very hot dry desert climate with short cool to cold winters and an extremely low, unreliable rainfall with no distinct seasonal pattern. The highest mean annual rainfall occurs in the Musgrave Ranges of the far north-west where it reaches 200 mm, with most of the remainder of the province having a mean annual rainfall of around 150 mm, but in the Simpson Desert and Cooper Creek areas this decreases to around 125 mm per annum. Temperatures vary from cold in winter to hot in summer, and seasonal and diurnal ranges are very high. Seasonal ranges tend to increase towards the north and east. Mean annual evaporation is extremely high, increasing from around 3100 mm in the south-west to 4000 mm in the central north. In general the soils of the province are moderately deep to deep and therefore able to store much of the irregular precipitation. Run-off from ranges and hills and the large areas of bare rock, increases the water available for local storage.About 60% of the central and eastern sections of the province are under pastoral lease and used for extensive livestock grazing. The holdings vary considerable in size, from 2000 km2 in southern parts to over 30 000 km2 in outlying northern areas. South of the dog fence sheep provide the majority of livestock; north of it, cattle. Livestock figures between 1965 and 1974 average about 50 000 cattle in the north-east, 70 000 cattle in the centre and central north and 3000 cattle and 265 000 sheep south of the dog fence. In the east and north-east holdings include much country which is not suitable for even the most extensive form of permanent grazing, and livestock are concentrated along the watercourses and in interdunal areas with bores for stockwater. Drought represents the major environmental hazard in the province and livestock numbers vary greatly through time.
The opal mining activities at Coober Pedy and the open-cut coal mine at Leigh Creek support over half of the province's population of less than 4000 people.
There are three conservation areas in the province, which together comprise 5% of its area, and a further 21% has no defined use. Nevertheless, habitat destruction by domestic and feral grazing animals such as sheep, cattle, rabbits, goats, donkeys and camels, and predation by introduced cats, foxes and, perhaps to a lesser extent, dogs has caused both a dramatic decline in numbers and a considerable restriction in range of many native desert-dwelling animals throughout the entire province.
The Amata Aboriginal Reserve occupies the north-west corner and 13.5% of the province.
Four environmental regions have been distinguished in this province: