Characteristics of Arid Australia

The rangelands, which cover more than 70 per cent of Australia, are arid and semi-arid areas where rainfall is too low or unpredictable to sustain intensive agriculture (i.e. cropping or mixed farming).

 

The environment in the rangelands has been dominated by three forces: low, unpredictable rainfall, patchy infertile soils and fire. More recently, since European settlement, the environment, particularly vegetation, has been affected by a fourth factor - grazing by introduced animals such as cattle.

The predominant land uses in the rangelands are pastoralism, conservation, tourism, mining, urban areas and Aboriginal lands - whose inhabitants may be involved in any of these uses. Within the rangelands, which includes central Australia, landscapes are diverse.

Below are some of the different landscape types found in central Australia

Ranges plain.JPG (45480 bytes)
(1) Ranges (2) Foothills and alluvial plains
timbered plains spinifex grasslands
(3) Timbered plains (4) Spinifex grasslands

Although some landscape types are fairly uniform (e.g. spinifex sandplain above), other landscapes have very diverse vegetation.  For instance the photo (2) above shows patches of bare ground, areas with scattered trees and shrubs and still other areas covered with grass and herbage species. In both photos (2) and (3), water runs off the bare areas to collect in depressions where sediment is deposited. The sediment contains valuable plant nutrients so the extra water and nutrients available in these areas improves plant growth.

 

As mentioned, rainfall in arid and semi-arid areas tends to be unreliable and erratic which means that the amount and composition of vegetation can change substantially following good rains. The photograph below on the left was taken after a period with little rainfall, and the photograph on the right was taken after a moderate rainfall.

dry conditions wet conditions

 

The characteristics of differences in vegetation type, in vegetation response to rainfall, and in vulnerability to desertification  mean that it is difficult to accurately monitor the condition of Australia’s rangelands. 


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