THE RANGELAND

Desertification

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What is desertification?

    Desertification has become a popular term in newspaper stories and TV programs on land degradation.

The UN has a convention on combating desertification.

The UN definition is extremely wwide. Not only arid and semit-arid areas but also dry sub-hunid zones are included.

The implication in many of these programs and articles is that the desert is encroaching on the rangeland.

There are photographs of sand dunes engulfing houses and roads.

What is shown is the desert physically moving into the rangeland. The theory had wide support.

It was the theoretical foundation for Algeria's huge Green Dam project.

The purpose was to establish a physical barrier of trees to stop the desert encroaching into the rangeland.

Is it useful as a term?

    With few exceptions the desert is not physically moving.

Land is being degraded and plant cover removed so the signs of the desert are expanding. The Algerian Green Dam is a good example.

Land degradation has taken place on the rangeland inside the protection of the Green Dam.

There are not many sand dunes because most of the soil is not sandy.

The degradation is intense and extreme. It was not cause by a physical movement of the desert but by local over grazing.

The desert is physically moving and causing severe environmental problems for some desert and rangeland towns but again the problem is often associated with local over-grazing. 

Livestock are kept in the towns and taken out for a walk. The result is totally desertification of the surrounding area.

Can it be reversed?

    Broken Hill a mining town in the rangeland of Australia shows that is can be reversed on a local scale with dramatic improvements to the quality of the air.

During the 19th and early 20th centuries a circle of land stretching 20 km from the town was used as a grazing common for sheep, cows and horse by the miners and other inhabitants.

The rangeland became degraded and the town permanently polluted with dust.

About 50 years ago the grazing common was finally closed and left from regeneration.

It is now mostly covered with shrubs and even some trees. The dust pollution has been reduced remarkably.

The Broken Hill regeneration took place naturally after all the livestock were removed. Intervention can make the process faster particularly in areas where the degradation is severe.

 The problem with severe degradation is that the surface soil has been swept by wind and water. Often the top soil which contains nutrients and organic matter has been removed. The hard sub soil provides a hostile environment for germination.

The pitter can assist in the restoration process. The pitter creates pits with a tine about a metre long and 10 cm deep. The provide a basin for seed to collect or be sown. Water runoff collects in them - they become the run on areas.

Pits are better than rips as heavy rain can flow down rips and form gutters.