I used to think that windbreaks were different from shelterbelts. But they’re the same. Both are barriers of trees that protect against the wind and reduce erosion.

The word ‘shelterbelt’ was first bandied about in 1934. That’s when the Roosevelt administration launched the ‘Great Plains Shelterbelt’ project in the US.

After much American and Canadian prairie land had been swept away in strong winds, the project was an attempt to slow the loss of topsoil. Drought, coupled with decades of poor farming practices, had turned formerly fertile land into the Dust Bowl.

By 1942, 30,233 shelterbelts – a total of 220 million trees – were planted in the Great Plains states.

Around here, shelterbelts are a feature of most pastures. Stands of trees protect livestock from the worst of the Winter weather, especially during lambing, and in Summer they provide valuable shade for grazing animals. They also slow evaporation rates of moisture from the ground, keeping the pasture greener for longer.

In times of bushfire, a shelterbelt can slow the spread of a fire by limiting wind speed. It can also filter sparks and deflect burning debris. Unless, of course, it consists of eucalypts which, along with pines, are probably the most flammable trees on earth.

In Marysville last Summer, many deciduous trees withstood the fire’s attack while eucalypts and other native species burned. It would make sense, then, if residential properties in fire-prone areas were protected by shelterbelts of oaks, chestnuts, fig, fruit and other trees that have fire resistant qualities.

A screen of deciduous trees would also keep the house cool in Summer, allow sunlight through in Winter and provide you with all the carbon you need for your compost heap in Autumn.

Here’s a salutary lesson on the need for shelterbelts in rural areas to conserve soil.

At mid afternoon on 8 February 1983, 500,000 tonnes of soil, blown from the Mallee in the state’s north-west, engulfed Melbourne, plunging the city into darkness. Most of the soil was carried away, some as far as New Zealand, while 1,000 tonnes of topsoil were dumped onto the city.

A devastating combination of widespread drought and high winds created that extraordinary event. (In the UK it would probably have been named ‘The Great Dust Storm of 1983′, or something similarly epic; here it was merely called ‘the dust storm’.)

Given the predictions of climate change in this part of the world, it’s likely that a dust storm of that magnitude will happen again. And this is where shelterbelts can play a role. By reducing wind speeds to a level below the soil movement threshold, they help limit erosion.

One of the biggest projects happening on the planet is the planting of a mega shelterbelt known as the Green Wall of China. Consisting of a series of forest strips, it’s been designed to hold back the Gobi Desert.

In northern China, vast quantities of land are consumed by deserts each year and much rests on the Green Wall’s success in slowing their advance. Its failure will result in an ecological disaster of immense proportions. But let’s not go there.

By the time the Green Wall of China is completed in 2074, it will be 4,500 km long. That’s a helluva lot of shelter.

Acknowledgements: Department of Primary Industries Victoria, Wikipedia