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Week 5/ 2007: Trees valuable for households in Sahara borderlands

“Desertification in Sahara’s southern borderlands is largely due to poor environmental care. The ever-increasing population cuts down the trees and cattle feed on the vegetation,” said project manager Jörn Laxén from the Viikki Tropical Resources Institute while addressing a Swedish-speaking gathering for journalists.

“Climate change is often blamed for problems that people could prevent with good environmental care.”

Laxén talked about the UN Millennium Development Goal to ensure environmental sustainability. He said that forests and the environment are easily excluded from national budgets as their products and profits are used locally and usually for free.

Laxén provided concrete examples of the usefulness of trees from his forthcoming doctoral dissertation in the field of environmental economics. He gathered his research data from two irrigation systems in northern and central Sudan where he studied the environmental economic impact of the alien tree species Prosopis juliflora. Prosopis is considered harmful in Sudan. Laxén disagrees.

“Prosopis is very useful to its environment, but its advantages and disadvantages vary from place to place. Tree plantations provide shelter against wind and sand and would prevent the Sahara’s shifting sand from reaching the villages and thus ruining the buildings. This would reduce the need for rebuilding, sand clearing and migration. Air quality will also improve.

Furthermore, tree plantations create better conditions for crops and protect irrigation channels. Prosopis is important forage for wandering cattle: without the species, people will have to halve their number of cattle, which in turn will decrease their intake of animal proteins in the form of milk and meat.

Villagers need firewood, light building material and other benefits that the trees offer, such as shelter from the sun for people and animals. Prosopis also improves the soil through biological nitrogen fixation, by increasing the amount of organic material, and by acting as a buffer zone against the desert.

But there are drawbacks. Prosopis spreads rapidly, and coppicing in fields and by irrigation channels is costly. Its sharp thorns can hurt people and animals and puncture tyres. But trees are necessary for sustainable development in the future. The alternative would be increased migration from desertified land, Laxén says.

Jörn Laxén’s dissertation will be publicly examined and available online in March.

Text: Madicken Malm
www.helsinki.fi/digitalcommunications

Translation: Valtasana Oy