21 September 2002

Africans go back to the land as plants reclaim the desert

AFRICA’S deserts are in retreat. Burkina Faso, one of the West African countries devastated by drought and advancing deserts 20 years ago, is growing greener again – so much so that families who fled to wetter coastal regions are starting to go home.

New research confirming this remarkable environmental turnaround in one of Africa’s most arid countries is to be presented to Burkina Faso’s ministers and international aid agencies in November. And it’s not just Burkina Faso. New Scientist has learned that a separate analysis of satellite images completed this summer reveals that dunes are retreating right across the Sahel region on the southern edge of the Sahara desert. Vegetation is ousting sand across a swathe of land stretching from Mauritania on the shores of the Atlantic to Eritrea 6000 kilometres away on the Red Sea coast.

Nor is it just a short-term trend. Analysts say the gradual greening has been happening since the mid-1980s, though has gone largely unnoticed. Only now is the evidence being pieced together.

Aerial photographs taken in June show “quite spectacular regeneration of vegetation”, in northern Burkina Faso, according to Chris Reij of the Free University, Amsterdam. There are more trees for firewood and more grassland for livestock. And a survey among farmers shows a 70 per cent increase in yields of local cereals such as sorghum and millet in one province in recent years. The survey, which Reij is collating, was paid for by Dutch, German and American overseas aid agencies.

Meanwhile, Kjeld Rasmussen of the University of Copenhagen has been looking in detail at sand dunes in the same area. Once they seemed to be marching south. But since the 1980s, he says, there has been a “steady reduction in bare ground” with “vegetation cover, including bushes and trees, on the increase on the dunes”.

Only 20 years ago, northern Burkina Faso was a prime example of the desertification crisis, with a high human population, expansion of farming into drier areas, declining grain yields and spreading soil erosion.

Fearing the worst, many families left to work in near-slave conditions on coffee and cocoa plantations in coastal West African countries such as Cote d’Ivoire. But as the plants return and the granaries refill there is now a slow trickle of people migrating back to the north of the country, says Reij.

Desertification is still often viewed as an irreversible process triggered by a deadly combination of declining rainfall and destructive farming methods. Last month, the UN Environment Programme told the World Summit in Johannesburg that over 45 per cent of Africa is in the grip of desertification, with the Sahel worst affected.

But a team of geographers from Britain, Sweden and Denmark has spent the summer re-examining archive satellite images taken across the Sahel. Andrew Warren of University College London told New Scientist that the unpublished analysis shows that “vegetation seems to have increased significantly” in the past 15 years, with major regrowth in southern Mauritania, northern Burkina Faso, north-western Niger, central Chad, much of Sudan and parts of Eritrea.

Warren believes the greening of the Sahel may be so extensive that the growing vegetation is now becoming an important “carbon sink” for the planet, soaking up carbon dioxide from the atmosphere and helping to moderate global warming.

But there’s confusion over why the Sahel is becoming green. Rasmussen believes the main reason is increased rainfall since the great droughts of the early 1970s and 1980s.

But farmers have also been adopting better methods of keeping soil and water on their land. In many areas, Reij says, the key has been a technique known as “contour bunding”. Farmers lay lines of stones along the contours of slopes to stop the occasional heavy rains from washing away soil, and to keep the water on the land long enough for it to soak into the soil. The technique was widely adopted after Bill Hereford, an Oxfam worker in Burkina Faso, suggested it 20 years ago.

In the Yatenga region alone, where the Oxfam project started, “thousands of hectares treated with contour stone bunds now have trees growing where nothing grew 15 years ago,” says Reij.

Water tables are rising and there is more vegetation for cattle. “Environmental rehabilitation is closely associated with villages which have undertaken these methods. Farmers with their backs to the wall started to experiment and innovate.”


©Copyright Reed Business Information Ltd.
Related: Greening Earth: Spatial patterns - Myneni
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