More crops for Africa as trees reclaim the desert
For once there is some good news from Africa. Farmers are reclaiming the desert, turning the barren wastelands of the Sahel region on the Sahara's southern edge into green, productive farmland.
Satellite images taken this year and 20 years ago show that the desert is in retreat thanks to a resurgence of trees. They are mainly ana trees (Faidherbia albida), a type of acacia. Wherever the trees grow, farming can resume.
Tree planting has led to the re-greening of as much as 3 million hectares of land in Niger, enabling some 250,000 hectares to be farmed again. The land became barren in the 1970s and early 1980s through poor management and felling of trees for firewood, but since the mid-1980s farmers in parts of Niger have been protecting them instead of chopping them down.
The results have been staggering, says Chris Reij of the Free University Amsterdam in the Netherlands, who presented the results at the From Desert to Oasis symposium in Niamey, Niger, last month. In areas where 20 years ago there was barely a tree, there are now between 50 and 100 per hectare. The change is particularly striking in the previously barren Zinder region to the south.
“Where 20 years ago there was barely a tree, there are now 50 to 100 per hectare. Production of cereals has soared”
Trees create a virtuous circle of benefits. Leaves and fruits provide food, fodder and organic matter to fortify the soil. More livestock means more manure, which further enriches the soil enabling crops to be grown, and spreads tree seeds so new trees grow. The trees also provide shelter for crops and help prevent soil erosion. In times of drought, firewood can be sold and food purchased to tide families over.
Coupled with simple measures such as ditches and holes to catch scarce rainwater and save it for irrigation, the programmes are helping communities in Niger re-establish control over their fate, simultaneously halting the march of the desert and helping to prevent famines like the one that hit Niger in July 2005.
"The spiral of degradation has been reversed," says Reij. "Since the middle of the 1980s, at least 250,000 hectares of strongly degraded land have been rehabilitated." Production of cereals such as millet and sorghum have soared by between 20 and 85 per cent since 1984 as a result, Reij says, and vegetable production has quadrupled.
Vegetation also creates climatic feedback loops which increase the amount of rainfall. Analysis of satellite images and rainfall in the Sahel between 1982 and 1999 show that 10 to 20 per cent more rain falls when land is green (Geophysical Research Letters, DOI: 10.1029/2006GL027065).
Given the benefits of encouraging tree growth, Reij and his colleagues hope to spread the practice to neighbouring countries, including Mali, Senegal and Burkina Faso. The programme will form part of the "Oasis" initiative to reclaim deserts, which was launched at the symposium by 11 African countries, with support from international research and government agencies.
Lauren Gelfand, an Oxfam spokeswoman based in Dakar, Senegal, welcomed the developments but cautioned that the recovery is fragile and can only be sustained through international aid and investment in transport infrastructure and education.
"The situation in Niger is much better than it was last year, but there are still pockets of insecurity," she says.
