A plan to slow the creep of the Sahara by planting gardens


This story at the origin Appeared on Dark Atlas and is part of Climate Office collaboration.

Seen from the sky, the new garden in the town of Boki Diawe, in northeastern Senegal, looks like an eye: wide open, unfazed, and flanked by a handful of clods dug into the surrounding soil, dark as patches of freckle on the nose. The soil is still sandy brown, but nearby there is a fringe of bright green.

If all goes according to plan, this garden will soon look just as lush. The circular garden, known locally as tolou keur-has recently been planted with papayas, cashews, lemons and more. One of the inner curved rows is dedicated to medicinal plants, while the outer row has been lined with baobab trees and Khaya senegalensis, the wood of which is also known as African mahogany.

The Garden is the latest iteration of the project known as the Great Green Wall, initially envisioned as a virulent belt that winds for thousands of kilometers across the Sahel region, from Senegal to Djibouti. Launched in 2007 by the African Union with the support of the European Union, the World Bank and the United Nations, the project was initially intended to help avoid desertification by thwarting the Sahara as it wandered south.

Desertification is the process by which lush lands degrade into a desert. The phenomenon is driven by “an interaction of natural and human factors,” explains Chukwuma J. Okolie, senior lecturer in surveying and geoinformatics at the University of Lagos in Nigeria. Okolie uses remote sensing data, such as satellite imagery, to track landscapes tilted towards desert conditions.

Drivers of desertification include climate variability and change, overgrazing, the construction of river dams and conflicts that displace populations and spur changes in land use. Long droughts can make fertile soils vulnerable, and winds and rains can wash them away. “Deforestation can speed up the process, because the trees act as windbreaks,” Okolie explains. This is where the concept of the Great Green Wall comes in.

The original plan emphasized trees as an anchor to the ground and as a buffer against the encroaching sand. Some elements of the idea made sense, says Geert Sterk, a geoscientist at Utrecht University who studies land degradation. “The roots of trees and shrubs hold the soil and canopies trap raindrops before they reach the soil surface and reduce strong winds,” by slowing down erosion by wind and rain. relatively rare but heavy rain, Sterk explained in an email.

But the ambitious plan did not really come to fruition. There have been political wrangling over where to draw the green line, and scientific debates over what is fueling desertification, as well as the effectiveness of the approach. From 2021, the project is only a fraction of the way to its goal to plant hundreds of millions of acres.

A new infusion of money, promised earlier this year by various governments and development banks, will give the project a boost and now the focus is on more local gardens. In the past seven months, more than 20 versions of these circular gardens have sprouted across Senegal.

Aly Ndiaye, an agricultural engineer born in Senegal who participated in the design of the tolou keur, Recount Reuters that the Great Green Wall should be made up of smaller, more productive gardens that are “permanent, useful and sequential,” a series of practical plots rather than an unbroken line of trees. Okolie agrees that the project cannot consist of driving a seedling into the ground. He says this must involve “trying to locate the best species that can thrive” under the given soil conditions and climate, while also appealing to the people who will feed them. Researchers to have found that agroforestry projects often fail when the focus is only on tree planting and residents are excluded from the process. “When the government plants trees, it’s the people in the community who care for them,” Okolie says. “The community must take ownership. “



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