Anatomy of a fall

Has the Great Green Wall of Africa project, launched in 2008, already collapsed? Many people think so, in view of the project's inertia. The political instability of many of the countries involved, and the blocking of promised funding, are today hampering soil rehabilitation through the planting of forests that may never have existed except on paper.

Thierry Berrod - Mona Lisa Production

While some may say that the idea has fizzled out, Duponnois prefers to warn: "It would be a disappointment and an extraordinary admission of weakness to abandon a project that has attracted so much media attention. A research director at theIRD, Robin Duponnois was also the project manager for the Great Green Wall (GMV) in Dakar. He notes bluntly that the objectives of the G GW "are a long way from being achieved, and won't be by 2050 either. However, the analysis on which the project is based is sound. We're not introducing anything, we're not destroying anything, we're listening to the local populations, the only risk is that there will be no effects".

In 2008, 11 countries took part in the launch of the operation: Senegal, Mauritania, Mali, Burkina-Faso, Niger, Nigeria, Chad, Sudan, Eritrea, Ethiopia and Djibouti. Objective: to plant trees on a 15 km-wide strip of land along a 7,000 km belt stretching from Dakar to Djibouti, to prevent the desertification of land degraded by human activities (read: Research en sol majeur, 10/11/2021, Magazine LUM 15). Hence the somewhat misleading term "wall against the desert", but the Sahara is not advancing, it's just recovering surface area", subtly nuances the researcher.

Under the trees

The idea is not new. The 1970s saw the birth of the "Green Dam" in southern Algeria(L'Algérie relaunch son mégaprojet du Barrage vert, 8/11/2023, Jeune Afrique), the "Great Wall" in China (see box), and the "green belts" in Ouagadougou and Cairo. Almost all have failed, but a valuable lesson can be drawn from these early failures: "All these projects were designed with exotic forest species, usually in monospecific plantations. In the end, these forests either failed to regenerate or were ravaged by pathogens," notes the forest biology specialist.

It was therefore decided by those involved in the Great Green Wall to plant only local trees. Two species are favored: Acacia Senegal, which produces the gum arabic prized in pharmaceuticals, and balanites, whose bark and thorns can also be put to good use. The GMV is initially presented as an environmental rehabilitation project," notes Robin Duponnois. But underneath the trees there are social and economic issues at stake, such as the combination of cultivation and livestock farming, which are always antagonistic in these regions, entrepreneurship, valorization of the local terroir, etc."(La Grande Muraille Verte. Capitalisation des recherches et valorisation des savoirs locaux, A.Dia, R.Duponnois, 2012, IRD Editions).

Locomotive without wagon

In Senegal, for example, multi-purpose gardens have been co-developed in many villages. "Women were trained to sell their produce and stop having to travel 30 kilometers to market every week. The gardens found their audience before they too were affected by the GMV project running out of steam. "In the village of Tessekere, the funding needed to repair a pipe never arrived, so the garden was gradually abandoned. There's no continuity in the development of the projects, even though we have the technique and the processes," he observes with a touch of bitterness.

A sentiment that Robin Duponnois immediately tempers: "In northern Senegal, you have acacia plantations that are doing very well. There are still nurseries and gum arabic production is picking up. Senegal remains the driving force behind the project. (read: La Grande muraille slowly makes its way in Senegal, 15/04/2016, Le Monde). A locomotive indeed, but without a wagon, since the GMV seems to be docked in most other countries, and the gas pedal of the Great Green Wall, launched with great fanfare in 2021, is still waiting in the field.

Trees of peace

Why is Senegal, with a GNP roughly equivalent to that of the other partners, one of the few countries to continue the effort? Because, for the time being, it enjoys a level of political stability that many other countries do not," replies the scientist. Burkina Faso, Mali, Nigeria, Eritrea... are in unstable situations, and the Great Green Wall is no longer a priority for these countries. And while international partners have pledged some pretty colossal sums, you don't put money into a country at war." It remains to be seen whether the wall will recover (read Accelerating the mobilization of African and international scientific expertise to boost interdisciplinary research for the success of the Sahelian Great Green Wall by 2030, 10/2022, Land).

Green dragon versus yellow dragon

It's the world's largest artificial forest, over 500,000 square kilometers (2009) of poplars, pines and willows, planted in China since the late 1970s to battle the Yellow Dragon. For years, these unimpeded storms from the Gobi desert have dumped hundreds of thousands of tonnes of sand as far south as Beijing, 350 km away. The idea was to reforest to fix the dunes and avoid these sand winds," explains Robin Duponnois. They also tested cyanobacteria to produce crusts at ground level, and set up large nurseries using highly sophisticated in vitro cultivation techniques. They have set up a whole system of canals for drip watering...".

Fifty years on, and despite the human and social cost of the many expropriations and population displacements it required, China's Great Green Wall is a success story. Vegetable-growing areas have been established, monospecific forests have given way to a diversification of species, and ecotourism has developed. " There's even a chairlift in the middle of the dunes," laughs the researcher. But China isn't stopping there. In 2018, it mobilized 60,000 soldiers(Le Figaro, 8/02/2018) to achieve its objectives by 2050: to plant 35 million hectares of forest 550 kilometers wide and 4,500 kilometers long. Not enough to turn its 20,000-kilometer-long stone twin green.

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