Like most people living along the Sahel – the drylands between Africa’s tropical savannahs and the Sahara Desert – Mustafa Ba is all too familiar with the effects of desertification.

Thanks to a combination of overgrazing and deforestation, he has watched the countryside around his Senegalese village, Mboula, turn into a dusty, unproductive wasteland.

“Trees provide us with many benefits,” explains Mustafa, as we sit on a mat in the centre of his village. “They are good for the soil and important for food security.”

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But in impoverished regions of rural Africa, selling firewood is a source of quick cash and many trees along the Sahel have been felled. Communities have paid a high price for such enterprise; with no trees to protect the land, vast swathes of the Sahel have succumbed to desertification.

According to the United Nations, Mustafa is one of 850 million people – nearly one eighth of the global population – to be directly affected by this process of land degradation.

But it’s not just a local problem; desertification has an impact on food production, which pushes up grocery bills around the world (the UN estimates Guatemala alone loses 24 per cent of its agricultural GDP due to desertification).

To raise awareness of the issue, the UN reserved June 17 as World Day to Combat Desertification, but behind the rhetoric it has also been supporting projects to tackle the phenomenon head on. One of those is Great Green Wall of Africa, a 4,800-mile “wall” of trees that is being planted across the continent between Senegal and Djibouti.

It took years to secure funding for this ambitious project but with the help of the African Union, European Union, World Bank and other international investors, it was approved in 2011. Mustafa was delighted.

“Instead of feeling alone facing this huge challenge of desertification, we feel connected to the rest of Africa and the outside world,” he says. “We knew we had to protect the land, but the Great Green Wall programme has helped provide us with technical assistance.”

Assuming the initiative is successful – detractors argue that is a big assumption – the Green Wall will snake through 11 countries and will form the backbone of a much wider dryland restoration project involving more than 20 African nations. So far, nearly 12 million trees have been planted in Senegal alone, but it’s not simply a case of sowing seeds and hoping for the best.

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“You need to plant the right species in the right place,” says Nora Berrahmouni, a Forestry Officer for the UN Food and Agriculture Organisation (UNFAO), as we drive through rural Senegal. “And by species that doesn’t mean a tree only – it could be a shrub or herbaceous plant. It’s about mimicking nature.”

For the Green Wall to succeed, Nora adds, it is essential the project involves and benefits local communities. To illustrate her point we visit Tessekele, a 600-hectare pilot site near the village of Widou. It’s a fairly underwhelming spectacle; the dusty scrubland doesn’t look particularly green, nor does it resemble a wall.

However, its spindly-looking acacia trees are rich in gum arabic, a ubiquitous additive used in anything from cosmetics to confectionary. Demand for this gum – extracted from the acacia by cutting into the bark – is currently outstripping supply thanks to an increase in demand from Asia, Europe and the US. Consequently, prices are rising and the trees are becoming more valuable standing than felled.

However, all trees play a vital role in agriculture, by fertilising the soil and provide shade, and the Green Wall project is trying to educate farmers about the relationship between healthy environments and crops.

“Taking care of the environment is perceived to be a luxury,” says Michele Bozzano, a Research Support Officer for Bioversity International. “But the difference between having a stable environment and not is the difference between being able to grow crops and crops failing.”

It’s not just agriculture that stands to benefit from a healthier environment. “Wildlife has returned to the site,” says Elimane Diop, the Chief Lieutenant of Widou, as he shows me around Tessekele. “We’ve seen antelope, hyena, porcupine and guinea fowl.”

The progress of the Green Wall is being monitored eagerly by other nations, particularly Turkey. “We are interested because in Turkey we are also suffering from desertification,” says Ismail Belen, Deputy General Director at Turkey’s Ministry of Forestry. “People ask me how that’s possible when we don’t have a desert, but desertification is not about the desert, it’s about land degradation.”

Ismail is keen to learn lessons from the Green Wall, which he romantically describes as a “modern-day Silk Road, only green.” But not everyone shares his enthusiasm; critics have expressed concerns about the management of the project.

“The Green Wall is run from the top down and depends on external management and external funds,” says Ced Hesse, a Drylands Researcher for the International Institute for Environment and Development (IIED). “And there is a tenure issue – when you plant a tree who does it belong to, who is going to look after it, who is going to harvest the crop?”

The UNFAO disputes this and claims the project is enfranchising local communities, although it does acknowledge the threat of climate change – how will the Green Wall survive in an area set to become drier and warmer? Well, with technical support from Kew Gardens in London, seed banks in Burkina Faso and Niger are giving it the best possible chance, cultivating seeds from the hardiest plants in Africa. “It’s about bringing back resilient ecosystems that are able to adapt to a changing climate,” says Nora.

But can attitudes adapt fast enough? At a desertification conference in Dakar recently, I entered the washrooms after ambassadors from several Green Wall nations to find the taps had been left running – in a nation short of water. Admittedly these were the actions of a few, but it doesn’t inspire confidence.

Mustafa Ba, on the other hand, does. Before the Green Wall was even approved, he had started a campaign in Mboula to fight desertification through the restoration of local drylands. His scheme has since received support from the Green Wall, but the natural regeneration that has occurred here since is largely down to his efforts.

This bodes well because if ambitions environmental projects like this are to succeed, they will need people like him – hardworking, enfranchised locals – to make it possible. “It really needs to happen at a local level,” explains Nora. “If everyone does their bit, everyone is a winner.”