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Plants are building our best defence against the greatest desert on Earth
A monumental undertaking, the Great Green Wall promises to transform the edges of the southern Sahara into a thriving, forested landscape. Once complete, it will be the largest living structure on the planet, three times the size of the Great Barrier Reef.
The initiative, first launched in 2007, has pledged that by 2030 an 8,000-kilometre (5,000-mile) band of vegetation will stretch from Senegal on the west coast to Djibouti in the east,1 helping to reverse desertification and improve food security for the people of the area. Here are five spectacular ways in which the Great Green Wall of Africa is influencing both the natural world and the lives of people living in the Sahel region.
In Ethiopia, native tree species – especially frankincense – are contributing to the success of the Great Green Wall (GGW). The country has experienced severe deforestation2 in the last 50 years, with climate change and poverty forcing the area into a vicious cycle. The necessity of using wood for fires and building materials means that few trees in the worst affected areas have a chance to reach maturity before they are felled or grazed by cattle.3 This exacerbates the decline in soil quality, shade for other crops, and protection from desert winds.4
The GGW project and its partners, such as the UK-based charity Tree Aid,5 are working to restore Ethiopia's once-lush forest cover by helping local communities to plant native species instead of relying on fast-growing but damaging water-hungry species such as eucalyptus.6 Native species being planted include Cordia africana, Milettia ferruginea7 and Boswellia papyrifera, better known as frankincense. Helping these trees grow to maturity has improved water retention in the soil and provided compost and shade for other crops. The project has also given local residents ways to make a living from the forests without cutting them down. The United Nations Convention to Combat Desertification (UNCCD) says that almost 220,000 jobs have been created in the area as a result of the one million hectares (2.5 million acres) of land that have already been restored.8
"The lives of many families have changed because of the additional income they get from selling frankincense,” says 26-year-old local woman, Birtukan Gebeyehu, who has been working with Tree Aid to grow this sustainable crop. "When you come to our area, trees are the beginning and the end. The whole system exists because there are trees.”9
The key to the success of the Great Green Wall will be in how it maximises local expertise. In Senegal, that means the development of spectacular, circular-shaped community gardens, called tolou keur.10 Partly driven by the Covid-19 pandemic, to help villagers become more self-sufficient when the country's borders closed to imports, these gardens are the brainchild of a Senegalese agricultural engineer, Aly Ndiaye.11 The outer walls are planted with drought-resistant trees and shrubs – including papaya, mango and moringa – and their size helps protect the smaller food-producing species planted in the inner circles. The leaves of the larger plants offer shade from the sun and shelter from the wind for those growing beneath, while the circular beds mean their roots grow inwards, which traps liquids, improving water retention. For some, a solar water pump helps with water distribution, while others rely on traditional irrigation canals.
"A thousand tolou keur is already 1.5 million trees,” Ndiaye says, envisioning a string of spiral gardens sprouting across Senegal. Less than a year after the first tolou keur was established, around 24 of these gardens are flourishing.12
According to the UNCCD, 16 million trees have been planted in the West African country of Burkina Faso as part of the Great Green Wall.13 In a country where 86% of the population relies on natural resources to survive and 60% on firewood for heating and cooking,14 poverty and hunger have forced deforestation in the wake of increased and prolonged droughts and floods.
As part of the GGW, Tree Aid has been helping local communities to produce non-timber forest products or NTFPs – products which can be harvested from trees without having to cut them down. The leaves of the baobab, for example, are full of iron and at the peak of the dry season its fruit provides calcium and vitamin C.15 Beside baobab leaves and fruits, these NTFPs include shea nuts, honey from bees pollinating the trees' blossom, African locust bean seeds and neem seeds. Village communities have also established nutrition gardens - small plots planted with baobab and moringa seedlings that produce food for the community to both eat and to sell.
According to the charity's data, the Swiss-funded four-year project reaped staggering results: a 42% reduction in chronic infant malnutrition and an increase in household incomes of 161%, which coincided with a 24% increase in large trees across the project sites, equating to an estimated 442,930 new trees across the project area.16
At Minawao refugee camp in north-eastern Cameroon, what was once encroaching desert is now a lush sea of green – another brick of forest in the Great Green Wall. The area is home to 60,000 refugees who have fled the Boko Haram insurgency in neighbouring Nigeria since 2013.17 The arrival of so many in what was already an arid landscape hastened desertification as more trees were felled for building and firewood. In 2018, a nursery was established to reforest the area. During the following four years, the community planted 360,000 saplings, becoming stewards to a flourishing area of vegetation that stretches over 100 hectares (250 acres).18 Now, the first trees planted are providing shade in which families can grow other crops.
"The trees bring us a lot,” says Lydia Yacoubou. She!s a refugee from Nigeria who manages the tree nursery, propagating saplings of fruit trees, moringa and acacia for people to plant around their homes. "First, they provide the shade necessary to grow food. Then, the dead leaves and branches can be turned into a fertiliser for cultivating. Finally, the forest attracts and retains water. Rainfall has even increased.”19
The Koulikoro region of Mali has seen the loss of 86% of its forests in a single decade. As part of the Great Green Wall, Tree Aid and other partnering charities are working with local communities to restore the forests of the region. This, in turn, will provide those communities with increased food security and better soil for crops.
While some saplings have been raised for planting, a key focus has been on regenerating 60,000 existing trees.20 "It's very possible to restore trees to a landscape without planting any trees,” says Jean-Marc Sinnassamy, a senior environmental specialist with the Global Environment Facility.21 "This is also a sustainable way of regenerating agroforestry and parkland.”
Regenerating trees relies on identifying and cultivating the stumps of native species that have been felled but are still capable of regrowth.22 The advantage of this method of reforestation is that it does not require the raising and establishing of fragile saplings, which can fail easily in arid conditions.
The Great Green Wall is a truly epic undertaking. While it's true that not every project established as part of the drive to reforest the Sahel has been successful, there are plenty of reasons to believe that the plan can succeed. When the resilience of plants is matched by the dedication of the people looking after them, it seems that even the driest desert might flourish.
This article was commissioned as part of 'Our Green Planet'. This is a digital initiative, from BBC Earth in association with The Moondance Foundation, to raise awareness for the beauty and fragility of our planet’s green ecosystems. Discover more here. #OurGreenPlanet.
Featured image © Xavier Bourgois | UNHCR
1. Great Green Wall 2. Rainforests 3. France 24. 4. Academia 5. Tree Air 6. France 24 7. Ecosia 8. Unccd 9. Tree Aid 10. Atlas Obscura 11. Wider Image 12. Aljazeera 13. Unccd 14. Geographical 15. We Forum 16. Tree Aid 17. Borgen Project 18. UNHR 19. UNHR 20. Tree Ai 21. National Geographic 22. Smith Sonaian Mag