Temps de lecture :2 minutes
The sky darkens and fills with a reddish dust; the horizon turns an orange colour and visibility lowers to a few dozen metres: Beijing, capital of one of the world’s leading powers, is paralysed by a sandstorm. These storms can strike over several regions, covering an area of up to 800,000 square kilometres (more than that of France) and affecting 250 million people. In one night, a storm can deposit 300,000 tons of dust onto the capital. Yet the nearest desert is 800 kilometres away.
It’s an old and natural phenomenon, and is not limited to China. But in Beijing, the number of sandstorms has increased sixfold in 50 years, and today there are a dozen a year. They are blamed on the degradation of land related to over-pasturing and deforestation, which causes soil erosion and the release of dust into the air. Moreover, the reduction in plant cover modifies the water cycle and decreases precipitation. The storms are therefore one of the manifestations of desertification, which, by hindering agriculture, threatens the food supply of 1,5 billion people in the world.
The most effective protection against this phenomenon is the forest, which fixes the soil and stops dust forming. Numerous reforestation programmes have been set up to combat it. In China, the most famous of them is called the Great Green Wall: it stretches over more than 4,000 kilometres and its construction should last until 2074.
In Africa, more limited and scattered “green belt” projects have encountered some success, in Mali and Mauritania for example. Around Nouakchott, the progression of the dunes has been stopped thanks to a system fences designed to block the build-up of sand while the plant cover develops. Woods serving as windbreaks have also been planted. Plantations also promote the development of agriculture by fixing the soils or as pastureland, and thus enable local communities to participate in the programmes: a guarantee of their success.
Extrait du livre « Des forêts et des hommes » rédigé par la rédaction de GoodPlanet à l’occasion de l’année internationale des forêts et disponible aux éditions de la Martinière.