7 September 2018

WORLD BEST NEWS: New research sheds light on an old myth about deserts in Sahel

To mark The World Best News Campaign, The Secretariat for Development Cooperation at SCIENCE republish some of the World Best News in 2018 involving SCIENCE researchers. This news is redirected and translated by The Secretariat for Development Cooperation at SCIENCE from The World Best News.

During the seventies the desert was spreading in the Sahel-area which is a part of Africa just south of Sahara. Many thought it was the local small-scale farmers fault because they cut down the trees in the area to get firewood for coocking. It was even called "The Sahel-syndrome". 

Trees in cultivated fields in Mali. Photo by Martin Brandt, Department of Geosciences and Natural Resource Management

But new Danish research opposes this myth that African farmers' hunt for firewook makes the desert spread. Even though the population in the dry areas do cut down trees on the savannah, they also protect the trees and plant new ones on their fields and in their villages because the trees provides fruit and shade.

Actually you can see, the more people living in the dry areas, the more trees will appear up to a certain level. This a new study shows, which a group of Danish and foreign researchers have conducted at the Department of Geosciences and Natural Resource Management at University of Copenhagen, and which is published in the scientific journal Nature Geoscience.

Counting trees from space
The researchers have analyzed thousands of commercial sattelite pictures, which now for the first time have becomed accessable outside of NASA. The pictures are of high enough quality to be able to count every single tree and bush and in that way get a precise overview of the vegetation in large areas within and surrounding 40.000 villages.

Postdoc Martin Brandt was project leader on the project:

”It is a myth that the tree cutting by locals and grazing made the desert spread. Researchers have earlier known this from smaller studies in which you visited villages and saw that they do not cut down the trees but with our study, we can for the first time prove what happens in each village actually happens in the whole region,” he tells.

But how can it be that the Sahel-region earlier on was drying out? The researchers believe that it broadly can be explained by natural fluctuations. The boarder to the desert is not stabil but moves back and forth over time.

Thumbnail image: Malte Kristiansen, Verdens Bedste Nyheder

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