The African Union’s Great Green Wall Project seeks to map trees to

Research Project Maps Trees in Africa in Effort to Stop Spreading Deserts

In an ecological use for algorithms, researchers have identified 1.8 billion tree canopies in West Africa’s Sehal and Sahara regions, the first time ever that trees have been mapped in detail over such a large area.

So how was it possible? Researchers analyzed a huge database of satellite images using artificial intelligence. They employed neural networks that are able to recognize objects, like trees, based on their shapes and colors.

To train it, the AI system was shown satellite images where trees had been manually traced. This involved lead author Martin Brandt going through the arduous process of identifying and labeling nearly 90,000 trees himself, beforehand.

In a review of the research, commissioned by Nature, scientists at New Mexico State University wrote that “it will soon be possible, with certain limitations, to map the location and size of every tree worldwide.”

Important Conservation Effort

In 2015, the number of trees on the planet was estimated at three trillion. This was scaled up from data collected in forests around the world. Because of a dearth of data from drier areas like the Sahel and Sahara deserts, the number underestimated tree cover in these regions.

The team was “very surprised” to find so many trees growing in dry areas, especially because understanding how much vegetation can be found in deserts is important for ecology.

“For preservation, restoration, climate change and so on, data like this are very important to establish a baseline,” says Jesse Meyer, a programmer at NASA who worked on the research in a press release. “In a year or two or ten, the study could be repeated… to see if efforts to revitalize and reduce deforestation are effective or not.”

Building a Great Green Wall

Along with counting the treetops, organizations in Africa have much bigger plans. They have introduced the idea and the actions of building a Great Green Wall across the central expanse of Africa to stop the expansion of the Sahara desert. In the past century, it has increased by 10 percent.

An entirely African-led initiative, the Great Green Wall is an ambitious project looking to grow an 8,000-kilometer (about 5,000-mile) natural wonder across the full width of Africa. Since 2007, millions of trees have been planted across the southern edge of the Sahara desert. Millions more are planned.

It was initially intended to be just a line of trees, stretching east to west, to help tackle the Sahara’s spread down south. However, the project, funded by the African Union, soon evolved into a variety of different environmental interventions, using a range of ecological tools to construct a belt of greenery across the continent. Although trees are still the primary focus, other methods are being used to help restore the land, based on the specific biogeographical needs of an individual area.

“Nigeria, Senegal, Burkina Faso, and Ethiopia have so far seen the most significant gains across the Sahel region. Over 17 million trees have been planted in Burkina Faso, equal to an area of about 31,000 acres. Nigeria has seen over 12 million acres of degraded land restored, while Senegal and Ethiopia have had similar levels of success.”

By the time the wall is complete, it will be the largest living structure on Earth, triple the size of the Great Barrier Reef, and is expected to help improve food security.

Africa expects that turning a huge swath of the Sahara desert into a green zone will create ecological security for future generations.

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