Deep learning identifies more than 1.8 billion trees in the Sahara, Sahel and sub-humid zones - Geographical Magazine

A combination of high-resolution satellite imaging and'deep learning' has identified more than 1.8 billion trees across the West African Sahara, Sahel and sub-humid zone – significantly more trees than were previously thought to exist in the region. The collaboration between NASA and several geoscience departments across the world used 11,128 satellite images from four satellites to count individual trees across 1.3 million square kilometres. The deep-learning approach has, for the first time, allowed researchers to identify individual trees across the dryland expanse. Because of the absence of closed canopies, many parts of the Sahara and the Sahel have previously been mapped with zero per cent tree cover. 'You need high-resolution satellite images to be able to detect individual trees and not just to make estimations based on identified areas of canopy cover,' says Martin Brandt from the University of Copenhagen.