The extent of forest in dryland biomes

Dryland biomescover two-fifths of Earth’s land surface, but their forest area is poorly known. Here, we report an estimate of global forest extent in dryland biomes, based on analyzing more than 210,000 0.5- hectaresample plots through a photo-interpretation approach using large databases of satellite imageryat (i) very high spatial resolution and (ii) very high temporal resolution, which are available through the Google Earth platform. We show that in 2015, 1327 million hectaresof drylands had more than 10% tree-cover, and 1079 million hectarescomprised forest. Our estimate is 40 to 47% higher than previous estimates, corresponding to 467 million hectaresof forest that have never been reported before. This increases current estimates of global forest cover by at least 9%.