Arid areas have more trees than previously thought

TREES LOOMNASA large in both environmental science and the wider social and political movement of environmentalism. Not for nothing are greens sometimes called “tree-huggers”. Generally, the arboreal news is gloomy, as large areas of forest are cleared and either burned or taken on a one-way trip to the saw mill. But a paper published in this week’s , by Martin Brandt of the University of Copenhagen and Compton Tucker of , America’s space agency, brings some welcome good news. A part of the world previously seen as lacking in trees has actually been shown to harbour almost 2bn of them.The area in question embraces the western end of the Sahara desert and the semi-desert Sahel region to its south. Few trees have shown up here in past surveys because such surveys have used satellite photographs that have insufficient resolution to spot individual trees’ canopies. Instead, they have looked for contiguous patches of green that represent woods and forests.