Forests, trees and water in arid lands: a delicate balance

Abstract

In arid lands, where competition for water is acute, trees should be planted only when and where necessary and possible. Arid lands are among the world’s most fragile ecosystems, made more so by periodic droughts and increasing overexploitation of meagre resources. Arid and semi-arid lands cover around one-third of the world’s land area and are inhabited by about one billion people, a large proportion of whom are among the poorest in the world. Forests, trees and grasses are essential