The clearing of the world's forests has had the greatest effect on the earth's surface, 15 to 45 percent being what remains of the 6 billion of hectares that were 8,000 years ago (31). He emphasizes the importance of the forest for the medicinal uses of indigenous healers and for ensuring that the planet remains habitable by providing “ecological services” (34). He also discusses mapping growth and developing strategies to manage and conserve the rest of the planet's tropical and temperate forests. He gives the example of Japan where the introduction of effective tree planting legislation and policies helped the country restore its forests to what they are today (Mosley