A tenth of the world's known tree species face extinction, according to a global survey by conservation groups. The three-year survey, the first of its kind, found out more than 8,750 of the 80,000-100,000 identified tree species were at risk of extinction, the main threat from the destruction of habitats through timber felling and forest clearance. Publication of the World List of Threatened Trees, compiled by the World Conservation Union (IUCN) and World Wide Fund for Nature (WWF), was timed to coincide with a meeting of the Intergovernmental Forum on Forests.