Book excerpt: Globally, forest vegetation and soils are both major stores of terrestrial organic carbon, and major contributors to the annual cycling of carbon between the atmosphere and the biosphere. Forests are also a renewable resource, vital to the everyday existence of millions of people, since they provide food, shelter, fuel, raw materials and many other benefits. The combined effects of an expanding global population and increasing consumption of resources, however, may be seriously endangering both the extent and future sustainability of the world's forests. About thirty chapters cover four main themes: the role of forests in the global carbon cycle; effects of past, present and future changes in forest land use; the role of forest management, products and biomass on carbon cycling, and socio-economic impacts.