The sustainable management of forest resources became an indispensable prerequisite for any policy addressing the actual and future challenges of globabl development. Forests and other tree resources are essential for the provision of ecosystem services and contribute largely to future food security, livelihoods and ecosystem stability. Forests and any other trees outside the forest play a relevant role all three great UN conventions (on Climate Change, on Biodiversity, and on Combatting Desertification). The policy processes to implement the measures in these conventions on sub-national, national, regional and international level are extremely complex. This complexity comes, among other factors, from a blend of different sectoral and national interests, from a large number of scientifically not yet entirely resolved issues and a wide range of different biophysical, social, cultural and political conditions all over the world.