Forest genetic resources are the heritable materials maintained within and among tree and other woody plant species that are of actual or potential economic, environmental, scientific or societal value. Trees are the foundation species of forest ecosystems and many of the world’s 58 000 tree species are also an important component in other ecosystems, such as savannas and agricultural landscapes. Most tree species have high levels of genetic diversity, offering great potential for increasing the production of both wood and non-wood forest products, as well as for improving the provision of environmental services. However, this potential remains largely untapped.