The recent acceleration of actions to conserve plant species using ex situ and in situ strategies has revealed the need to understand how these two approaches might be better developed and integrated in their application to tree species. Here we review some of the recent successes relating mainly to tree seed biology that have resulted in the development and application of innovative actions across five areas: (1) the expansion of living collections to conserve threatened tree species in sufficient numbers to ensure a broad genetic diversity in their progeny; (2) the generation of viability constants to enable estimates to be made of storage longevity of tree seeds in the dry state; (3) improvement in the diagnosis of tree seed storage behaviour through the development of predictive models, reliable prognoses of desiccation tolerance and use of botanical information systems, such as GIS, to correlate information on species distribution and their physiological characteristics; (4) advances in storage preservation biotechnology to enhance the future application of cryopreservation procedures to recalcitrant species in biodiversity hotspots where many are under threat of extinction; (5) integration of ex situ and in situ conservation approaches to ensure that best practice in horticultural and forestry are combined to maintain or enhance genetic diversity, especially in high value species and those with small and vulnerable populations. These actions can lead to greater impact if supported by greater efforts to create seed banks and to collate databases world-wide so that data, knowledge and collections are more available to the scientific, forestry and NGO communities. Throughout this review we have used examples from the mega-biodiversity countries of Brazil and China, as a way of illustrating wider principles that can be applied in many countries. Future development of current research approaches, the adherence to conservation policy and the expanding needs for education are also considered briefly.