Management and use of ex situ genetic resources of some tropical Acacia species in Queensland

Genetic advancement of tropical Acacia species can be undertaken quickly with only limited resource inputs. Open-pollinated seedling seed orchards constituting conservation/breeding populations of Acacia aulacocarpa and A. mangium in north Queensland have been cycled within 6 years. Even after heavy phenotypic thinning, the first-generation seed orchards remain genetically diverse and constitute a valuable source of genetic material for several purposes. Realised genetic gain is already apparent for A. mangium, especially in reduced incidence of low forking. Promising A. aulacocarpa clones have been identified and are to be further evaluated; their rankings are stable across two very different trial environments. The genetic resources accumulated have also enabled exploratory production and testing of interspecific hybrids of A. auriculiformis and A. mangium. Alternative strategies for hybrid development are outlined. The methods developed for population improvement and use of hybridisation could be applied in all countries planting these species. Suggestions are made on measures required to ensure long-term conservation of genetic diversity ex situ.