No abstract

No abstract

No abstract

No abstract

The challenge for low-rainfall plantation forestry is to develop financially viable plantations using hardy species that produce commercial products as well as delivering environmental benefits. Since 1999, forest research agencies have co-operated on tree improvement for dryland southern Australia through the Australian Low Rainfall Tree Improvement Group (ALRTIG). A small number of key species, including hardwoods (tree-sized eucalypt species), softwoods (Pinus brutia, P. pinaster and P. radiata) and two mallee eucalypt species yielding foliar essential oils were selected for genetic evaluation and improvement. Selection was based on their adaptability, growth rates, yields of potential commercial products, and availability of reliable information and genetic resources. Improvement for the hardwood and softwood species aims to develop breeds that will maximise the net present value (stumpage value less growing costs) of logs produced on rotations of 20-40 y. Breeding will be based on recurrent selection for general combining ability, primarily in open-pollinated breeding populations based on selections from the best natural provenances and planted stands. A total of 29 provenance-progeny trials of the key species have been established across a range of dry land sites. These trials are now yielding information on the genetic control of growth, stem form and branching traits. This will enable production of genetically-improved planting stock through later conversion of some trials to seedling seed orchards and development of clonal seed orchards. Interim seed production areas based on planted stands of known best provenances have been developed for short-term production of somewhat-improved seed, and genetic gain trials to compare these seed sources with unimproved material have been established.