Choosing the most promising species
One of the NZDFI’s earliest and most critical tasks was to identify the durable eucalypt species believed to have the best potential in NZ dryland conditions. Information was gathered and analysed from the following sources:
- natural populations in suitable parts of Australia, and Australian research and expertise
- old established plantings in New Zealand
- New Zealand research and expertise
- other parts of the world where eucalypts have been adopted, including South Africa and some South American countries
- more recent plantings in Marlborough which were a forerunner to the NZDFI.
Species selected by the NZDFI
Five species have been selected as the focus for tree improvement work:
- E. argophloia Western white gum
- E. bosistoana Coast grey box
- E. globoidea White stringybark
- E. tricarpa Red ironbark
- E. quadrangulata White-topped box gum
A further small number of secondary contenders may be considered in future, depending on the performance of the primary five species. These include E. camaldulensis and E. cladocalyx.
The NZDFI believes it is important at this stage to work with a relatively large range of species, rather than narrowing its genetic improvement efforts down to only one or two species. This approach will reduce the risks associated with certain eucalypts’ vulnerability, for example, to frost or pests and diseases.
Species selection criteria
Some of the species were selected partly on performance in earlier trials; others were chosen specifically for their timber properties or ability to hybridise. All species meet the following criteria:
- Class 1 or 2 durability (Australian standard)
- Good growth
- Good stiffness and strength properties
- Drought resistance
- Relatively good frost tolerance
- Established timber potential from experience in Australian markets.