SELECTING THE MOST PROMISING SPECIES

One of NZDFI’s earliest and most critical tasks was to identify the durable eucalypt species believed to have the best potential in New Zealand 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

The two primary species which are the focus of tree improvement work are:

• E. bosistoana          Coast grey box
• E. globoidea            White stringybark

Secondary species which are part of our trials:

• E. argophloia           Western white gum
• E. camaldulensis     Red river gum
• E. cladocalyx            Sugar gum
• E. eugenioides         Thin-leaved stringy bark
• E. longifolia              Woollybutt
• E. macrorhyncha    Red stringybark
• E. notabilis               Blue Mountains mahogany
• E. quadrangulata   White-topped box gum
• E. tricarpa                Red ironbark

NZDFI began by working with a relatively large range of species to reduce the risks associated with certain eucalypts’ vulnerability, for example, to frost or pests and diseases. As time has gone on, we have identified some winners and losers: our major breeding efforts are focused on E. bosistoana and E. globoidea at present but as resources allow we plan to add at least one further species to the breeding programme. Our 2023 demonstration trial assessment identified E. macrorhyncha as the next most promising species amongst NZDFI's trial plantings.

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.