Species selected for genetic improvement

The NZDFI’s tree improvement programme focuses on five species. Having a range of species reduces the risk from biotic and abiotic threats, and increases the potential choice of suitable site types. Having five species will also enable hybridisation between some species, combining their best genetic traits.

The Top Five

The ‘Top 5’ species with the most potential for New Zealand dryland sites are:

• E argophloia          Western white gum
• E bosistoana         Coast grey box
• E globoidea           White stringybark
• E quadrangulata  White-topped box gum
• E tricarpa               Red iron bark

We have also established NZ seed stands for three more species: E. macrorhyncha (Red stringybark), E camaldulensis (Red river gum) and E cladocalyx (Sugar gum). Further tree improvement with these species is planned in due course.

Selection criteria

We selected species on a range of criteria. Some have performed well in earlier New Zealand trials, others were chosen specifically for their heartwood colour and ability to hybridise. All species meet the following criteria:

• Class 1 or 2 durability (Australian standard)
• good growth
• good stiffness and strength properties
• drought resistant
• relatively good frost tolerance
• established timber potential from experience in Australian markets.