Project Update July 2024 - June 2025 - NZ Dryland Forests Innovation

Since our last Project Update ...

It’s been a year since we completed the case study ‘Marlborough’s Future is Durable - A regional development case study on the potential for a durable hardwood industry’.

Marlborough Case Study - NZ Dryland Forests Innovation

With a hiatus in significant long-term funding, much of our research work was paused. However, ongoing support from the University of Canterbury (UC) School of Forestry via their undergraduate summer scholarship and PhD programmes has seen some excellent projects continue, and we report on students' activities and progress in this Project Update.

In addition, in October 2024 we submitted a one-year project proposal to Forest Growers Research: ‘Selection and deployment of elite E. bosistoana for short-rotation hardwood forestry’. The application was successful and work began in March 2025.

Over the summer 2024-25, NZDFI supported two University of Canterbury (UC) summer scholarship undergraduate students, James Garrill and Lauren Booth, to undertake a permanent sample plot (PSP) re-measurement programme. In the latter part of the summer a third student, Sam Davis, also helped out

Repeated measurement of PSPs over a forest rotation is necessary to fully capture and understand the site characteristics that influence species’ performance. Our PSP network captures data across the different environments of NZDFI’s trial sites.

This contributes to developing regional stand-level models to assist forest growers and managers make informed decisions about species/site selection, silviculture and to calculate potential economic profitability.

With good weather over the summer, there were few delays and 258 PSPs were re-measured at 25 NZDFI trial sites located across Marlborough, Wairarapa, Hawkes Bay and Gisborne. Some new PSP’s were also established. In summary the students completed:

75 E. bosistoana PSPs plus four new PSPs
52 E. globoidea PSPs plus three new PSPs
Around 30 PSPs each of E. cladocalyx, E. macrorhyncha, E. quadrangulata and E. tricarpa.

The students also worked with Ruth McConnochie to assist with completing the first assessment of the 2021 E. bosistoana progeny trial at Gibbs property in Waipara, North Canterbury, and two of the 2012 E. bosistoana progeny trials at Dillons in Marlborough and McNeills in Hawkes Bay.

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In October 2024, UC and NZDFI submitted a proposal to Forest Growers Research for funding from the Forest Growers Levy Trust for the selection and deployment of elite E. bosistoana for short-rotation hardwood forestry. This was approved in December with Te Uru Rākau – New Zealand Forest Service also contributing funds. The project is also supported by the Marlborough Research Centre and Proseed NZ. Associate Prof Clemens Altaner is project leader, and is working with Frederick Anthonio, PhD candidate at the School of Forestry.

The project aims to identify elite new trees to expand Proseed’s commercial seed production of XyloGene® branded E. bosistoana seed. Producing more high-quality XyloGene® seed from Proseed’s clonal orchards will ensure durable eucalypt growers can scale up planting a durable hardwood forest resource with the best genetics available.

While selecting a small number of elite trees from a few top-performing families for seed production maximises short term genetic gain for deployment, it reduces genetic diversity. Genetic diversity is important in long-term tree breeding as inbreeding or self-pollination is known to cause a reduction in the germination and growth potential of resultant seed.

Currently, Proseed’s clonal seed orchards contain 15 families represented by a total of 22 clones. Assuming an equal proportion of seed from each family, the estimated gains from the top-ranked families in this clonal seed orchard compared to the unimproved breeding population is 11.4% for diameter at breast height (DBH) and 22.6% for heartwood content. The introduction of additional clones of elite trees will diversify the seed orchard and further advance genetic gain.

Two of NZDFI’s E. bosistoana breeding trials, planted in 2012 on contrasting sites, were unscreened and include 87 families requiring phenotypic assessment of all key traits. We plan to identify up to 10 elite families with superior growth, form and wood properties (i.e. heartwood quantity and quality). Top selections of trees from these families will be grafted by Proseed for deployment in the clonal seed orchard.

An analysis to rank and select elite families has been undertaken using growth and form data collected in summer 2024 at the Dillon (Marlborough) and McNeill (Hawkes Bay) sites, plus data collected from the JNL Ngaumu site (Wairarapa) in 2019. The means were ranked and the sum of the rankings for the two traits – growth and form – were calculated to produce an overall ranking of the families for each site.

The top 25 families for each site have been compared with the interaction of these families between the three sites There are 22 families in common among two of the sites. The five families shown in bold print in the ranking below are in the group of top-ranked families at all three sites.

Further analysis will calculate genetic and site correlations for these growth and form traits. The data was also used to select at least 10 trees of suitable size in each family at the Dillon and McNeill sites from which core samples could be taken for measurement of heartwood and extractive content.

Initially, around 780 trees from 81 families at the McNeill site and 770 trees from 80 families at the Dillons site, were identified for core sampling.

Marlborough Research Centre (MRC) contracted a crew of professional consultants and technicians to undertake the core sampling operations in April. This crew included Ash Millen and Ruth McConnochie, supported by Buck Forestry field staff Travis Gaffney, Kevin Ewing, Ili Naitini and Neori Vuidreketi. Frederick Anthonio also assisted the core sampling team by collecting and labelling cores.

Ultimately, 826 trees from 80 families were sampled at the McNeill site, and 751 trees from 80 families were sampled at the Dillon site. The core samples were transported to University of Canterbury School of Forestry Wood Technology Centre where heartwood and extractive content will be measured.

Special thanks to our landowners Susan Dillon at the Throne in Marlborough and Ben McNeill at Waimarama in Hawkes Bay. Thanks also to Juken NZ Ltd, Wairarapa.

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Contributor: Shaf van Ballekom, Proseed NZ

Proseed have propagated root stock ready for grafting new E. bosistoana selections for their clonal seed orchard based on the wood properties results from the 2012 Dillon and McNeill progeny trials. There is plenty of space within the orchard for these new clones. The existing trees have been flowering and producing plenty of seed with over 1,000,000 viables collected last year.

Further grafting of top selections of E. globoidea has not been very successful so full development of this orchard is constrained. The limited quantities of seed produced since 2021 have produced seedlings sold under the XyloGene brand. The new forests planted with these seedlings are showing significant gains in growth and form.

Welcome to Alfie Misena Torres

Alfie is a forester from the University of the Philippines with a theoretical and practical experience in forestry and environmental science. He joined the School of Forestry on 1^st May, 2025 and is currently developing a proposal about the utilization of durable eucalypt by-products under the supervision of Associate Professor Clemens Altaner. His research plan is to add value to eucalyptus processing residues with a focus on innovative high-energy solid and liquid fuels, and engineered wood products. Utilizing waste eucalyptus biomass can address solid waste disposal challenges, reduce greenhouse gas emissions, and increase the value of eucalyptus wood.

Update from Hasini Hewawitharanage

Hasini Hewawitharanage is from Sri Lanka and started her PhD in October 2023.

My research aims to investigate the molecular origins of growth stresses and wood collapse in Eucalyptus quadrangulata with a focus on uronic acids, the major charged groups in the cell wall. These negatively charged groups are present as galacturonic acid in the primary cell wall and as methyl-glucuronic acid in the secondary cell wall. Since growth stresses develop during secondary wall formation, this study hypothesizes that methyl-glucuronic acid may contribute to the generation of growth stresses through electric repulsion. Further, the role of galacturonic acid in wood collapse was assessed, as its concentration in the pit membranes could influence permeability and drying behaviour.

Gas chromatography (GC) following acid methanolysis was used to quantify uronic acid levels in samples with high and low growth stresses, as well as in samples with high and low volumetric shrinkage, to explore possible associations. Results showed that higher methyl-glucuronic acid levels were associated with increased growth stresses, while higher galacturonic acid levels were linked to greater wood collapse. This suggested that uronic acid might play a role in both, growth stress generation and collapse.

Further, X-ray fluorescence (XRF) analysis revealed significant differences in inorganic ion content in sap between high and low collapse groups, supporting the idea that ionic interactions influence water moment and mechanical stability.

Future work will explore the localization of these charged groups and ions using microscopy and investigate the genetic control of uronic acid.

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Progress Report: Shiva Pariyar

I am completing the third-year of my PhD studies at the New Zealand School of Forestry, University of Canterbury. Over the past two years, I have been working on developing an individual tree-level paropsine-based foliar insect herbivory in E. bosistoana breeding trials. This study is being conducted across three NZDFI trial sites in the South Island; Martin, Lawson, and Dillon. Between October 2024 and March 2025, I carried out fortnightly data collections using UAV-mounted LiDAR (Zenmuse L1) and multispectral imagery (MicaSense RedEdge-P Dual Camera). These efforts build on my previous UAV LiDAR data collection campaign undertaken at the Martin site during the 2023-2024 growing season.

In total, I have sampled 521 E. bosistoana trees, spanning a wide range of canopy conditions from completely intact crowns to severely defoliated individuals. In addition to capturing high-resolution UAV data, I clipped leaf samples, recorded precise tree locations, and measured key dendrometric variables such as diameter at breast height, tree height, and crown dimensions. These detailed datasets are critical for understanding the structural and physiological impacts of foliar insect herbivory over time. I am currently analysing these datasets to develop a robust predictive model that quantifies individual tree-level total-crown foliar insect herbivory using UAV LiDAR-derived structural metrics. The goal of this model is to provide a fast, efficient, scalable and objective method for evaluating defoliation severity across E. bosistoana stands.

This work holds significant practical value: tree breeders will benefit from the ability to identify more resistant families, clones, and provenances under insect pressure, enabling proactive genetic improvement, while forest managers can use the model outputs to implement timely silvicultural or pest management interventions. By linking tree health to productivity outcomes, I want my research to help optimise yield, maintain ideal rotation lengths, and ultimately enhance the resilience and performance of NZDFI’s Eucalyptus plantations under increasing biotic stress.

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Update from Frederick Antonio

Frederick Anthonio is from Ghana, and joined the School of Forestry in 2024.

My research project aims to identify genetic and environmental factors influencing decay resistance. Understanding these influences will support the production of naturally durable trees suitable for outdoor applications such as vineyard posts.

Phenotypic analysis for heartwood traits has been expanded to include the 2012 NZDFI breeding populations at Dillon and McNeill. With this addition, cores are now available for all eight breeding trials included in the study. Wood cores have been inoculated with both white-rot and brown-rot fungi to directly assess natural durability. LiDAR data has been processed to extract key topographic attributes for individual trees, representing environmental variables. While the durability trials are ongoing, I am currently developing predictive models that integrate genetic and environmental factors.

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Update from Milad Lezgi

My research explores the feasibility of using high-stiffness, naturally durable Eucalyptus bosistoana in mass timber applications. I began by evaluating the mechanical properties of 100-year-old New Zealand-grown E. bosistoana, including the modulus of elasticity, shear modulus, Poisson’s ratios, and strength properties in compression, tension, shear, and bending. Embedment strength and stiffness were also determined in both longitudinal and transverse directions, providing essential data for connection design.

I then investigated the bonding performance of 3-layer E. bosistoana cross-laminated timber (CLT) panels. While single-species E. bosistoana panels exhibited poor bonding performance, mixing it with a lower-density species, radiata pine, improved the results. I also applied different adhesives, but none of the tested adhesives (1C-PUR, MUF, PRF, and RF) met the requirements of the relevant standards.

Given these challenges, I have shifted focus to mechanical joints for laminate connection.

I utilized the off-cuts of E. bosistoana boards to manufacture wooden dowels, an approach that adds value to processing waste, and used them to produce dowel cross-laminated timber (DCLT) panels. I first conducted comprehensive dowel pull-up tests to evaluate spacing criteria, including end, edge, and inter-dowel distances, ensuring geometrical configurations suitable for both DCLT and general engineering connection design with E. bosistoana. I will assess the in-plane behaviour of DCLT panels made out of E. bosistoana as an adhesive-free engineered wood product, which has attracted attention due to its environmentally friendly approach.

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Final word from Paul Millen: The Australian Opportunity

Last October I attended the Forestry Australia symposium held in Ballarat in south western Victoria. The theme was ‘Healthy and resilient forests for our future’ and around 300 attended. It was also attended by a small group of protestors who set up outside the venue on the 1^st day of the conference.

They were protesting the continuation of logging in Victoria despite their success in 2023 in getting the closure of Victoria’s (and Western Australia’s) publicly owned native eucalypt forests to commercial harvesting.

This closure has resulted in a massive decrease in the native durable hardwood log supply resulting in many sawmills and wood processing businesses closing.

While there is significant funding to support local businesses that have been impacted, and to plant new plantations, there is no industry led strategy or plan to establish native durable eucalypt plantations other than by those involved in the ‘Durable Eucalypt Forum. This includes Heartwood Plantations based in Gippsland. The population of Melbourne is already five million and set to grow to eight million by 2050.

In my view, this presents New Zealand forest growers in the North Island a huge market opportunity to invest in growing durable eucalypt plantations to produce logs for export to Australia. As our closest neighbour, they are experts in hardwood processing and we have a long history of trade. There are many NZ forestry people working over there and some forestry companies are based in both countries already.

We really need to work with the Australians on this because we currently have an advantage due to the NZDFI Science team having worked tirelessly on durable eucalypt breeding, research and development. Now is the time to scale up establishing planting regional durable eucalypt plantations to create hardwood supply catchments that can supply both New Zealand and Australian markets.

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