Armed with a newly-completed PhD and findings that have already captured the interest of key industry publications, Radiata Pine Breeding Company (RPBC)’s newest recruit Duncan McLean has big plans for research that will benefit the future of Pinus radiata in New Zealand’s forest estates.

After completing a Master’s degree in plant breeding at Massey University, which included work on poplars and willows and their use in bio remediation and soil stabilisation, Duncan’s research interest was fortuitously diverted into forestry.

Duncan was introduced to RPBC’s Mark Paget, who had several potential research ideas for Duncan to consider working on. Having chosen a topic, Duncan received support from RPBC in the form of a PhD stipend while he undertook work on his thesis. Duncan was fortunate enough to be supervised by Te Whare Wānanga o Waitaha | University of Canterbury School of Forestry Professor Luis Apiolaza and his co-supervisor Associate Professor David Evison. 

“During my PhD my passion for forestry has grown,” says Duncan. “The challenge of working with really long breeding cycles and how you maximise your outputs over a long period of time really keeps me engaged.”

Simulating Deployment

One of the outputs of his research that he was most pleased with was being able to simulate the deployment phase of the programme.

“It was a good way to kick off the discussion about how we could boost the deployment of improved germplasm from the breeding programme to the production forest and how we could look at optimising things like seed orchards and the structure of the seed orchards to maximise the output from the breeding programme.  

“What really interested me about the programme itself is that it’s not just about breeding improved trees  – you’re also working within the deployment space too to try and get those improvements out into the production forest as quickly as possible. Both of those areas are equally important. 

“There can be a barrier to deploying new improved germplasm for many crop species for various reasons. In forestry, we must go through the process of committing new seed parents in the seed orchards which may compromise seed yield. Similarly, extensive trials have to be managed and assessed over several years prior to the wide-scale deployment of production clones.”

Big Data is Valuable to Gain Breeding Insight

The availability of good data is key in gaining valuable insights to improve breeding strategies, such as genotype by environment interaction, an interest that developed during his PhD studies and was encouraged by Professor Apiolaza. “With a better understanding,” says Duncan, “we could really be maximising genetic gain by understanding and exploiting those interactions to enhance production, particularly in the clonal deployment space.” One of Duncan’s key projects with RPBC will expand on this PhD research.

“I will take that research and have a look at some of the environmental variables that may explain these interactions, particularly for growth traits in radiata. Basically, we’ve got rainfall, soil types, altitude, aspect, silviculture and management methods, all these different influences that are happening in forest stands. It’s therefore quite hard to know what may be causing changes in genotype rankings between environments. To do that, we need to start including higher resolution environmental data into our genetic evaluation models. This includes things like rainfall and soil type to effectively look at what may be driving  changes in genotype performance over different environments.”

Technological advancements and the availability of data sets are set to transform understanding in this area, says Duncan. The initial data set Duncan used to investigate genotype by environment interaction in his PhD was limited in its geographic range but in his postdoctoral research he will have access to a more comprehensive data set.

Duncan will also be using a mixture of empirical data and simulated data to work on the issue of optimising the training populations to suit within-family selection and maximise the predictive ability of individual performance within families for genomic selection.

Preserving the Germplasm Archive and Genetic Diversity

Another of Duncan’s projects  focuses on RPBC’s germplasm archive.  His goal is to determine what RPBC needs to retain as seed and ortet collections in order to maintain a population that represents the genetic diversity of the wider germplasm collection.

During the establishment of a breeding programme, genotypes (genetically unique individuals) are selected from wild stands to form a genetically diverse breeding population. Breeders become caretakers for these diverse landrace collections, not only for the benefit of the breeding programme, but also for long-term conservation, just in case we have to go back to this collection in the future and seek new genetic diversity  in the event, for example, of a serious disease incursion or to manage future challenges due to changes in climate.

Despite the prevalence of Pinus radiata in New Zealand and Australian production forestry, the wider public may not  be aware that the species is endangered  in its native environment due to its limited natural distribution range and pressures from introduced pests. This means that some of the genotypes we are working with today, particularly from the Guadalupe and Cedros islands, may be the last remaining genotypes of their kind.   

In addition, much of RPBC’s extensive germplasm collection is stored in production forest stands across shareholders’ forests throughout New Zealand, many of which are approaching the age at which they are felled.

“These stands are essentially being removed,” Duncan explains, “so we need to decide what we  need to keep from this gene pool that underpins RPBC. The best way to imagine this is like a triangle: at the top, you have the elite production population, which has a low level of genetic diversity but high performance in terms of breeding values. Further down the triangle, you have the breeding population and then you get to the conservation germplasm at the base, which often includes unimproved and founder material, originating from native Pinus radiata stands, such as those on Cedros and Guadalupe Islands.”

The project also involves exploring whether RPBC can reduce the number of ortets in the archive to simplify the management of these resources and reduce duplication while still preserving essential genetic diversity; maintaining numerous in situ archives over decades can become difficult to manage well. “We’re looking at whether we can maintain the same level of genetic diversity with fewer ortets, which would help us allocate resources more efficiently without compromising long-term sustainability,” he says.

Supporting a Research Culture

Duncan values the openness of the RPBC team to consider new projects and  ideas. “I have different research ideas, like any researcher out there, and I feel like RPBC has an ear for it. They really want to hear it and they’re passionate about new ideas. It creates a positive and more vibrant atmosphere when we can bounce ideas off each other.” Duncan is excited to have the opportunity to work with his postdoc supervisor AgResearch’s Ken Dodds – a highly regarded animal scientist and statistical geneticist.

Duncan would also like to see others following his example and pursuing postgraduate forestry research. “There are a lot of kiwis who doubt themselves and don’t think they’re capable of doing a PhD, but they’re actually very, very capable.”

Duncan say she is grateful for the financial and technical support he and other postgraduate students receive from RPBC. “You finish your four-year forestry honours degree and you could step straight into a PhD programme, but you’ve got the temptation of those really cool forestry companies you can go and work for. It’d be nice to see some collaboration to get people into their Masters and PhD, to get that little extra bit of backing into the research space.”

Tree Breeding Legacy

As he works with RPBC’s archive of material and empirical data sets, Duncan says he’s acutely aware of the legacy of tree breeders who have come before him.

“You’ve got to think about all the people who have gone out of their own way to work in often difficult conditions measuring trees.You definitely take the guardianship of the data seriously to make sure that all the work that everyone’s put into this data set actually becomes fruitful. I’ve done quite a lot of field work and I know the kind of effort that goes into it and the attention to detail that’s required. I’m the one that gets to sit here and do the fancy data crunching, but there are a lot of vital people involved before it gets to that stage.”

A Lifelong Connection to Forestry

Duncan’s appreciation for the work that goes into forestry stems from his upbringing nearNelson on his family’s lifestyle property.Growing up, he observed the forestry lifecycle firsthand – from harvest and replanting to estate development. He also had the opportunity to plant native trees alongside his parents as they re-forested what had once been a sheep and beef farm.

During a recent visit to the valley where his family once lived, Duncan experienced a full circle moment. “I went down to the valley and looked up, and I could see all the pollen coming off the trees. These were the trees I’d seen planted as a kid. It was really cool to see that continuation,” he recalls.

Working for the Future

Duncan is acutely aware that much of his work today is focused on long-term benefits for others.

“A lot of the work we do isn’t for now; it’s for 25 years’ time, 50 years’ time - it’s for New Zealand’s future,” he says. “I really like that. You’re not planting for yourself. You’re never going to see the net value of that forest - it’s going to be your grandkids.  

He also reflects on how Pinus radiata trees are often undervalued. “We live around these trees all the time, but many people look at them purely as a production crop. People go past them and think ‘ugly monoculture,’ but what you’re looking at is technology. These trees have a really long story of hands that have touched them, since being brought here from their natural homes of California and Mexico. To lose that connection is a shame. To not see them as living beings is a shame.”

Learn More About Duncan’s Work

·     Forest Ecology and Management (https://www.sciencedirect.com/science/article/pii/S0378112724001993)

·     Tree Genetics and Genomes (https://link.springer.com/article/10.1007/s11295-023-01607-9)