07 October 2022

Birch Breeding in Europe

A group of birch breeders from around the Baltic Sea met in Helsinki on the 6th of September. The purpose of the meeting was to share experiences and progress in tree breeding between countries. Funding was provided by the Nordic Forest Research organisation (SNS).

Oliver Sheridan and Grace Jones from Teagasc both attended the meeting.  The Teagasc birch breeding program is largely coordinated by Oliver, whereas Grace studied birch during her PhD and now works with Sitka spruce continuous cover forestry.

Group photo in front of a birch “realised-gain” demonstration on day two

On the first day we travelled to LUKE’s tree breeding station Haapastensyrjä, where there were numerous large greenhouses and an extensive planted area of interesting cultivators.  LUKE is Finland’s National Natural Resources Institute, and has a range of sites and offices, yet this station was close to Helsinki and had some excellent birch examples.  After a casual meet-and-greet with coffee, the key organisers Mateusz Liziniewicz (from Skogforsk, Sweden) and Matti Haapanen (from LUKE) gave a welcome and introductory presentations about forestry and birch breeding in their respective countries.  The day featured many presentations, to provide national forestry context and describe how far each members birch breeding work had progressed.  We were also fortunate to get perspectives from Poland, Estonia and Latvia, and hear about specific projects and research.

It was apparent during the sessions that Finland has some very impressive birch stands, and we were lucky to see them with the experts involved.  Finland’s birch tree breeding program has been consistently selecting birches from before the 1960’s, whereas many of the other represented countries started after 1980.  Poland and Ireland’s birch improvement programs have been running for just over 20 years, selecting a range of plus trees from around the country and creating controlled crosses.  Estonia had some intermittent birch improvement efforts, but then struggled getting seed from seed orchards.  Each country had unique challenges and ideas.  Of the two main European birch species for timber production, silver birch has been the main focus of tree breeding for most participants.  In Ireland there was a larger native population of downy birch than silver birch, and so we are rather unique in focusing on downy birch.  The Forestry Research Institute of Sweden (Skogforsk) has also bred some downy birch, but this work is intermittent.  

Oliver Sheridan presenting about Irish Forestry and birch breeding, next to Mateusz Liziniewicz

Day two started in Tampere, about 2 hours north of Helsinki.  We first visited the plus-tree “E1970”, selected as a plus-tree since the stem was straight, large, and had small branches.  We later saw some offspring from this tree, and they also had nice straight stems and reasonable growth.  Tree breeding takes advantage of similarities between relatives, to try and create a population of trees with better traits than the total population they are selected from.  Seeing both the parents and the offspring is a really great way to illustrate this.

Alongside some interesting differences, there were many similarities between our countries, not surprising considering we’re all nearby European countries.  One common theme was the dominance of conifers in plantation forestry, and this is also a trend globally.  Birch was at most 25 % of the standing forest volume, and only 3.4 % in Ireland.  In some countries birch is mostly used for fuel or pulpwood, yet there seems to be more commercial interest in birch when there is a reliable domestic market; many Baltic countries have veneer mills that process birch.  Birch may become even more important due to increasing considerations for biodiversity, forest resilience, and changing climatic conditions.

Breeding programs can select birches that are more suitable for certain wood products (like veneers), select a range of birches to increase genetic diversity, and breed for a range of growing conditions and resistance to certain forest pests.  One major benefit of birch is that it can have relatively short breeding cycles and short genomes.  This means it is possible to have many generations in a relatively short time-span, and if genetic markers are found we can see if individuals will likely have certain traits.  In general terms, there may be DNA sequences (genetic markers) that are more common in individuals that have desirable form or growth (traits).  Here whole genome analysis could determine if an individual has inherited genes for better trait performance, instead of waiting until the tree is fully grown.  Nearly all the participants had considered traits like size, straightness, and branching, yet less than half of the participants were breeding birch for wood or fibre traits: wood density, hardness, fibre length, grain angle, etc.  Genome analysis could change this if genetic markers are identified that relate to wood traits.

Outdoor progeny trial (left) and indoor seed orchard with ladder to collect seeds (right)

Overall, it was nice to hear how the respective countries’ birch breeding efforts were going.  Participants spanned from Norway to Poland, and it was excellent that so many could attend this meeting.  No doubt we are all eager to hear everyone’s progress over the coming years, and hopefully we can meet again in the future.

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