The commercial forester’s goal of better returns on shorter rotations, has particular appeal for all growers of broadleaves where the difference in price between firewood and veneer timber can be 100 fold, and the time between seed and harvest makes planting an act of faith. Although silviculture can help, it has long been recognised that improving the quality of the planting stock could hold potentially massive benefits for the countryside.
FTT’s Oak Group was formed to initiate and support research into the improvement of oak by selective breeding. The initial objective was to identify two hundred ‘elite’ oak trees selected for their excellent phenotypic characters: straight trunks, light branching, superior vigour and timber quality. Work at the Oxford Forestry Institute had also identified a link between large spring vessel sizes in the wood, and the presence of shake. All trees ‘selected’ were therefore microscopically assessed and of these, 100 trees were rejected as having large vessels. Acorns from the remaining 100 superior mother trees were collected over three years and seedlings raised at Forest Research’s nursery at Roslin. The nursery stock was planted in eight 1-2 hectare ‘breeding seedling orchards’ across Great Britain and Ireland during the winter of 2002/03.
The orchards will be managed (over 50 years) to exclude any obviously inferior lines and the resulting ‘improved’ acorns will become available for multiplication and release to the nursery trade. It is hoped that the seed orchards should begin to produce acorns within 20 years. Similar projects using tropical hardwood species have yielded up to 30% increases in average growth rates. Comparable results can be expected with oak. Funding for the research has been raised from a wide range of individuals, institutions and trusts including the Scottish Forestry Trust, the Dulverton Trust, Leverhulme Trust, Northmoor Trust and the Forest Service of the Republic of Ireland.
Oak Research at East Malling
A Defra/Forestry Commission funded broadleaved tree improvement project at East Malling Research has two main objectives relating to oak:
- To collect and propagate ‘plus’ trees of oak
- To characterise oak clones for a range of traits and form
Using FTT’s ‘Oak Register’, some 100 UK oak plus trees have been collected and grafted at EMR. Graftwood was collected between December and March using a shotgun to shoot down young, vigorous growth from the crown of the trees. For each plus tree, at least six replicates have been propagated on to two-year-old seedlings. Survival of clones has been very high, at around 85%.
The oak group established eight breeding seedling orchards in 2003 which are managed by the Northmoor Trust. Details of these can be read on the research reports for establishment (2003) (1.1Mb), year 2 (2004) (0.3Mb) and year 5 (2007) (3.8Mb).
Two Masters students carried out their dissertations in the oak breeding seedling orchard at the Northmoor Trust in 2008. Nick Evans from Imperial College Wye, investigated the form of young oak (download his dissertation (25 Kb)) and Jennifer Peters from the University of York, in collaboration with the Centre for Ecology and Hydrology, Wallingford, looked at the effect of exotic oak phenotypes on an associated community of herbivorous insects (download her dissertation (27 Kb)).
A possible means of estimating vessel sizes quickly and accurately in oak trees would be a great asset to tree breeders. Trees with large earlywood vessels could then be removed from breeding programmes as their progeny would be predisposed to a serious defect, shake (especially on traditionally shake-prone sites). This study aimed to determine whether measurements of acoustic velocity might discriminate between trees with large vessels and those with small ones. The results proved to be completely negative.