Growing quality broadleaved trees

Growing quality broadleaves was the core message of the seminar and field day organised by Future Trees Trust (FTT) on 7 October. Founded in 1991, FTT is dedicated to improving tree quality in Ireland and Britain to ensure that all broadleaves are grown from seed that has been improved and qualifies to the highest standard demanded under EU regulations.

Essentially, tree breeding involves selecting offsprings of superior, or plus, trees and over time testing the best progeny or cuttings to produce quality trees which will have high yield and excellent form (straight stems and regular branching). In recent years, tree breeding objectives have been broadened to include resilience against climate change and disease.

Currently, the trust has tree improvement programmes for seven key native and non-native broadleaved species comprising ash, birch, cherry, oak, sweet (or Spanish) chestnut, sycamore and walnut. The FTT event included research updates and progress reports on tree improvement programmes with the emphasis on oak, birch, sweet chestnut and sycamore in Irish seed stands.

The real value of the project lies in the co-ordination of research across Britain and Ireland, which avoids costly and unnecessary duplication and, as a result, ensures value for money for organisations funding the various tree improvement programmes.

FTT supporters in Ireland include the Forest Sector Development Division in the Department of Agriculture, Food and the Marine (DAFM), Teagasc and Coillte.

DAFM’s Brian Clifford outlined the role of his section in supporting a sustainable and viable broadleaved forestry programme, the objectives of which include “extending the use of indigenous, well adapted and improved planting stock, in afforestation and reforestation”.

Oak

The long-term aim of FTT is “to ensure that by 2050, all broadleaved trees in Great Britain and Ireland are grown from seed that has been improved by conventional selection and breeding to a ‘tested’ or ‘qualified’ level,” said John Fennessy, chair of the FTT oak group.

Tested and qualified are the highest accepted seed origins in accordance with EU regulations. Improved trees will increase “the recoverable volumes of timber by up to 20% over current levels,” he maintained.

He outlined progress on the oak improvement programme, which dates to 1997. Potential improved material is selected from best (seed) stands making individual selections within these stands of plus trees.

Cuttings are grafted from plus trees which are used to establish clonal seed orchards. The FTT had established eight oak seed orchards in 2003; one in Rathluirc, Co Cork, with the remainder in the UK.

Selection of plus trees in the past was based on visual assessment, as straight fast-growing trees were chosen, which is still the case. However, this approach alone is no longer sufficient, as it fails to identify the actual quality of the wood hidden from view, including defects such as shake (cracks or splits in wood) which occurs in oak and sweet chestnut.

“A strong relationship exists between vessel size and shake,” explained John. “Original plus trees are now checked for vessel size and those over 160 microns are rejected,” he said. “Vessel size checks have recently been made by NUI Galway in many of the Irish plus trees previously unchecked.”

Chestnut

The FTT programme contains eight selected sweet chestnut seed stands covering 36ha. “Three are located in Coillte woodlands in Kerry, Waterford and Wicklow, while five are located in southern Britain,” said Karen Russell, an independent forestry consultant and secretary of the FTT chestnut group. “Four seed orchards have been established in Kilmacthomas, Co Wicklow, Mucklagh, Co. Wicklow, Torry Hill, Kent, and Shenmore, Herefordshire.”

While the core objective of this and other tree improvement programmes is to identify, conserve and utilise seed stands and outstanding plus trees, she said the project also aims to increase the quality, quantity and use of timber from coppice. Sweet chestnut is the only species on the project that responds positively to coppicing.

She also emphasised the importance of providing the industry with high-quality seed and seedlings to produce high end-use timber which is suitable for commercial use, including finger-jointing and glulam technologies.

Sycamore

The sycamore programme provides the highest degree of cross-national co-operation, as outlined by Teagasc’s Rodrigo Olave.

Seven seed stands have been registered in the Republic, five in Britain and one in Northern Ireland (NI). Two conservation collections of plus trees have been established by Teagasc in Ireland and Maelor Nurseries in England, while five clonal seed orchards have been established in NI, England, Scotland and in Ireland by None so Hardy Nurseries. In addition, two progeny trials are under way in Gloucestershire and Antrim.

Birch

The FTT event included a visit to the birch seed orchard at Ballymurn, which is a partnership between None-so-Hardy Nurseries and Teagasc. A commercial indigenous birch tree improvement programme was identified because imported seed from good-quality stands failed in Ireland “as birch is very closely adapted to the ecology of its origin,” explained Teagasc researcher Oliver Sheridan.

None-so-Hardy nursery manager John Kavanagh told delegates that the orchard was established in a large purpose-built tunnel to provide greater control against cross-contamination from outdoor sources of pollen, as well as accelerating seed production.

“The orchard consists of 90 individual clones replicated three times in a large purpose-built tunnel,” he explained. “The clones are planted in 50-litre pots at 1.0 x1.8m spacing and irrigated through a drip-feed irrigation system. Spacing will be increased as the plants get older and seed production should begin between three and four years.”

Long way to go

Summarising, the FTT programme, development officer Tim Rowland outlined future plans, including “pushing the limits of improved trees in difficult sites and producing studies into faster-growing species and timber properties”.

Seed production in species such as oak is irregular and while 2016 is proving to be an excellent mast year with an abundance of acorns, seed production can be low for periods as long as seven years. As a result, he maintains that “further research is required into vegetative propagation for infrequent seeding species”.

He also identified the need for further genetic studies into timber form, branching habit and shake to improve wood quality.

He was encouraged by the performance of the various projects in Ireland and Britain, but acknowledged that the programme “still had a long way to go”.

Minister of State with responsibility for forestry Andrew Doyle said that the €111.6m allocation for forestry announced in budget 2017 “will provide funding for over 7,100ha of new forests, almost 800ha more than the total area planted in 2015”. He maintained that this level of funding will support the construction of “110km of new forest roads and for forest management initiatives which will improve the productivity of our forests, while maintaining the highest environmental standards”.

The level of funding provided is also significant given the recent EU proposals on climate change mitigation, he maintained. “Payments under the new reconstitution scheme to help farmers affected by the winter storms of 2013 and 2014 will also commence in 2017,” he said.