Birch Improvement Programme
Birch (silver and downy) research progress to date
A survey was conducted during 1998/1999 to identify good birch stands and individual plus trees. Good stands of mature birch were rare and often the trees were in small groups or were scattered throughout an area. Most of the stands were unmanaged. Downy birch was more common than silver birch.
Three progeny/provenance trials were established in 2001. Seed lots from 33 provenances (B. pendula and B. pubescens) and 37 controlled crosses of plus trees (B. pubescens) and some overseas B. pendula material were included in the field trials. The trials were designed to field-test the value of the seed lots, to record tree growth in conditions representative of afforestation and for seed collection. Trees on one site were severely damaged by hares. The two remaining sites were assessed after 1, 2, 4, 6, 8 and 10 growing seasons for height, diameter and stem quality. The trial site in Tipperary was assessed again in 2014 prior to its first thinning.
Two progeny field trials were established in 2017 with plant material raised from seed collected from the Teagasc “qualified” indoor downy birch seed orchard. The trials were located in Waterford and Sligo. The Waterford site is a heavy well-drained soil while the Sligo site is a low-lying, blanket peat soil.
Teagasc Seed Orchards
In 2009 an indoor downy birch seed orchard was established at Teagasc Centre, Kinsealy. The seed orchard was housed in a large multispan polytunnel. The trees in the seed orchard were clones of 56 individual downy birch trees, selected after six growing seasons in the field trials. Protocols were established to manage the indoor seed orchard.
In 2012, the Teagasc indoor seed orchard was updated with 90 plus tree selections (downy and silver), based on data collected after 10 growing seasons from the Tipperary birch trial site. In 2013, this orchard (downy birch) was awarded the improved designation 'qualified' under an EU directive on the marketing of forest reproductive material. The Teagasc Improvement Programme is now working towards achieving the highest possible category under this directive ‘tested’.
In 2014, the research reached a stage in the Birch Improvement Programme where there was material suitable for commercial exploitation. Teagasc’s commercial partner None So Hardy Nurseries, with the support from the Department of Agriculture, Food and the Marine (DAFM) under the Forest Genetic Resources Reproductive Material: Seed Stand and Seed Orchard Scheme constructed a new purpose built, high-sided polytunnel to house the birch plant material supplied to them by Teagasc.
None So Hardy Nurseries have a supply of downy birch plants from both the ‘qualified’ and ‘selected’ categories suitable for planting from the improvement programme. Their new ‘qualified’ seed orchard started producing seed in 2017, with seed production increasing year on year, supplying sufficient seed to satisfy the demand for the home market.
Because of this long-term investment in forestry research, birch is now a grant-aided species. It can be planted under Grant and Premium Category GPC 8 as a pure timber crop if ‘qualified’ or ‘selected’ seed is used or under GPCs 9 and 10 for the Native Woodland Scheme where ‘source identified’ seed is also allowed.
Overview of seed categories
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Quality |
Name |
Description |
|---|---|---|
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^ ^ ^ ^ ^ ^ ^ |
Tested |
Tested seed derives from the selection of individual trees or stands which have been evaluated for genetic quality or, in comparison to accepted standards, have been shown to be superior. |
|
Qualified |
Qualified seed derives from the selection of superior individual trees. No testing has been carried out. |
|
|
Selected |
Selected seed is collected from stands showing superior characteristics: e.g. better form, growth rate, health. |
|
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Source identified |
Source identified seed comes from general or specific locations. No specific superior qualities recognised. |
Silver Birch (Betula pendula)
The survey conducted in 1998/1999 identified silver birch being less common than downy birch. As a result, very few plus trees of silver birch were identified for inclusion in the Teagasc Improvement Programme, certainly not enough to base entirely a native breeding programme. To augment the small number of Irish silver birch clones, scion material for 36 plus trees was obtained from our colleagues in the Future Trees Trust (FTT) birch group in Scotland in 2013. FTT has developed, under the control of Forest Research UK, four populations based on plus tree selections. One population is the South Scotland North England collection. This collection represents the best trees selected in stands of birch in an area bound by the rivers Clyde, Forth, Mersey and Humber. This is the closest geographically to Ireland.
Thirty five plus trees grafted successfully with two copies of each used to establish an indoor seed orchard in 2014 at Teagasc Research Centre, Kinsealy (and later relocated to Teagasc Ashtown). These plants have produced very little seed to date. When sufficient seed is produced by the plus trees in the seed orchard, the aim will be to establish a number of field trials to assess the material under Irish conditions.
In spring 2013, small amounts of open-pollinated (OP) (half-sibling) seed was also obtained from FTT, representing 12 different female parents from this collection. The plus trees were part of an indoor seed orchard located at the Northern Research Station, Scotland. The 12 families were kept separate throughout.
In winter and spring 2013/2014 respectively, three small observational field trials were established in Wexford, Mayo and Cavan with plants raised from the 12 different seedlots. The objective is to assess the suitability of the Scottish indoor silver birch seed orchard material for growing in Ireland in terms of growth traits and adaptability.
Main objectives of silver birch improvement are to:
- Increase the number of silver birch plus trees in the Teagasc indoor seed orchard
- Establish silver birch progeny field trials aimed at parental ranking to obtain additional genetic gain through rogueing poor performing seed orchard plus trees
- Determine if the seed production from the 35 Scottish silver birch plus trees in the Teagasc indoor seed orchard has potential in Ireland
- Obtain qualified category for indoor silver birch seed orchard and eventually leading to tested category
- Commercialise improved silver birch similar to the downy birch with NSH Nurseries
