Irish Birch and Alder Improvement Programme
Improving the genetic quality of Irish Birch and Alder.
Two species of birch are native to Ireland; downy birch (Betula pubescens) and silver birch (Betula pendula). Until recently, birch (downy and silver) was not on the recommended species list for afforestation grants. Two factors have prevented the listing of birch as a recommended species; the poor stem quality of naturally regenerated birch and the poor survival and growth rates that has followed importation of seed from abroad.
However, experience from abroad indicated that birch had improvement potential. The development of birch as a commercial forest tree species supports government policy in the desire to increase diversity in Irish forestry, to increase the forest area in Ireland and to increase the broadleaf component of Irish forestry.
Common alder (Alnus glutinosa) also known as black alder or European alder is also a native species and is on the Forest Service Schedule.
The physiology of birch and alder means that they can be planted on land that would be less suitable for other broadleaf species e.g. oak. Birch has a short rotation period, about 40 to 50 years, in comparison to other native broadleaves. The current demand for birch is high, with estimated sales of 1.8 million plants annually. The rotation age for black alder is 50 to 70 years and estimated sales are 1 million plants annually.
20 years of tree improvement
The birch project began with an initial study ‘Pilot project for genetic improvement of Irish Birch’ (1998-2000). This has been followed by a series of other CoFoRD and FORGEN funding. The alder improvement programme was initiated in 2005 and currently the Irish Birch and Alder Improvement Programme is funded by Teagasc. In a recent CoFoRD review, birch and alder were confirmed as native species of high potential for improvement in an Irish context.
The overall objective of the research is the development of a sustainable supply of improved, adapted and healthy seed and plant material of birch and alder within the framework of the EU Forest Reproductive Material (FRM) regulations. The approach to develop sources of improved planting stock has been;
- Locating the best examples of mature trees (plus trees) of these species on which to base the improvement programme
- Collecting scion wood from plus trees for vegetative propagation by grafting
- Establishing clone banks to preserve the genotypes
- Establishing seed orchards
- Establishing progeny trials to assess the value of the trees as parents
A new purpose built multispan polytunnel at Teagasc Ashtown replaces the existing structure in Kinsealy to house the birch and alder indoor seed orchard collections. Assessment, management and collection of data will continue into the future for all of the progeny field trials.
It is imperative that when plus trees are selected in the wild that they are preserved. One way to ensure that they are not lost is to clone them. This can be easily done by asexual propagation e.g. grafting. The grafted plants are genetically identical to the original (mother) plant. A gene bank was established at Teagasc, Oak Park, Carlow, consisting of the full collection of birch and alder plus tree clones, with room to add new selections if required.
Research progress to date
- Birch and Alder Improvement Technology Update 6644 (PDF)
- The Improvement of Irish Birch Phase 1: Selection of individuals and populations (PDF)
- Progress in the selection and improvement of Irish birch (PDF)
- Sustaining and Developing Ireland’s Forest Genetic Resources: An outline strategy (PDF)
- Contact Oliver Sheridan, forestry researcher Teagasc