• Advanced and conventional methods for vegetative propagation of selected lines of oak and cherry.

      Douglas, Gerry C. (Teagasc, 1999-04-01)
      Oak and wild cherry (Prunus avium) are important broadleaved species. We have identified superior trees and conserved them by grafting. Methods for the large scale propagation of selected trees was evaluated using the technology of micropropagation. For oak we could establish shoot cultures from mature oaks but their propagation rate was too low and difficult for practical application. With wild cherry micropropagation is a feasible option for large scale production of selected material. Genetic fingerprinting technology was developed and applied to oaks. We showed that all material propagated vegetatively from oak was genetically similar to the original donor tree. Furthermore we used genetic fingerprinting to analyse a unique stand of elite oaks in Co. Westmeath and determined that the selected trees were not closely related to each other. The analysis of genetic fingerprints of 16 elite oaks also showed that five of them had an unusual pattern of DNA and one tree was identified as a rare triploid tree.
    • Alley coppice—a new system with ancient roots

      Morhart, Christopher D.; Douglas, Gerry C.; Dupraz, Christian; Graves, Anil R.; Nahm, Michael; Paris, Perluigi; Sauter, Udo H.; Sheppard, Jonathan; Spiecker, Heinrich (Springer, 2014-05)
      Context: Current production from natural forests will not satisfy future world demand for timber and fuel wood, and new land management options are required. Aims: We explore an innovative production system that combines the production of short rotation coppice in wide alleys with the production of high-value trees on narrow strips of land; it is an alternative form of alley cropping which we propose to call ‘alley coppice’. The aim is to describe this alley coppice system and to illustrate its potential for producing two diverse products, namely high-value timber and energy wood on the same land unit. Methods: Based on a comprehensive literature review, we compare the advantages and disadvantages of the alley coppice system and contrast the features with well-known existing or past systems of biomass and wood production. Results: We describe and discuss the basic aspects of alley coppice, its design and dynamics, the processes of competition and facilitation, issues of ecology, and areas that are open for future research. Conclusion: Based on existing knowledge, a solid foundation for the implementation of alley coppice on suitable land is presented, and the high potential of this system could be shown.
    • Ash dieback on the island of Ireland

      McCracken, A.R.; Douglas, Gerry C.; Ryan, C.; Destefanis, M.; Cooke, L.R. (Swedish University of Agricultural Sciences, 2017)
      On the island of Ireland it is estimated that there are over half a million kilometres of hedgerows (400,000+ km in the Republic of Ireland (Rep. Ireland) and 113,000+ in Northern Ireland (Northern Ireland). Ash (Fraxinus excelsior) is the second most important component, after hawthorn (Crataegus monogyna), in large proportions of this hedgerow network. In the Rep. Ireland over 20,000 ha of ash have been planted since 1990, primarily for sawlogs and to provide material for the manufacture of hurleys, which are used in an important national sport called hurling, and for camogie sticks used to play camogie. Ash dieback, caused by Hymenoscyphus fraxineus, was first identified on the island in October 2012 and since then has been detected at 306 sites (195 in Rep. Ireland and 111 in Northern Ireland). In the vast majority of cases the outbreaks have been on young, imported trees planted within the previous 5 – 6 years and it was evident that the pathogen had been introduced on trees for planting. On a small number of occasions there was evidence of the pathogen cycling within a plantation or moving from the plantation to infect neighbouring hedgerow trees. One possible mechanism by which the pathogen can build up sufficient inoculum is by the formation of apothecia on infected woody tissue high up on the plants. Rep. Ireland and Northern Ireland have strict policies of eradication and containment, as set out in the All-Ireland Chalara Control Strategy. To date over 2.1 million trees have been destroyed as part of an eradication strategy. It is considered that this prompt and far-reaching action has had a significant impact, significantly mitigating and preventing the rapid establishment of the pathogen and limiting its spread. The interventions since the disease was first confirmed have helped to protect the considerable investment in ash plantations of the last 20 years. The pathogen has not, however, been eradicated from the island of Ireland and it remains to be seen how widespread, and how quickly ash dieback will become established on the island of Ireland. The latest figures from the Republic of Ireland are that 733 hectares of ash plantation has been reconstituted with another species as a result of Chalara and this has cost our state €2.6 million so far; in addition, Chalara has been found and confirmed in all 26 counties of the Republic of Ireland to a greater or lesser extent. As a result the current policies and procedures regarding Chalara are under review.
    • Collection and rejuvenation of rare/scarce plants for the nursey stock industry.

      Murphy, R.F.; Douglas, Gerry C. (Teagasc, 1999-12-01)
      The main objectives of this project were: • Location of scarce/rare or new plants of high garden merit with tolerance to disease and pests • Rejuvenation. • Conservation of rejuvenated plants in the original gardens from which they were collected, at the Kinsealy Research Centre and in other selected locations. • Evaluation of the collection for a variety of uses – foliage, patio etc. over a range of different conditions and locations. • Plant identification. • Commercialisation of these plants by the trade to extend their range of plants.
    • Establishment of a bovine/Quercus silvopastoral experiment in lowland Ireland.

      Short, Ian; McAdam, J.; Culleton, Noel; Douglas, Gerry C. (CAB International, 2005)
      A silvopastoral experiment was established at Teagasc in County Wexford, Ireland, in 2002 with oak (Quercus robur L.) in an alley design and bovines. The experiment includes some treatments with trees produced with an enhanced root system (RPM). The treatments are: (1) control pasture plots; (2) RPM agroforestry (400 stems/ha); (3) conventional agroforestry (400 stems/ha); (4) RPM forestry (6600stems/ha; and (5) conventional forestry (6600 stems/ha). The trees were successfully established and cattle were successfully managed in combination with the trees. In the first year, height growth of bare-root oaks was significantly greater in the forestry treatment compared to the agroforestry treatment and, overall, RPM oaks were taller than bare-root plants. Among the RPM trees, the agroforestry system resulted in a greater stem diameter than those in the forestry plots. Height increment was greater for RPM trees than for bare-root trees.
    • High levels of gene flow and genetic diversity in Irish populations of Salix caprea L. inferred from chloroplast and nuclear SSR markers

      Perdereau, Aude C; Kelleher, Colin T; Douglas, Gerry C.; Hodkinson, Trevor R (Biomed Central, 2014-08-07)
      Background Salix caprea is a cold-tolerant pioneer species that is ecologically important in Europe and western and central Asia. However, little data is available on its population genetic structure and molecular ecology. We describe the levels of geographic population genetic structure in natural Irish populations of S. caprea and determine the extent of gene flow and sexual reproduction using both chloroplast and nuclear simple sequence repeats (SSRs). Results A total of 183 individuals from 21 semi-natural woodlands were collected and genotyped. Gene diversity across populations was high for the chloroplast SSRs (H T  = 0.21-0.58) and 79 different haplotypes were discovered, among them 48% were unique to a single individual. Genetic differentiation of populations was found to be between moderate and high (mean G ST  = 0.38). For the nuclear SSRs, G ST was low at 0.07 and observed heterozygosity across populations was high (H O  = 0.32-0.51); only 9.8% of the genotypes discovered were present in two or more individuals. For both types of markers, AMOVA showed that most of the variation was within populations. Minor geographic pattern was confirmed by a Bayesian clustering analysis. Gene flow via pollen was found to be approximately 7 times more important than via seeds. Conclusions The data are consistent with outbreeding and indicate that there are no significant barriers for gene flow within Ireland over large geographic distances. Both pollen-mediated and seed-mediated gene flow were found to be high, with some of the populations being more than 200 km apart from each other. These findings could simply be due to human intervention through seed trade or accidental transportation of both seeds and pollen. These results are of value to breeders wishing to exploit natural genetic variation and foresters having to choose planting material.
    • High levels of gene flow and genetic diversity in Irish populations of Salix caprea L. inferred from chloroplast and nuclear SSR markers

      Perdereau, Aude C; Kelleher, Colin T; Douglas, Gerry C.; Hodkinson, Trevor R (Biomed Central, 2014-08-07)
      Background: Salix caprea is a cold-tolerant pioneer species that is ecologically important in Europe and western and central Asia. However, little data is available on its population genetic structure and molecular ecology. We describe the levels of geographic population genetic structure in natural Irish populations of S. caprea and determine the extent of gene flow and sexual reproduction using both chloroplast and nuclear simple sequence repeats (SSRs). Results: A total of 183 individuals from 21 semi-natural woodlands were collected and genotyped. Gene diversity across populations was high for the chloroplast SSRs (HT = 0.21-0.58) and 79 different haplotypes were discovered, among them 48% were unique to a single individual. Genetic differentiation of populations was found to be between moderate and high (mean GST = 0.38). For the nuclear SSRs, GST was low at 0.07 and observed heterozygosity across populations was high (HO = 0.32-0.51); only 9.8% of the genotypes discovered were present in two or more individuals. For both types of markers, AMOVA showed that most of the variation was within populations. Minor geographic pattern was confirmed by a Bayesian clustering analysis. Gene flow via pollen was found to be approximately 7 times more important than via seeds. Conclusions: The data are consistent with outbreeding and indicate that there are no significant barriers for gene flow within Ireland over large geographic distances. Both pollen-mediated and seed-mediated gene flow were found to be high, with some of the populations being more than 200 km apart from each other. These findings could simply be due to human intervention through seed trade or accidental transportation of both seeds and pollen. These results are of value to breeders wishing to exploit natural genetic variation and foresters having to choose planting material.
    • High levels of variation in Salix lignocellulose genes revealed using poplar genomic resources

      Perdereau, Aude C.; Douglas, Gerry C.; Hodkinson, Trevor R.; Kelleher, Colin T. (Biomed Central, 2013-08-07)
      Background: Little is known about the levels of variation in lignin or other wood related genes in Salix, a genus that is being increasingly used for biomass and biofuel production. The lignin biosynthesis pathway is well characterized in a number of species, including the model tree Populus. We aimed to transfer the genomic resources already available in Populus to its sister genus Salix to assess levels of variation within genes involved in wood formation. Results: Amplification trials for 27 gene regions were undertaken in 40 Salix taxa. Twelve of these regions were sequenced. Alignment searches of the resulting sequences against reference databases, combined with phylogenetic analyses, showed the close similarity of these Salix sequences to Populus, confirming homology of the primer regions and indicating a high level of conservation within the wood formation genes. However, all sequences were found to vary considerably among Salix species, mainly as SNPs with a smaller number of insertions-deletions. Between 25 and 176 SNPs per kbp per gene region (in predicted exons) were discovered within Salix. Conclusions: The variation found is sizeable but not unexpected as it is based on interspecific and not intraspecific comparison; it is comparable to interspecific variation in Populus. The characterisation of genetic variation is a key process in pre-breeding and for the conservation and exploitation of genetic resources in Salix. This study characterises the variation in several lignocellulose gene markers for such purposes.
    • Vegetative propagation of dieback-tolerant Fraxinus excelsior on

      Douglas, Gerry C.; Namara, J.M.; O'Connell, K.; Dunne, L.; Grant, Jim (Swedish University of Agricultural Sciences, 2017)
      Ash trees which are tolerant to Hymenoscyphus fraxineus may be selected in all age classes among heavily infected populations. They may be produced also by controlled crossings of disease tolerant trees, because the genetic component of inheritance for disease tolerance is high. For mature and juvenile plant material, the deployment of disease tolerant genotypes could be potentially achieved by vegetatively propagating selected genotypes. We describe a system to vegetatively propagate selected ash genotypes and we discuss the prospects and options for using vegetative propagation on all age classes of trees. Mature trees were rejuvenated through the process of micropropagation to establish mother plants in large trays which were cut back repeatedly (hedged) to produce at least two crops of cuttings per year. The rooting capacity of ten genotypes was tested by a commercial nursery over a period of three years, to assess the feasibility of using hedged mother plants for efficient propagation. Commercial practise was to treat cuttings with 0.25% IBA, insert them in plug pots and maintain them covered with fine plastic within low plastic tunnels in a non heated greenhouse and without supplementary heating at the cutting base. In the first year, the mean rooting rate was 53 % for the first crop of cuttings and 35 % for the second. In the second and third years the rooting rates improved to over 80% for each crop of cuttings as experience was gained in handling the material. Rooting rate varied among the genotypes. We assessed the growth and development of micropropagated ash trees in the field from an observation clonal trial, consisting of four mature genotypes which had been established in 2002 in five replicate plots. The micropropagated trees were generally similar in height and dbh to seed derived control trees and developed normally. These observations are discussed in the context of using vegetative propagation as a tool in breeding and for the large scale deployment of ash with tolerance to H. fraxineus.