WIT RepositoryAchieving effective Rhododendron control by investigating novel methods of forest vegetation managementEdwardDalyauthorIn Ireland one of the most serious invasive alien species which poses a threat to local biodiversity, particularly to our native woodlands, is Rhododendron ponticum L.. Rhododendron was first introduced to Ireland during the 19th century as an ornamental garden plant and has since become an established invasive species throughout Ireland. Rhododendron has also, in recent decades, become a significant management issue in plantation forests throughout Ireland. This study sets out to improve our understanding of the auto-ecology and invasion dynamics of rhododendron in Irish forests and to investigate control options to inform future rhododendron management plans. The study was divided into three broad areas. The first study sought to investigate the efficacy of a recently discovered Irish isolate of the fungal pathogen Chondrostereum purpureum as an inhibitor of rhododendron and Betula pendula (birch) sprouting in Ireland. The treated stumps were monitored for fungal colonisation and adventitious sprouting for the ensuing 18 months. The results demonstrated that a combination of mechanical cutting and the subsequent application of C. purpureum is not an effective method of vegetation management for either rhododendron or birch. As a successful primary invader, rhododendron is often found in areas when recent land management activities have taken place. Disturbed substrate coverage and the absence of predators provide rhododendron with optimum regeneration conditions. Many land management practices (particularly in a forestry situation) expose soil. To assess how the disturbance of vegetation relates to successful rhododendron establishment the degree to which the depth of substrate affects the germination of rhododendron seeds was tested. This second study demonstrated that even small decreases in forest litter depth, sufficient to expose bare substrate, facilitates rhododendron seedling establishment. The third study set out to investigate whether the prevention of grazing of native scrub species in woodland sites could be used to prevent the spread of rhododendron. The findings to date suggest that fencing does increase the survival of native scrub species birch and Ilex aquifolium (holly). Also of note, in some of the plots, the holly and holly/ birch mix have successfully suppressed the re-growth of rhododendron. In conclusion, rhododendron has become a huge problem in plantation forest habitats and in order to control it effectively and economically an integrated pest management strategy will have to be employed utilising a mixture of novel bio-controls, innovative management strategies exploiting weaknesses such as seed longevity, viability and litter depth, and ensuring that other plant species can compete free of grazing pressures.*NONE OF THESE*2014Waterford Institute of Technology;School of ScienceThesis

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