Mitigation Measures for the Nationally Threatened Triangular Club-rush (Schoenoplectus triqueter)
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Clients: RPS-MCOS /Limerick County Council /Direct Route This rare and legally protected bulrush is recorded in Ireland only from the River Shannon and a few of its tributaries (the Maigue and Owenagarney rivers) in counties Limerick and Clare. There has been a dramatic decline of the species in Britain. The development of the Limerick Southern Ring Road, including the Limerick Tunnel, will impact populations of this plant within the Shannon estuary. BEC Consultants worked with RPS-MCOS and Limerick County Council to develop mitigation measures to minimise the impacts caused to this plant. BEC Consultants carried out an examination of the genetic variation in the native populations of Triangular Club-rush using molecular markers in an attempt to determine the population genetic structure and hence potential genetic erosion through the loss of certain colonies. Our results show very little population structure but considerable genetic variation, which was surprising given the species clonal spread and low seed set. Surveys of the distribution of the plant within the estuary have also been carried out. A sub-sample of Triangular Club-rush plants have been translocated to storage containers at the Botanic Gardens at Trinity College Dublin where they are monitored. BEC Consultants, working with Direct Route the project construction engineers, removed Triangular Club-rush plants from the line of the road. These plants are currently being stored in purpose built storage tanks and will be returned to the estuary following construction of the tunnel. |
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