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2012 – Review of Work To Control Non-Native Invasive Plant Species

Most people suspected it but Met Éireann confirmed it, that “Summer 2012” was one of the dullest, wettest and coolest in many years. Despite these weather difficulties MulkearLIFE’s dedicated partners, the Office of Public Works and Limerick County Council, were able to treat substantial section of the Mulkear catchment for invasive riparian plant species.

Giant Hogweed and Himalayan Balsam, Mulkear River (Image: Ruairí Ó Conchúir)

Non-native invasive plant species are problematic throughout the Mulkear catchment. Limerick County Council, with support and guidance from MulkearLIFE, were able to treat a significant section of river in their area of jurisdiction during the months of March, April and May 2012. Over 20 km of river channel was treated by Limerick County Council using a boat mounted spraying system in the main channel of the Mulkear River. A truck-mounted system was used on the smaller tributary rivers. Regrettably, the rains brought treatment work to a halt after the 1st June 2012.

Limerick Co. Co.‘s Boat Crew, Mulkear River, March 2012 (Image: Glen Wightman)

Dense swarms of invasive plants, particularly of Giant Hogweed and Japanese Knotweed, alter the ecology and habitat of riparian zones by suppressing indigenous plant species. This results in a significant reduction in floral and faunal diversity and can in certain circumstances create a monoculture of one or two non-native species. Dense stands of Giant Hogweed, Japanese Knotweed and Himalayan Balsam can suppress and exclude other plants from riparian zones. Such excluded plants have traditionally played a critically important role in riverbank stabilisation. The loss of native riparian plants and the consequential destabilisation of riverbanks impacts negatively on biodiversity.

Limerick Co. Co.‘s Boat Crew, Mulkear River, March 2012 (Image: Glen Wightman)

MulkearLIFE’s other main project partner, the Office of Public Works has an ongoing treatment programme to control and manage Giant Hogweed and various knotweed species in their area of jurisdiction. The Office of Public Works completed treatment work on 24.1kms of river channel in the Newport and Annagh river catchments. In contrast to previous years, all work was completed on foot using knapsack sprayers.

The OPW’s NNIS Unit, Clare Annagh River, May 2012 (Image: Ruairí Ó Conchúir)

All treatment work is undertaken using the herbicide Glyphosate (sold under a number of brand names Roundup®, Gallup®, etc.) as it the only chemical applicant with the necessary approval for use near water. Both the Office of Public Works and Limerick County Council’s spray crews are trained in the proper use of herbicides and comply with all health and safety considerations. Great care is given during spraying operations to minimise any harmful damage to non-target species and fauna. Monitoring work by MulkearLIFE staff has shown that treated areas have reduced densities of invasive plants and a reestablishment of native species.

Considerable work on invasive plant species was also undertaken by the Mulkear Conservation Volunteers. Significant work was undertaken at various High Nature Value (HNV) sites, including Annacotty on the Mulkear River and above Bilboa Bridge on the Bilboa River, addressing Himalayan Balsam and Pheasant Berry.

Close-up of pheasant berry (Image: Ruairí Ó Conchúir)

Pheasant Berry is an emerging non-native invasive plant species, which is taking over large stretches of certain riparian zones in the catchment.

MCV members remove pheasant berry above Bilboa Bridge (Image: Glen Wightman)

MulkearLIFE also undertook considerable outreach work on invasives during 2012. This included working directly with other LIFE projects (IRD Duhallow – DuhallowLIFE and the CAISIE LIFE Project), our colleagues in IFI (Swords), the National Biodiversity Centre, Invasive Species Ireland, including presenting at the Invasive Species Ireland National Forum. More importantly, it included training and support to local development associations and Tidy Towns groups.

Castleconnell Anglers discuss techniques with OPW during study visit (Image: RÓC)

Perhaps most importantly, it included the hosting of the first ever seminar in Ireland specifically aimed at addressing community engagement in the control and management of non-native invasive plant species along rivers and water bodies.

Catherine Daly & Ruairí Ó Conchúir, NNIS Community Seminar, Nov. 2012 (Image: GW)

The seminar, which was significantly over-subscribed, was an overwhelming success. A second seminar will be hosted in the first half of 2013.

Field trip, NNIS Community Seminar, Nov. 2012 (Image: Glen Wightman)

MulkearLIFE looks forward to 2013 and our ongoing work to control and manage the NNI riparian plant species in the catchment. We look forward to working in partnership not only with our own Project Partners but also with the many groups and individuals who helped progress our work in 2012. We look forward to restoring many river banks into species rich riparian zones.

Species rich riparian zone, Bilboa River, above Blackboy Br. (Image: Ruairí Ó Conchúir)

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Mulkear LIFE, Inland Fisheries Ireland, Ashbourne Business Park, Dock Road, Limerick, Ireland
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