MulkearLIFE has this week completed a major programme of tree planting at selected sites along the Mulkear River and various tributaries including the Dead, Clare and Newport Rivers. Areas selected for tree planting have included sites where rubble mats were built in 2011, artificial otter holt sites and sites where tree planting would improve otter habitat. In addition, planting occurred at sites of high amenity value and sites of High Nature Value (HNV).
Tree planting on rubble mat site, Mulkear River (Image: Ruairí Ó Conchúir)
Given the Mulkear’s long history of drainage dating back to at least 1874, large stretches of the Mulkear are devoid of any riparian tree cover. The riparian zone refers to the zone of vegetation either side of a river, a watercourse or water body. Riparian woodlands are one of the rarest native woodland types in Ireland. This type of woodland is threatened by drainage works and clearance activities, hence their management is of critical importance. Well-managed native riparian woodlands play an important part in conserving and expanding woodland biodiversity, in addition to providing habitats essential to the lifecycle of freshwater organisms. Building on work completed previously, MulkearLIFE has undertaken a considerable amount of work over the last two weeks to address this through the planting of hundreds of Irish sourced native trees to enhance the native biodiversity and a range of other project actions through the support and co-operation of Inland Fisheries Ireland and project partners, Limerick County Council and the Office of Public Works. The trees planted included ash, birch, willow, rowan or mountain ash and oak.
Trees planted on rubble mat site, Mulkear River (Image: Glen Wightman)
Good practice management of riparian vegetation provide a number of other benefits. Well managed river bank vegetation provides cover and foraging habitat for water birds, terrestrial invertebrates and for the European Otter, the population of which the project is working to increase through the Mulkear Catchment. The riparian can provide a valuable wildlife corridor linking fragmented or isolated habitats and thus it is critical that the zone be protected and enhanced where possible.
Pristine riparian zone – Upper Newport River (Image: Ruairí Ó Conchúir)
The protective function of native riparian woodland is particularly relevant to water quality, which also affects instream biodiversity value. The value of such riparian woodlands for the perspective of nature conservation is exceptional. In the Lower Mulkear and in the Mulkear Shannon confluence the riparian (or alluvial) woodlands provide an important refuge for woodland species. In addition, such woodland provide a vital conduit for the transfer of nutrients between terrestrial and aquatic ecosystems and play a vital role in capturing nutrients and silt which run off from adjacent lands.
Alluvial woodlands Mulkear-Shannon confluence (Image: Ruairí Ó Conchúir)
River banks which are protected by well structured vegetation invariably require less maintenance and repair and aside from the biodiversity benefit this also confers an important economic benefit. The continual repair and erosion of river banks has an economic cost to landowners and stage agencies charged with the maintenance of such work. In addition, the presence of well established native vegetation helps to reduce the opportunities for undesirable invasive species to become dominant. In addition, the increased hydraulic roughness provided by bank side vegetation can help to slow flood flows thereby reducing flood risk downstream.
In high amenity value areas which are in constant use by the general public, areas like Annacotty weir, the effective management of the riparian zone is also likely to result in an improvement in the visual amenity and public enjoyment of the watercourses. In the case of Annacotty weir, considerable tree planting has taken place over the past month. This work has been supported by the Mulkear Conservation Volunteers, the Annacotty Tidy Town Committee and Limerick County Council.
Tree planting on HNV site of high amenity value, Annacotty (Image: Yvonne Ryan)
The tree planning has been coupled with vegetation management, including on site management of Giant Hogweed and the implementation of the ongoing management plan for Himalayan Balsam on site.
Aside from a comprehensive programme of tree planning, several of MulkearLIFE’s other project actions tackle issues of concern regarding the management of the riparian zone. Specific areas include addressing the very considerable threat of invasive species, livestock management with the riparian zone, trail enhancement and biodiversity enhancement.