management of riparian zones in sacs with...

BEST PRACTICE GUIDE NUMBER FOUR

MANAGEMENT OF RIPARIAN ZONES in SACs with particular reference to the management of Non-Native Invasive Plant Species

Drawing on the Experience of MulkearLIFE 2009 to 2014

Overview of MulkearLIFEMulkearLIFE (www.mulkearlife.com) was established in Ireland and ran for a five-year period between 2009 and 2014. The main project objective was to restore, through in-stream rehabilitation works, degraded habitats along stretches of the Mulkear River and its main tributaries for Atlantic salmon, sea lamprey

and European otter. Inland Fisheries Ireland (IFI) was the co-ordinating project partner, together with the Office of Public Works and Limerick County Council. The National Parks & Wildlife Service (NPWS) provided funding support. Other important supporters included Coillte, ESB Fisheries, Teagasc, local farmers and anglers.

IntroductionThe following guidance document is based on the experience of MulkearLIFE, the European Commission funded LIFE+ Nature project (LIFE07/NAT/IRL/000342 IShannonSACLAEO). It provides an introduction to the work of MulkearLIFE and advice on the management of riparian zones in Special Areas of Conservation (SACs) with particular reference to the management of non-native invasive plants. It is designed to assist local authorities, government agencies, land owners, developers and others to comply with the law and such parties to play a proactive role in the protection and enhancement of riparian habitat.

Riparian zones act as wildlife corridors and need effective management

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BEST PRACTICE GUIDE NUMBER 4 Management of Riparian Zones in SACs with particular reference

to the management of Non-Native Invasive Plant Species

Key Achievements of MulkearLIFE:

– Installation 28 rubble mats on 10 km of the Mulkear River, utilising over 5,000 tonnes of rock, which enhanced habitat for salmonids and lamprey species by improving instream and riparian biodiversity.

– Enhancement of over 15km of river channel through additional instream measures (random boulders, vortex and stone weirs) using 1,500 tonnes of rock which added additional beneficial flow complexity.

– Research, design, manufacture and successful installation of lamprey passes to assist sea lamprey ascend Annacotty weir, which was a major barrier, on the Lower Mulkear River.

– Following 15 months planning and consultation, the partial removal Ballyclogh weir as a barrier to salmonid and sea lamprey passage, opening up 184km of river channel and improving upstream habitat.

– Treatment of over 200 kms of river bank (riparian habitat) to control non-native invasive plant species (with focus on giant hogweed & knotweed species) and the manual removal of other invasives (Himalayan balsam and pheasant berry) from High Nature Value (HNV) sites in the catchment.

– Improvement of otter habitat through tree planting, enhancement of river connectivity and installation of artificial otter holts at sites degraded in past historical drainage programmes.

– Establishment of the Mulkear Conservation Volunteers to undertake practical, river and riparian based, conservation activities: 47 outings (amounting to over 1,120 unit days) improving river biodiversity.

– Establishment of a river based an Environmental Education Programme. This included 74 classroom engagements and separate, river based, field trips with almost 2,000 schoolchildren and their teachers.

– Delivering training workshops and field-trips for 360 people and 66 illustrated talks to 2,120 people.

– Worked directly with local farmers to address water quality concerns and installed alternative watering solutions away from rivers.

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The Lower Shannon SAC The Lower Shannon is of international nature conservation importance for its populations of Atlantic salmon (Salmo salar), Sea Lamprey (Petromyzon marinus) and European otter (Lutra lutra) amongst other species. As a result, the river is a Special Area of Conservation (SAC) for these species and others species and qualifying features. The designation of SACs is obligatory under the Habitats Directive. It is a method used by the Irish government and the European Union to protect endangered species and habitats.

The Mulkear RiverThe Mulkear River rises in the Slievefelim and Silvermine mountains and flows through counties Tipperary and Limerick, before joining the Shannon River below Annacotty in County Limerick. The catchment consists of upland and lowland habitats, typical of many Irish river

systems. The upland areas are extensive, with mountains in excess of 400m. The lowland areas are largely flat river plains, with surrounding improved agricultural pastures and a scattering of small towns and villages The main channel of the Mulkear river is approximately 21.5 km long, and together with its tributaries, it drains a catchment area of approximately 650 km².

The principal tributaries are the Dead, Bilboa and Newport rivers. Within the catchment, there are 10 Special Areas of Conservation (SAC’s) which have been designated as part of the Natura 2000 Network of designated European sites. The qualifying species include Atlantic salmon, lamprey, European otter and other species and habitats. They also contain a wide range of supporting biodiversity important to the conservation objectives of the EU including species of interest like the European eel.

The Mulkear catchment as part of the Lower Shannon SAC

Mulkear River CatchmentOverview

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What is Riparian Management?‘Riparian’ refers to the area immediately beside a water course or water body. The riparian zone plays a key role in protecting and enhancing water quality and aquatic ecosystems. Given that streams, rivers and lakes act as biodiversity corridors and ‘stepping stones’ in the landscape, the positive impacts of a well-managed riparian zone extend far beyond the water body itself.

Well-managed riparian zones play an important part in conserving and expanding biodiversity, in addition to providing habitats essential to the lifecycle of freshwater organisms.

The protective function of native riparian woodlands is particularly relevant to water quality, which also affects the instream biodiversity value. Riparian woodlands are also of significant importance to nature conservation, landscape enhancement and recreation. They are often the only woodlands remaining in certain areas and therefore often form the last refuge for certain species. They also provide a vital conduit for the transfer of nutrients between terrestrial and aquatic ecosystems and play an important role in capturing nutrients and silt, which can run off adjacent lands and negatively impact on watercourses.

Good riparian management also provides a number of other benefits. For example, well managed bankside vegetation provides cover and foraging habitat for otters, terrestrial invertebrates and waterbirds. The riparian zone tends to be continuous and therefore provides a valuable wildlife corridor linking fragmented or isolated habitats. Banks with well-structured vegetation are likely to require less maintenance and repair. In addition, the presence of well-established native vegetation helps to reduce the opportunities for undesirable invasive species to become dominant.

Effective riparian management can also:

– Prevent dominant species from out-competing other species, thereby increasing plant diversity and habitat diversity

– Encourage the development of native plant assemblages which provide more suitable habitat for native invertebrates

– Improve water quality by increasing the buffer between land and channel, allowing sensitive species of macrophyte and invertebrate to survive

– Provide fish with shelter and spawning habitat, through the creation of diverse and well-structured marginal vegetation

– Reduce bank erosion through the stabilising effect of the root structure and protecting the channel from the direct force of flow by plant biomass.



Species-rich riparian zone, Bilboa River

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MulkearLIFE and Riparian ManagementMulkearLIFE’s work programme has tackled a number of riparian management issues within the Mulkear catchment. The specific areas where management work has been undertaken include; optimal livestock management, improving otter habitat, removing riparian coniferous forestry plantations and replanting these areas with native trees, general biodiversity enhancement work and a very significant programme on the control and management of non-native invasive riparian plant species.

Livestock ManagementWater quality had been identified as an issue requiring attention within the Mulkear Catchment. While many of the agricultural sources impacting water quality have been addressed, certain specific problems, including trampling of the river banks and direct access to rivers was identified as an issue in the Mulkear catchment. MulkearLIFE’s programme of work involved direct liaison with farmers. MulkearLIFE promoted water harvesting, fencing of riparian areas and sustainable water abstraction with the farming community. Please see MulkearLIFE’s best practice guide to sustainable water management on farms in close proximately to SACs.

Forestry Large portions of the headwaters of the Mulkear catchment are planted with Sitka Spruce. Coniferous plantations in river catchments can lead to acidification problems and sedimentation from logging operations. In conjunction with MulkearLIFE, Coillte carried out the removal of coniferous stands and replanted these with native trees. This work benefitted both riparian biodiversity and water quality. Unfortunately, sites selected were outside the SAC and were discontinued as funded LIFE project actions.

Cattle access to rivers can cause serious problems in regards to erosion, siltation of the riverbed and faecal fouling

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Otter Habitat ImprovementMulkearLIFE has also worked on the enhancement of habitat for otters. This work included tree planting in areas where there is a lack of riparian vegetation and a low population of otter. This work was part of wider habitat and biodiversity enhancement work. The project also constructed artificial otter holts in certain areas. A best practice guide on otters has been prepared by MulkearLIFE.

Invasive SpeciesNon-native invasive plant species (giant hogweed, Japanese knotweed & Himalayan balsam) have been problematic along the entire course of the River Mulkear and throughout large areas of the Mulkear catchment. The aim of the management aspect of MulkearLIFE’s work on non-native invasive plant species was not only to stop, but reverse the damage caused by these riparian plants. These species grow vigorously and shade out less vigorous native flora, with the resultant loss of dependant insects and other animals. As a consequence of out-competing native riverside plants, banks can be left bare in the winter and susceptible to erosion during spates and floods. Sediment from erosion can infill spawning gravels for trout and salmon, rendering them less optimal for spawning.

Establishing management control measures within the catchment for invasive plants was been an important objective of MulkearLIFE. Following detailed annual planning with Limerick County Council and the Office of Public Works sites were selected for inclusion in the annual work programme. This work continued from 2009 to 2014 to restore the natural riparian zone. A management programme to sustain progress in the AfterLIFE phase of the project (2015 to 2020) has also been developed. What follows is a guidance note focused on the three most common species, Giant hogweed, Japanese knotweed and Himalayan balsam.



Mulkear Conservation Volunteers remove Himalayan Balsam on the Bilboa River

Addressing Japanese knotweed (Glen Wightman)

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Giant Hogweed (Heracleum mantegazzianum)

Best Practice Guidance for the Control and Management of Non Native Invasive Plant Species

IdentificationTall plant (to 4 m) with hollow, red-spotted and hairy stems and large umbrella-shaped, white flower head. Leaves are up to 1.5 m wide and sharply divided.

ImpactsDetrimental to human health! Sap produced by the plant is hazardous to humans, particularly in the presence of direct sunlight, causing skin inflammation. Shades and out-competes native plant species.

Pre-control assessmentEstablish the distribution and abundance of the weed in the target area. Mark the location of all weed stands present on a map or using a GPS and record the area of infestation. The percentage cover and any native vegetation encountered should also be recorded. Data should be entered into a GIS mapping system if possible.

It is important that suitable protective gear is worn to cover all exposed areas when working with Giant hogweed as contact with its sap can cause severe inflammation of the skin, including burns and blistering.

Effective control measuresHerbicide treatment using glyphosate (as Round-up Biactive) has been successfully used by MulkearLIFE in the Mulkear Catchment. A catchment approach to treatment must be taken and spraying must commence at the farthest upstream site from which the plant is recorded. Spraying should commence in March or early April, when the plants have expanded their leaves and reached a height of >15 cm. Experience in Ireland has shown that young seedlings and small plants (<15 cm) are less susceptible to glyphosate than their larger counterparts. An application rate of 5 litres of glyphosate per hectare is sufficient to kill treated vegetation. Sections treated in March/April should be retreated in May, or later, if required.

The whole catchment must again be surveyed in July and any plants that have flowered, or are likely to flower, should be de-headed or chopped down before seeds are produced. The cut umbels must be removed from the area and destroyed. Any regrowth should be sprayed with glyphosate as the plant will again attempt to flower and set seed.

Giant hogweed is also dangerous to humans

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A further glyphosate treatment in September throughout the catchment will kill late-developing plants or seedlings that survive earlier treatments. Treatment will be necessary over a four (or more) year period to achieve eradication. Herbicide application should only be carried out by suitably qualified contractors or operators with strict reference to the product label, local land use, health and safety considerations and any pertinent regulations. Herbicide should be applied in a manner (e.g. using spot treatment when possible) to minimise drift to any adjacent non-target native plant species present. Knapsack sprayers are most appropriate for bankside work with long-lances useful for treating hard to reach areas. Stem injection of herbicide may be used to complement knapsack spraying and is an extremely effective, if timely, approach.

RequirementsGlyphosate herbicide; personal protective equipment, qualified contractor(s) / operators, knapsack sprayer / long-lance, long-reach clippers, bags for disposal of vegetation, stem injection gear.

Post-control monitoringIn order to properly evaluate the efficacy of the control measures implemented and to monitor the natural recovery of the native habitat, post-control assessment is necessary. Such monitoring should initially be conducted in July (as described in the previous section) to assess the need for further control and additionally on at least an annual basis. Re-survey the treated area in the same manner used during the pre-control assessment and compare the results. Consider appropriate remediation measures to enhance habitat recovery, if required, in consultation with appropriate experts and agencies. This may include the re-planting, re-location or transplantation of native species.

Additional considerationsAn appropriate risk assessment, which includes Health & Safety considerations, should be carried out before any control or survey work is undertaken. Permission or licences from the appropriate authorities may be required to carry out invasive species control work in some locations such as Natural Heritage Areas, Special Areas of Conservation, Special Protection Areas and some waterways. The requirements listed under each control method are not prescriptive and only provide information on the principal items required.

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The OPW address giant hogweed on the Annagh River

IdentificationTall (to 3 m) bank-side plant with hollow mottled stems. This species can grow in dense thickets. Leaves are ovate or spade-shaped with a straight base and acute point. Flowering occurs in late summer and flowers are white or cream arranged in loose clusters.

ImpactsReduces soil stability along river banks when plant dies back in winter. The rhizomes can be extensive and grow to 3 metres deep and up to 7 metres distant from the parent plant. These can interfere with building foundations and damage tarmac roadways and concrete surfaces. This species competes with and shades out native plants forming a dense canopy.


Effective control measuresHerbicide treatment using glyphosate (as Round-up Biactive) has been successfully used by MulkearLIFE. This herbicide can be used as a foliar application, through stem injection or as stump cut application where the stems are cut and the herbicide is directly applied immediately after cutting. Treatment can be carried out between May and October. For best results, it is recommended that foliar treatment is conducted in July, with follow-up treatment in September (application rate of 5 litres per hectare). For stem injection, treatment is most effective when applied to flowering stems (late summer to October). For stump cut application, treatment is most effective in September / October before senescence occurs. Stem injection and stump cut application can be used to treat individual knotweed canes when they are interspersed among native vegetation, thus avoiding non-target impacts. For stem injection, glyphosate should be injected into the cane between the 1st and 2nd node above the stem base. For stump cut application, individual stems should be cut 20 cm above their base and 4 cm above a node, and the cut surface should be hollowed out to create a well. The herbicide can then be applied within 15 minutes of cutting with a pipette. For both treatments, a 10 ml dose per stem is recommended (made up of 5 parts water and 1

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Japanese knotweed Fallopia japonica (and related knotweed species)


Japanese knotweed one of the most problematic invasive species in the Mulkear Catchment

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part glyphosate). For extensive stands, it may be also necessary to mechanically excavate a 7 m area around the stand to 3 m depth to remove any knotweed rhizomes present. The excavated spoil should be disposed of in a bio-secure manner (e.g. removed to a licensed landfill facility). Excavation equipment should be disinfected on site after use to prevent any further spread of the knotweed outside of the treatment area as plants will regenerate from rhizomes fragments remaining in the spoil. Excavation is a costly option and every effort should be made to treat the knotweed stands in situ, if feasible. Repeat herbicide treatment will be necessary over a three to four year period to achieve eradication.

Herbicide application should only be carried out by suitably qualified contractors or operators, with strict reference to the product label, local land use, health and safety considerations and any pertinent regulations. Herbicide should be

applied in a manner (e.g. using spot treatment when possible) to minimise drift to any adjacent non-target native plant species present. Knapsack sprayers are most appropriate for bankside work with long-lances useful for treating hard to reach areas.

Requirements & Post-control monitoringAs above (see giant hogweed)

Other Knotweed SpeciesThe methods outlined above for the control of Japanese knotweed Fallopia japonica can also be used for the control and management of related knotweed species, including giant knotweed and Himalayan knotweed.



OPW track machine (Glen Wightman) Protective equipment and bio-security is key

IdentificationTall annual plant (to 3 m) with pink-purple trumpet flowers and fleshy, hollow stems. Leaves have serrated edges and pointed tips. Seed capsules pop to the touch when mature.

ImpactsIt reduces soil stability along river banks when the plant dies back in winter. It also competes with and shades out native plant species.


Effective control measuresIt is possible to eradicate Himalayan balsam from infested river catchments because its morphology and life cycle display a number of weaknesses that are uncharacteristic of other such high profile invasive species. These include the following;

– the plant has an annual life cycle, meaning it germinates, grows, flowers, seeds and dies in the one year

– the plant has a shallow root ball so is easily removed by hand-pulling

– the majority of the seeds germinate after one year and

– seeds are the only propagation method of this species.

Ideally, Himalayan balsam control should be undertaken from mid-May to the end of June, well before the seed capsules appear. As seeds present in the soil can remain viable for up to two years, repeated control over a number of years in the target area is required to achieve eradication. The following methods have been successfully trialled and used by the Office of Public Works and Limerick City and County Council, with input from the Mulkear Conservation Volunteers, during the operational phase of MulkearLIFE.

Manual removal (hand-picking) is the optimal method of control, especially to treat low density infestations. Manual removal can selectively target individual plants and minimise any impact to adjacent non-target native plant species. The combination of Himalayan balsam attributes described above means it is also possible for

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Himalayan balsam Impatiens glandulifera


Himalayan balsam, a problem throughout the Mulkear

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large, well organised groups of individuals to physically remove the plants from long sections of river bank. This is commonly referred to as ‘balsam bashing’.

On river banks, plant removal should commence at the farthest upstream site from which it was recorded and continue progressively downstream. To manually remove the plant, the stem should be gripped about 0.5m above the ground and carefully pulled. As the plants tend to grow in dense patches, it is often possible to remove two or more plants in one go. The minimum of pressure is normally required to remove the root in its entirety from the ground due to its shallow root. Having removed the balsam plant from the ground, it should be thrown landward, away from the river, and gathered into piles. Covering the piles with a layer of jute material in order to eliminate light can hasten its demise and ensure that it will not flower and set seed. The jute will rot with the composting balsam plants. Where it is not possible to leave the plant piles in situ, they should be transported to suitable licensed composting facilities.

Herbicide TreatmentHerbicide treatment, using glyphosate has also been successfully used by MulkearLIFE in the Mulkear Catchment for the treatment of

Himalayan balsam. Herbicide treatment can be an effective means to target extensive dense stands of Himalayan balsam, where manual removal is not a feasible option. Herbicide application should only be carried out by suitably qualified contractors or operators with strict reference to the product label, local land use, health and safety considerations and any pertinent regulations. Two principal herbicides can be used to control Himalayan balsam, glyphosate and 2-4D amine. Which herbicide to use is dictated by the nature of the infestation; only certain formulations of glyphosate and 2-4D amine are approved for use near waterways. Glyphosate is a non-selective herbicide whereas 2-4D amine is a selective herbicide targeting broad-leaved weeds, but having no effect on narrow-leaved plants such as grasses. Therefore, 2-4 D amine is more appropriate for extensive but low density infestations interspersed with native grasses. Herbicide should be applied in a manner (e.g. using spot treatment when possible) to minimise drift to any adjacent non-target native plant species present. Knapsack sprayers are most appropriate for bankside work with long-lances useful for treating hard to reach areas.

Requirements & Post-control monitoringAs above (see giant hogweed)



Himalayan balsam at Annacotty on the Mulkear Mulkear Conservation Volunteers at work

Procedures for Site Specific Management Planning for Invasive Species In order to manage invasive plant species effectively in the riparian zone, it is essential that the relevant guidelines for each individual species above are followed. However site specific management plans should also be developed to provide the greatest chance of control:

1. Confirm the identification of invasive species. Incorrect identification could result in ineffective control and the spread of the species to additional areas, resulting in a breach of invasive species legislation.

2. If the area is large, carry out a survey and produce a distribution map, indicating the location across the site, including rivers/streams. Talk to adjacent land owners and make them aware of the problem and what you plan to do, if possible work in partnership. You may be unable to prevent reintroduction from upstream without the help of other landowners. Consider designated sites and protected species on or near to the management area, as if present, a licence may be required.

3. Observe the optimum treatment times and procedures outlined in this guide. Decide if the programme should aim for continuous control on a yearly basis, or eradication from the site. Base your decision on an understanding of the biology, size of infestation, potential for reintroduction and site sensitivities.

4. Consider if you can successfully and safely carry out the work or, if professional practitioners, with relevant training and certificates, should undertake the work. Remember health and safety legislation.

5. Identify if sufficient resources are/will be available to complete the work within the planned timescale. If work will take more than 1 year to complete, ensure you have sufficient funds to complete the work.

6. Ensure compliant disposal options for the plant material are in place prior to commencing work.

7. Monitor for regrowth and/or reintroduction during site visits. Ensure staff training / orientation.

8. Ensure that all these factors are included in the site specific control and management plan.

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Mulkear Conservation Volunteers removing Himalayan balsam on the Mulkear River at Annacotty

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Other Best Practice Guides in this series:

- Enhancement of Atlantic Salmon Population and Biodiversity Considerations of Habitat Restoration in SACs

- Management of Upstream Passage for Adult Sea Lamprey in SACs

- Management Guidelines for European Otter (Lutra lutra) in SACs

- Guide to Sustainable Water Management on Farms in Close Proximately to SACs

All images by Ruairí Ó Conchúir unless otherwise stated.

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