ALIENS
The Living River Project - The River Avon System Non-native Invasive Plant Strategy
Introduction
The Living River Project is an exciting £1 m project focusing on the River Avon and its catchment in Wiltshire, Hampshire and Dorset and will involve people throughout the catchment with the conservation of its natural heritage. The project will tell the story of the river system and how its exceptional natural heritage has developed alongside the world famous cultural heritage of the area. It will invest resources from a range of partners in long-lasting improvements to biodiversity and access and will use innovative methods to engage audiences across the catchment and secure their support for its conservation. Its goal is to improve the river and wetland environment through both practical work and by increasing local understanding of the river system.
Non-native Invasive Plant Species on the River Avon System
The presence of non-native invasive plants is identified as a significant threat to the characteristic species and habitats of the River Avon. Their impact and management is a major concern due to the dominant behaviour and difficulty to control once established. Three of the most infamous bankside species are now established within the river valley, largely down to the favourable conditions that river corridors provide for their arrival and spread. These include Japanese Knotweed (Fallopia japonica), Giant Hogweed (Heracleum mantegazzianum) and Himalayan Balsam (Impatiens glandulifera) respectively. They may not impact directly on the composition of in-channel macrophyte communities, but influence conditions in the following ways:
- Loss of bankside vegetation diversity and undermining of structural stability
- Increased shading and/or siltation through bank erosion
- Loss of optimum habitat for characteristic species (e.g. Desmoulin’s whorl snail, up-winged invertebrates, water voles) by out-competing native vegetation
This alteration in habitat structure and biological communities is known to impact directly on salmonid fisheries for which the Avon is a prestigious & lucrative river for its brown trout and salmon fisheries. As well as hindering conservation efforts & the viability for angling the presence of these plant species pose great management and access concerns if left uncontrolled.
Aquatic species of non-native plants are locally present within still and slow-flowing habitats, particularly in the Blashford and Ringwood areas, although they are not known to have impacted the main river habitat yet. Nevertheless, the extensive ditch network and expanse of New Forest streams, largely confined to the Hampshire extent of the floodplain, provides a significant risk for transfer and colonisation. Key species include Australian swamp stonecrop (Crassula helmsii), floating pennywort (Hydrocotyle ranunculoides) and parrot’s feather (Myriophyllum aquaticum). These species pose the following effects:
- Smoother and replace native vegetation, particularly Ranunculus communities, affecting salmon, bullhead & lamprey habitat
- Die-back of vegetation underneath reduces water quality by depleting oxygen levels and contributing to elevated organic matter depositions on the river bed and gravel substrate.
(Left to Right)Himalayan balsam at Quidhampton on the Nadder, close-up of a balsam flower, Japanese Knotweed and Martin de Retuerto, Pete Reading and Darren Smith discussing the problem at Blashford.
A Strategy for the River Avon Catchment
Stark lessons are to be learned from the River Frome in neighbouring Dorset where ten years ago Himalayan balsam was present in small patches. Left uncontrolled it has established itself into vast swathes of bankside monocultures and is now prohibitively costly to eradicate.
Learning from the experiences of other projects in the UK the project will develop and demonstrate a strategic approach to dealing with invasive plants across the catchment, that engages stakeholders in planning, action and monitoring, and will be sustainable after the project has finished. The experiences gained will be transferable to watercourses throughout the UK and Europe. The programme will produce:
Progress in 2007
This year has focussed on two elements; raising awareness and ground-truthing. The latter has involved a systematic survey of much of the river to update records held by the respective county biological record centres. This will enable the prioritisation of control efforts from next year onwards. All anglers and visitors to the river are encouraged to submit their sightings of non-native plants using the following link. Living River
The project is currently working with fisheries across the entire catchment to establish a coordinated programme of control activities for summer 2008.
For further details contact
Martin de Retuerto - Wessex Chalk Streams Project
Tel: 01380 737008
Email: martin.deretuerto@naturalengland.org.uk
Other links:
Info on Living River Project, target invasive plants, how to spot them and what to do www.livingriver.org.uk/what_can_do/go_for_walk
NOTE: Link to online reporting form to follow Online Reporting Form
Target Description
GIS databases of invasive non-native plants, based at a single county biological records centres and kept up to date
Database shall collate all three respective county records (Wiltshire, Hampshire & Dorset) in compatible formats. Data will be used to manage existing affected sites & identify new sites. Current information is inconsistent and not available in one accessible format. As part of a comprehensive awareness raising programme people will be encouraged to submit records of target species.
Creation of a self-sustaining Stakeholder Forum, tackling issues independently & using demonstration projects for reference
Forum will assist in developing a 20-year catchment wide action plan and be self-sustaining after completion of the Living River Project. Membership will consist of all key stakeholders and will drive the implementation and prioritisation for tackling control and raising awareness.
A 20-year catchment wide plan for the eradication of Japanese Knotweed, Giant Hogweed and Himalayan Balsam.
Overseen by the stakeholder forum the plan will take a strategic approach and be the driver for dissemination of control activities. It will be realistic and practical.Two demonstration projects (Salisbury District & Blashford, Ringwood) Based locally demonstration projects will be focus areas for targeting control activities during the life of the Living River project and act as pilots for implementing work throughout the wider catchment. Working closely with stakeholders (e.g. fishing clubs, landowners, local authorities, NGOs etc) awareness raising will be comprehensively delivered using a variety of formats with a programme for physical control undertaken using volunteers.
Contacts
Martin de Retuerto (Invasive plants lead)
Wessex Chalk Streams Project (Wiltshire Wildlife trust)
Tel: 01380 737008
Email: martin.deretuerto@naturalengland.org.uk
Sarah Yarrow (Project Manager)
Living River Project
Tel: 01722 334856
Email: sarah.yarrow@naturalengland.org.uk
Martin Gilchrist (Project Officer)
Living River Project
Tel: 01722 334856
Email martin.gilchrist@naturalengland.org.uk