Exmoor Non-Native Invasive Species (ENNIS) Project

GB Secretariat Invasive Non-Native Species (INNS) definition - ‘any non-native animal or plant that has the ability to spread causing damage to the environment, the economy, our health and the way we live’.

Invasive non-native species (INNS) are the second largest cause of global biodiversity loss after habitat fragmentation. Not only do they negatively affect our native wildlife and habitats (both aquatic and terrestrial) but they also pose a risk to our economy, health and welfare. According to the GB Non-Native Species Secretariat INNS management costs the UK an estimated £1.7 billion a year.

On Exmoor,  invasive species are leading to the decline of some of our iconic species and degradation of our nationally recognised Sites of Special Scientific Interest (SSSIs) and Special Areas of Conservation (SACs) which are of importance at an international level. For example, the River Barle SSSI, known for its otters, kingfishers and salmonid population, is threatened by signal crayfish, Himalayan balsam, Japanese knotweed, skunk cabbage and montbretia alone. So, it is really important that we take action to control and stop the spread of INNS.

For the last 15 years, Exmoor National Park has been at the forefront of tackling issues related to

non-native invasive species with its work on controlling Japanese and Himalayan knotweed; and more recently its innovative trials on the organic control of knotweed and sterilisation of signal crayfish. However, the full extent to which invasive species threaten the National Park is unknown.

We are delighted to announce that through the Water Environment Grant, Exmoor National Park Authority has been awarded funding for a two-year project dedicated to identifying and controlling INNS within the National Park boundary. The Water Environment Grant is jointly funded by the European Agricultural Fund for Rural Development and Defra. The project is a partnership between Exmoor National Park Authority, Environment Agency, National Trust, Natural England and Nicky Green Associates.

Our Exmoor Non-Native Invasive Species (ENNIS) Project will:

  • Continue working with contractors on the annual treatment of Japanese and Himalayan knotweed across the National Park.
  • Trial innovative organic approaches to control knotweed and montbretia with Rootwave technology which uses electrocution to boil plant cells.
  • Work with volunteers and local communities to control Himalayan balsam on the River Barle and determine where else in the park Himalayan balsam can be found.  
  • Treat skunk cabbage (and other localised but significant invasive species such as fringecups and New Zealand pigmyweed) at an early stage of infestation in the National Park before they become a major threat.
  • Continue to work on the River Barle alongside Nicky Green who is trialling an innovative method of controlling signal crayfish involving the sterilisation of males.
  • Determine the distribution of signal crayfish on the Little Exe, Haddeo and Lyn.
  • Raise awareness of INNS within the National Park through a programme of public events and the use of social media.

We would love to get more volunteers involved with our project. There will be opportunities to survey for invasive plants, help with the crayfish project, or simply report sightings of invasive species online through our Wild Watch scheme.

If you have seen any of these invasive species within Exmoor National Park we would like to hear about them.

Signal Crayfish 
Japanese Knotweed 
Himalayan Knotweed 
Himalayan Balsam 
Skunk Cabbage 
New Zealand Pygmyweed

If you would like to:

  • Report your sighting of an invasive species please click here.
  • Volunteer for our project then please sign up here.

Exmoor Non-Native Invasive Species Project - Volunteers apply here

This Project is funded by the European Agricultural Fund for Rural Development.

Exmoor Knotweed Consent Form