WISP – Wye Invasive Species Project


The aim of WISP is to support the local communities of the lower Wye Valley AONB in tackling 3 Invasive Non-Native Species across our project area (the catchments south of Monmouth) – Himalayan balsam, Japanese knotweed and American Skunk Cabbage. These are the worst offenders, causing significant problems and they are found throughout the lower Wye Valley. Together we will work to control the spread of these species and help to reverse the catastrophic decline of our biodiversity.

Click on the pictures below to read about our 3 target species and find out what we are doing and what you can do to tackle them. Further down the page are buttons where you can report sightings, grant consent (access & INNS control) as a landowner or resident, get involved as a community and find resources to improve your knowledge. 

Himalayan Balsam

Large leaves of the American Skunk Cabbage

American Skunk Cabbage

Japanese Knotweed

Japanese Knotweed

Why do we need WISP?

Invasive Non-Native Species (INNS) are the second greatest threat to biodiversity¹ after habitat loss and fragmentation. They can also significantly increase the flood risk as they can block waterways and, by leaving riverbanks and hillslopes bare of stabilising vegetation every winter, they increase erosion and lead to more sediment and debris entering our watercourses. With our biodiversity in catastrophic decline and high rainfall events increasing in frequency and severity as our climate changes, you can understand why we’re taking this so seriously. 

And of course, these INNS don’t solely impact our ecology, they impact us too. INNS have been estimated to cost the UK economy at least £1.8 billion pounds annually². They mainly affect farming and horticultural sectors, but can affect transport, construction, recreation, aquaculture and utilities. There are hidden costs too. For example, the increased sedimentation of rivers increases water companies’ costs of treating the water to make it safe for public consumption, and that translates into higher water bills. Growing so tall and densely along riverbanks – Himalayan Balsam is now Britain’s largest annual plant –  they can impede visibility and access and alter the appearance of our landscapes and riverscapes (something that’s very difficult to put a price on). 

Our target species produce large numbers of seeds every year, which are spread by humans, by wind and by water, or they have stubborn rhizomes (roots).  Seeds, plant and root fragments are readily spread by water and new populations of plants are often found downstream of original sites. So, to be effective, plant control needs to work at a catchment scale (encompassing all the small streams that feed into the main river) so all the plants are removed and there is nothing left to re-infest rivers downstream.

With all the landowners, communities and stakeholders within these river catchments, working at a catchment scale is a serious challenge. By working with landowners, residents, local councils, local fisheries, community volunteers and land managers we are co-ordinating action and undertaking control work to get these invasive plant populations into a maintenance state. But we can only do this if we all work together

¹ Biodiversity is defined by the World Wildlife Fund as, ‘all the different kinds of life you’ll find in one area—the variety of animals, plants, fungi, and even microorganisms like bacteria that make up our natural world. Each of these species and organisms work together in ecosystems, like an intricate web, to maintain balance and support life. Biodiversity supports everything in nature that we need to survive: food, clean water, medicine, and shelter.’

² F. Williams, R. Eschen, A. Harris, D. Djeddour, C. Pratt, R.S. Shaw, S. Varia, J. Lamontagne-Godwin, S.E. Thomas, S.T. Murphy (2010). The Economic Cost of Invasive Non-Native Species to the British Economy. CABI, Wallingford, 198 pp.

Report It

Operation WISPER