Most valuable nature sites on frontlines of harm from invasive non-native species

• Reports of Invasive Non-Native Species show protected nature sites are being ravaged by species including Himalayan balsam and Giant hogweed
• Local Action Groups in these sites are working tirelessly to control the spread of invaders but need much more support from Government
• Nature coalition calls for greater Government prioritisation of, and resources to tackle the threat of invasive species
  

New analysis from environmental coalition Wildlife and Countryside Link reveals the harm being caused to beloved nature sites and treasured British wildlife by harmful invasive species. The research, released to coincide with Invasive Non-Native Species (INNS) week 12-18 May, details the Sites of Special Scientific Interest across England and Wales where most invasive species sightings have been reported.

Using data from INNS Mapper collected since 2018, Link has taken reports of invasive species and mapped them across Sites of Special Scientific Interest (SSSI) across England and Wales. [1] Dearne Valley Wetlands emerged as the SSSI with the most reports of INNS at nearly 800, with other sites fighting back the tide of INNS including the River Derwent in Derbyshire and River Dee in North Wales (please see a list of the ten worst affected sites in the release below). The effects of invasive species are undermining the health of key nature sites and their ability to contribute to the Government's target of protecting 30% of land and sea for nature by 2030.

Conservationists are shining a light on the work of Local Action Groups working to manage INNS in some of the country’s most important nature sites. Local Action Groups working in these cherished nature sites have undertaken detailed surveys on the presence of INNS and have dedicated programmes to stopping their spread. But these groups are under-resourced, struggling with low-level funding that is short-term, with many groups facing potential funding losses.

Lisa Manning, policy officer at Wildlife and Countryside Link, said: “Across the country we’re seeing cherished nature sites ravaged by invasive species. Our waterways are being smothered by Floating pennywort, Water voles being predated by American mink and even our health put at risk by exposure to Giant hogweed. We applaud the work done by Local Action Groups to turn the tide, but Government must give them much more support. Invasive species are a serious obstacle to restoring nature, so it’s time that Westminster takes the threat seriously and allocates long-term funding and resources.”

Jennifer Kril, Living Rivers Officer at Derbyshire Wildlife Trusts, said: “The beautiful River Derwent, and wider catchment area, is one of the many places seeing its landscape and wildlife hampered by invasive species. We’ve been proud of the work done so far by local groups and individuals to control the damage caused by species including Himalayan balsam. But tackling invasive species needs a catchment and landscape-scale approach. It’s therefore vital that catchment partnerships, who are made up of stakeholders with a common vested interest in the health of our rivers, are properly funded in the long-term to allow this level of coordination to go ahead.”

Alastair Penny, Invasive Non-Native Species Officer at Eden Rivers Trust, said: “We have a fantastic team of volunteers who join us across the catchment to pull up and ‘bash’ the Balsam each summer. This year we have our Big Balsam Bash weekend in July, with events planned at multiple locations along the Eden. More hands really do make a difference when it comes to removing Balsam! If we can connect with more groups along the entire length of the Eden, we can link up to create a catchment wide community ready to fight off this invasive.

“But we need to secure long-term funding to really get on top of the issue. Without funding, invasive species will continue to dominate our riverbanks. With funding, we can revisit sites to make sure that it’s gone for good, improve access along the riverbanks, help to restore important habitats and allow endangered native species to survive and thrive.”

Emma Tuckey, Reserve Manager at RSPB Old Moor in the Dearne Valley, said: “Our expert warden team works year-round to tackle any invasive non-native species at Old Moor, and we are constantly on high alert for the threat of these species establishing on the site. Thankfully we don’t have Himalayan balsam on our land but the plant causing the main problem for us here is Crassula because it outcompetes with native aquatic plants, blocks sunlight and this alters the ecosystem of our ponds. Whilst we have focussed efforts to control non-native invasive plant species on the nature reserve at RSPB Old Moor, other landowners may not have the same resources or capacity. So, a joined-up approach, with resources and funding, is what is needed to tackle this issue.”

With over 1,600 reports the most reported invasive species is Himalayan balsam (which outcompetes native species and can cause riverbank damage and river-clogging causing higher flood-risk). Other highly reported invasive plants include Giant hogweed (with sap that can cause burns to skin) and Japanese knotweed (which can cause structural damage), with highly reported animals including American mink (which are prolific predators and have significantly contributed to water vole declines and cause harm to fisheries).

Due to a lack of formal monitoring in place from Government this data relies on local wildlife groups having the resources to run INNS monitoring. This means that the data is the tip of the iceberg, with other SSSIs without monitoring in place likely having even higher numbers of INNS and no dedicated local action to control them.

Table 1 - SSSIs with the most reports of INNS (and the number of reports). Download full datasheet and briefing notes here.

Table 2 - Most common INNS reported (and the number of reports)

Invasive species are a major driver of nature loss and economic harm, and can cause huge damage in a number of ways. They compete with native wildlife for food and even predate them as seen with the decline of species including Water Voles and ground-nesting seabirds due to American Mink. Invasive plants like Japanese Knotweed are also known to cause huge economic damage, while Himalayan Balsam can dominate waterway banks and increase flood risk. The overall price tag of invasive species is estimated at around £4 billion per year for the damage they cause to infrastructure, industries such as fishing and forestry, our rivers and other water bodies, and homes. [2]

Wildlife and Countryside Link’s Invasive Non-Native Species Working Group is calling for:

• Increased resource: Increased long-term, relevant and timely funding for INNS management from Government including funding for Local Action Groups (LAGs), and continuing the Water Restoration Fund. to create a biosecurity create a biosecurity “citizens army” and support more local projects
• Prevention powers: Prevention of INNS spread is key. The Government should increase the powers of the Non-Native Species inspectorate so that it may carry out border inspections to prevent new invasive species entering the UK.
• Aquatic and horticultural measures: Plant imports and water-based transport are key routes for invasive species spreading. Securing growth in the UK’s domestic horticulture industry and an enhanced aquatic biosecurity programme via renewed water company funding of the Aquatic Biosecurity Partnership are key measures needed
• Quicker response to new threats: Speed up the process of listing GB Invasive Species of Special Concern to rapidly respond to new threats, as well as proactively managing the listed species that are already widespread and causing harm.

ENDS

Notes to editors:

1. INNS Mapper is an app and website for the reporting of sightings, surveys and management of INNS (invasive non-native species) in England, Wales and Scotland. It is free to use and aims to provide an effective resource to support INNS programmes and coordinate efforts, with open access data.
2. Analysis by Link on the economic costs of invasive species was first undertaken in 2021, and was updated in 2024 following on from other reputable analysis. The economic impact has been found to be approximately the same as it was in 2021, though the impending arrival of new species (exacerbated by warming temperatures and extreme weather) could see a sharp rise in coming years.
   1. This figure includes impacts from invasive fungi such as Hymenoscyphus fraxineus which causes Ash Dieback (which has an annual cost alone of £883.5m.
   2. When fungi are not included the figure is closer to £2 billion.