Invasive species are plants and animals that humans have introduced—accidentally or deliberately—outside their natural range
While not all non-native species cause harm, invasive ones can spread quickly and damage the environment, the economy, and even our health. These species often outcompete native wildlife, disrupt ecosystems, and are difficult to control once established.
Check out and learn about some common invasive species here!
Why are they a problem?
Invasive species are recognised as one of the five main drivers of biodiversity loss globally!
They damage ecosystems in many ways—competing for resources, such as light and water, predating on native species, they can carry new diseases, and hybridise with native species.
Their impact isn’t just ecological. In Great Britain alone, invasive species are estimated to cost nearly £2 billion every year.
Once introduced, invasive species can spread naturally—but human activity plays a big role.
Everyday activities like walking, gardening, and fishing can unintentionally move seeds, fragments, or organisms from one location to another.
That’s why simple actions—like cleaning boots or equipment—can make a big difference in slowing their spread.
Find out more about how you can Stop the Spread of invasive species on our biosecurity webpage!
© WaREN - NWWT
So, what’s being done to tackle the problem here in North Wales?
What are we doing about it?
Across North Wales, a range of projects are tackling invasive species and protecting important habitats.
Cotoneaster © Lin Cummins
Tackling cotoneaster on limestone grasslands
Clwydian Limestone Links is the latest project addressing the spread of cotoneaster across our precious limestone grasslands. The popular garden plant is spread when birds deposit seeds after eating the berries. Unfortunately, cotoneaster can quickly take over on our SSSI sites such as Graig Fawr and Moel Hiraddug, crowding out our rare species such as dark red helleborine and the ecosystems they support.
Over the coming years, we will be surveying and managing cotoneaster at these sites to help restore and protect these valuable ecosystems.
Allium triquetrum ©LisaToth
Preventing garden escapes
Through the Garden Escapers project we've worked to prevent ornamental plants which might currently be showing 'invasive behaviour' in gardens from escaping into the wild and becoming future invasive species. To raise awareness amongst gardeners – and support them to tackle invasive species – we have developed a bilingual multi-media Gardeners’ Toolkit which includes:
Explore the Toolkit here!
© Jess Minett - WaREN
Working at a landscape scale
The Wales Resilient Ecological Network (WaREN) is helping develop a coordinated, long-term approach to tackling invasive species across Wales.
We’re working with partners and landowners through the Landscape Scale Control of INNS project, managing invasive species across whole landscapes for greater impact.
Restoring the River Dee
The Restoring the Dee Together project adopts a strategic, catchment‑based approach to surveying and controlling invasive species such as Himalayan balsam, Japanese knotweed, and American skunk cabbage across the Afon Dyfrdwy (River Dee).
Working from the source downstream, the project targets invasive species spread at its origin - building on over a decade of work managing invasive species across the Upper Dee.
Oyster thief (Colpomenia peregrina) © NWWT
Monitoring our coasts
In the marine environment, invasive species can spread easily by “hitching a ride” on boats or debris.
Our Shoresearch volunteers play a vital role in monitoring these species. So far, they’ve recorded species including:
Pacific oyster
Slipper limpet
Wireweed
Orange-tipped sea squirt
Volunteers also follow Check, Clean, Dry principles to prevent spreading species between sites.
There are lots of things we can all do to help tackle the threats posed by invasive species:
What can I do?
We all have a role to play in tackling invasive species—and small actions can make a big difference.
How to get involved in Invasive Species Week
Share your experiences using #INNSweek
But most of all have fun learning about invasive species, biosecurity and how you can help protect our environment.
© Zoe Richards - Ramblers Cymru
