Invasive non-native species - have you spotted any?

You may not be aware, but it is likely you will have come into contact with invasive species at some time, whether it’s at home in your garden, on your travels, playing outdoors or even when you’re out shopping. They lurk in our water courses, dominate our riverbanks and even cause structural problems to our homes. They are just waiting for an opportunity to spread - and that opportunity could be you!

What are Invasive Non-Native Species (INNS)?

An invasive species can be any kind of living organism—a plant, insect, fish, fungus or bacteria — that has been introduced outside its natural range and can cause harm. They impact our environment, economy, infrastructure, leisure and enjoyment and even human health. Species are given the label “invasive” when they grow and reproduce quickly (by seed, plant fragment or reproduction); there are no natural mechanisms for control (such as predators); they spread aggressively out-competing other native species for resources (light, oxygen and food). These species are so efficient at reproducing and spreading that they completely suppress our native species and end up changing the shape of look of our natural environment.  

The spread of Invasive species is a world-wide problem and they have now been dubbed as the greatest threat to global biodiversity after habitat loss. In the UK it is estimated that invasive species cost the British economy £1.7 billion each year in trying to tackle the problem (figure is taken from 2010 report and is expected to have increased).

Fortunately, in Cumbria, we only have relatively few invasive species, but we also have many freshwater resources; lakes, tarns, rivers and becks, that are of great ecological and economic significance. INNS have the potential to cause substantial damage to these fragile ecosystems, so it is vital that we all take responsibility for protecting them.

These pages should help you get to know the main invasive threats to Cumbria, their impacts and what YOU can do to tackle them.

Quick facts!

- Clearing the Olympic site of Japanese knotweed has been estimated at £70 million. It is estimated that in 2003 it cost the UK £1.56 billion

- There are 1,402 non-native plants in the UK, but only 108 (8%) are considered invasive.

- Approximately 60% of invasive plants come from horticulture.

- It is a criminal offence to plant or cause to grow a non-native invasive species that is listed on Schedule 9 in the wild. This offence carries penalties of up to £5,000 fine and/or 2 years imprisonment.

- Research indicates that it takes at least ten years to eradicate giant hogweed where it has succeeded in seeding, and four to five years to eradicate Japanese knotweed

Aquatic Invasive Species

The work of the West Cumbria Rirvers Trust (WCRT) predominantly focuses on aquatic and riparian invasive species as these are a serious threat to our very sensitive water habitats.


Our work on invasive non-native species is part of a county-wide collaborative project called the Cumbria Freshwater Invasive Non Native Species (CFINNS) Initiative. The Initiative is a pilot, multi-catchment project for freshwater and riparian invasive non-native species.

Our work is funded and carried out in partnership with many organisations, including the Environment Agency, Natural England, the Lake District National Park (LDNP), National Trust (NT), Derwent Owners Association, Cumbria Probation Service and perhaps most importantly - a significant number of volunteers who are passionate about their environment and work tirelessly to keep Himalayan balsam in check.