Invasive species are one of the top 5 drivers of global biodiversity loss

What are INNS?

An invasive Non-Native Species (INNS) is 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.

Non-Native vs Invasive Non-Native

Non-Native Species (NNS) are everywhere; you’ll come across them whether you live on the Cornish coast to the Scottish Highlands and you might not even know that they weren’t native. A plant, animal or even pathogen is classed as an NNS if they have been transported outside of their native range.  These introductions are always human mediated; can be deliberate or accidental and have spanned the course of history. The domestic sheep, sycamore and even the Little Owl have all been introduced into Great Britain whether that be centuries ago, such as the domesticated sheep in 10,000 BC, or relatively recently like the Little Owl in the late 1800s [1].

For the majority of NNS their introduction has very little impact or can even build resilience to environmental changes within an ecosystem. Non-native species, such as the sycamore, are considered as a functional alternative to replace native trees that are undergoing severe declines. However, 10-15% of introduced NNS cause detrimental impacts and are known as Invasive Non-Native Species (INNS) or Invasive Alien Species (IAS).

Why do INNS Matter?

INNS are very good at overwhelming habitats they are introduced into. INNS grow and reproduce quickly and in high numbers, disperse easily and often have a wide range of tolerance to different conditions. In addition, INNS can manipulate the habitats they’ve been introduced to which can lower an ecosystem’s resilience to changes such as drought, as well as creating conditions which favour further invasions and population expansion.

Environmental impacts

Invasive species can cause a huge amount of harm to our native flora and fauna and damage important ecosystems; from outcompeting native species for resources, to directly preying on native species and spreading pathogens and diseases. The latest IPBES report states invasive species as one of the top five drivers for global biodiversity loss.
















Photo by GBNNSS

Economic Impacts

Invasions cost our economy £1.8 billion per year through management and losses in production and recreation. There are also large economic costs associated with increased flooding and erosion or repairing damage caused by INNS. The cost of biodiversity and ecosystem services losses through invasions has not yet been calculated but is certainly significant.

Public Health

From the severe burns caused by giant hogweed to our skin, to the reduction in opportunities for recreation and our general enjoyment of natural areas, invasive species have wide ranging impacts which impact the whole of society.


Yorkshire is the largest county in the UK, falling between the Pennines to the West and the North Sea to the East. It hosts a diverse range of habitats from expansive upland moorlands to rich lowland meadows. The diverse range of habitats within the county provide invaluable places for wildlife to thrive. Unfortunately they also provide opportunities for a number of Invasive Non-Native Species which are both exacerbating existing environmental pressures and having impacts of their own.


The majority of INNS records are found along Yorkshire's waterways, particularly our river and canal network. This is one of the key dispersal pathways for invasive species. There is also a pattern of greater INNS densities within the heavily urban areas of South and West Yorkshire. Perhaps this is owing to greater human populations in these locations and the opportunities for human dispersal of the species

You can explore the distribution of individual INNS using our webtool INNS Mapper

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Key species

Giant hogweed, Japanese knotweed and Himalayan balsam can be found right across Yorkshire and are spread rapidly across our river, rail and road networks. We work together in partnerships with other charities and statutory bodies to manage these species, reduce their densities and negate the negative impacts they cause. You can help us record and manage them!

Floating pennywort is in very low densities in Yorkshire and is actively managed by the Environment Agency and their partners the RSC every year. The aquatic plant produces dense mats of vegetation which block rivers increasing flood risk and limiting navigation. This reduces light availability and subsequently growth of submerged plants which can impact water quality[1]. This plant has overwhelmed rivers in other parts of the country, and we want to prevent this from happening[2]. We need help to record where this species and others pop up so we can tackle them quickly!

Some species are difficult to manage once they are established. Aquatic plants like New Zealand pygmyweed and curly waterweed can be found in still waters. They limit access of recreational users to watercourses, cause blockages and limit navigation. Zebra mussels cause blockages in pipes and water quality issues10[3]. This is a problem for the water industry however it can impact recreational users too!

Taking the fight to INNS

Explore how we are we working with partners to tackle these species in Yorkshire

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