What is a Non-Native Invasive Species
By Jennifer Holmes

What is a Non-Native Invasive Species

What is a non-native invasive species?

Also known as INNS (Invasive Non-Native Invasive Species) the ‘Non-Native’ part is commonly described as a species which has been introduced into areas outside of their natural habitat through human actions and pose a threat to native wildlife. ‘Invasive’ means it’s growth pattern is harmful or destructive to other species.

In the plant world this means that they have been introduced into the wild and their invasive growth pattern or structure means they out-compete the native plant species which previously have thrived there. They do this by either reducing oxygen or light levels in the habitat’s environment or by depleting food or reproductive sources. The picture below shows how destructive Canadian Goldenrod can be; it has taken over the land to the point where not even grass can grow.


Environmental control is the only way we can protect our native species, both on land and on water. In our Climate Change blog series last year we discussed the effects that climate change would bring and how non-native invasive species often have a greater ability to adapt or modify their growth patterns to thrive in different habitats and climates, so where are we now in 2023?

River being taken over by goldenrod

New report published

The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) has just published the results of its four-year Assessment on Invasive Alien Species and their Control. It includes some stark facts about the threats invasive species pose to our environment:

  • Key Role in 60% of Global Plant & Animal Extinctions
  • Annual Costs Now >$423 Billion – Have Quadrupled Every Decade Since 1970

It goes on to state: “The severe global threat posed by invasive alien species is underappreciated, underestimated, and often unacknowledged… more than 37,000 alien species have been introduced by many human activities to regions and biomes around the world.”


“This conservative estimate is now rising at unprecedented rates. More than 3,500 of these are harmful invasive alien species – seriously threatening nature, nature’s contributions to people and good quality of life. Too often ignored until it is too late, invasive alien species are a significant challenge to people in all regions and in every country.”

Crassula helmsii plants covering a lake

Controlling invasive species is paramount

Whether a species is native to the UK or not all invasive species need to be controlled. Invasive and aquatic plants (such as Crassula, American Skunk Cabbage, Floating pennywort and Azolla) can be controlled by a variety of methods including herbicide treatments, biological methods, and complete removal by excavation. The key to successfully reducing the effect of invasive species on our natural ecosystems is to catch it early. Invasive species generally have a rapid growth rate which enables them to literally take over the habitat, smothering flora and fauna alike.

But what does taking action mean?

First off it means identifying the species, this can be done by having a professional survey carried out, and then forming a plan to control or eradicate the invading species. Sometimes a longer-term option by herbicide application is the most effective, or a mechanical method such as hand-pulling or even biological control using a species that will naturally deplete (or ingest) the target plants. And of course there is always extraction by excavating the contaminated ground. Once the species has been correctly identified, the method of control or removal will depend on several factors, including the environmental impact, land use and of course cost.

We will look at all factors and put together a carefully considered plan that benefits everyone.

For more information on species visit our Target Weeds section.

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