Invasive species week 2023

This year’s Invasive Species Week takes place on 15th to 21st May 2023 and the Non-native Species Information Portal is packed with information and guidance on what you can do to stop the spread of these species.

What are invasive non-native species?

A non-native species is one which is transported from its native range to a new region with the assistance of humans. Invasive non-natives (NNIS) are those that have a harmful impact.
How many are there?
Most non-natives are harmless but around 10-15% of these have become invasive.
There has been a dramatic increase in numbers over recent years with 10 to 12 new species becoming established every year.
Invasive species are easily spread, for example, Japanese knotweed spreads so rapidly not only through its root system but because any fragment of its stem or root will grow to form a new plant. This makes it very difficult to get rid of.
What are the problems?
They have a range of environmental, economic, health and social impacts in Britain.

Harm to the Environment:

Worldwide they are one of the greatest threats to biodiversity, even more so than pollution. In Britain they threaten the survival of native wildlife, spread harmful diseases and damage our natural ecosystems.

For example, Japanese knotweed will grow in any soil no matter how poor and quickly invades the spaces, shading out native plants.

Economic impact:

Problems caused by these species cost at least £1.7 billion
every year in Britain. Costs include damage to infrastructure and losses to production, for example, crops including forestry and agricultural.

Health and social impacts:

They can  also affect our health and the way we live. Some species, such as Floating Pennywort, make flooding worse. Others are a health hazard such as Giant  Hogweed, which causes skin burns, and Oak Processionary Moth which causes skin irritation and respiratory problems.

Legal responsibilities

Non-native species legislation in England,  Scotland and Wales prohibit the spread of  non-native species and require landowners  to manage and dispose of non-native  species in order to prevent spread.

What can we do?

Prevent them from establishing. Take precautions to prevent spread from site to site. Detect and rapidly respond if they are found on our sites. Where they have become established plan to follow site rules to prevent spread.


Be aware and report : You should be advised as part of any site work instruction if there are invasive non- native species on site and what precautions are needed. If you come across any that haven’t been identified, make sure you report them to the Tilhill Manager