University of Bristol
Wellcome Trust
Recommended by:
Society of Biology
PEEP for Physics & Ethics at GCSE

Non-native invasive Species – their impact on the environment.

Click to enlarge.
Harlequin ladybirds.

What is a non-native invasive species?

These are species of plants and animals that are not native (natural) to an area and are often known under a number of different names:

  • Non-native species
  • Introduced species
  • Exotic species
  • Non-indigenous species
  • Alien species
  • Transplants
  • Invasive species

An official US definition was provided for President Clinton in 1999:
‘Invasive species’ means an alien species whose introduction does or is likely to cause economic or environmental harm or harm human health.

Why are non-native invasive species important?

According to the Convention on Biological Diversity: 

Open quoteThe threat to biodiversity due to invasive alien species is considered second only to that of habitat loss. Therefore they are a serious impediment to conservation and sustainable use of global, regional and local biodiversity, with significant undesirable impacts on the goods and services provided by ecosystems.Close quote
 Original source

Click to enlarge
Japanese knotweed
Photo: Tom Heutte,
USDA Forest Service

  • In 2003, DEFRA estimated that control measures for non-native species like Japanese knotweed and giant hogweed cost over £1.4 BILLION whereas in a decade of growing commercial GM crops around the world there have been no significant cases of habitat destruction at all.
  • In the USA, over $2 billion are spent annually removing zebra mussels from water inlets to factories.  More info
  • Not all non-native species are harmful but according to the  
     Global Species Database, there are 84 species in the UK which are harmful. The database does not list all those in the UK which are considered a threat e.g the Muntjac deer.

 How do invasive species cause harm?


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