Japanese Knotweed:

Introduced to Britain in the 19th century as an ornamental plant
Grows up to 1 meter in 4 weeks (3cm a day) pushing through concrete and tarmac
Can lie dormant underground for up to 20 years and a root can spread up to 7 meters
No natural predator and threatens plants and animals
Can ruin house prices - value can half
In 2003 the cost of eradicating it was £1.5 billion, in 2009 it was £3 billion
Have to use industrial strength herbicides and weed killers

Mitten Crabs:

1 of the worlds top 100 invasive species
Accidental introduction - came from eastern Asia and Europe to north England
They caused damage to fishing gear and competed with native species
Destroyed local freshwater species, burrowing nature of crabs damages embankments
Management is difficult due to abundance

Cane Toads:

	Created by Caitlyn Grayston over 7 years ago

A-Level Geography (A Level Biodiversity Under Threat) Note on Alien Species, created by Caitlyn Grayston on 01/06/2017.