Invasive species

Coming soon to an ecosystem near you!

The Tens Rule

10% of introduced species escape

10% of escaped species become established

10% of established species become invasive

The Tens Rule

10% of introduced species escape

10% of escaped species become established

10% of established species become invasive

0.1% of species introduced become invasive

Exceptions

Ornamental trees and shrubs

Plantation species

Crop plants, biocontrol agents

Disturbance

How can disturbance facilitate invasion?

Disturbance

How can disturbance facilitate invasion?

reduce competition

increase resourceavailability

• difficulty of detection

• exponential population growth

• post-invasion evolution (local adaptation)

• increased availability of favorable sites

Rare Species

Narrow Geographic Range

Small Population Size Habitat Specificity

Invasive Species

Broad Geographic Range

Large Population Size Wide Range of Habitats

Rapid dispersal: short generation time

long reproductive period

prolific seed production

successful dispersal

successful establishment

Lots of seeds!

multiflora rose

Japanese barberry

Oriental bittersweet

Long fruiting period

glossy buckthorn

Successful seedling establishment

Common buckthorn(Rhamnus cathartica)

2% sun 28% sun 100% sun

Ellsworth, Harrington & Fownes (2004)

4.5 m in 12 weeks!

Impacts

Reduced populationsize and biodiversityof native species

Invasive species are the second major cause ofextinctions globally(main cause on islands)

Pale swallowwortCynanchum rossicum

Introduced mosquitoes spread avian malaria

Difficult to eradicate

Norway maple