introduced and invasive species. introduced species also known as: nonnative, nonindigenous, alien,...
TRANSCRIPT
Introduced and Invasive Species
Introduced species
Also known as: nonnative, nonindigenous, alien, exotic
Introductions can occur naturally, but now are driven primarily by human factors (esp. trade, travel)
From introduced to invasive
• Vast majority of introductions do not result in establishment of invasives
• However, repeated introductions can lead to invasions (European starlings were introduced 4 times)
• Propagule pressure
Ecological context
• Not just about species attributes• Disturbance can reduce competition
from native plans• Nutrient availability• Community diversity• Enemy release hypothesis
Cozumel Thrasher
Invasives in Canada
Zebra mussel
• Originally native to Russia• First detected in Great Lakes in 1988,
near Detroit/Windsor• Ballast water of ocean-going ships
1992 2001
2010
Leafy Spurge
How do we reduce or manage species introductions?
Canada’s approach to Leafy Spurge
• Biological control: Sheep, Beetles• Elbow Pasture, SK: 1200 sheep
• Reduced spurge density from 80-100 stems/m2 to 20-50 stems/m2 in a few years
• Cattle stocking 36% higher• Beetles: down to 10%
http://www4.agr.gc.ca/AAFC-AAC/display-afficher.do?id=1186596698988&lang=eng
Pragmatic approaches
1) Prevention
Pragmatic approaches
2) Eradication: shoot first, ask questions later
video
Pragmatic approaches
3) Management
-Chemical or biological control-Habitat modification-Manual removal-Problem: costs $$$ year after year
What about human values?
The Oatmeal’s Take Video