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Introduced and Invasive Species

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.

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Introduced and Invasive Species

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  1. Introduced and Invasive Species

  2. Introduced species Also known as: nonnative, nonindigenous, alien, exotic Introductions can occur naturally, but now are driven primarily by human factors (esp. trade, travel)

  3. 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

  4. Ecological context • Not just about species attributes • Disturbance can reduce competition from native plans • Nutrient availability • Community diversity • Enemy release hypothesis

  5. Cozumel Thrasher

  6. Invasives in Canada

  7. Zebra mussel • Originally native to Russia • First detected in Great Lakes in 1988, near Detroit/Windsor • Ballast water of ocean-going ships

  8. 1992 2001 2010

  9. Leafy Spurge

  10. How do we reduce or manage species introductions?

  11. 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

  12. Pragmatic approaches 1) Prevention

  13. Pragmatic approaches 2) Eradication: shoot first, ask questions later video

  14. Pragmatic approaches 3) Management • Chemical or biological control • Habitat modification • Manual removal • Problem: costs $$$ year after year

  15. What about human values?

  16. Video The Oatmeal’s Take

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