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The Wolves and Moose on Isle Royal

The Wolves and Moose on Isle Royal

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The Wolves and Moose on Isle Royal

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  1. The Wolves and Moose on Isle Royal

  2. Isle Royale images from: http://www.kgcphoto.com/isle_royale_national_park.htm

  3. Wolf and moose images from http://blog.kingsoutdoorworld.com/2007/02/

  4. alright – back to work…

  5. Largest island in lake Superior • Isolated from mainland most of the time • Home to moose and wolves For now: • concentrate on actions between wolves and moose herd • ignore other influences on moose population (such as ?) • rather limited “systems” approach (see additional reading on web page)

  6. How to describe feedback: size of moose herd size of wolf pack more food on four legs positive feedback size of wolf pack size of moose herd more hungry mouths to feed negative feedback

  7. Example of a Feedback Loop Size of moose herd More food for wolves Appetite for moose Size of wolf pack

  8. Note: A feedback loop needs to be closed ! Therefore it needs at least • two components • two connections between these components

  9. Or Somewhat Simplified: positive size of moose herd size of wolf pack negative

  10. size of moose herd size of wolf pack How to analyze a feedback loop: • Need to disturb the system • Doesn’t matter where you start • Analyze how disturbance moves through the system • How does wolf – moose system behave ?

  11. Sign of Feedback Loop • number of negative couplings determines sign of feedback loop • even number of negative couplings: positive feedback loop • odd number of negative couplings: negative feedback loop

  12. Effects of Negative of Positive Feedbacks

  13. Effects of Negative of Positive Feedbacks • positive feedback: input signal will be amplified • negative feedback: input signal will be damped

  14. Size of wolf and deer herds From Science Times (3/19/1996) (http://www.admin.mtu.edu/urel/PressReleases/feature/wolves/wolf.html)