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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-4523
DTSTART:20170411T050500Z
DTEND:20170411T180000Z
DTSTAMP:20260419T042904Z
LAST-MODIFIED:20170317T200614Z
LOCATION:4274 Chamberlin (refreshments will be served)
SUMMARY:The influence of spatial connectivity on landscape regime shif
 ts and pattern formation after external pulses\, Chaos & Complex Syste
 ms Seminar\, Zak Ratajczak\, UW Department of Zoology
DESCRIPTION:Ecosystems are often exposed to driver pulses\, such as cl
 imate oscillations or consumer outbreaks. We currently lack robust the
 oretical predictions for when a driver pulse will elicit regime shifts
 \, which are instances when an ecosystem no longer recovers to its ess
 ential form\, functions\, and feedbacks. We used a spatially extended 
 vegetation model where increases in grazing pressure can force patches
  of the landscape to undergo a regime shift from a high productivity s
 tate to a self-reinforcing low-productivity state. We considered a fac
 torial combination of driver pulses that increase grazing pressure by 
 differing intensities and for differing durations. These pulses were a
 pplied to simulated landscapes with high underlying spatial heterogene
 ity and differing levels of spatial connectivity between adjacent patc
 hes. We considered two scales of resistance to regime shifts: landscap
 e integrity\, defined as when >95% of the landscape returned to a high
  biomass state and refugia potential\, defined as the ability to keep 
 >5% of the landscape in the high biomass state. High connectivity land
 scapes had greater landscape integrity\, meaning that they could withs
 tand more intense and longer pulses\, and still have a majority of the
  landscape return to a high biomass state. Low connectivity systems\, 
 in contrast\, had greater refugia potential\, meaning that at least a 
 small portion of the landscape was able to return to a high biomass st
 ate\, even after more intense or longer pulses. Systems with intermedi
 ate connectivity had a more balanced combination of landscape integrit
 y and refugia potential. These landscapes also tended to form coherent
  spatial patterns after driver pulses that nearly forced a landscape-s
 cale regime shift. Such pattern formation could potentially be used as
  a warning sign for adaptive management. Ensemble\, these simulations 
 suggest that underlying landscape characteristics can greatly alter th
 e landscape and patch-scale potential for regime shifts in response to
  various external pulses.
URL:https://www.physics.wisc.edu/events/?id=4523
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