references/scheffer-2009.html
Scheffer, M. (2009). Critical Transitions in Nature and Society. Princeton, NJ, Princeton University Press. |
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Outline: |
Critical Transitions Definition:
Linear, threshold, catastrosphe fold
hysteresis happens when you go back on the catrostrophe fold
example with turbidity and vegetaion, increasing of decreasing nutrients as the driving force
similar diagram for climate moisture and microclimate moisture
graphical model for poverty trap
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Example 1: shallow lakes
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Example 2: local climate, trees and precipitation
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RestorationFind out how to reduce the resilience of the bad state first, and then flip out of the bad state with less effort.
example: dry tropical forestTrees are required to maintain soil moisture. If you plant trees get the browsers eat them. After a good rain year, many trees will automatically sprout and do well enough to protect the soil if you can keep them from getting eaten.
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Notes:
pg 2 - "Understanding such transitions can open up surprising new ways of managing change."
"Tipping point" book is about social traps and shifts
pg 6 - "Regime shifts seem often triggered by a major external impact. ...
such disturbances are not always the complete story. "
"A much trickier aspect is that systems may gradually become increasingly fragile to the point that even a mino perturbation will trigger a drastic change toward another state. I will call such changes critical transitions.
pg 7 - "underlying structures of the real world show up in the mirror world of math with a beautiful clarity that can never be seen in reality."
pg 13 - equilibrium in dynamical systems
steady state - also called an attractor
such as when birth rate = death rate
pg 16 - alternative equilibria such as the Allee effect, in which there is a population level below which the population can't have net growth
two states are carrying capacity and total disappearance of the population
pg 18 - catastrophic shifts - vs. the simpler threshold
catastrophic shifts lead to hysteresis
pg 22 - width of the basin of attraction is the Hollings resilience
"size of the valley of basin of attraction around a state that corresponds to the maximum perturbation that can be taken without causing a shift to an alternative stable state."
examples:
figure 2.5 shallow lake
figure 2.10 moisture in a forest
figure 2.14 poverty trap