1. Introduction to Ecological Resilience
Jan Sendzimir
International Institute of
Applied Systems Analysis
Laxenburg, Austria

2. Surprise in Florida Bay
Sea grass
Clear Water
Muddy Water
Algae Blooms
Florida Bay

3. Ecological Succession South-eastern North America
Premise: system tends toward stable equilibrium
Vegetation characteristic of different successional stages
(After E.P. Odum 1971 Fundamentals of Ecology)

4. Adaptive Cycle Graphic Metaphor for Dynamism of Resilience Dynamic systems do not tend toward a stable equilibrium, but cycle through four phases (r  K   )
These definitions emerged from the need to characterize regimes common to resource management systems.

5. Resilience Theory
Develop common tools to study the development, decline, and collapse or persistence of socio-ecological systems.
You are resilient if your identity persists:
In the face of shock or disturbance the same set of organizing processes remain to control the behavior and structure of a resilient system.

6. Ecological Resilience is related to the…
Size of the Stability Domain
Amount of change a system can undergo and still retain the same controls on function and structure
Degree to which system can:
Self-organize
Learn and adapt
 the amount of stress it can sustain and still retain the same configuration of interactions between ecological variables.

7. Resilience: Three Levels of Meaning
Metaphor related to sustainability
A property of dynamic models
A quantity measurable in field studies

8. Lake Eutrophication The flip from clear to turbid water
Some lakes remain clear for decades until one
summer storm churns up the sediments, and it
remains turbid for decades, despite all “cures.”

9. Percent Of Lake Covered By Macro- Phytes Phosphorus in Water
Response of charophyte vegetation in the shallow Lake Veluwe to increase of the phosphorus concentration in the s.
Figure from Scheffer et al Nature Vol. 413 pp

10. Hysteresis Percent Of Lake Covered By Macro- Phytes28 1 2 27 3 26
5, 6…25 4
Response of charophyte vegetation in the shallow Lake Veluwe to increase and subsequent decrease of the phosphorus concentration. Red dots represent years of the forward switch in the late 1960s and early 1970s. Black dots show the effect of gradual reduction of the nutrient loading leading eventually to the backward switch in the 1990s.

11. If the equilibrium curve is folded backwards (c), three equilibria can exist for a given condition. Equilibria on the dashed middle section are unstable and represent the border between the basins of attraction of the two alternative stable states on the upper and lower branches.
Figure from Scheffer et al Nature Vol. 413 pp

12. Examples of Multiple Stable States
Coral Reefs
coral vs. algae
Arid Landscapes
shrubland vs. grassland
Shallow Lakes
eutrophic vs. clear
North Florida Forest
longleaf pine savanna & fire vs. hardwood forest without fire

13. Stability Landscape View of Multiple “Stable” States
Potential
Energy
Ecosystem State
An ecosystem may have multiple stability domains. Within each domain many configurations are possible with the same set of processes organizing structure and function

14. Stability Landscape View of Evolution Shift from one domain to the next as the rules change
As it changes, a system
modifies its own possible states.
Here a smaller and smaller
perturbation can shift the
equilibrium from one stability
domain to another.
Finally the stability domain
disappears and the system
spontaneously changes state.

15. External conditions affect the resilience of multi-stable ecosystems to perturbation.
The bottom plane shows the equilibrium curve. The stability landscapes depict the equilibria and their basins of attraction at five different conditions. Stable equilibria correspond to valleys; the unstable middle section of the folded equilibrium curve corresponds to a hill. If the size of the attraction basin is small, resilience is small and even a moderate perturbation may bring the system into the alternative basin of attraction.

16. Resilience as Metaphor
Simple story to communicate complex ideas
Explain consequences of equilibrium-based sciences and derivative policies
Not as a testable hypothesis
Theory itself is rarely tested directly
As a generator of concepts useful in generating testable hypotheses

17. Resilience as Metaphor Guiding how we define its aspects
To assess resilience in terms of a hierarchal context,
measure the resilience of what to what.
These aspects change depending on the temporal, social, and spatial scale at which one measures.
Geomorphology
Soil P
Lake Sediment P
A socioecological system can be resilient at one time scale because of the technology it has adopted. Iron axes, for example, probably helped emerging agricultural societies
to persist over a particular span of time because they enabled their possessors to clear more forest and grow more food. But at a longer time scale, once some threshold of forest cover had been crossed, fallowing could no longer maintain soil fertility and the resilience of the system was compromised (Ruthenberg 1976).
Water P
Resilience at one scale can be subsidized by resilience at a broader scale in space and/or time.
Panarchy -A Cross-scale Nested
Set of Adaptive Cycles

18. Resilience: Three Levels of Meaning
Metaphor related to sustainability
A property of dynamic models
A quantity measurable in field studies

19. In theory and in the model, resilience is tracked as the size of the attractor for the clear water condition.
Plot of system equilibria
on axes of fast (water P) and slow (sediment P) variables
Slow Variable
(Sediment Phosphorus)
Fast
Variable
(Water
Phos-
phorus)
Higher R
Lower R
Resilience of clear water state to large runoff events,.

20. Resilience As a property of dynamic models
Resilience within & between scales1
Surface waters & non-point source pollution2.
Rangeland management3
Fire-driven forest dynamics4
1 - Peterson G, Allen CIR, Holling CS Ecological resilience, biodiversity, and scale. Ecosystems 1:6–18.
2 - Carpenter SR, Caraco NF, Correll DL, Howarth RW, Sharpley, AN, Smith VH Nonpoint pollution of surface waters with phosphorus and nitrogen. Ecol Appl 8:559–68.
3 - Janssen MA, Walker BH, Langridge J, Abel N An adaptive agent model for analysing co-evolution of management and policies in a complex rangeland system.
Ecol Model 131:249–68.
4 - Peterson GD Contagious disturbance and ecological resilience [dissertation]. Gainesville (FI): University of Florida.

21. Resilience Indicator Fish Population Dynamics Model
Rates of
Birth
and
Mortality
(per year)
birth
birth
Fish Population Density (number per ha.)

22. Resilience As a property of dynamic models
Are system-specific.
Not all are measurable in the field
May be possible to calculate them in the model.

23. Resilience: Three Levels of Meaning
Metaphor related to sustainability
A property of dynamic models
A quantity measurable in field studies

24. Status of 9 Indicator Variables during the Adaptive Cycle
In practice, resilience could be tracked by monitoring the slowly changing variables that control the attractor for the clear water condition.
Soil P affects the persistence of clear water in 2 ways:
Resilience (shape of attractor)
Probability distribution of disturbances (major runoff events)

25. Using Model Insights to identify R Indicators
Ecological
Soil P, Animal stocking densities, Built area
Institutional
Best practices
Education, enforcement or innovation
Economic
Markets for water quality, soil runoff
Social
Networks to facilitate appropriate action
Power asymmetries between interest groups

26. Resilience: Three Levels of Meaning
Metaphor related to sustainability
A property of dynamic models
A quantity measurable in field studies