1. Ecological Resiliency
Presentation to Multi-hazard Roundtable
Jan. 16, 2008
Susan Bolton, Ph.D., P.E.
University of Washington

2. Ecological Resiliency
Emerges from ecosystem features which follow the ‘rules’ of thermodynamics, conservation of mass and energy, natural selection and evolution

3. Overarching ecological principles
Thermodynamics and conservation of mass and energy
Energy flows, solar based
Materials are reused and recycled
Natural selection and evolution
Self-organization
Disturbance and thresholds

4. Ecosystem a self-organizing system with no blueprint or design
would need a large amount of information to predict final outcome
redundancy of function but not necessarily of structure
based on solar energy
reuse of materials
many possible outcomes and pathways
current state reflects past history (disturbances)
has a tipping point or threshold where a new state is categorically different from previous and cannot return
everything is connected

5. Definitions Engineering resilience Ecological resilience
Rate at which a system returns to a single steady state or cyclic state following a disturbance
Ecological resilience
Amount of change (disturbance) a system can withstand before it changes to a new set of reinforcing processes and structures

6. Traditional vs. ecological engineering
Seeks stability
Accepts inevitability of change
Resists disturbance
Absorbs and recovers from disturbance
One equilibrium point
Multiple, non-stable equilibria
Single acceptable outcome
Multiple acceptable outcomes
Predictability
Unpredictability
Fail-safe
Safe-fail
Narrow tolerances
Wide tolerances
Rigid boundaries and edges
Flexible boundaries and edges
Efficiency of function
Persistence of function
Redundancy of structure
Redundancy of function
Engineering Resilience
Ecological Resilience

7. Additional information
Holling, C.S Resilience and stability of ecological systems. Annual Review of Ecology and Systematics. 4:2-23
Gunderson, L.H Ecological Resilience – in Theory and Application. Annual Review of Ecological Syst. 31:
Bergen, S.D., S.M. Bolton, and J.L. Fridley Design principles for ecological engineering. Ecological Engineering 18:
Huggett, A.J The concept and utility of ‘ecological thresholds’ in biodiversity conservation. Biological Conservation 124: