Catastrophic regime shifts in social-ecological systems

Christopher Britton-Foster

• Focus Paper:Kinzig AP, Ryan P, Etienne M, Allison H, Elmqvist T, Walker BH (2006) Resilience and regime shifts: assessing cascading effects. Ecology Society 11(1): 23.

• Supporting Paper:Scheffer M, Carpenter SR (2003) Catastrophic regime shifts in ecosystems: linking theory to observation. Trends Ecol Evol 18: 648–56.

Outline

• Regimes and resilience

• What is hysteresis?

• The cascading effect

• Case studies

• Implications for management

Regimes and Resilience

• Regimes are dynamic, never stable

• Alternative regimes: two different regimes that could exist under the same external conditions

Regimes and Resilience

• Resilience: the capacity of a system to absorb changes and disturbance while still retaining the same function

• Catastrophic regime shift

Scheffer & Carpenter 2003

Hysteresis

Kinzig et al, 2006

Multiple Thresholds

• Multiple thresholdsEcologicalEconomicCultural

The cascading effect

• Breaching one threshold between alternative regimes can trigger the breaching of multiple other thresholds at different scales

• Perturbation can be :– Large or Tiny– Slow or Fast

• Creates a new, resilient regime that is often irreversible

Case studies

Thomas Kleitz

Foodsubs.com

http://cookappeal.blogspot.ca/

Causse Méjean, France

Fedou becomes less of the cultural identity

Farmers move toward timber or Roquefort

More grassland fragmentation

No more Fedou cheese production

Encroaching pine patches

http://www.agricorner.com/

Western Australian Wheatbelt

Rising water table

Salinization and waterlogging

Less arable land

Fewer viable farms

Fewer native plant patches

Rural towns become unviable

Goulburn-Broken Catchment, Australia

Mark Edwards

Farms become unviable

Processing plants close down

Irreversible shift away from an agricultural economy

Drought

Irrigation more expensive

Goulburn-Broken Catchment, Australia

Mark Edwards

Less arable land

Processing plants close down

Irreversible shift away from an agricultural economy

Heavy rainfall

Waterlogging and salinization of soil

Fewer viable farms

Native plant patches die

Less natural regulation of watertable

Madagascar Dry Forests

Farmers move to urban centre

Rural poverty

Cultural protection of sacred forests erodes

Less pollination to agricultural fields

Even fewer viable farms

Increasing aridity

Implications for Natural Resource Management

• CAS and the Cascading effect: Adaptation drives more change at different scales (positive feedback)

• Identifying which thresholds are most susceptible to external influences (e.g. climate change)

• Managing for just one variable = blindness to other critical interactions

• “Rule of Hand”

Discussion Topics

• Can natural resource managers be expected to predict the influence of their actions on all of a system’s thresholds?

• Are speculations about possible regime shifts good enough to base important management decisions on?