Download Adaptive cycle and Panarchy

Adaptive cycle and Panarchy
Adaptive
cycle
of recovery
(succession)
after disturbance
Complex
system
undergoes
change
through
‘adaptive cycle’
r=growth (pioneer; stand initiation)
K=carrying capacity (competition, niche specialization) (mature to old-growth)
Ω=release, new opportunities (disturbance)
α=re-organization and recovery (new forest seeds in) Gunderson & Holling 2002
Four stages of adaptive cycle
Metaphor
Ecology
Biological
Psychological
Economic
1
Exploitation
Birth
Development
Growth
2
Conservation
Maturity
Sanity
Consolidate
3
Release
Death
Madness
Collapse
4
Reorganization Decay
Healing
Rebuild
1) Exploitation: rapid expansion, e.g., population grows.
2) Conservation: population reaches carrying capacity and stabilizes for a time.
3) Release: population declines due to a competitor, or changed conditions
4) Reorganization: certain members of the population are selected for their ability to
survive despite the competitor or changed conditions that triggered the release.
Adaptive cycle: four stages
r
K
Ω
α
Ω
r
K
α
Three properties of adaptive cycle
Potential: the number and kinds of future options available (e.g. high levels of
biodiversity provide more future options than low levels)
Connectedness: the degree to which a system can control its own destiny
through internal controls, as distinct from being influenced by external variables
Resilience: how vulnerable a system is to unexpected disturbances and surprises
that can exceed or break that control. The adaptive cycle is the process that
accounts for both the stability and change in complex systems.
There are ‘discontinuities’ in variables of interest
Discontinuities determine dominant scales
Temporal scale
Adaptive cycles occur at multiple discontinuous scales in
natural ecosystems
Spatial scale
Panarchy
• A term adopted to better represent
complex adaptive systems than ‘hierarchy’
• Hierarchy describes “top-down rule”
• Panarchy refers to a specific form of
governance or rule (archy) that would
encompass (pan) all others
What is panarchy?
“The term [panarchy] was coined as an antithesis to the
word hierarchy (literally, sacred rules). Our view is that
panarchy is a framework of nature's rules, hinted at by the
name of the Greek god of nature, Pan.”
Lance Gunderson and C. S. Holling,
Panarchy: Understanding
Transformations in Systems of Humans
and Nature, Island Press, p.21, 2001.
Panarchy: all-encompassing nested set of
adaptive cycles operating at discrete scales
(Gunderson and Holling 2001).
These cycles connect with cycles
‘above’ and ‘below’ them in the
hierarchy:
“Revolt" – this occurs when
fast, small events overwhelm
large, slow ones, as when a
small fire in a forest spreads to
the crowns of trees, then to
another patch, and eventually
the entire forest
“Remember" – this occurs
when the potential accumulated
and stored in the larger, slow
levels influences the
reorganization. For example,
after a forest fire the processes
and resources accumulated at a
larger level slow the leakage of
nutrients, and options for
renewal draw from the seed
bank, physical structures and
surrounding species that form a
biotic legacy.
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Panarchy predicts discontinuities in adaptive cycles across scales
Three Core Properties of Complex Systems that follow Panarchy Theory
Allen, Craig R., et al. "Panarchy: Theory and Application." Ecosystems 17.4 (2014):
578-589.
Cup-and-ball model: changes to new stability domain through shift in
variables or parameters
e.g., variable=species composition
e.g., parameter=climate
Global to
arctic
Mann et al.
Polar
amplification
Chapman and Walsh
Permafrost is thawing
in many places,
not just southern margins
Four mechanisms affect permafrost thaw:
a)
b)
c)
d)
Active layer thickening
Talik formation
Erosion
Thermokarst development
Positive feedback to atmospheric GHGs
Schuur et al. 2008
Mineral deposit, Siberia
Schuur et al. 2008
Cryoturbated soil, thin peat, Alaska
Frozen peat, Canada, Siberia
Melting permafrost
Hudson Bay, Canada
Both the variables and the parameters are changing in the Arctic
e.g., variable=species composition
e.g., parameter=climate
IPCC FAR projected global warming
Mean Annual Temperature and Precipitation Predictions for BC
Four Impacts to Forests
1. Reduced snow pack
2. Increased forest fires
3. Forest dieback and species migrations
4. Forests shifted from net CO2 source to
sink
1. Dramatic decline in snowpack by 2040
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch11s11-5-3-5.html
2. Increasing area burned annually in Canada
3. Massive shifts in forest composition
http://cfcg.forestry.ubc.ca/projects/climate-data/climatebc-and-bioclimatic-envelope-modelling
4. Changed from CO2 sink to source
New study shows declining productivity and carbon
sequestration in Canadian boreal forest
NASA, Dec. 2011
Pan, PNAS, 2012
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Potential Impacts of Climate Change in Forests
BC Ministry of Forests
1. Increased forest fire frequency and severity due to
warming and drying.
2. Increased disturbances due to insects and disease.
3. Potential ranges of species will move northward and
upward in elevation.
4. New assemblages of species will occur in space and
time.
5. Species may be unable to move into areas of suitable
climate due to barriers to movement, slow migration
rates, unsuitable growing substrate or lack of habitat.
Summary
• Complex adaptive systems are inherently stable
• Stable systems change but are homeostatic, like a dancer
• Stables systems have resistance, where small disturbances
are contained, and resilience, where the system returns to
the same stability domain
• Complex systems change through adaptive cycles
• Adaptive cycles and panarchy are stabilizing characteristics
• Positive feedbacks and crossing tipping points can lead to
loss of stability
• Climate change could cause instability
• Maintaining complexity will be crucial