Linking Threats to Assets in Complex Ecological and Socio-Economic Systems: Qualitative Modelling for Tourism Development in North Western Australia
Jeffrey Dambacher & Keith HayesCSIOR Mathematical and Information Sciences
Geoff HosackOregon State University
Risk-Based Management of Natural Resources
• Depends on models• Risk assessment predicated on model linking threats to asset
• Natural systems are complex• Realistic representation of causality is difficult• Ecological and socioeconomic systems have feedback
• Experts versus stakeholder participation• Stakeholders typically not involved in model development yet live with the risk
• Model uncertainty• Difficult to address
• Results conditional on all parameters• Typically a narrow field of models considered
Threat AssetModel
Model Uncertainty
Parametric Uncertainty• Precise measurements• Expert opinion• Simulations with plausible parameter space• Receives majority of attention and effort in modelling
Model Structure Uncertainty• Within a model: feedback cycles with opposing sign• Between models: different interactions or variables• Largely ignored
“Model structure uncertainty is the 800 pound gorilla in
the middle of the room that no-one talks about”
Scott Ferson
Methods
• Causal Graphical Models
• Bayesian belief network (BBN)
• Qualitative model (QM)
• Model uncertainty
• Qualitative Prediction weights
• Merging of BBN and QM
Bayesian Belief Networks
• group of nodes connected by directed arrows such that there are no cycles (loops)
• “child” nodes with incoming arrows are probabilistically dependent on “parents” values
X1
X2 X3
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Qualitative ModellingQualitative Modelling
CCOMMUNITY OMMUNITY MMATRIXATRIXCCOMMUNITY OMMUNITY MMATRIXATRIX
SIGNED DIGRAPHSSS IGNEDIGNED DD IGRAPHSIGRAPHS
PREDATOR-PREYPPREDATORREDATOR--PPREYREY
MUTUALISMMMUTUALISMUTUALISM
COMMENSALISMCCOMMENSALISMOMMENSALISM
COMPETITIONCCOMPETITIONOMPETITION
+++
++++++
+++ +++
--- --- ---
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SELF-EFFECTSSELFELF--EFFECTEFFECT
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Press Press PerturbationsPerturbationsPress Press PerturbationsPerturbations
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Krebs et al. (1995) ExperimentKrebs et al. (1995) Experiment
• Hare food addition: hares increased
• Predator exclosures: hares increased
• Food and exclosures: hare increase multiplicative
• Fertilization: vegetation increased, hares neutral ?
• Hare food addition: hares increased
• Predator exclosures: hares increased
• Food and exclosures: hare increase multiplicative
• Fertilization: vegetation increased, hares neutral ?
V H PV H P
V H PV H P
Positive InputPositive InputVVEG.EG. H HAREARE P PRED.RED.
Positive InputPositive InputVVEG.EG. H HAREARE P PRED.RED.
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MMODELODEL A AMMODELODEL A A
MMODELODEL B BMMODELODEL B B
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CCRITICALRITICAL E EXPERIMENTXPERIMENTCCRITICALRITICAL E EXPERIMENTXPERIMENT
Qualitative Prediction WeightsQualitative Prediction Weights
Impact to CoralImpact to Coral from Input to Algae from Input to Algae 358 feedback cycles 358 feedback cycles + 82, - 276, 194 net + 82, - 276, 194 net Prediction weight Prediction weight W = 194/276 = 0.54 W = 194/276 = 0.54
Negative response Negative response in coral seems in coral seems likely....likely....but how likely?but how likely?
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Prediction Weight Wi j
Testing prediction weights (W) through simulations
• Proportion of simulations with correct sign given by least square fit to non-linear function
• Sign of each element of adj(–ºA) converted into a probability and incorporated into the CPTs of a BBN via a linear relationship
Qualitative predictions to CPT
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Snowshoe hare example
Model A Model B
Sym_Adj (-°A) Sym_Adj (-°B)
Adj (-°A) W Adj (-°B) W
The null model = fully connected community matrix
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Sym_Adj_Null
0 0 0
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Snowshoe hare CPT
Model Incr(Veg) Incr(Veg) Unch(Veg) Decr(Veg) Incr(Hare) Unch(Hare) Decr(Hare) Incr(Lynx) Unch(Lynx) Decr(Lynx)A Incr 0.96 0.02 0.02 0.96 0.02 0.02 0.96 0.02 0.02A Unch 0.02 0.96 0.02 0.02 0.96 0.02 0.02 0.96 0.02A Decr 0.02 0.02 0.96 0.02 0.02 0.96 0.02 0.02 0.96B Incr 0.96 0.02 0.02 0.33 0.33 0.33 0.96 0.02 0.02B Unch 0.02 0.96 0.02 0.02 0.96 0.02 0.02 0.96 0.02B Decr 0.02 0.02 0.96 0.33 0.33 0.33 0.02 0.02 0.96
Null Incr 0.33 0.33 0.33 0.33 0.33 0.33 0.33 0.33 0.33Null Unch 0.02 0.96 0.02 0.02 0.96 0.02 0.02 0.96 0.02Null Decr 0.33 0.33 0.33 0.33 0.33 0.33 0.33 0.33 0.33
Snowshoe hare BBN
Lynx
IncreaseUnchangedDecrease
80.59.739.73
Snowshoe_hare
IncreaseUnchangedDecrease
0 100 0
Vegetation
IncreaseUnchangedDecrease
100 0 0
Alternative_models
ABNull
4.2671.124.7
Input_to_Veg
IncreaseUnchangedDecrease
100 0 0
Ningaloo Project Objectives
• Qualitative models of ecosystem and socio-economic system with tourism impacts in a marine park
• Complement quantitative modelling• Integrative framework for expert and
stakeholder knowledge• Evaluate management strategies
-
+
Increasednutrients
+
+
+
Increasedharvest
-
monitoring
management
Monitoring and management add two negative feedback cycles
Management problem: trophic cascade effects of recreational fishing
Coral Reef ModelCoral Reef Model
Netica Example
Monitoring and management add 1026 feedback cycles
Coral Reef ModelCoral Reef Model
Thank you