Ecological Modeling: A Common-Sense Approach to Theory and Practice Book

Preface     xi
Acknowledgments     xiii
Introduction     1
Common-sense solutions: three exercises     1
Modeling theory     2
Modeling practice     2
Theory, practice, and common sense     3
Intended use of this book     3
Common-sense solutions: three exercises
Common-sense solutions     5
Three problems     6
Harvesting food for the winter     6
Estimating the probability of population extinction     12
Managing the Commons     20
The systems approach to problem solving     49
The conceptual model (Phase I)     50
The quantitative model (Phase II)     51
Model evaluation (Phase III)     51
Model application (Phase IV)     51
The three problems revisited: the systems approach in theory and practice     51
Modeling theory
Theory I: the conceptual model     53
State the model objectives (I[subscript a])     54
Bound the system-of-interest (I[subscript b])     55
Categorize the components within the system-of-interest (I[subscript c])     57
State variables     57
Material transfers     59
Sourcesand sinks     61
Information transfers     61
Driving variables     62
Constants     62
Auxiliary variables     62
Identify the relationships among the components that are of interest (I[subscript d])     63
Submodels     63
Represent the conceptual model (I[subscript e])     65
Conceptual-model diagrams     65
Describe the expected patterns of model behavior (I[subscript f])     66
Theory II: the quantitative model     67
Select the general quantitative structure for the model (II[subscript a])     68
Choose the basic time unit for the simulations (II[subscript b])     72
Identify the functional forms of the model equations (II[subscript c])     72
Information on which to base the choice of functional forms     73
Selecting types of equations to represent the chosen functional forms     73
Estimate the parameters of the model equations (II[subscript d])     75
Statistical analyses within the context of simulation model parameterization     75
Quantifying qualitative information     76
Deterministic- versus stochastic-model parameterization     76
Execute the baseline simulation (II[subscript e])     77
Baseline simulations for stochastic models     78
Theory III: model evaluation     79
Assess the reasonableness of the model structure and the interpretability of functional relationships within the model (III[subscript a])     81
Evaluate the correspondence between model behavior and the expected patterns of model behavior (III[subscript b])     82
Examine the correspondence between model projections and the data from the real system (III[subscript c])     84
Quantitative versus qualitative model evaluation     86
Determine the sensitivity of model projections to changes in the values of important parameters (III[subscript d])     86
Interpreting sensitivity analysis within a model evaluation framework     87
Theory IV: model application     89
Develop and execute the experimental design for the simulations (IV[subscript a])     89
Analyze and interpret the simulation results (IV[subscript b])     91
Communicate the simulation results (IV[subscript c])     91
Modeling practice
Some common pitfalls     93
Phase I pitfalls: the conceptual model     93
Phase II pitfalls: the quantitative model     97
Phase III pitfalls: model evaluation     100
Phase IV pitfalls: model application     102
The modeling process in practice      105
Preliminary conceptual model (CM)     106
How to begin     106
Adding new components to the model     108
Describing expected patterns     108
Describing the plan of attack     108
Intermediate developmental models (IDM[subscript i])     109
Evaluate-adjust cycle for each developmental model     110
Sensitivity analysis of the last developmental model     112
Final model (FM)     112
Theory, practice, and common sense
The common-sense problems revisted     115
Harvesting food for the winter     115
The preliminary conceptual model (CM)     115
The last (only) intermediate development model (IDM[subscript last])     116
The final model (FM)     117
Estimating the probability of population extinction     117
The preliminary conceptual model (CM)     117
The intermediate development models (IDM[subscript i])     118
The final model (FM)     118
Managing the Commons     118
The preliminary conceptual model (CM)     118
The intermediate development models (IDM[subscript i])     120
The final model (FM)     121
Reflections     123
The systems approach as a complement to other methods of problem solving     123
Ecological modeling as a problem-solving process     126
Expectations for ecological models     127
A final thought     129
References     131
Introduction to the ecological modeling literature     133
Scientific reports for the examples in Chapter 2     139
Effect of deforestation on rate of food harvest     139
Effect of hurricane frequency on probability of population extinction     141
Effect of stocking rate on forage and animal production     143
Index     149