Changes between Version 2 and Version 3 of EwEugAnOverviewOfEcosim
- Timestamp:
- 2010-11-21 22:33:32 (13 years ago)
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EwEugAnOverviewOfEcosim
v2 v3 1 1 == 3.1 An overview of Ecosim == 2 2 3 Ecosim provides a dynamic simulation capability at the ecosystem level, with key initial parameters inherited from the base Ecopath model. See [ wiki:EcosimInputs Ecosim Inputs] and [wiki:EcosimOutputs Ecosim Outputs] for links to instructions for using Ecosim.3 Ecosim provides a dynamic simulation capability at the ecosystem level, with key initial parameters inherited from the base Ecopath model. See [EwEugEcosimInputs Ecosim Inputs] and [EwEugEcosimOutputs Ecosim Outputs] for links to instructions for using Ecosim. 4 4 5 5 The key computational aspects are in summary form: … … 7 7 * Use of mass-balance results (from Ecopath) for parameter estimation; 8 8 9 * Variable speed splitting enables efficient modelling of the dynamics of both ‘fast’ (phytoplankton) and ‘slow’groups (whales);9 * Variable speed splitting enables efficient modelling of the dynamics of both 'fast' (phytoplankton) and 'slow' groups (whales); 10 10 11 11 * Effects of micro-scale behaviours on macro-scale rates: top-down vs. bottom-up control incorporated explicitly. … … 15 15 * Multi-stanza life stage structure by monthly cohorts, density- and risk-dependent growth; 16 16 17 * Stock-recruitment relationship as ‘emergent’property of competition/predation interactions of juveniles.17 * Stock-recruitment relationship as 'emergent' property of competition/predation interactions of juveniles. 18 18 19 19 Ecosim uses a system of differential equations that express biomass flux rates among pools as a function of time varying biomass and harvest rates, (for equations see Walters et al., 1997; Walters et al., 2000; Christensen and Walters, 2004). Predator prey interactions are moderated by prey behaviour to limit exposure to predation, such that biomass flux patterns can show either bottom-up or top down (trophic cascade) control (Walters et al., 2000. By doing repeated simulations Ecosim allows for the fitting of predicted biomasses to time series data.