Changes between Version 2 and Version 3 of EwEugAnOverviewOfEcosim


Ignore:
Timestamp:
2010-11-21 22:33:32 (9 years ago)
Author:
shermanl
Comment:

--

Legend:

Unmodified
Added
Removed
Modified
  • EwEugAnOverviewOfEcosim

    v2 v3  
    11== 3.1 An overview of Ecosim == 
    22 
    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. 
     3Ecosim 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. 
    44 
    55The key computational aspects are in summary form: 
     
    77  * Use of mass-balance results (from Ecopath) for parameter estimation; 
    88 
    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); 
    1010 
    1111  * Effects of micro-scale behaviours on macro-scale rates: top-down vs. bottom-up control incorporated explicitly. 
     
    1515  * Multi-stanza life stage structure by monthly cohorts, density- and risk-dependent growth; 
    1616 
    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. 
    1818 
    1919Ecosim 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.