Changes between Version 5 and Version 6 of EwEugRepresentationOfMultiStanzaLifeHistoriesInEcopathEcoSimAndEcospace


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Timestamp:
2010-01-28 15:11:37 (9 years ago)
Author:
varunr
Comment:

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  • EwEugRepresentationOfMultiStanzaLifeHistoriesInEcopathEcoSimAndEcospace

    v5 v6  
    3939Representation of stanzas that occur outside the modelled system? It is common, especially in models for coastal ecosystems, to have species that spend only part (or none) of their time in the system.  For example, juvenile rearing may be in the modelled ecosystem, but adult foraging and harvest impacts may occur in outside areas.  The preferred way to handle trophic/fishery impacts for such species in EwE is to treat part (or all) of the diet for outside-migrant stanzas as imported, rather than to model the movement into and out of the system as immigration/emigration rates.  With the diet import convention, EwE will still handle overall fishery impacts at the population scale whether or not these impacts occur within the modelled system; all that will be “lost’ is dynamic change in food availability (and feeding rates) and predation mortality of organisms during times when they are outside the modelled system (outside world treated as having constant trophic conditions).  Most often, the stanzas that reside outside the modelled system are older fish, for which the assumption of constant resource availability and natural mortality risk may be quite reasonable.  When it appears that using the diet-import convention is inappropriate due to changing trophic conditions outside the modelled system, then the modelled system should be extended to include the ‘outside’ trophic interactions of concern. 
    4040 
    41 The multi-stanza representation is quite flexible, and users may find other ways to use it for effectively representing ‘problem processes’ in ecological systems.  Such findings can be reported to [http://www.ecopath.org/ !EcoPath] for use by others. 
     41The multi-stanza representation is quite flexible, and users may find other ways to use it for effectively representing ‘problem processes’ in ecological systems.  Such findings can be reported to [http://www.ecopath.org/ EcoPath] for use by others.