Changes between Version 4 and Version 5 of EwEugPredatorSatiationAndHandlingTimeEffects


Ignore:
Timestamp:
2010-11-22 01:44:51 (9 years ago)
Author:
shermanl
Comment:

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  • EwEugPredatorSatiationAndHandlingTimeEffects

    v4 v5  
    1919 
    2020 1. The oscillatory behaviour may be a numerical artifact of the procedure used to update ''P'',,''sj'',,; or 
    21  
    22  2. The model's 'correct' behaviour for the parameter combinations you have provided is indeed a predator-prey cycle. 
     21 1. The model's 'correct' behaviour for the parameter combinations you have provided is indeed a predator-prey cycle. 
    2322 
    2423If the oscillation has a period of several time steps (months), it is very likely a predator-prey cycle.  Persistent predator-prey cycles are commonly predicted by models that include handling time, along with strong top-down control (high vulnerabilities ''v'',,''ij'',, of prey to predators).  If you think the cycle is unrealistic, you should adjust the prey vulnerabilities (Ecosim [EwEugVulnerabilitiesFlowControl Vulnerabilities] form) to lower values (toward 'bottom up', prey vulnerability control) rather than just setting high ''R'',,''j'',, values.  If you see very short cycles indicating numerical instability in the ''P'',,''sj'',, adjustment procedure (usually happens for fast turnover groups like microzooplankton), you should set higher ''R'',,''j'',, values for the offending groups.  This amounts to admitting that Ecosim is limited in its ability to represent very fast dynamic changes in groups that turn over very rapidly.