Changes between Version 1 and Version 2 of EwEugBalancingaModel


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Timestamp:
2010-02-05 17:00:37 (9 years ago)
Author:
varunr
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Added images.

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  • EwEugBalancingaModel

    v1 v2  
    99Problems in parameter estimation will be shown in the ''Status panel''. Two types of message may be displayed in the ''Status panel'' while you are balancing your model: 
    1010 
    11   Information messages [../Resources/Images/03000051.png]. Information messages provide feedback on regular events in EwE. Information events are confirmations of things that went well.  Examples are opening the model; successful edits; and successful balancing (i.e., parameterization) of the model.Warning messages [../Resources/Images/03000052.png]. Warnings occur when EwE was not able to complete an action and requires the user to fix a problem, usually with the input data. For example, one of the most important of these is when parameterization fails (i..e., the model failed to balance). When this occurs, you will get the message “Your model is NOT balanced! Computed Ecotrophic Efficiencies (''EE'') invalid for one or more group(s).”  Clicking on the “+” icon next to this message expands the message to show which groups are causing the problem. 
     11  Information messages [[[Image(wiki:EwEugImages:03000051.png)]]]. Information messages provide feedback on regular events in EwE. Information events are confirmations of things that went well.  Examples are opening the model; successful edits; and successful balancing (i.e., parameterization) of the model. Warning messages [[[Image(wiki:EwEugImages:03000052.png)]]]. Warnings occur when EwE was not able to complete an action and requires the user to fix a problem, usually with the input data. For example, one of the most important of these is when parameterization fails (i..e., the model failed to balance). When this occurs, you will get the message “Your model is NOT balanced! Computed Ecotrophic Efficiencies (''EE'') invalid for one or more group(s).”  Clicking on the “+” icon next to this message expands the message to show which groups are causing the problem. 
    1212 
    1313An exhaustive set of guidelines for how a model should be balanced cannot be given. However, if it existed, such a set would include the following general guidelines: 
     
    2121  * Start by looking at the estimated values. Are the ''EE'' values possible (less than 1)? Are the ''GE'' (= ''P/Q'') values physiologically realistic (0.1-0.3 for most groups, perhaps lower for top predators and higher for very small organisms, (e.g., up to 0.5 for bacteria). If not decide from where the problem is the biggest if you want to balance your model starting from the bottom (producers) or from the top down; 
    2222 
    23   * Search out one group with a bigger problem and try to solve this. Are the ''P/B, Q/B'' and ''B'' values appropriate for this group? What would happen to, e.g., the ''GE'' and the ''EE'' if you changed the parameters? If the problem is the consumption by predators, look at the [[Predation mortality.htm|Predation mortality]] form, and identify the quantitatively most important predators. Check the diet compositions and ''B'' and ''Q/B'' values for these predators; 
     23  * Search out one group with a bigger problem and try to solve this. Are the ''P/B, Q/B'' and ''B'' values appropriate for this group? What would happen to, e.g., the ''GE'' and the ''EE'' if you changed the parameters? If the problem is the consumption by predators, look at the [wiki:EwEugPredationMortality Predation mortality] form, and identify the quantitatively most important predators. Check the diet compositions and ''B'' and ''Q/B'' values for these predators; 
    2424 
    2525  * Continue for as long as necessary, documenting carefully what changes are made. It may be a good idea to save the data file under a new name each time changes are made (e.g. starting with ‘Model_1’, on to ‘Model_2’ etc.); 
     
    3939  * Examine the respiration/biomass (R/B) ratios for each group. Generally this ratio reflects activity level. For fish it should as a rule be in the range 1-10 year-1, for copepods perhaps around 50-100. Please consult physiology handbooks for more information. If the ratio seems high it may be necessary to change the (assumed) proportion of the food that is not assimilated on the basic input form; 
    4040 
    41   * Examine the [[Electivity.htm|Electivity]] form. Do the preferences seem reasonable? 
     41  * Examine the [wiki:EwEugElectivity Electivity] form. Do the preferences seem reasonable? 
    4242 
    43   * Examine the [[Predation mortality.htm|Predation mortalities]] under the''Mortalities'' node in the ''Navigator window''. The predation mortality spreadsheet will show you how important the various predators are for any group. Does this show what you expect? Are the predators shown to be the most important predators in accordance with what you expect? If not, re-evaluate your model’s diet compositions. __The information on the mortality forms is very important__! 
     43  * Examine the [wiki:EwEugPredationMortality Predation mortalities] under the''Mortalities'' node in the ''Navigator window''. The predation mortality spreadsheet will show you how important the various predators are for any group. Does this show what you expect? Are the predators shown to be the most important predators in accordance with what you expect? If not, re-evaluate your model’s diet compositions. __The information on the mortality forms is very important__! 
    4444 
    4545  * Noting how the energy balance of a group is formulated, it is clear that, for instance, increasing the proportion of the consumption that is not assimilated will leave less energy to respiration (production being unaffected). This will result in a lower R/B ratio and a larger flow to the detritus. The latter may be necessary to balance the model if there is only little system surplus production. 
     
    5353It is necessary to break such loops, e.g., by entering the P/B for one of the groups. If all ecotrophic efficiencies are low it indicates that the trophic transfer efficiencies are low. This may be OK for a system with high production and low abundance of organisms. It may however also indicate that the estimates of the biomasses in the system are too low. 
    5454 
    55 ../Resources/Images/08000055.png 
     55[[Image(wiki:EwEugImages:08000055.png)]] 
    5656 
    5757__'''Problem 2: Cannibalism (0-order cycles)'''__ 
     
    6565In this example it is assumed that the consumption is unknown for the predator and the (used part of the) production, (i.e., the B, P/B or EE) unknown for all of the prey groups. In this case, it will not be possible for the program to calculate meaningful parameters and it will (probably) resort to the trivial solution: set the Q/B for the predator to zero, and see what can be estimated for the other groups. The problem is easily identified from an examination of the estimated parameters and statistics. The solution may well be to either input a gross efficiency for the predator or one of the missing input parameters for one of the prey groups. 
    6666 
    67 ../Resources/Images/08000056.png 
     67[[Image(wiki:EwEugImages:08000056.png)]]