Changes between Version 2 and Version 3 of EwEugBasicEstimates


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Timestamp:
2010-11-23 01:20:50 (8 years ago)
Author:
shermanl
Comment:

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  • EwEugBasicEstimates

    v2 v3  
    66The parameter estimation program outputs a number of indices that may be of use for assessing the status of the overall ecosystem and of its constituent groups. These can be found in the current (''Basic estimates'') form as well as on the [wiki:EwEugKeyIndices Key indices], [wiki:EwEugMortalities Mortalities], [wiki:EwEugConsumptionEcopath Consumption], [wiki:EwEugRespiration Respiration], [wiki:EwEugNicheOverlap Niche overlap], [wiki:EwEugElectivity Electivity], [wiki:EwEugSearchRates Search rates] and [wiki:EwEugFisheryEcopath Fishery] forms. 
    77 
    8 Notes on most of the parameters below have already been provided in the notes on [[Basic input.htm|Basic parameters]], but we repeat them here as a reminder. 
     8Notes on most of the parameters below have already been provided in the notes on [EwEugBasicInput Basic parameters], but we repeat them here as a reminder. 
    99 
    1010'''Trophic level''' 
     
    1212Lindeman (1942) introduced the concept of trophic levels. In Ecopath, the trophic levels are not necessarily integers (1, 2, 3...) as proposed by Lindeman, but can be fractional (e.g., 1.3, 2.7, etc.) as suggested by Odum and Heald (1975). A routine assigns definitional trophic levels (TL) of 1 to producers and detritus and a trophic level of 1 + [the weighted average of the preys' trophic level] to consumers. 
    1313 
    14 Following this approach, a consumer eating 40% plants (with TL = 1) and 60% herbivores (with TL = 2) will have a trophic level of 1 + [0.4 · 1 + 0.6 · 2] = 2.6. The fishery is assigned a trophic level corresponding to the average trophic level of the catch, i.e. without adding 1 as is done for ‘ordinary’ predators. 
     14Following this approach, a consumer eating 40% plants (with TL = 1) and 60% herbivores (with TL = 2) will have a trophic level of 1 + [0.4 · 1 + 0.6 · 2] = 2.6. The fishery is assigned a trophic level corresponding to the average trophic level of the catch, i.e. without adding 1 as is done for 'ordinary' predators. 
    1515 
    1616The trophic level is a dimensionless index. 
     
    3030This is the Biomass in habitat area x Habitat area. 
    3131 
    32 '''Production/biomass''' 
     32'''Production / Biomass''' 
    3333 
    34 Enter the Production/Biomass (''P/B'') ratio for each group using consistent units, e.g., per year. The ''P/B'' ratio is equivalent to the instantaneous rate of total mortality (Z) used by fisheries biologists (Allen 1971). Entry of ''P/B'' ratios is optional. 
     34Enter the Production / Biomass (''P/B'') ratio for each group using consistent units, e.g., per year. The ''P/B'' ratio is equivalent to the instantaneous rate of total mortality (Z) used by fisheries biologists (Allen 1971). Entry of ''P/B'' ratios is optional. 
    3535 
    3636Production includes fishery yield plus predation plus net migration plus biomass change plus other mortality; or 
     
    4848'''Ecotrophic efficiency''' 
    4949 
    50 The ecotrophic efficiency (''EE'') is the fraction of the production that is used in the system, i.e. either passed up the food web, used for biomass accumulation, migration or export. Ecotrophic efficiency is difficult to measure directly. It varies between 0 and 1 and can be expected to approach 1 for groups with considerable predation pressure. The part of the production that is not included in the ''EE'' is often called ‘[[Other mortality.htm|other mortality]]’. ''EE'' is dimensionless, and the entry of'' EE'' values is optional. 
     50The ecotrophic efficiency (''EE'') is the fraction of the production that is used in the system, i.e. either passed up the food web, used for biomass accumulation, migration or export. Ecotrophic efficiency is difficult to measure directly. It varies between 0 and 1 and can be expected to approach 1 for groups with considerable predation pressure. The part of the production that is not included in the ''EE'' is often called '[EwEugOtherMortality other mortality]'. ''EE'' is dimensionless, and the entry of'' EE'' values is optional. 
    5151 
    5252The ecotrophic efficiency of a detritus group is defined as the ratio between the flow out of a detritus box, and the flow into the same box. ''EE'' for detritus cannot be entered, it is always calculated.