Changes between Version 1 and Version 2 of EwEugRespiration
 Timestamp:
 20101123 01:31:22 (13 years ago)
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EwEugRespiration
v1 v2 1 1 == 7.9 Respiration == 2 Ecopath ’s estimates of respiration can be obtained by selecting ''Consumption'' under the'' Parameterization node'' in the ''Navigator window''. The ''Respiration'' form displays the predicted values for respiration and assimilation of food by all groups.2 Ecopath's estimates of respiration can be obtained by selecting ''Consumption'' under the'' Parameterization node'' in the ''Navigator window''. The ''Respiration'' form displays the predicted values for respiration and assimilation of food by all groups. 3 3 4 4 '''Respiration''' 5 5 6 Respiration includes all nonusable ‘model currency’that leaves the box representing a group.6 Respiration includes all nonusable 'model currency' that leaves the box representing a group. 7 7 8 8 When the currency is energy or carbon, the bulk of the assimilated food will end up as respiration. If, however, a nutrient (e.g. phosphorus or nitrogen) is used as currency, all nutrients that leave the box is reutilized; in this case, respiration is nil. … … 16 16 [[Image(wiki:EwEugImages:08000068.png)]] ''' Eq. 23''' 17 17 18 where ''Resp,,i,,'' is the respiration of group ''i'', ''GS,,i,,'' is the fraction of ''is consumption that is not assimilated, ''Q,,i,,'' is the consumption of ''i'', and ''TM,,i,,'' is the proportion of the production that can be attributed to primary production. If the unit is a nutrient ''TM,,i,,'' is equal to zero, irrespective of whether the group is an autotroph or not (nutrients are not ‘produced’), and, ''P,,i,,'' is the total production of group ''i''.''18 where ''Resp,,i,,'' is the respiration of group ''i'', ''GS,,i,,'' is the fraction of ''is consumption that is not assimilated, ''Q,,i,,'' is the consumption of ''i'', and ''TM,,i,,'' is the proportion of the production that can be attributed to primary production. If the unit is a nutrient ''TM,,i,,'' is equal to zero, irrespective of whether the group is an autotroph or not (nutrients are not 'produced'), and, ''P,,i,,'' is the total production of group ''i''.'' 19 19 20 20 Respiration is used, in Ecopath, only for balancing the flows between groups. Thus, it is not possible to enter respiration data. However, known respiration values (i.e., the metabolic rate) of a group can be compared with the output, and the input parameters adjusted to achieve the desired respiration. For an application of this approach, see Browder, 1993. … … 32 32 The three values needed for the estimation are all input parameters. Assimilation is a flow expressed, e.g., in t/km^2^/year. 33 33 34 '''Respiration /Assimilation'''34 '''Respiration / Assimilation''' 35 35 36 36 The (dimensionless) ratio of respiration to assimilation cannot exceed 1, because respiration cannot exceed assimilation. For top predators, whose production is relatively low, the respiration/assimilation ratio can be expected to be close to 1, while it will tend to be lower, but still positive, for organisms at lower trophic levels. 37 37 38 '''Production /Respiration'''38 '''Production / Respiration''' 39 39 40 40 The (dimensionless) ratio production / respiration express the fate of the assimilated food. Computationally, this ratio can take any positive value, though thermodynamic constraints limit the realized range of this ratio to values lower than 1. 41 41 42 '''Respiration /Biomass'''42 '''Respiration / Biomass''' 43 43 44 44 The ''R/B'' ratio can be seen as an expression of the activity of the group. The higher the activitylevel is for a given group, the higher the ratio. The ''R/B ''ratio is strongly impacted by the assumed fraction of the food that is not assimilated, see the basic input form. If the ratio is too high, this may be due to ''GS'' being too low.