Predation: Grazing

SC-IPM Processes (Predator-Prey)

Overview

Grazing generally describes a type of feeding, in which a herbivore feeds on plants (such as grasses), and also on other multicellular autotrophs (such as algae). Grazing differs from true predation because the organism being eaten from is not generally killed ...

-- Grazing (WP)

Formulas

In this model, the predators (ie, G, grazers) are Zooplankton and the prey (ie, P, producers) are Phytoplankton. This Generic Process uses a pair of ordinary differential equations (ODEs), based on a set of "constant parameters":

  • G.assim_eff - assimilation efficiency of grazers
  • G.conc - Carbon concentration of grazers
  • G.grazing_rate - grazing rate of grazers
  • P.conc - Carbon concentration of producers

As SC-IPM evaluates each candidate model structure against the training data, it estimates appropriate values for all numeric values:

    t1 & = & G.conc * G.grazing\_rate \\{\operatorname{d}\!G.conc\over\operatorname{d}\!t} & = & -t1 * G.assim\_eff \\{\operatorname{d}\!P.conc\over\operatorname{d}\!t} & = & -t1

Data Structures

:description
  "grazing by a predator upon prey"

:name      :grazing

:constants { }

:entity-roles {
  :G { :types [ :grazer   ] }
  :P { :types [ :producer ] }
}

:equations {
  ;; carbon concentration of grazer
  ;; (eg, zooplankton)
  :G.conc {
    :type     :ODE
    :infix    "G.assim_eff * G.grazing_rate * G.conc"
    :prefix   "(* G.assim_eff G.grazing_rate G.conc)"
  }

  ;; carbon concentration of producer
  ;; (eg, phytoplankton)
  :P.conc {
    :type     :ODE
    :infix    "-1 * G.grazing_rate * G.conc"
    :prefix   "(* -1 G.grazing_rate G.conc)"
  }
}

See Data Structures for details.

References

See Also


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Topic revision: r9 - 03 Aug 2013, RichMorin
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