detritus_dynamics: Detritus dynamics

In gustavdelius/mizerUR: Unstructured Resources for Mizer

Description

Calculates the detritus biomass at the next timestep from the current detritus biomass.

Usage

detritus_dynamics(
  params,
  n,
  n_pp,
  n_other,
  rates,
  t,
  dt,
  detritus_external = params@other_params$UR$detritus_external,
  detritus_proportion = params@other_params$UR$detritus_proportion,
  ...
)

Arguments

detritus_external	Rate of change from external sources
detritus_proportion	Proportion of consumption by fish that flows into the detritus component.
...	Arguments passed on to UR_dynamics params A MizerParams object n A matrix of current species abundances (species x size) n_pp A vector of current plankton abundance by size n_other List of abundances of other dynamic components rates A list of rates as returned by getRates() t Current time dt Time step size

Details

The equation for the time evolution of the detritus biomass B is assumed to be of the form

dB/dt = inflow - consumption * B + external

where

• inflow comes from feces, calculated as a proportion detritus_proportion of the biomass consumed by all consumers.

• consumption is by detritivorous species, where the encounter rate is specified by rho[, "detritus", ].

• external is an influx from external sources. It can be negative in which case it represents a loss to external sources.

This equation is solved analytically to

B(t+dt) = B(t) exp(-consumption * dt) +(inflow + external)/(consumption) * (1 - exp(-consumption * dt)).

This avoids the stability problems that would arise if we used the Euler method to solve the equation numerically.

Value

A single number giving the biomass of detritus at next time step

See Also

Other resource dynamics functions: carrion_dynamics()

gustavdelius/mizerUR documentation built on June 24, 2020, 6:28 p.m.