ranmilne: Milne Stochastic Ceiling Model for Population Size

In jarioksa/ecostudy: Ecology Teaching Package

Milne Stochastic Ceiling Model for Population Size

Description

Milne Ceiling model is a stochastic model where the population growth is in the range zero to carrying capacity. It seems to be particularly suitable for small populations which are often close to their carrying capacity, and is much used in metapopulation research (Hanski 2005).

Usage

ranmilne(N0, r, sd, K, time = 100, rep = 1)
## S3 method for class 'ranmilne'
plot(x, lty = 1, lwd = 1, col = 4, ...)
## S3 method for class 'ranmilne'
lines(x, ...)
## S3 method for class 'ranmilne'
traj(x, ...)

Arguments

N0	Initial population size(s).
r, sd	Normally distributed growth rate and its standard deviation
K	Carrying capacity.
time	Number of time steps.
rep	Number of replicated simulations.
x	A ranmilne result object.
lty, lwd, col	Line type, width and colour.
...	Other arguments passed to functions.

Details

The logarithmic population size n at time t is given as n_{t-1} + N(r, s) where N() is a random normal variate with expectation r and standard deviation s. Simulated responses > K are made to K and responses < 0.5 are made to 0 (extinct).

Value

The function returns an object of class "ranmilne" which is a list with following items:

traj	Simulated results as a traj object. Function traj extracts the simulation results.
N0, r, sd, K, time, rep	Model parameters.
call	Function call.

Note

The current version returns the simulated population size as a real number. It may be that the return value should be an integer, but this was not yet checked.

Author(s)

Jari Oksanen

References

Hanski, I (2005) The Shrinking World: Ecological Consequences of Habitat Loss. International Ecological Institute, 307 p.

See Also

ranlogist.

Examples

sim <- ranmilne(50, r = 0.5, sd = 1, K = 50, rep = 10)
sim
plot(sim)

jarioksa/ecostudy documentation built on June 27, 2022, 6:03 a.m.