Common forms of density dependence

Use pre-defined forms of density dependence based on common density-dependence functions.

Usage

beverton_holt(k, exclude = NULL)

ricker(k, exclude = NULL)

Arguments

k

carrying capacity used to define models of density dependence. See details for currently implemented models and their parameters.

exclude

vector of classes to exclude from calculation of total population density. Defaults to NULL, in which case all classes are used

Value

functions that can be used with density_dependence to specify common models of density dependence

Details

Additional functions are provided to define common forms of density dependence. Currently implemented models are the Ricker model and Beverton-Holt model, both with a single parameter k.

Examples

# define a population matrix (columns move to rows)
nclass <- 5
popmat <- matrix(0, nrow = nclass, ncol = nclass)
popmat[reproduction(popmat, dims = 4:5)] <- c(10, 20)
popmat[transition(popmat)] <- c(0.25, 0.3, 0.5, 0.65)

# define a dynamics object
dyn <- dynamics(popmat)

# add some density dependence
dd <- density_dependence(
  masks = reproduction(popmat, dims = 4:5),
  funs = ricker(1000)
)

# update the dynamics object
dyn <- update(dyn, dd)

# simulate trajectories
sims <- simulate(dyn, nsim = 100, options = list(ntime = 50))

# and plot
plot(sims)