steps (version 1.3.0)

competition_density: Competition density function

Description

Adjusts the life-stage transition matrix in each cell based on the carrying capacity in the cell and a density dependence function - default is Beverton-Holt. The user may specify which life-stages are affected by density dependence. If R_max is not provided this is calculated from the local cell-based transition matrices internally. By providing initial stable age distribution values, performance can be increased as the function internally calculates these values through optimisation.

Usage

competition_density(
  stages = NULL,
  mask = NULL,
  R_max = NULL,
  stable_age = NULL
)

Arguments

stages

which life-stages contribute to density dependence - default is all

mask

a matrix of boolean values (TRUE/FALSE), equal in dimensions to the life-stage transition matrix and specifying which vital rates (i.e. survival and fecundity) are to be modified by the function

R_max

optional value of maximum growth rate (lambda) if known

stable_age

optional vector of stable age distributions if known

Examples

# Vital rates (survival and fecundity) modified based on approach to carrying capacity
# by the 2nd and 3rd life stages.

if (FALSE) {
mod_fun <- competition_density(stages = c(2, 3))

ls <- landscape(population = egk_pop, suitability = NULL, carrying_capacity = egk_k)

pd <- population_dynamics(change = growth(egk_mat, transition_function = mod_fun))

simulation(landscape = ls, population_dynamics = pd, habitat_dynamics = NULL, timesteps = 20)
}