fast_dispersal: Fast diffusion-based dispersal

In steps-dev/steps: Spatially- and Temporally-Explicit Population Simulator

Fast diffusion-based dispersal

Description

The fast_dispersal function uses kernel-based dispersal to modify the population with a user-defined diffusion distribution and a fast-fourier transformation (FFT) computational algorithm. It is computationally efficient and very fast, however, only useful for situations where dispersal barriers or arrival based on habitat or carrying capacity are not required (e.g. a homogeneous landscape or where diffusion alone is sufficient to explain dispersal patterns). Dispersal is not constrained to suitable habitat or available carrying capacity.

Usage

fast_dispersal(
  dispersal_kernel = exponential_dispersal_kernel(distance_decay = 0.1),
  dispersal_proportion = set_proportion_dispersing()
)

Arguments

dispersal_kernel	a single built-in or user-defined distance dispersal kernel function.
dispersal_proportion	a built-in or custom function defining the proportions of individuals that can disperse in each life stage.

Examples

# Example of fast kernel-based dispersal where all life stages disperse.
# The default dispersal kernel uses a decay parameter to control how far
# populations disperse. Note proportions of populations to disperse are
# controlled by approach to carrying capacity.

## Not run: 
fft_dispersal <- fast_dispersal(dispersal_proportion = density_dependence_dispersing(),
                     dispersal_kernel = exponential_dispersal_kernel(distance_decay = 1000))

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

pd <- population_dynamics(change = growth(egk_mat),
                          dispersal = fft_dispersal,
                          density_dependence = ceiling_density())

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

## End(Not run)

steps-dev/steps documentation built on Dec. 9, 2023, 10:51 p.m.