growth: Population Growth Functions

In rangr: Mechanistic Simulation of Species Range Dynamics

Population Growth Functions

Description

Population growth functions are used during simulation conducted by the sim function. The user is required to specify the name of a growth function while initialising the sim_data object using initialise.

Usage

exponential(x, r, ...)

ricker(x, r, K, A = NA)

gompertz(x, r, K, A = NA)

Arguments

x	number of individuals
r	intrinsic population growth rate
...	not used, added for compatibility reasons
K	carrying capacity
A	coefficient of Allee effect (A <= 0: weak, A > 0: strong, NA: none)

Details

x can be a vector, matrix, SpatRaster or any other R object for which basic arithmetic operations produce valid results. These functions are intended to be used in the sim function, where x is a matrix of the same dimensions as the SpatRaster object specified in n1_map parameter.

Value

Object of the same dimensions as x that contains expected number of individuals in the next time step.

References

Boukal, D. S., & Berec, L. (2002). Single-species models of the Allee effect: extinction boundaries, sex ratios and mate encounters. Journal of Theoretical Biology, 218(3), 375-394. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1006/jtbi.2002.3084")}

Gompertz, B. (1825) On the Nature of the Function Expressive of the Law of Human Mortality, and on a New Mode of Determining the Value of Life Contigencies. Philosophical Transactions of the Royal Society of London, 115, 513-583. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1098/rstl.1825.0026")}

Ricker, W.E. (1954) Stock and Recruitment. Journal of the Fisheries Research Board of Canada, 11, 559-623. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1139/f54-039")}

Hostetler, J.A. and Chandler, R.B. (2015), Improved state-space models for inference about spatial and temporal variation in abundance from count data. Ecology, 96: 1713-1723. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1890/14-1487.1")}

Courchamp, F., L. Berec and J. Gascoigne. 2008. Allee Effects in Ecology and Conservation. Oxford University Press, New York. 256 pp. ISBN 978-0-19-857030-1

Examples

x <- 1:10
exponential(x, r = 0.4)

ricker(x, r = 2, K = 5)
ricker(x, r = 2, K = 5, A = -5)

gompertz(x, r = 1.2, K = 5)
gompertz(x, r = 1.2, K = 5, A = 5)

rangr documentation built on April 12, 2025, 1:40 a.m.