pop.projection {popbio} | R Documentation |
Calculate population growth rates by projection
Description
Calculates the population growth rate and stable stage distribution by
repeated projections of the equation n(t+1)=An(t)
Usage
pop.projection(A, n, iterations = 20)
Arguments
A |
A projection matrix |
n |
An initial age or stage vector |
iterations |
Number of iterations |
Details
Eventually, structured populations will convergence to a stable stage distribution where each new stage vector is changing by the same proportion (lambda).
Value
A list with 5 items
lambda |
Estimate of lambda using change between the last two population counts |
stable.stage |
Estimate of stable stage distribution using proportions in last stage vector |
stage.vector |
A matrix with the number of projected individuals in each stage class |
pop.sizes |
Total number of projected individuals |
pop.changes |
Proportional change in population size |
Author(s)
Chris Stubben
References
see section 2.2 in Caswell 2001
See Also
stage.vector.plot
to plot stage vectors
Examples
## mean matrix from Freville et al 2004
stages <- c("seedling", "vegetative", "flowering")
A <- matrix(c(
0, 0, 5.905,
0.368, 0.639, 0.025,
0.001, 0.152, 0.051
), nrow=3, byrow=TRUE,
dimnames=list(stages,stages))
n <- c(5,5,5)
p <- pop.projection(A,n, 15)
p
damping.ratio(A)
stage.vector.plot(p$stage.vectors, col=2:4)
A <- whale
#n <- c(4,38,36,22)
n <- c(5,5,5,5)
p <- pop.projection(A,n, 15)
p
stage.vector.plot(p$stage.vectors, col=2:4, ylim=c(0, 0.6))
## convergence is slow with damping ratio close to 1
damping.ratio(A)
pop.projection(A, n, 100)$pop.changes
[Package popbio version 2.8 Index]