Dear friends,
I am creating a population ecology course for undergraduate students in
Brazil. I have already showed how to proceed with basic population matrix
models in R using basic functions as well as the popbio package and its
functions that simulate stochastic dynamics of deterministic matrices.
However, I have not been successful in finding resources to implement
accessible density dependent matrix dynamics. I find quite complex IPM
models, which are out of the scope of the course, or too simplistic
approaches like simple ceiling.
I need to use a matrix of transitions in which at least one of the
transitions would be replaced by a density dependent function related to
the density of a given stage. Something like
C = matrix(c(0, 0, 5.905, 0.368, 0.639, 0.025, 0.001, 0.152,
0.051), nrow = 3, byrow = TRUE, dimnames = list(fases, fases))
seedlings vegetative reproductive
seedlings 0.000 0.000 5.905
vegetative 0.368 0.639 0.025
reproductive 0.001 0.152 0.051
This matrix would be repeatedly multiplied by a vector of population
densities like
fases = c(1,2,3,4,5,6,7,8)
However, I need to replace for instance C(2,1) by a function related to the
density of seedlings in the previous year, like Value = 0.568/(1+0.584*N),
in which N is the number of seedlings in the previous year.
Do anyone have an idea on how to implement that? I implemented that in
Excel, but since I have been showing all course contents in R I would not
like to restrict this theme to Excel.
Thank you very much in advance,
Alexandre
--
Dr. Alexandre F. Souza
Professor Adjunto III
Universidade Federal do Rio Grande do Norte
CB, Departamento de Ecologia
Campus Universitário - Lagoa Nova
59072-970 - Natal, RN - Brasil
lattes: lattes.cnpq.br/7844758818522706
http://www.docente.ufrn.br/alexsouza
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