raref2: Estimates the species richness for a given number of sampled individuals on the basis of the corresponding rarefaction curve
Description
raref2 computes an estimation of the species richness by thinning the data matrix so that the overall corresponding density is comprised in a fixed interval.
Usage
raref2(matrix, dens, tolerance, nrandom=99)
Arguments
matrix
matrix is a typical species-sample matrix. Rows correspond to samples whereas columns stand for species.
dens
A number corresponding to the density for which a species richness estimation is required.dens must be comprised within the range of the observed density.
tolerance
A number used to calculate the range of acceptable values for the density of simulated communities. Let $D$ be largest density (com1 or com2). The acceptable interval is $D \pm tolerance \times D$.
nrandom
nrandom is the number of a randomizations used in the bootstrap estimation. Values of nrandom
Value
raref2 returns a list with two components.
mean.bootThe mean value of the bootstrap estimates of the species richness.
sd.bootThe standard deviation of the bootstrap estimates.