Gives the expected species richness in random subsamples of size sample from the community. The size of sample should be smaller than total community size, but the function will work for larger sample as well (with a warning) and return non-rarefied species richness (and standard error = 0). Rarefaction can be performed only with genuine counts of individuals. The function rarefy is based on Hurlbert’s (1971) formulation, and the standard errors on Heck et al. (1975).

Returns probabilities that species occur in a rarefied community of size sample.

Draws a rarefaction curve for each row of the input data. The rarefaction curves are evaluated using the interval of step sample sizes, always including 1 and total sample size. If sample is specified, a vertical line is drawn at sample with horizontal lines for the rarefied species richnesses.

When subsampling by community size, slope of the rarefaction curve and species probabilities are computed using community size-1