blender (version 0.1.1)

simulation: Simulate reduced richness landscapes

Description

reduce randomly selects species for inclusion in a reduced-richness landscape based on the original. shuffle randomizes species locations among sites.

Usage

blender.reduce(landscape, richness)
  blender.shuffle(landscape)

Arguments

landscape

A binary presence-absence data.frame for species (rows) at sites(columns)

richness

An integer number of species to include in a reduced landscape

Value

• A data.frame based on landscape

Details

Species are sampled by reduce without replacement. Species are randomized by shuffle in order to preserve their occupancy rates (row sums) but not local richness (column sums).

References

These functions were used in the simulations in Harris, D. J., K. G. Smith, and P. J. Hanly. 2011. "Occupancy is nine-tenths of the law: Occupancy rates determine the homogenizing and differentiating effects of exotic species." The American Naturalist.