Requires two or more columns, each containing presence/absence (1/0) of different taxa down the rows (positive abundance is treated as presence).
Four non-parametric species richness estimators are included in PAST: Chao 2, first- and second-order jackknife, and bootstrap. All of these require presence-absence data in two or more sampled quadrats of equal size. Colwell & Coddington (1994) reviewed these estimators, and found that the Chao2 and the second-order jackknife performed best.
The output from Past is divided into two panels. First, the richness estimators and their analytical standard deviations (only for Chao2 and Jackknife1) are computed from the given set of samples. Then the estimators are computed from 1000 random resamplings of the samples with replacement (bootstrapping), and their means and standard deviations are reported. In other words, the standard deviations reported here are bootstrap estimates, and not based on the analytical equations.
For mathematical details, see the Past manual.
- Chao2: The Chao2 estimator (Chao 1987) is calculated as in EstimateS version 8.2.0 (Colwell 2009), with bias correction.
- Jackknife 1: First-order jackknife (Burnham & Overton 1978, 1979; Heltshe & Forrester 1983)
- Jackknife 2: Second-order jackknife (Smith & van Belle 1984)
- Bootstrap: Bootstrap estimator (Smith & van Belle 1984)
References
Burnham, K.P. & W.S. Overton. 1978. Estimation of the size of a closed population when capture probabilities vary among animals. Biometrika 65:623-633.
Burnham, K.P. & W.S. Overton. 1979. Robust estimation of population size when capture probabilities vary among animals. Ecology 60:927-936.
Chao, A. 1987. Estimating the population size for capture-recapture data with unequal catchability. Biometrics 43, 783-791.
Colwell, R.K. & J.A. Coddington. 1994. Estimating terrestrial biodiversity through extrapolation. Philosophical Transactions of the Royal Society (Series B) 345:101-118.
Heltshe, J. & N.E. Forrester. 1983. Estimating species richness using the jackknife procedure. Biometrics 39:1-11.
Smith, E.P. & G. van Belle. 1984. Nonparametric estimation of species richness. Biometrics 40:119-129.