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An incidence-based richness estimator for quadrats sampled without replacement Open Access


Author or creator
Shen, T.J.
He, F.
Additional contributors
Sampling without replacement
Richness estimator
Quadrat sampling
Zero-truncated binomial distribution
Maximum likelihood estimate
Modified beta distribution
Type of item
Journal Article (Published)
Most richness estimators currently in use are derived from models that consider sampling with replacement or from the assumption of infinite populations. Neither of the assumptions is suitable for sampling sessile organisms such as plants where quadrats are often sampled without replacement and the area of study is always limited. In this paper, we propose an incidence-based parametric richness estimator that considers quadrat sampling without replacement in a fixed area. The estimator is derived from a zero-truncated binomial distribution for the number of quadrats containing a given species (e.g., species i) and a modified beta distribution for the probability of presence-absence of a species in a quadrat. The maximum likelihood estimate of richness is explicitly given and can be easily solved. The variance of the estimate is also obtained. The performance of the estimator is tested against nine other existing incidence-based estimators using two tree data sets where the true numbers of species are known. Results show that the new estimator is insensitive to sample size and outperforms the other methods as judged by the root mean squared errors. The superiority of the new method is particularly noticeable when large quadrat size is used, suggesting that a few large quadrats are preferred over many small ones when sampling diversity.
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License information
© 2008 Ecological Society of America. This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.
Citation for previous publication
Shen, TJ; He, F (2008). An incidence-based richness estimator for quadrats sampled without replacement. Ecology, 89(7), 2052-2060. DOI: 10.1890/07-1526.1.
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