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Quantifying biodiversity: procedures and pitfalls in the measurement and comparison of species richness
Author(s) -
Gotelli Nicholas J.,
Colwell Robert K.
Publication year - 2001
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1046/j.1461-0248.2001.00230.x
Subject(s) - species richness , rarefaction (ecology) , ecology , taxon , sampling (signal processing) , body size and species richness , biodiversity , species diversity , abundance (ecology) , rank abundance curve , biology , statistics , species evenness , mathematics , computer science , computer vision , filter (signal processing)
Species richness is a fundamental measurement of community and regional diversity, and it underlies many ecological models and conservation strategies. In spite of its importance, ecologists have not always appreciated the effects of abundance and sampling effort on richness measures and comparisons. We survey a series of common pitfalls in quantifying and comparing taxon richness. These pitfalls can be largely avoided by using accumulation and rarefaction curves, which may be based on either individuals or samples. These taxon sampling curves contain the basic information for valid richness comparisons, including category–subcategory ratios (species‐to‐genus and species‐to‐individual ratios). Rarefaction methods – both sample‐based and individual‐based – allow for meaningful standardization and comparison of datasets. Standardizing data sets by area or sampling effort may produce very different results compared to standardizing by number of individuals collected, and it is not always clear which measure of diversity is more appropriate. Asymptotic richness estimators provide lower‐bound estimates for taxon‐rich groups such as tropical arthropods, in which observed richness rarely reaches an asymptote, despite intensive sampling. Recent examples of diversity studies of tropical trees, stream invertebrates, and herbaceous plants emphasize the importance of carefully quantifying species richness using taxon sampling curves.