title: Limited sampling hampers "big data" estimation of species richness in a tropical biodiversity hotspot.
abstract: Macro-scale species richness studies often use museum specimens as their main source of information. However, such datasets are often strongly biased due to variation in sampling effort in space and time. These biases may strongly affect diversity estimates and may, thereby, obstruct solid inference on the underlying diversity drivers, as well as mislead conservation prioritization. In recent years, this has resulted in an increased focus on developing methods to correct for sampling bias. In this study, we use sample-size-correcting methods to examine patterns of tropical plant diversity in Ecuador, one of the most species-rich and climatically heterogeneous biodiversity hotspots. Species richness estimates were calculated based on 205,735 georeferenced specimens of 15,788 species using the Margalef diversity index, the Chao estimator, the second-order Jackknife and Bootstrapping resampling methods, and Hill numbers and rarefaction. Species richness was heavily correlated with sampling effort, and only rarefaction was able to remove this effect, and we recommend this method for estimation of species richness with "big data" collections.
authors.affiliation: Ecoinformatics & Biodiversity, Department of Bioscience, Aarhus University Ny Munkegade 114, Aarhus C, DK-8000, Denmark.
authors.forename: Kristine
authors.initials: K
authors.lastname: Engemann
authors.affiliation: Ecology & Evolutionary Biology, University of Arizona Biosciences West 310, Tuscon, Arizona, 85721.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Enquist
authors.affiliation: Ecoinformatics & Biodiversity, Department of Bioscience, Aarhus University Ny Munkegade 114, Aarhus C, DK-8000, Denmark.
authors.forename: Brody
authors.initials: B
authors.lastname: Sandel
authors.affiliation: Ecology & Evolutionary Biology, University of Arizona Biosciences West 310, Tuscon, Arizona, 85721.
authors.forename: Brad
authors.initials: B
authors.lastname: Boyle
authors.affiliation: Missouri Botanical Garden P.O. 299, St. Louis, Missouri, 63166-0299.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Jørgensen
authors.affiliation: Integrative Biology, University of California 3040 VLSB, Berkeley, California, 94720-3140.
authors.forename: Naia
authors.initials: N
authors.lastname: Morueta-Holme
authors.affiliation: Department of Biology, University of North Carolina Chapel Hill, North Carolina, 27599-3280.
authors.forename: Robert K
authors.initials: RK
authors.lastname: Peet
authors.affiliation: CEFE UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier EPHE 1919 route de Mende, Montpellier, CEDEX 5, F-34293, France.
authors.forename: Cyrille
authors.initials: C
authors.lastname: Violle
authors.affiliation: Ecoinformatics & Biodiversity, Department of Bioscience, Aarhus University Ny Munkegade 114, Aarhus C, DK-8000, Denmark.
authors.forename: Jens-Christian
authors.initials: JC
authors.lastname: Svenning
keywords: Ecuador; rarefaction; resampling; richness estimation; sampling effort