Biodivers Conserv (2018) 27:2443–2448
Improving the estimation of area of occupancy for IUCN
Red List assessments by using a circular buﬀer approach
Frank T. Breiner
· Ariel Bergamini
Received: 23 August 2017 / Revised: 28 March 2018 / Accepted: 2 May 2018 /
Published online: 4 May 2018
© Springer Science+Business Media B.V., part of Springer Nature 2018
Abstract The area of occupancy (AOO) is one of the main measures used by IUCN to
quantify range size for species. AOO represents the area of suitable habitat currently occu-
pied by the taxon and is usually quantiﬁed by counting the number of occupied cells in
a uniform grid that covers the entire range of a taxon. However, this methodology adds
uncertainty by the location of the origin of the grid frame. In this communication paper,
we tested the inﬂuence of the origin of the grid frame used to quantify AOO and found
for Swiss bryophytes that 14 species (out of 1089) fall into a diﬀerent Red List category
when the origin of the grid frame was shifted. With this and theoretical examples we show
that AOO quantiﬁed by circles around the occurrences (a circular buﬀer approach) would
reduce uncertainty signiﬁcantly because they are independent of the origin of a grid frame.
A circular buﬀer approach to quantify AOO contribute thus to more robust and accurate
Red Lists and its usage is in accordance with the IUCN criteria.
Keywords AOO · Bryophytes · Conservation · Extinction risk · Geographic range · Risk
assessment · Species distribution · Threatened species
Communicated by David Hawksworth.
This article belongs to the Topical Collection: Biodiversity legal instruments and regulations.
Electronic supplementary material The online version of this article (https ://doi.org/10.1007/s1053
1-018-1555-5) contains supplementary material, which is available to authorized users.
* Frank T. Breiner
Swiss Federal Research Institute WSL, Biodiversity and Conservation Biology, Zürcherstrasse
111, 8903 Birmensdorf, Switzerland
Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
Present Address: Wetlands International, Horapark 9, 6717 LZ Ede, The Netherlands