Accounting for uncertainty when mapping species distributions: The need for maps of ignorance

Accurate mapping of species distributions is a fundamental goal of modern biogeography, both for basic and applied purposes. This is commonly done by plotting known species occurrences, expert-drawn range maps or geographical estimations derived from species distribution models. However, all three kinds of maps are implicitly subject to uncertainty, due to the quality and bias of raw distributional data, the process of map building, and the dynamic nature of species distributions themselves. Here we review the main sources of uncertainty suggesting a code of good practices in order to minimize their effects. Corresponding authors (*both authors contributed equally to this work): Duccio Rocchini, Fondazione EdmundMach, Research and Innovation Centre, Department of Biodiversity and Molecular Ecology, GIS and Remote Sensing Unit, Via E. Mach 1, 38010 S. Michele all’Adige (TN), Italy Email: [email protected], [email protected] Joaquı́n Hortal, Departamento de Biodiversidad y Biologı́a Evolutiva, Museo Nacional de Ciencias Naturales (CSIC), C/José Gutiérrez Abascal 2, 28006, Madrid, Spain Email: [email protected] Progress in Physical Geography 35(2) 211–226 a The Author(s) 2011 Reprints and permission: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0309133311399491 ppg.sagepub.com at Circolo Giuridico on April 1, 2011 ppg.sagepub.com Downloaded from Specifically, we claim that uncertainty should be always explicitly taken into account and we propose the creation of maps of ignorance to provide information on where the mapped distributions are reliable and where they are uncertain.