Handbook of protocols for standardized measurement of terrestrial invertebrate functional traits Marco Moretti* ,1 , Andr  e T. C. Dias 2 , Francesco de Bello 3,4 , Florian Altermatt 5,6 , Steven L. Chown 7 , Francisco M. Azc  arate 8 , James R. Bell 9 , Bertrand Fournier 10 , Micka € el Hedde 11 , Joaqu  ın Hortal 12,13 ,S  ebastien Ibanez 14 , Erik € Ockinger 15 , Jos  e Paulo Sousa 16 , Jacintha Ellers †,17 and Matty P. Berg †,17,18 1 Biodiversity and Conservation Biology, Swiss Federal Research Institute WSL, Z€ urcherstrasse 111, 8903 Birmensdorf, Switzerland; 2 Departamento de Ecologia, Instituto de Biologia Roberto Alc^ antara Gomes, Universidade do Estado do Rio de Janeiro (UERJ), Maracan~ a, Rio de Janeiro, Brazil; 3 Institute of Botany, Czech Academy of Sciences, Dukelska 135, 379 82 T r ebo n, Czech Republic; 4 Faculty of Sciences, University of South Bohemia, Na Zlate Stoce 1, 370 05  Cesk e Bud ejovice, Czech Republic; 5 Department of Aquatic Ecology, Eawag: Swiss Federal Institute of Aquatic Science and Technology, 8600 D€ ubendorf, Switzerland; 6 Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Z€ urich, Switzerland; 7 School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia; 8 Terrestrial Ecology Group (TEG), Department of Ecology, Universidad Aut  onoma de Madrid, C/Darwin 2, 28049 Madrid, Spain; 9 Rothamsted Research, West Common, Harpenden, Hertfordshire AL5 2JQ, UK; 10 Laboratoire Chrono-Environnement, UMR 6249 CNRS, Universit  e de Bourgogne Franche-Comt  e, 16 route de Gray, 25030 Besanc ßon Cedex, France; 11 INRA, AgroParisTech, Universit  e Paris-Saclay, UMR 1402 Ecosys, Route de Saint-Cyr, RD 10, 78026 Versailles Cedex, France; 12 Departamento de Biogeograf  ıa y Cambio Global, Museo Nacional de Ciencias Naturales (MNCN-CSIC), C/Jose Gutierrez Abascal 2, 28006 Madrid, Spain; 13 Centre for Ecology, Evolution and Environmental Changes (Ce3C), Faculdade de Ci ^ encias da Universidade de Lisboa (FCUL), Ed. C2, Campo Grande, 1749-06 Lisboa, Portugal; 14 Laboratoire d’Ecologie Alpine, CNRS UMR 5553, Universit  e Savoie Mont Blanc, 73376 Le Bourget-du-Lac, France; 15 Department of Ecology, Swedish University of Agricultural Sciences, P.O. Box 7044, 750 07 Uppsala, Sweden; 16 Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, 3000-456 Coimbra, Portugal; 17 Department of Ecological Science, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands; and 18 Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Postbox 11103, 9700 CC Groningen, The Netherlands Summary 1. Trait-based approaches are increasingly being used to test mechanisms underlying species assemblages and biotic interactions across a wide range of organisms including terrestrial arthropods and to investigate consequences for ecosystem processes. Such an approach relies on the standardized measurement of functional traits that can be applied across taxa and regions. Currently, however, unified methods of trait measurements are lacking for terrestrial arthropods and related macroinvertebrates (terrestrial invertebrates hereafter). 2. Here, we present a comprehensive review and detailed protocol for a set of 29 traits known to be sensitive to global stressors and to affect ecosystem processes and services. We give rec- ommendations how to measure these traits under standardized conditions across various ter- restrial invertebrate taxonomic groups. 3. We provide considerations and approaches that apply to almost all traits described, such as the selection of species and individuals needed for the measurements, the importance of intraspecific trait variability, how many populations or communities to sample and over which spatial scales. 4. The approaches outlined here provide a means to improve the reliability and predictive power of functional traits to explain community assembly, species diversity patterns and ecosystem processes and services within and across taxa and trophic levels, allowing compar- ison of studies and running meta-analyses across regions and ecosystems. *Correspondence author. E-mail: marco.moretti@wsl.ch † These two authors share the senior authorship. © 2016 The Authors. Functional Ecology © 2016 British Ecological Society Functional Ecology 2016 doi: 10.1111/1365-2435.12776