C.E. Thimothy Paine, Helge Bruelheide, Susan Doust, Andy Hector, S. Joseph Wright, Jean-Louis Doucet, Alain Paquette, Kasso Daïnou, Paul V. A. Fine, Nils Bourland, Hervé Jactel, Sabrina E. Russo, Martin Baruffol, Kaoru Kitajima, Juan M. Posada, Kalle Rainio, Christian Messier, Xuefei Li, Roland C. de Gouvenain, Daniel Piotto, Cristina Martínez-Garza, Christopher Baraloto, Lucy Amissah, Julia Koricheva, Rakan A. Zahawi, Mariacarmen Ruiz-Jaen, Michael Scherer-Lorenzen, Karen D. Holl, Lourens Poorter, Catherine Potvin, Campbell O. Webb, Harald Auge, Claire Fortunel, Christopher D. Philipson, Josephine Haase, Biological and environmental sciences, University of Stirling, Wageningen University and Research Centre [Wageningen] (WUR), Forestry Research Institute of Ghana, Helmholtz Centre for Environmental Research (UFZ), German Institute for Integrative Biodiversity Research (iDiv), Ecologie des forêts de Guyane (UMR ECOFOG), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-AgroParisTech-Université de Guyane (UG)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Florida International University (FIU), University of Zürich [Zürich] (UZH), Gembloux Agro-BioTech, Université de Liège, Martin-Luther-Universität Halle Wittenberg (MLU), Gembloux Agro-Bio Tech [Gembloux], University of Rhode Island (URI), Australian Antarctic Division (AAD), Australian Government, Department of the Environment and Energy, Lawrence Berkeley National Laboratory [Berkeley] (LBNL), University of Maryland [College Park], University of Maryland System, University of Freiburg [Freiburg], Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), University of California [Santa Cruz] (UCSC), University of California, Biodiversité, Gènes & Communautés (BioGeCo), Institut National de la Recherche Agronomique (INRA)-Université de Bordeaux (UB), Universität Zürich [Zürich] (UZH), Smithsonian Tropical Research Institute, Kyoto University [Kyoto], Royal Holloway [University of London] (RHUL), Universidad Autonoma del Estado de Morelos (UAEM), Université du Québec à Montréal (UQAM), Universidade Federal da Bahia (UFBA), Universidad Nacional de Rosario [Santa Fe], University of Turku, University of Nebraska System, Université McGill, Arnold Arboretum, Harvard University [Cambridge], Las Cruces Biological Station, University of Oxford [Oxford], Wageningen University and Research [Wageningen] (WUR), Helmholtz Zentrum für Umweltforschung = Helmholtz Centre for Environmental Research (UFZ), Université des Antilles (UA)-Université de Guyane (UG)-Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA), Florida International University [Miami] (FIU), Universität Zürich [Zürich] = University of Zurich (UZH), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Université du Québec à Montréal = University of Québec in Montréal (UQAM), McGill University = Université McGill [Montréal, Canada], and Gibson, David
Plant functional traits, in particular specific leaf area (SLA), wood density and seed mass, are often good predictors of individual tree growth rates within communities. Individuals and species with high SLA, low wood density and small seeds tend to have faster growth rates. If community-level relationships between traits and growth have general predictive value, then similar relationships should also be observed in analyses that integrate across taxa, biogeographic regions and environments. Such global consistency would imply that traits could serve as valuable proxies for the complex suite of factors that determine growth rate, and, therefore, could underpin a new generation of robust dynamic vegetation models. Alternatively, growth rates may depend more strongly on the local environment or growth-trait relationships may vary along environmental gradients. We tested these alternative hypotheses using data on 27 352 juvenile trees, representing 278 species from 27 sites on all forested continents, and extensive functional trait data, 38% of which were obtained at the same sites at which growth was assessed. Data on potential evapotranspiration (PET), which summarizes the joint ecological effects of temperature and precipitation, were obtained from a global data base. We estimated size-standardized relative height growth rates (SGR) for all species, then related them to functional traits and PET using mixed-effect models for the fastest growing species and for all species together. Both the mean and 95th percentile SGR were more strongly associated with functional traits than with PET. PET was unrelated to SGR at the global scale. SGR increased with increasing SLA and decreased with increasing wood density and seed mass, but these traits explained only 3.1% of the variation in SGR. SGR-trait relationships were consistently weak across families and biogeographic zones, and over a range of tree statures. Thus, the most widely studied functional traits in plant ecology were poor predictors of tree growth over large scales. Synthesis. We conclude that these functional traits alone may be unsuitable for predicting growth of trees over broad scales. Determining the functional traits that predict vital rates under specific environmental conditions may generate more insight than a monolithic global relationship can offer. The most widely studied functional traits in plant ecology, specific leaf area, wood density and seed mass, were only weakly associated with tree growth rates over broad scales. Assessing trait-growth relationships under specific environmental conditions may generate more insight than a global relationship can offer. © 2015 British Ecological Society.