Linking seed size and number to trait syndromes in trees
Michał Bogdziewicz, Marie‐Claire Aravena Acuña, Robert A. Andrus, Davide Ascoli, Yves Bergeron, Daniel Brveiller, Thomas Boivin, Raúl Bonal, Thomas Caignard, Maxime Cailleret, Rafael Calama, Sergio Donoso Calderón, J. Julio Camarero, Chia‐Hao Chang‐Yang, Jérôme Chave, Francesco Chianucci, Natalie L. Cleavitt, Benoı̂t Courbaud, Andrea Cutini, T. Curt, Adrian J. Das, Hendrik Davi, Nicolas Delpierre, Sylvain Delzon, Michael C. Dietze, Laurent Dormont, William Farfán-Ríos, Catherine A. Gehring, Gregory S. Gilbert, Georg Gratzer, Cathryn H. Greenberg, Arthur Guignabert, Qinfeng Guo, Andrew Hacket‐Pain, Arndt Hampe, Qingmin Han, Kazuhiko Hoshizaki, Inés Ibáñez, Jill F. Johnstone, Valentin Journé, Thomas Kitzberger, Johannes M. H. Knops, Georges Künstler, Richard K. Kobe, Jonathan G. A. Lageard, Jalene M. LaMontagne, Mateusz Ledwoń, Theodor D. Leininger, Jean‐Marc Limousin, James A. Lutz, Diana Macias, Anders Mårell, Eliot J. B. McIntire, Emily Moran, Renzo Motta, Jonathan A. Myers, Thomas A. Nagel, Shoji Naoe, Mahoko Noguchi, Michio Oguro, Hiroko Kurokawa, Jean‐Marc Ourcival, Robert Parmenter, Ignacio Manuel Pérez-Ramos, Łukasz Piechnik, Tomasz Podgórski, John R. Poulsen, Tong Qiu, Miranda D. Redmond, Chantal D. Reid, Kyle C. Rodman, Pavel Šamonil, Jan Holík, C. Lane Scher, Harald Schmidt Van Marle, Barbara Seget, Mitsue Shibata, Shubhi Sharma, Miles R. Silman, Michael A. Steele, Jacob N. Straub, I‐Fang Sun, Samantha Sutton, Jennifer J. Swenson, Peter A. Thomas, María Uriarte, Giorgio Vacchiano, Thomas T. Veblen, Boyd R. Wright, S. Joseph Wright, Thomas G. Whitham, Kai Zhu, Jess K. Zimmerman, Magdalena Żywiec, James S. Clark
Abstract
Abstract Aim Our understanding of the mechanisms that maintain forest diversity under changing climate can benefit from knowledge about traits that are closely linked to fitness. We tested whether the link between traits and seed number and seed size is consistent with two hypotheses, termed the leaf economics spectrum and the plant size syndrome, or whether reproduction represents an independent dimension related to a seed size–seed number trade‐off. Location Most of the data come from Europe, North and Central America and East Asia. A minority of the data come from South America, Africa and Australia. Time period 1960–2022. Major taxa studied Trees. Methods We gathered 12 million observations of the number of seeds produced in 784 tree species. We estimated the number of seeds produced by individual trees and scaled it up to the species level. Next, we used principal components analysis and generalized joint attribute modelling (GJAM) to map seed number and size on the tree traits spectrum. Results Incorporating seed size and number into trait analysis while controlling for environment and phylogeny with GJAM exposes relationships in trees that might otherwise remain hidden. Production of the large total biomass of seeds [product of seed number and seed size; hereafter, species seed productivity (SSP)] is associated with high leaf area, low foliar nitrogen, low specific leaf area (SLA) and dense wood. Production of high seed numbers is associated with small seeds produced by nutrient‐demanding species with softwood, small leaves and high SLA. Trait covariation is consistent with opposing strategies: one fast‐growing, early successional, with high dispersal, and the other slow‐growing, stress‐tolerant, that recruit in shaded conditions. Main conclusions Earth system models currently assume that reproductive allocation is indifferent among plant functional types. Easily measurable seed size is a strong predictor of the seed number and species seed productivity. The connection of SSP with the functional traits can form the first basis of improved fecundity prediction across global forests.