Co-limitation towards lower latitudes shapes global forest diversity gradients
Jingjing Liang, Javier G. P. Gamarra, Nicolas Picard, Mo Zhou, Bryan C. Pijanowski, Douglass F. Jacobs, Peter B. Reich, Thomas W. Crowther, G.J. Nabuurs, Sergio de‐Miguel, Jingyun Fang, Christopher W. Woodall, Jens‐Christian Svenning, Tommaso Jucker, Jean‐François Bastin, Susan K. Wiser, Ferry Slik, Bruno Hérault, Giorgio Alberti, Gunnar Keppel, Geerten Hengeveld, Pierre L. Ibisch, Carlos Alberto Silva, Hans ter Steege, Pablo L. Peri, David A. Coomes, Eric B. Searle, Klaus von Gadow, Bogdan Jaroszewicz, Akane Abbasi, Meinrad Abegg, Yves C. Adou Yao, Jesús Aguirre‐Gutiérrez, Angélica M. Almeyda Zambrano, Jan Altman, Esteban Álvarez‐Dávila, Juan Gabriél Álvarez‐González, Luciana F. Alves, Bienvenu H.K. Amani, Christian Amani, Christian Ammer, Bhély Angoboy Ilondea, Clara Antón‐Fernández, Valerio Avitabile, Gerardo A. Aymard C., Akomian Fortuné Azihou, Johan A. Baard, Timothy R. Baker, Radomir Bałazy, Meredith L. Bastian, Rodrigue Batumike, Marijn Bauters, Hans Beeckman, Nithanel Mikael Hendrik Benu, Robert Bitariho, Pascal Boeckx, Jan Bogaert, Frans Bongers, Olivier Bouriaud, Pedro H. S. Brancalion, Susanne Brandl, Francis Q. Brearley, Jaime Briseno-Reyes, Eben N. Broadbent, Helge Bruelheide, Erwin Bulte, Ann Christine Catlin, Roberto Cazzolla Gatti, Ricardo G. César, Han Y. H. Chen, Chelsea Chisholm, Emil Cienciala, Gabriel Dalla Colletta, José Javier Corral‐Rivas, Aníbal Cuchietti, Aida Cuní‐Sanchez, Javid Ahmad Dar, Selvadurai Dayanandan, Thalès de Haulleville, Mathieu Decuyper, Sylvain Delabye, Géraldine Derroire, Ben DeVries, John Diisi, Tran Van Do, Jiří Doležal, Aurélie Dourdain, Graham Durrheim, Nestor Laurier Engone Obiang, Corneille E. N. Ewango, Teresa J. Eyre, Tom M. Fayle, Lethicia Flavine N. Feunang, Leena Finér, Markus Fischer, Jonas Fridman, Lorenzo Frizzera, André Luís de Gasper, Damiano Gianelle, Henry B. Glick
Abstract
The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers.