The number of tree species on Earth
Roberto Cazzolla Gatti, Peter B. Reich, Javier G. P. Gamarra, Tom Crowther, Cang Hui, Albert Morera, Jean‐François Bastin, Sergio de‐Miguel, G.J. Nabuurs, Jens‐Christian Svenning, Josep M. Serra‐Diaz, Cory Merow, Brian J. Enquist, Maria Kamenetsky, Junho Lee, Jun Zhu, Jinyun Fang, Douglass F. Jacobs, Bryan C. Pijanowski, Arindam Banerjee, Robert Giaquinto, Giorgio Alberti, Angélica M. Almeyda Zambrano, Esteban Álvarez‐Dávila, Alejandro Araujo‐Murakami, Valerio Avitabile, Gerardo A. Aymard C., Radomir Bałazy, Christopher Baraloto, Jorcely Barroso, Meredith L. Bastian, Philippe Birnbaum, Robert Bitariho, Jan Bogaert, Frans Bongers, Olivier Bouriaud, Pedro H. S. Brancalion, Francis Q. Brearley, Eben N. Broadbent, Filippo Bussotti, Wendeson Castro da Silva, Ricardo G. César, Goran Češljar, Víctor Chama Moscoso, Han Y. H. Chen, Emil Cienciala, Connie J. Clark, David A. Coomes, Selvadurai Dayanandan, Mathieu Decuyper, Laura E. Dee, Jhon del Águila Pasquel, Géraldine Derroire, Marie-Noël Djuikouo Kamdem, Tran Van Do, Jiří Doležal, Ilija Đorđević, Julien Engel, Tom M. Fayle, Ted R. Feldpausch, Jonas Fridman, David J. Harris, Andreas Hemp, Geerten Hengeveld, Bruno Hérault, Martin Herold, Thomas Ibanez, Andrzej M. Jagodziński, Bogdan Jaroszewicz, Kathryn J. Jeffery, Vivian Kvist Johannsen, Tommaso Jucker, Ahto Kangur, V.N. Karminov, Kuswata Kartawinata, Deborah Kennard, Sebastian Kepfer‐Rojas, Gunnar Keppel, Mohammed Latif Khan, P. K. Khare, Timothy J. Kileen, Hyun Seok Kim, Henn Korjus, Amit Kumar, Ashwani Kumar, Diana Laarmann, Nicolas Labrière, Mait Lang, Simon L. Lewis, Н. В. Лукина, Brian Maitner, Yadvinder Malhi, Andrew R. Marshall, О. В. Мартыненко, Abel L. Monteagudo Mendoza, Petr Ontikov, Edgar Ortiz‐Malavasi, Nadir Pallqui Camacho, Alain Paquette, Minjee Park
Abstract
One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global ground-sourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are ∼73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness.