%N 6
%T The number of tree species on Earth
%A Roberto Cazzolla Gatti
%A Peter B Reich
%A Javier GP Gamarra
%A Tom Crowther
%A Cang Hui
%A Albert Morera
%A Jean-Francois Bastin
%A Sergio de-Miguel
%A Gert-Jan Nabuurs
%A Jens-Christian Svenning
%A Josep M Serra-Diaz
%A Cory Merow
%A Brian Enquist
%A Maria Kamenetsky
%A Junho Lee
%A Jun Zhu
%A Jinyun Fang
%A Douglass F Jacobs
%A Bryan Pijanowski
%A Arindam Banerjee
%A Robert A Giaquinto
%A Giorgio Alberti
%A Angelica Maria Almeyda Zambrano
%A Esteban Alvarez-Davila
%A Alejandro Araujo-Murakami
%A Valerio Avitabile
%A Gerardo A Aymard
%A Radomir Balazy
%A Chris Baraloto
%A Jorcely G Barroso
%A Meredith L Bastian
%A Philippe Birnbaum
%A Robert Bitariho
%A Jan Bogaert
%A Frans Bongers
%A Olivier Bouriaud
%A Pedro HS Brancalion
%A Francis Q Brearley
%A Eben North Broadbent
%A Filippo Bussotti
%A Wendeson Castro da Silva
%A Ricardo Gomes Cesar
%A Goran Cesljar
%A Victor Chama Moscoso
%A Han YH Chen
%A Emil Cienciala
%A Connie J Clark
%A David A Coomes
%A Selvadurai Dayanandan
%A Mathieu Decuyper
%A Laura E Dee
%A Jhon Del Aguila Pasquel
%A Geraldine Derroire
%A Marie Noel Kamdem Djuikouo
%A Van Do Tran
%A Jiri Dolezal
%A Ilija D Dordevic
%A Julien Engel
%A Tom M Fayle
%A Ted R Feldpausch
%A Jonas K Fridman
%A David J Harris
%A Andreas Hemp
%A Geerten Hengeveld
%A Bruno Herault
%A Martin Herold
%A Thomas Ibanez
%A Andrzej M Jagodzinski
%A Bogdan Jaroszewicz
%A Kathryn J Jeffery
%A Vivian Kvist Johannsen
%A Tommaso Jucker
%A Ahto Kangur
%A Victor N Karminov
%A Kuswata Kartawinata
%A Deborah K Kennard
%A Sebastian Kepfer-Rojas
%A Gunnar Keppel
%A Mohammed Latif Khan
%A Pramod Kumar Khare
%A Timothy J Kileen
%A Hyun Seok Kim
%A Henn Korjus
%A Amit Kumar
%A Ashwani Kumar
%A Diana Laarmann
%A Nicolas Labriere
%A Mait Lang
%A Simon L Lewis
%A Natalia Lukina
%A Brian S Maitner
%A Yadvinder Malhi
%A Andrew R Marshall
%A Olga V Martynenko
%A Abel L Monteagudo Mendoza
%A Petr V Ontikov
%A Edgar Ortiz-Malavasi
%A Nadir C Pallqui Camacho
%A Alain Paquette
%A Minjee Park
%A Narayanaswamy Parthasarathy
%A Pablo Luis Peri
%A Pascal Petronelli
%A Sebastian Pfautsch
%A Oliver L Phillips
%A Nicolas Picard
%A Daniel Piotto
%A Lourens Poorter
%A John R Poulsen
%A Hans Pretzsch
%A Hirma Ramirez-Angulo
%A Zorayda Restrepo Correa
%A Mirco Rodeghiero
%A Rocio Del Pilar Rojas Gonzales
%A Samir G Rolim
%A Francesco Rovero
%A Ervan Rutishauser
%A Purabi Saikia
%A Christian Salas-Eljatib
%A Dmitry Schepaschenko
%A Michael Scherer-Lorenzen
%A Vladimir Seben
%A Marcos Silveira
%A Ferry Slik
%A Bonaventure Sonke
%A Alexandre F Souza
%A Krzysztof Jan Sterenczak
%A Miroslav Svoboda
%A Hermann Taedoumg
%A Nadja Tchebakova
%A John Terborgh
%A Elena Tikhonova
%A Armando Torres-Lezama
%A Fons van der Plas
%A Rodolfo Vasquez
%A Helder Viana
%A Alexander C Vibrans
%A Emilio Vilanova
%A Vincent A Vos
%A Hua-Feng Wang
%A Bertil Westerlund
%A Lee JT White
%A Susan K Wiser
%A Tomasz Zawila-Niedzwiecki
%A Lise Zemagho
%A Zhi-Xin Zhu
%A Irie C Zo-Bi
%A Jingjing Liang
%V 119
%D 2022
%J Proceedings of The National Academy of Sciences of the United States of America (PNAS)
%K Science & Technology, Multidisciplinary Sciences, Science & Technology - Other Topics, biodiversity, forests, hyperdominance, rarity, richness, BIODIVERSITY, RICHNESS, DIVERSITY, SAMPLE, PATTERNS, HETEROGENEITY, COMPLETENESS, ABUNDANCE, COVERAGE, ECOLOGY
%L discovery10149177
%I NATL ACAD SCIENCES
%O This work is licensed under a Creative Commons Attribution 4.0 International License. The images
or other third-party material in this article are included in the Creative Commons license,
unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license,
users will need to obtain permission from the license holder to reproduce the material. To view a copy of this
license, visit http://creativecommons.org/licenses/by/4.0/
%C United States
%X 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.