The number of tree species on Earth
Authors: Cazzolla Gatti Roberto , Reich Peter B. , Gamarra Javier G. P. , Crowther Tom , Hui Cang , Morera Albert , Bastin Jean-Francois , de-Miguel Sergio , Nabuurs Gert-Jan , Svenning Jens-Christian , Serra-Diaz Josep M. , Merow Cory , Enquist Brian , Kamenetsky Maria , Lee Junho , Zhu Jun , Fang Jinyun , Jacobs Douglass F. , Pijanowski Bryan , Banerjee Arindam , Giaquinto Robert A. , Alberti Giorgio , Almeyda Zambrano Angelica Maria , Alvarez-Davila Esteban , Araujo-Murakami Alejandro , Avitabile Valerio , Aymard Gerardo A. , Balazy Radomir , Baraloto Chris , Barroso Jorcely G. , Bastian Meredith L. , Birnbaum Philippe , Bitariho Robert , Bogaert Jan , Bongers Frans , Bouriaud Olivier , Brancalion Pedro H. S. , Brearley Francis Q. , Broadbent Eben North , Bussotti Filippo , Castro da Silva Wendeson , César Ricardo Gomes , Češljar Goran , Chama Moscoso Víctor , Chen Han Y. H. , Cienciala Emil , Clark Connie J. , Coomes David A. , Dayanandan Selvadurai , Decuyper Mathieu , Dee Laura E. , Del Aguila Pasquel Jhon , Derroire Géraldine , Djuikouo Marie Noel Kamdem , Van Do Tran , Dolezal Jiri , Đorđević Ilija Đ. , Engel Julien , Fayle Tom M. , Feldpausch Ted R. , Fridman Jonas K. , Harris David J. , Hemp Andreas , Hengeveld Geerten , Herault Bruno , Herold Martin , Ibanez Thomas , Jagodzinski Andrzej M. , Jaroszewicz Bogdan , Jeffery Kathryn J. , Johannsen Vivian Kvist , Jucker Tommaso , Kangur Ahto , Karminov Victor N. , Kartawinata Kuswata , Kennard Deborah K. , Kepfer-Rojas Sebastian , Keppel Gunnar , Khan Mohammed Latif , Khare Pramod Kumar , Kileen Timothy J. , Kim Hyun Seok , Korjus Henn , Kumar Amit , Kumar Ashwani , Laarmann Diana , Labrière Nicolas , Lang Mait , Lewis Simon L. , Lukina Natalia , Maitner Brian S. , Malhi Yadvinder , Marshall Andrew R. , Martynenko Olga V. , Monteagudo Mendoza Abel L. , Ontikov Petr V. , Ortiz-Malavasi Edgar , Pallqui Camacho Nadir C. , Paquette Alain , Park Minjee , Parthasarathy Narayanaswamy , Peri Pablo Luis , Petronelli Pascal , Pfautsch Sebastian , Phillips Oliver L. , Picard Nicolas , Piotto Daniel , Poorter Lourens , Poulsen John R. , Pretzsch Hans , Ramírez-Angulo Hirma , Restrepo Correa Zorayda , Rodeghiero Mirco , Rojas Gonzáles Rocío Del Pilar , Rolim Samir G. , Rovero Francesco , Rutishauser Ervan , Saikia Purabi , Salas-Eljatib Christian , Schepaschenko Dmitry , Scherer-Lorenzen Michael , Šebeň Vladimír , Silveira Marcos , Slik Ferry , Sonké Bonaventure , Souza Alexandre F. , Stereńczak Krzysztof Jan , Svoboda Miroslav , Taedoumg Hermann , Tchebakova Nadja , Terborgh John , Tikhonova Elena , Torres-Lezama Armando , van der Plas Fons , Vásquez Rodolfo , Viana Helder , Vibrans Alexander C. , Vilanova Emilio , Vos Vincent A. , Wang Hua-Feng , Westerlund Bertil , White Lee J. T. , Wiser Susan K. , Zawiła-Niedźwiecki Tomasz , Zemagho Lise , Zhu Zhi-Xin , Zo-Bi Irié C. , Liang Jingjing 
Published: January 2022

Significance
Tree diversity is fundamental for forest ecosystem stability and services. However, because of limited available data, estimates of tree diversity at large geographic domains still rely heavily on published lists of species descriptions that are geographically uneven in coverage. These limitations have precluded efforts to generate a global perspective. Here, based on a ground-sourced global database, we estimate the number of tree species at biome, continental, and global scales. We estimated a global tree richness (≈73,300) that is ≈14% higher than numbers known today, with most undiscovered species being rare, continentally endemic, and tropical or subtropical. These results highlight the vulnerability of global tree species diversity to anthropogenic changes.