The number of tree species on Earth

Cazzolla Gatti, R.; Reich, P.B.; Gamarra, J.G.P.; Crowther, T.; Hui, C.; Morera, A.; Bastin, J.; de-Miguel, S.; Nabuurs, G.; Svenning, J.; Serra-Diaz, J.M.; Merow, C.; Enquist, B.; Kamenetsky, M.; Lee, J.; Zhu, J.; Fang, J.; Jacobs, D.F.; Pijanowski, B.; Banerjee, A.; Giaquinto, R.A.; Alberti, G.; Almeyda Zambrano, A.M.; Alvarez-Davila, E.; Araujo-Murakami, A.; Avitabile, V.; Aymard, G.A.; Balazy, R.; Baraloto, C.; Barroso, J.G.; Bastian, M.L.; Birnbaum, P.; Bitariho, R.; Bogaert, J.; Bongers, F.; Bouriaud, O.; Brancalion, P.H.S.; Brearley, F.Q.; Broadbent, E.N.; Bussotti, F.; Castro da Silva, W.; César, R.G.; Češljar, G.; Chama Moscoso, V.; Chen, H.Y.H.; Cienciala, E.; Clark, C.J.; Coomes, D.A.; Dayanandan, S.; Decuyper, M.; Dee, L.E.; Del Aguila Pasquel, J.; Derroire, G.; Djuikouo, M.N.K.; Van Do, T.; Dolezal, J.; Đorđević, I.Đ.; Engel, J.; Fayle, T.M.; Feldpausch, T.R.; Fridman, J.K.; Harris, D.J.; Hemp, A.; Hengeveld, G.; Herault, B.; Herold, M.; Ibanez, T.; Jagodzinski, A.M.; Jaroszewicz, B.; Jeffery, K.J.; Johannsen, V.K.; Jucker, T.; Kangur, A.; Karminov, V.N.; Kartawinata, K.; Kennard, D.K.; Kepfer-Rojas, S.; Keppel, G.; Khan, M.L.; Khare, P.K.; Kileen, T.J.; Kim, H.S.; Korjus, H.; Kumar, A.; Kumar, A.; Laarmann, D.; Labrière, N.; Lang, M.; Lewis, S.L.; Lukina, N.; Maitner, B.S.; Malhi, Y.; Marshall, A.R.; Martynenko, O.V.; Monteagudo Mendoza, A.L.; Ontikov, P.V.; Ortiz-Malavasi, E.; Pallqui Camacho, N.C.; Paquette, A.; Park, M.; Parthasarathy, N.; Peri, P.L.; Petronelli, P.; Pfautsch, S.; Phillips, O.L.; Picard, N.; Piotto, D.; Poorter, L.; Poulsen, J.R.; Pretzsch, H.; Ramírez-Angulo, H.; Restrepo Correa, Z.; Rodeghiero, M.; Rojas Gonzáles, R.D.P.; Rolim, S.G.; Rovero, F.; Rutishauser, E.; Saikia, P.; Salas-Eljatib, C.; Schepaschenko, D.; Scherer-Lorenzen, M.; Šebeň, V.; Silveira, M.; Slik, F.; Sonké, B.; Souza, A.F.; Stereńczak, K.J.; Svoboda, M.; Taedoumg, H.; Tchebakova, N.; Terborgh, J.; Tikhonova, E.; Torres-Lezama, A.; van der Plas, F.; Vásquez, R.; Viana, H.; Vibrans, A.C.; Vilanova, E.; Vos, V.A.; Wang, H.; Westerlund, B.; White, L.J.T.; Wiser, S.K.; Zawiła-Niedźwiecki, T.; Zemagho, L.; Zhu, Z.; Zo-Bi, I.C.; Liang, J.

doi:10.1073/pnas.2115329119

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.

Cazzolla Gatti, R.; Reich, P.B.; Gamarra, J.G.P.; Crowther, T.; Hui, C.; Morera, A.; Bastin, J.; de-Miguel, S.; Nabuurs, G.; Svenning, J.; Serra-Diaz, J.M.; Merow, C.; Enquist, B.; Kamenetsky, M.; Lee, J.; Zhu, J.; Fang, J.; Jacobs, D.F.; Pijanowski, B.; Banerjee, A.; Giaquinto, R.A.; Alberti, G.; Almeyda Zambrano, A.M.; Alvarez-Davila, E.; Araujo-Murakami, A.; Avitabile, V.; Aymard, G.A.; Balazy, R.; Baraloto, C.; Barroso, J.G.; Bastian, M.L.; Birnbaum, P.; Bitariho, R.; Bogaert, J.; Bongers, F.; Bouriaud, O.; Brancalion, P.H.S.; Brearley, F.Q.; Broadbent, E.N.; Bussotti, F.; Castro da Silva, W.; César, R.G.; Češljar, G.; Chama Moscoso, V.; Chen, H.Y.H.; Cienciala, E.; Clark, C.J.; Coomes, D.A.; Dayanandan, S.; Decuyper, M.; Dee, L.E.; Del Aguila Pasquel, J.; Derroire, G.; Djuikouo, M.N.K.; Van Do, T.; Dolezal, J.; Đorđević, I.Đ.; Engel, J.; Fayle, T.M.; Feldpausch, T.R.; Fridman, J.K.; Harris, D.J.; Hemp, A.; Hengeveld, G.; Herault, B.; Herold, M.; Ibanez, T.; Jagodzinski, A.M.; Jaroszewicz, B.; Jeffery, K.J.; Johannsen, V.K.; Jucker, T.; Kangur, A.; Karminov, V.N.; Kartawinata, K.; Kennard, D.K.; Kepfer-Rojas, S.; Keppel, G.; Khan, M.L.; Khare, P.K.; Kileen, T.J.; Kim, H.S.; Korjus, H.; Kumar, A.; Kumar, A.; Laarmann, D.; Labrière, N.; Lang, M.; Lewis, S.L.; Lukina, N.; Maitner, B.S.; Malhi, Y.; Marshall, A.R.; Martynenko, O.V.; Monteagudo Mendoza, A.L.; Ontikov, P.V.; Ortiz-Malavasi, E.; Pallqui Camacho, N.C.; Paquette, A.; Park, M.; Parthasarathy, N.; Peri, P.L.; Petronelli, P.; Pfautsch, S.; Phillips, O.L.; Picard, N.; Piotto, D.; Poorter, L.; Poulsen, J.R.; Pretzsch, H.; Ramírez-Angulo, H.; Restrepo Correa, Z.; Rodeghiero, M.; Rojas Gonzáles, R.D.P.; Rolim, S.G.; Rovero, F.; Rutishauser, E.; Saikia, P.; Salas-Eljatib, C.; Schepaschenko, D.; Scherer-Lorenzen, M.; Šebeň, V.; Silveira, M.; Slik, F.; Sonké, B.; Souza, A.F.; Stereńczak, K.J.; Svoboda, M.; Taedoumg, H.; Tchebakova, N.; Terborgh, J.; Tikhonova, E.; Torres-Lezama, A.; van der Plas, F.; Vásquez, R.; Viana, H.; Vibrans, A.C.; Vilanova, E.; Vos, V.A.; Wang, H.; Westerlund, B.; White, L.J.T.; Wiser, S.K.; Zawiła-Niedźwiecki, T.; Zemagho, L.; Zhu, Z.; Zo-Bi, I.C.; Liang, J. (2022). The number of tree species on Earth. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 119 (6): e2115329119. doi: 10.1073/pnas.2115329119 handle: http://hdl.handle.net/10449/72594