Robert K. Colwell

Museum Curator Adjoint in Entomology

robertkcolwell [at]

Museum of Natural History

University of Colorado

Boulder, CO 80309, USA

robertkcolwell [at]

Museum of Natural History

University of Colorado

Boulder, CO 80309, USA

An estimate of the number of tropical tree species

Journal article

J. Slik, V. Arroyo‐Rodríguez, S. Aiba, P. Álvarez-Loayza, L. Alves, P. Ashton, P. Balvanera, M. Bastian, P. Bellingham, E. van den Berg, L. Bernacci, Polyanna da Conceição Bispo, L. Blanc, K. Böhning‐Gaese, P. Boeckx, F. Bongers, B. Boyle, M. Bradford, F. Brearley, Mireille Breuer-Ndoundou Hockemba, S. Bunyavejchewin, Darley Calderado Leal Matos, M. Castillo-Santiago, E. Catharino, Shauna-Lee Chai, Yukai Chen, R. K. Colwell, R. Chazdon, C. Clark, D. Clark, D. Clark, H. Culmsee, K. Damas, H. Dattaraja, G. Dauby, P. Davidar, S. DeWalt, J. Doucet, Á. Duque, G. Durigan, K. Eichhorn, P. V. Eisenlohr, E. Eler, C. Ewango, Nina Farwig, K. Feeley, L. Ferreira, Richard Field, Ary T. de Oliveira Filho, C. Fletcher, O. Forshed, G. Franco, G. Fredriksson, T. Gillespie, J. Gillet, G. Amarnath, Daniel M. Griffith, J. Grogan, N. Gunatilleke, David Harris, R. Harrison, A. Hector, J. Homeier, N. Imai, A. Itoh, P. Jansen, C. Joly, B. D. De Jong, K. Kartawinata, E. Kearsley, D. Kelly, D. Kenfack, M. Kessler, K. Kitayama, R. Kooyman, E. Larney, Y. Laumonier, S. Laurance, W. Laurance, M. Lawes, I. Amaral, Susan G. Letcher, J. Lindsell, Xinghui Lu, A. Mansor, A. Marjokorpi, Emanuel H. Martin, H. Meilby, F. Melo, D. Metcalfe, V. Medjibe, J. Metzger, J. Millet, D. Mohandass, J. Montero, M. de Morisson Valeriano, B. Mugerwa, H. Nagamasu, R. Nilus, S. Ochoa-Gaona, Onrizal, N. Page, P. Parolin, M. Parren, N. Parthasarathy, E. Paudel, Andrea Permana, M. Piedade, N. Pitman, L. Poorter, A. Poulsen, J. Poulsen, J. Powers, R. Prasad, J. Puyravaud, J. Razafimahaimodison, J. Reitsma, J. dos Santos, Wilson Roberto Spironello, Hugo Romero-Saltos, F. Rovero, A. Rozak, K. Ruokolainen, E. Rutishauser, F. Saiter, P. Saner, Bráulio A. Santos, Fernanda Santos, S. K. Sarker, Manichanh Satdichanh, C. Schmitt, J. Schöngart, M. Schulze, M. Suganuma, D. Sheil, Eduardo da Silva Pinheiro, P. Sist, T. Stévart, R. Sukumar, I. Sun, T. Sunderland, H. Suresh, E. Suzuki, M. Tabarelli, Jangwei Tang, N. Targhetta, I. Theilade, Duncan W. Thomas, P. Tchouto, Johanna Hurtado, R. Valencia, J. V. van Valkenburg, Tran Van Do, R. Vásquez, H. Verbeeck, V. Adekunle, S. Vieira, C. Webb, Timothy J. S. Whitfeld, S. Wich, John N. Williams, F. Wittmann, Hannsjoerg Wöll, Xiaobo Yang, C. Y. Adou Yao, S. Yap, T. Yoneda, R. Zahawi, R. Zakaria, R. Zang, R. L. de Assis, Bruno Garcia Luize, Eduardo M. Venticinque
Proceedings of the National Academy of Sciences, 2015

Semantic Scholar DOI PubMed


APA   Click to copy
Slik, J., Arroyo‐Rodríguez, V., Aiba, S., Álvarez-Loayza, P., Alves, L., Ashton, P., … Venticinque, E. M. (2015). An estimate of the number of tropical tree species. Proceedings of the National Academy of Sciences.

Chicago/Turabian   Click to copy
Slik, J., V. Arroyo‐Rodríguez, S. Aiba, P. Álvarez-Loayza, L. Alves, P. Ashton, P. Balvanera, et al. “An Estimate of the Number of Tropical Tree Species.” Proceedings of the National Academy of Sciences (2015).

MLA   Click to copy
Slik, J., et al. “An Estimate of the Number of Tropical Tree Species.” Proceedings of the National Academy of Sciences, 2015.

BibTeX   Click to copy

  title = {An estimate of the number of tropical tree species},
  year = {2015},
  journal = {Proceedings of the National Academy of Sciences},
  author = {Slik, J. and Arroyo‐Rodríguez, V. and Aiba, S. and Álvarez-Loayza, P. and Alves, L. and Ashton, P. and Balvanera, P. and Bastian, M. and Bellingham, P. and van den Berg, E. and Bernacci, L. and da Conceição Bispo, Polyanna and Blanc, L. and Böhning‐Gaese, K. and Boeckx, P. and Bongers, F. and Boyle, B. and Bradford, M. and Brearley, F. and Hockemba, Mireille Breuer-Ndoundou and Bunyavejchewin, S. and Matos, Darley Calderado Leal and Castillo-Santiago, M. and Catharino, E. and Chai, Shauna-Lee and Chen, Yukai and Colwell, R. K. and Chazdon, R. and Clark, C. and Clark, D. and Clark, D. and Culmsee, H. and Damas, K. and Dattaraja, H. and Dauby, G. and Davidar, P. and DeWalt, S. and Doucet, J. and Duque, Á. and Durigan, G. and Eichhorn, K. and Eisenlohr, P. V. and Eler, E. and Ewango, C. and Farwig, Nina and Feeley, K. and Ferreira, L. and Field, Richard and de Oliveira Filho, Ary T. and Fletcher, C. and Forshed, O. and Franco, G. and Fredriksson, G. and Gillespie, T. and Gillet, J. and Amarnath, G. and Griffith, Daniel M. and Grogan, J. and Gunatilleke, N. and Harris, David and Harrison, R. and Hector, A. and Homeier, J. and Imai, N. and Itoh, A. and Jansen, P. and Joly, C. and Jong, B. D. De and Kartawinata, K. and Kearsley, E. and Kelly, D. and Kenfack, D. and Kessler, M. and Kitayama, K. and Kooyman, R. and Larney, E. and Laumonier, Y. and Laurance, S. and Laurance, W. and Lawes, M. and Amaral, I. and Letcher, Susan G. and Lindsell, J. and Lu, Xinghui and Mansor, A. and Marjokorpi, A. and Martin, Emanuel H. and Meilby, H. and Melo, F. and Metcalfe, D. and Medjibe, V. and Metzger, J. and Millet, J. and Mohandass, D. and Montero, J. and de Morisson Valeriano, M. and Mugerwa, B. and Nagamasu, H. and Nilus, R. and Ochoa-Gaona, S. and Onrizal and Page, N. and Parolin, P. and Parren, M. and Parthasarathy, N. and Paudel, E. and Permana, Andrea and Piedade, M. and Pitman, N. and Poorter, L. and Poulsen, A. and Poulsen, J. and Powers, J. and Prasad, R. and Puyravaud, J. and Razafimahaimodison, J. and Reitsma, J. and dos Santos, J. and Spironello, Wilson Roberto and Romero-Saltos, Hugo and Rovero, F. and Rozak, A. and Ruokolainen, K. and Rutishauser, E. and Saiter, F. and Saner, P. and Santos, Bráulio A. and Santos, Fernanda and Sarker, S. K. and Satdichanh, Manichanh and Schmitt, C. and Schöngart, J. and Schulze, M. and Suganuma, M. and Sheil, D. and da Silva Pinheiro, Eduardo and Sist, P. and Stévart, T. and Sukumar, R. and Sun, I. and Sunderland, T. and Suresh, H. and Suzuki, E. and Tabarelli, M. and Tang, Jangwei and Targhetta, N. and Theilade, I. and Thomas, Duncan W. and Tchouto, P. and Hurtado, Johanna and Valencia, R. and van Valkenburg, J. V. and Do, Tran Van and Vásquez, R. and Verbeeck, H. and Adekunle, V. and Vieira, S. and Webb, C. and Whitfeld, Timothy J. S. and Wich, S. and Williams, John N. and Wittmann, F. and Wöll, Hannsjoerg and Yang, Xiaobo and Yao, C. Y. Adou and Yap, S. and Yoneda, T. and Zahawi, R. and Zakaria, R. and Zang, R. and de Assis, R. L. and Luize, Bruno Garcia and Venticinque, Eduardo M.}


Significance People are fascinated by the amazing diversity of tropical forests and will be surprised to learn that robust estimates of the number of tropical tree species are lacking. We show that there are at least 40,000, but possibly more than 53,000, tree species in the tropics, in contrast to only 124 across temperate Europe. Almost all tropical tree species are restricted to their respective continents, and the Indo-Pacific region appears to be as species-rich as tropical America, with each of these two regions being almost five times as rich in tree species as African tropical forests. Our study shows that most tree species are extremely rare, meaning that they may be under serious risk of extinction at current deforestation rates. The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher’s alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ∼40,000 and ∼53,000, i.e., at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as species-rich as the Neotropics, with both regions having a minimum of ∼19,000–25,000 tree species. Continental Africa is relatively depauperate with a minimum of ∼4,500–6,000 tree species. Very few species are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating species richness in trees that may help refine species richness estimates of tree-dependent taxa.


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