• DOI:10.1126/science.1243092
• Corpus ID: 206551051

Hyperdominance in the Amazonian Tree Flora

@article{terSteege2013HyperdominanceIT,
  title={Hyperdominance in the Amazonian Tree Flora},
  author={Hans ter Steege and Nigel C. A. Pitman and Daniel Sabatier and Christopher Baraloto and Rafael P. Salom{\~a}o and Juan Guevara and Oliver L. Phillips and Carolina V. Castilho and William Ernest Magnusson and Jean-François Molino and Abel Lorenzo Monteagudo and Percy N{\'u}{\~n}ez Vargas and Juan Carlos Montero and Ted R. Feldpausch and Eur{\'i}dice N. Honorio Coronado and Timothy J. Killeen and Bonifacio Mostacedo and R Vasquez and Rafael Leandro de Assis and John W. Terborgh and Florian Wittmann and Ana Andrade and William F. Laurance and Susan G. W. Laurance and Beatriz Schwantes Marimon and Ben H Marimon and I C Guimar{\~a}es Vieira and I{\^e}da Le{\~a}o do Amaral and Roel J. W. Brienen and Hern{\'a}n Castellanos and Dairon C{\'a}rdenas L{\'o}pez and J F Duivenvoorden and Hugo F. Mogoll{\'o}n and Francisca Dion{\'i}zia de Almeida Matos and N{\'a}llarett D{\'a}vila and Roosevelt Garc{\'i}a‐Villacorta and Pablo Roberto Stevenson Diaz and Fl{\'a}via Regina Capelotto Costa and Thaise Em{\'i}lio and Carolina Levis and Juliana Schietti and P Souza and Alfonso Alonso and Francisco Dallmeier and {\'A}lvaro Javier Duque Montoya and Maria Teresa Fernandez Piedade and Alejandro Araujo-Murakami and Luzmila Arroyo and Rogerio Gribel and Paul V. A. Fine and Carlos Augusto Peres and Marisol Toledo and Gerardo A. Aymard C. and Timothy R. Baker and Carlos E. Cer{\'o}n and Julien Engel and Terry W. Henkel and Paul J. M. Maas and Pascal P{\'e}tronelli and Juliana Stropp and Charles Eugene Zartman and Doug Daly and David A. Neill and Marcos Silveira and Marcos A. Rios Paredes and J{\'e}r{\^o}me Chave and Di{\'o}genes de Andrade Lima Filho and Peter M{\o}ller J{\o}rgensen and Alfredo F. Fuentes and Jochen Sch{\"o}ngart and Fernando Cornejo Valverde and Anthony Di Fiore and Eliana M. Jimenez and Mar{\'i}a Cristina Pe{\~n}uela Mora and Juan Phillips and Gonzalo Galilaeo Rivas and Tinde R. van Andel and P von Hildebrand and B Hoffman and Egl{\'e}e L. Zent and Yadvinder S. Malhi and Adriana Prieto and Agust{\'i}n Rudas and Ademir R. Ruschell and Natalino Silva and Vincent A. Vos and Stanford Zent and Alexandre A. de Oliveira and Angela Cano Schutz and T Gonzales and Marcelo Trindade Nascimento and Hirma Ramírez-Angulo and Rodrigo Sierra and Milton Tirado and Mar{\'i}a Natalia Uma{\~n}a Medina and Geertje M. F. van der Heijden and C{\'e}sar I. A. Vela and Emilio Vilanova Torre and Corine F. Vriesendorp and Ophelia Wang and Kenneth R. Young and Cl{\'a}udia Baider and Henrik Balslev and Cid Ferreira and Italo Mesones and Armando Torres‐Lezama and Ligia Estela Urrego Giraldo and Roderick Zagt and Miguel Alexiades and Lionel Hernandez and Isau Huamantupa-Chuquimaco and William Milliken and Walter Palacios Cuenca and Daniela Pauletto and Elvis H. Valderrama Sandoval and Luis VALENZUELA GAMARRA and Kyle G. Dexter and Kenneth J. Feeley and Gabriela Lopez-Gonzalez and Miles R. Silman},
  journal={Science},
  year={2013},
  volume={342}
}

• H. ter Steege, N. Pitman, +117 authors M. Silman
• Published 18 October 2013
• Environmental Science
• Science

Introduction Recent decades have seen a major international effort to inventory tree communities in the Amazon Basin and Guiana Shield (Amazonia), but the vast extent and record diversity of these forests have hampered an understanding of basinwide patterns. To overcome this obstacle, we compiled and standardized species-level data on more than half a million trees in 1170 plots sampling all major lowland forest types to explore patterns of commonness, rarity, and richness. A map of Amazonia showing the location of the 1430 Amazon Tree Diversity Network (ATDN) plots that contributed data to this paper. The white polygon marks our delimitation of the study area and consists of 567 1° grid cells (area = 6.29 million km2). Orange circles indicate plots on terra firme; blue squares, plots on seasonally or permanently flooded terrain (várzea, igapó, swamps); yellow triangles, plots on white-sand podzols; gray circles, plots only used for tree density calculations. Background is from Visible Earth. CA, central Amazonia; EA, eastern Amazonia; GS, Guyana Shield; SA, southern Amazonia; WAN, northern part of western Amazonia; WAS, southern part of western Amazonia. More details are shown in figs. S1 to S3. Methods The ~6-million-km2 Amazonian lowlands were divided into 1° cells, and mean tree density was estimated for each cell by using a loess regression model that included no environmental data but had its basis exclusively in the geographic location of tree plots. A similar model, allied with a bootstrapping exercise to quantify sampling error, was used to generate estimated Amazon-wide abundances of the 4962 valid species in the data set. We estimated the total number of tree species in the Amazon by fitting the mean rank-abundance data to Fisher’s log-series distribution. Results Our analyses suggest that lowland Amazonia harbors 3.9 × 1011 trees and ~16,000 tree species. We found 227 “hyperdominant” species (1.4% of the total) to be so common that together they account for half of all trees in Amazonia, whereas the rarest 11,000 species account for just 0.12% of trees. Most hyperdominants are habitat specialists that have large geographic ranges but are only dominant in one or two regions of the basin, and a median of 41% of trees in individual plots belong to hyperdominants. A disproportionate number of hyperdominants are palms, Myristicaceae, and Lecythidaceae. Discussion The finding that Amazonia is dominated by just 227 tree species implies that most biogeochemical cycling in the world’s largest tropical forest is performed by a tiny sliver of its diversity. The causes underlying hyperdominance in these species remain unknown. Both competitive superiority and widespread pre-1492 cultivation by humans are compelling hypotheses that deserve testing. Although the data suggest that spatial models can effectively forecast tree community composition and structure of unstudied sites in Amazonia, incorporating environmental data may yield substantial improvements. An appreciation of how thoroughly common species dominate the basin has the potential to simplify research in Amazonian biogeochemistry, ecology, and vegetation mapping. Such advances are urgently needed in light of the >10,000 rare, poorly known, and potentially threatened tree species in the Amazon. Seeing the Trees in the Forest Despite botanical exploration over two centuries, knowledge of the species composition and quantitative distribution of the trees of the Amazonian forest has remained decidedly patchy. Ter Steege et al. (1243092) report the results from a network of 1170 tree plots arrayed across the Amazon Basin and Guiana Shield, in which the species of all trees with stem diameter >10 centimeters were identified. The tree flora comprised a total of about 16,000 species. However, just 227 very common Amazonian species accounted for half of the trees in the Amazon—the world's most diverse forest. Amazonia harbors 16,000 tree species, 1.4% of which account for half of all individual trees. The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional scales. Here, we provide empirical data on the commonness, rarity, and richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extrapolations suggest that Amazonia harbors roughly 16,000 tree species, of which just 227 (1.4%) account for half of all trees. Most of these are habitat specialists and only dominant in one or two regions of the basin. We discuss some implications of the finding that a small group of species—less diverse than the North American tree flora—accounts for half of the world’s most diverse tree community.