Condit, R.;Pitman, N.;Leigh, E. G.;Chave, J.;Terborgh, J.;Foster, R. B.;Nunez, P.;Aguilar, S.;Valencia, R.;Villa, G.;Muller-Landau, H. C.;Losos, E.;Hubbell, S. P.
Beta-diversity in tropical forest trees
Science
2002
Journal Article
295
5555
666-669
plants trees Ecuador Panama distributions beta-diversity ecology inventories large spatial scales turnover vegetation composition Parque Nacional del Manu Cocha Cashu Los Amigos Diamante Pakitza Madre de Dios Bibliography
The high alpha-diversity of tropical forests has been amply documented, but beta-diversity -- how species composition changes with distance -- has seldom been studied. We present quantitative estimates of beta-diversity for tropical trees by comparing species composition of plots in lowland terra firme forest in Panama, Ecuador, and Peru. We compare observations with predictions derived from a neutral model in which habitat is uniform and only dispersal and speciation influence species turnover. We find that beta-diversity is higher in Panama than in western Amazonia and that patterns in both areas are inconsistent with the neutral model. In Panama, habitat variation appears to increase species turnover relative to Amazonia, where unexpectedly tow turnover over great distances suggests that population densities of some species are bounded by as yet unidentified processes. At intermediate scales in both regions, observations can be matched by theory, suggesting that dispersal limitation, with speciation, influences species turnover.