Compositional response of Amazon forests to climate change

Esquivel-Muelbert, A. and Baker, T.R. and Dexter, K.G. and Lewis, S.L. and Brienen, R.J.W. and Feldpausch, T.R. and Lloyd, J. and Monteagudo-Mendoza, A. and Arroyo, L. and Álvarez-Dávila, E. and Higuchi, N. and Marimon, B.S. and Marimon-Junior, B.H. and Silveira, M. and Vilanova, E. and Gloor, E. and Malhi, Y. and Chave, J. and Barlow, J. and Bonal, D. and Davila Cardozo, N. and Erwin, T. and Fauset, S. and Hérault, B. and Laurance, S. and Poorter, L. and Qie, L. and Stahl, C. and Sullivan, M.J.P. and ter Steege, H. and Vos, V.A. and Zuidema, P.A. and Almeida, E. and Almeida de Oliveira, E. and Andrade, A. and Vieira, S.A. and Aragão, L. and Araujo-Murakami, A. and Arets, E. and Aymard C, G.A. and Baraloto, C. and Camargo, P.B. and Barroso, J.G. and Bongers, F. and Boot, R. and Camargo, J.L. and Castro, W. and Chama Moscoso, V. and Comiskey, J. and Cornejo Valverde, F. and Lola da Costa, A.C. and del Aguila Pasquel, J. and Di Fiore, A. and Fernanda Duque, L. and Elias, F. and Engel, J. and Flores Llampazo, G. and Galbraith, D. and Herrera Fernández, R. and Honorio Coronado, E. and Hubau, W. and Jimenez-Rojas, E. and Lima, A.J.N. and Umetsu, R.K. and Laurance, W. and Lopez-Gonzalez, G. and Lovejoy, T. and Aurelio Melo Cruz, O. and Morandi, P.S. and Neill, D. and Núñez Vargas, P. and Pallqui Camacho, N.C. and Parada Gutierrez, A. and Pardo, G. and Peacock, J. and Peña-Claros, M. and Peñuela-Mora, M.C. and Petronelli, P. and Pickavance, G.C. and Pitman, N. and Prieto, A. and Quesada, C. and Ramírez-Angulo, H. and Réjou-Méchain, M. and Restrepo Correa, Z. and Roopsind, A. and Rudas, A. and Salomão, R. and Silva, N. and Silva Espejo, J. and Singh, J. and Stropp, J. and Terborgh, J. and Thomas, R. and Toledo, M. and Torres-Lezama, A. and Valenzuela Gamarra, L. and van de Meer, P.J. and van der Heijden, G. and van der Hout, P. and Vasquez Martinez, R. and Vela, C. and Vieira, I.C.G. and Phillips, O.L. (2019) Compositional response of Amazon forests to climate change. Global Change Biology, 25 (1). pp. 39-56. ISSN 1354-1013

Abstract

Most of the planet's diversity is concentrated in the tropics, which includes many regions undergoing rapid climate change. Yet, while climate-induced biodiversity changes are widely documented elsewhere, few studies have addressed this issue for lowland tropical ecosystems. Here we investigate whether the floristic and functional composition of intact lowland Amazonian forests have been changing by evaluating records from 106 long-term inventory plots spanning 30 years. We analyse three traits that have been hypothesized to respond to different environmental drivers (increase in moisture stress and atmospheric CO 2 concentrations): maximum tree size, biogeographic water-deficit affiliation and wood density. Tree communities have become increasingly dominated by large-statured taxa, but to date there has been no detectable change in mean wood density or water deficit affiliation at the community level, despite most forest plots having experienced an intensification of the dry season. However, among newly recruited trees, dry-affiliated genera have become more abundant, while the mortality of wet-affiliated genera has increased in those plots where the dry season has intensified most. Thus, a slow shift to a more dry-affiliated Amazonia is underway, with changes in compositional dynamics (recruits and mortality) consistent with climate-change drivers, but yet to significantly impact whole-community composition. The Amazon observational record suggests that the increase in atmospheric CO 2 is driving a shift within tree communities to large-statured species and that climate changes to date will impact forest composition, but long generation times of tropical trees mean that biodiversity change is lagging behind climate change.