Patiño, S. and Lloyd, J. and Baker, T.R. de and Quesada, C.A. and Paiva, R. and Mercado, L.M. and Schmerler, S. and Schwarz, M. and Santos, A.J.B. and Aguilar, A. and Czimczik, Claudia I. and Gallo, J. and Horna, V. and Hoyos, E.J. and Jimenez Rojas, Eliana Maria and Palomino, W. and Peacock, J. and Peña Cruz, A. and Sarmiento, Carlos and Sota, A. and Turriago, J.D. and Villanueva, B. and Vitzthum, P. and Alvarez, E. and Arroyo, L. and Baraloto, C. and Bonal, Damien and Chave, Jerome and Costa, A.C.L. and Herrera, R. and Higuchi, Niro and Killen, T. and Leal, L. and Luizão, F.J. and Meir, Patrick and Monteagudo, A. and Neill, D.A. and Nuñez Vargas, P. and Peñuela, M.C. and Pitman, N. and Priante Filho, N. and Prieto, A. and Panfil, S.N. and Rudas, A. and Salomao, R. and Silva, Javier and Silveira, Marcos and Soares de Almeida, S. and Torres Lezama, Armando and Vasquez, R. and Vieira, I. and Malhi, Y. and Phillips, Oliver L.
Branch xylem density variations across the Amazon Basin.
"Biogeosciences", v. 6
Xylem density is a physical property of wood that varies between individuals, species and environments. It reflects the physiological strategies of trees that lead to growth, survival and reproduction. Measurements of branch xylem density, ρx, were made for 1653 trees representing 598 species, sampled from 87 sites across the Amazon basin. Measured values ranged from 218 kg m−3 for a Cordia sagotii (Boraginaceae) from Mountagne de Tortue, French Guiana to 1130 kg m−3 for an Aiouea sp. (Lauraceae) from Caxiuana, Central Pará, Brazil. Analysis of variance showed significant differences in average ρx across regions and sampled plots as well as significant differences between families, genera and species. A partitioning of the total variance in the dataset showed that species identity (family, genera and species) accounted for 33% with environment (geographic location and plot) accounting for an additional 26%; the remaining "residual" variance accounted for 41% of the total variance. Variations in plot means, were, however, not only accountable by differences in species composition because xylem density of the most widely distributed species in our dataset varied systematically from plot to plot. Thus, as well as having a genetic component, branch xylem density is a plastic trait that, for any given species, varies according to where the tree is growing in a predictable manner. Within the analysed taxa, exceptions to this general rule seem to be pioneer species belonging for example to the Urticaceae whose branch xylem density is more constrained than most species sampled in this study. These patterns of variation of branch xylem density across Amazonia suggest a large functional diversity amongst Amazonian trees which is not well understood.