Biogeosciences Discuss., 5, 2003–2047, 2008 Biogeosciences www.biogeosciences-discuss.net/5/2003/2008/ Discussions BGD © Author(s) 2008. This work is distributed under 5, 2003–2047, 2008 the Creative Commons Attribution 3.0 License. Biogeosciences Discussions is the access reviewed discussion forum of Biogeosciences Amazonian xylem density variation S. Patino˜ et al. Branch xylem density variations across Amazonia Title Page Abstract Introduction S. Patino˜ 1,2,3, J. Lloyd2, R. Paiva4, C. A. Quesada2,5, T. R. Baker2, A. J. B. Santos5,6,†, L. M. Mercado7, Y. Malhi8, O. L. Phillips2, A. Aguilar9, E. Alvarez11, L. Conclusions References Arroyo12, D. Bonal3, A. C. L. Costa13, C. I. Czimczik14, J. Gallo15, R. Herrera16, N. Tables Figures Higuchi5, V. Horna17, E. J. Hoyos18, E. M. Jimenez9, T. Killeen19, E. Leal10, F. Luizao˜ 5, P. Meir20, A. Monteagudo21,22, D. Neill23, P. Nu´ nez-Vargas˜ 21, W. Palomino21, J. Peacock2, A. Pena-Cruz˜ 22, M. C. Penuela˜ 9, N. Pitman24, N. Priante J I 25 1 26 27 10 28,29 Filho , A. Prieto , S. N. Panfil , A. Rudas , R. Salomao˜ , N. Silva , J I M. Silveira30, S. Soares de Almeida10, A. Torres-Lezama31, J. D. Turriago15, R. Vasquez-Mart´ ´ınez21, M. Schwarz16, A. Sota16, J. Schmerler16, I. Vieira10, B. Back Close 15 9 Villanueva , and P. Vitzthum Full Screen / Esc 1Instituto de Investigacion´ de Recursos Biologicos´ Alexander von Humboldt. Diagonal 27 No. 15-09, Bogota´ D.C, Colombia Printer-friendly Version 2Earth and Biosphere Institute, School of Geography, Univ. of Leeds, LS2 9JT, UK Interactive Discussion 3UMR-ECOFOG, INRA, 97310 Kourou, French Guiana 4Secretraria´ Municipal de Desenvolvimento e Meio Ambiente na Prefeitura Municipal de Maues,´ Maues,´ Brazil 2003 BGD 5 Institito National de Pesquisas Amazonicas,ˆ Manaus, Brazil 5, 2003–2047, 2008 6Departamento de Ecologia, Universidade de Bras´ılia, Brazil 7Centre for Ecology and Hydrology, Wallingford, UK 8 Amazonian xylem Oxford University, Centre for the Environment, Oxford, UK 9 density variation Universidad Nacional de Colombia Sede Amazon´ıa, Leticia, Colombia 10 Museu Paraense Emilio Goeldi, Belem, Brazil S. Patino˜ et al. 11Equipo de Gestion´ Ambiental, Interconexion´ Electrica´ S.A. ISA., Medell´ın, Colombia 12Museo Noel Kempff Mercado, Santa Cruz, Bolivia 13 Universidade Federal de Para,´ Belem, Brazil Title Page 14Department of Earth System Science, University of California, Irvine, CA, USA 15Departamento de Biolog´ıa, Universidad Distrital, Bogota,´ Colombia Abstract Introduction 16 Max-Planck-Institut fur¨ Biogeochemie, Jena, Germany Conclusions References 17Abteilung Okologie¨ und Okosystemforschung,¨ Albrecht-von-Haller-Institut fur¨ Pflanzenwis- senschaften, Universitat¨ Gottingen,¨ Gottingen,¨ Germany Tables Figures 18Departamento de Ciencias Forestales, Univ. Nacional de Colombia, Medell´ın, Colombia 19 Center for Applied Biodiversity Science, Conservation Int., Washington D.C., WA, USA J I 20School of Geography, University of Edinburgh, Edinburgh, Scotland, UK 21Herbario Vargas, Universidad Nacional San Antonio Abad del Cusco, Cusco, Peru´ J I 22 Proyecto Flora del Peru,´ Jard´ın Botanico´ de Missouri, Oxampapa, Peru´ Back Close 23Herbario Nacional del Ecuador, Quito, Ecuador 24Center for Tropical Conservation, Duke University, Durham, NC, USA Full Screen / Esc 25Universidade Federal do Mato Grosso, Cuiaba, Brazil 26Department of Botany, University of Georgia, Athens, GA, USA Printer-friendly Version 27Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Bogota,´ Colombia Interactive Discussion 28CIFOR, Tapajos, Brazil 29EMBRAPA Amazonia Oriental, Belem, Brazil 30Departamento de Cienciasˆ da Natureza, Universidade Federal do Acre, Rio Branco, Brazil 2004 31Facultad de Ciencias Forestales y Ambiental, Universidad de Los Andes, Merida,´ Venezuela †deceased BGD Received: 27 February 2008 – Accepted: 10 March 2008 – Published: 9 May 2008 5, 2003–2047, 2008 Correspondence to: S. Patino˜ ([email protected]) Amazonian xylem density variation S. Patino˜ et al. Title Page Abstract Introduction Conclusions References Tables Figures J I J I Back Close Full Screen / Esc Printer-friendly Version Interactive Discussion 2005 Abstract BGD Measurements of branch xylem density, Dx, were made for 1466 trees representing 503 species, sampled from 80 sites across the Amazon basin. Measured values ranged 5, 2003–2047, 2008 from 240 kg m−3 for a Brosimum parinarioides from Tapajos in West Para,´ Brazil to −3 5 1130 kg m for an Aiouea sp. from Caxiuana, Central Para,´ Brazil. Analysis of vari- Amazonian xylem ance showed significant differences in average Dx across the sample plots as well as density variation significant differences between families, genera and species. A partitioning of the total variance in the dataset showed that geographic location and plot accounted for 33% S. Patino˜ et al. of the variation with species identity accounting for an additional 27%; the remaining 10 “residual” 40% of the variance accounted for by tree to tree (within species) variation. Variations in plot means, were, however, hardly accountable at all by differences in Title Page species composition. Rather, it would seem that variations of xylem density at plot Abstract Introduction level must be explained by the effects of soils and/or climate. This conclusion is sup- ported by the observation that the xylem density of the more widely distributed species Conclusions References 15 varied systematically from plot to plot. Thus, as well as having a genetic component Tables Figures branch xylem density is a plastic trait that, for any given species, varies according to where the tree is growing and in a predictable manner. Exceptions to this general rule may be some pioneers belonging to Pourouma and Miconia and some species within J I the genera Brosimum, Rinorea and Trichillia which seem to be more constrained in J I 20 terms of this plasticity than most species sampled as part of this study. Back Close 1 Introduction Full Screen / Esc The Amazon Basin remains the home to the most diverse and largest contiguous trop- Printer-friendly Version ical forest on the planet (Malhi and Grace, 2000; Laurance et al., 2004). Different ecological systems and vegetation formations exist within its boundary creating a mo- Interactive Discussion 25 saic of forests and vegetation types with a floristic complexity the basis of which is still not well understood (Phillips et al., 2003). 2006 How and why species are distributed and where trees can grow in this mosaic of trop- ical forest types is a central question for tropical ecology (Pitman et al., 2001; Phillips BGD et al., 2003). On the one hand water availability has been considered as an important 5, 2003–2047, 2008 factor determining tree species distributions at global (Woodward, 1987) and regional 5 scales (Borchert, 1998; Veenendaal and Swaine, 1998; Bongers et al., 1999). Tree physiology data also shows that it may be one key factor determining species distri- Amazonian xylem butions in tropical rain forest despite the substantial rainfall they receive (Meinzer et density variation al., 1999; Engelbrecht et al., 2002, 2005, 2006, 2007; Tyree et al., 2003; Baltzer et al., 2008). On the other hand, although water shortage (seasonality and rainfall) is S. Patino˜ et al. 10 not considered by some as an important selective pressure determining the functional composition of moist and wet tropical forest (Baker et al., 2004b; ter Steege and Ham- Title Page mond, 2004), it clearly does help to determine overall diversity and distribution patterns of canopy tree genera across the Amazon basin (ter Steege et al., 2006). Light as a Abstract Introduction factor explaining coexistence of trees has also been considered (Poorter and Arets, Conclusions References 15 2003) and climate more than geographic distance in lowland forest seems also to af- fect species composition (Pitman et al., 2001) and distributions (Bongers et al., 1999; Tables Figures Baltzer et al., 2008). Additionally, even if there clearly is some “distance-decay” i.e. the similarity between two sites declines as the distance between them increases, see J I (Soininen et al., 2007) in Amazonian forest communities (Condit et al., 2002; Tuomisto 20 et al., 2003), consistent with the view of plant species distribution as a partly random J I controlled process (Hubbell, 2001), it is also clear that substrate-mediated processes Back Close play a significant deterministic role in controlling species distributions across Amazo- nian landscapes (Gentry, 1988; Tuomisto et al., 1995, 2003; Phillips et al., 2003), this Full Screen / Esc also being the case for other tropical forests (Harms et al., 2001; Robert et al., 2007). 25 These theories are by no means exclusive, and one of the main purposes of the work Printer-friendly Version described in this special issue (Lloyd et al., 2008a1) was to interface dedicated plant physiological trait data with species abundance, climate and soil type information to Interactive Discussion 1Lloyd, J., Grace, J., and Meir, P.: Introducing the “Biogeochemistry and Function of Amazon Forest” project, Biogeosciences Discuss., in preparation, 2008a. 2007 help understand the underlying factors controlling species distribution, composition and stand dynamics at the Basin-wide scale. In what is the first of a series of papers, we BGD here analyse in detail geographic and taxonomic patterns of tree branch wood density 5, 2003–2047, 2008 across Amazonia. Although wood density (Dw) is most often measured on tree boles 5 sampled after destructive