Articles | Volume 7, issue 5
Biogeosciences, 7, 1515–1541, 2010

Special issue: Biogeochemistry and function of Amazon Forest

Biogeosciences, 7, 1515–1541, 2010

  17 May 2010

17 May 2010

Variations in chemical and physical properties of Amazon forest soils in relation to their genesis

C. A. Quesada1,6, J. Lloyd1, M. Schwarz2,*, S. Patiño3,4, T. R. Baker1, C. Czimczik2,**, N. M. Fyllas1, L. Martinelli5, G. B. Nardoto5, J. Schmerler2, A. J. B. Santos6,†, M. G. Hodnett7, R. Herrera8, F. J. Luizão6, A. Arneth2,***, G. Lloyd2, N. Dezzeo8, I. Hilke2, I. Kuhlmann2, M. Raessler2, W. A. Brand2, H. Geilmann2, J. O. Moraes Filho6, F. P. Carvalho6, R. N. Araujo Filho6, J. E. Chaves6, O. F. Cruz Junior6, T. P. Pimentel6, and R. Paiva6 C. A. Quesada et al.
  • 1Earth and Biosphere Institute, School of Geography, University of Leeds, Leeds, LS2 9JT, UK
  • 2Max-Planck-Institut fuer Biogeochemie, Jena, Germany
  • 3Instituto de Investigación de Recursos Biológicos, Alexander von Humboldt, Bogotá, Colombia
  • 4UMR-ECOFOG, INRA, 97310, Korou, French Guiana, France
  • 5Centro de Energia Nuclear na Agricultura, Piracicaba, Brazil
  • 6Institito Nacional de Pesquisas da Amazônia, Manaus, Brazil
  • 7Centre for Ecology and Hydrology, Wallingford, UK
  • 8Instituto Venezuelano de Investigaciones Científicas, Caracas, Venezuela
  • *now at: Fieldwork Assistance, Postfach 101022, 07710 Jena, Germany
  • deceased on 29 June 2006
  • **now at: Department of Earth System Science, University of California, 2103 Croul Hall, Irvine, CA, 92697-3100, USA
  • ***now at: Geography and Ecosystem Analysis, Lund University, Lund, Sweden

Abstract. Soil samples were collected in six South American countries in a total of 71 different 1 ha forest plots across the Amazon Basin as part of the RAINFOR project. They were analysed for total and exchangeable cations, C, N, pH with various P fractions also determined. Physical properties were also examined and an index of soil physical quality proposed. A diverse range of soils was found. For the western areas near the Andean cordillera and the southern and northern fringes, soils tend to be distributed among the lower pedogenetic levels, while the central and eastern areas of Amazonia have more intensely weathered soils. This gives rise to a large variation of soil chemical and physical properties across the Basin, with soil properties varying predictably along a gradient of pedogenic development. Nutrient pools generally increased slightly in concentration from the youngest to the intermediate aged soils after which a gradual decline was observed with the lowest values found in the most weathered soils. Soil physical properties were strongly correlated with soil fertility, with favourable physical properties occurring in highly weathered and nutrient depleted soils and with the least weathered, more fertile soils having higher incidence of limiting physical properties. Soil phosphorus concentrations varied markedly in accordance with weathering extent and appear to exert an important influence on the nitrogen cycle of Amazon forest soils.

Final-revised paper