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Geophysical Monograph Series



  • Rain forest ecology—Amazon River Region
  • Biosphere—Research—Amazon River Region
  • Climatic changes—Amazon River Region
  • Amazon River Region—Climate

Index Terms

  • 1631 Global Change: Land/atmosphere interactions
  • 1632 Global Change: Land cover change



Soil carbon dynamics

S. Trumbore and P. Barbosa de Camargo

The amount of organic carbon (C) stored in the upper meter of mineral soils in the Amazon Basin (∼40 Pg C) represents ∼3% of the estimated global store of soil carbon. Adding surface detrital C stocks and soil carbon deeper than 1 m can as much as quadruple this estimate. The potential for Amazon soil carbon to respond to changes in land use, climate, or atmospheric composition depends on the form and dynamics of soil carbon. Much (∼30% in the top ∼10 cm but >85% in soils to 1 m depth) of the carbon in mineral soils of the Oxisols and Ultisols that are the predominant soil types in the Amazon Basin is in forms that are strongly stabilized, with mean ages of centuries to thousands of years. Measurable changes in soil C stocks that accompany land use/land cover change occur in the upper meter of soil, although the presence of deep roots in forests systems drives an active C cycle at depths >1 m. Credible estimates of the potential for changes in Amazon soil C stocks with future land use and climate change are much smaller than predictions of aboveground biomass change. Soil organic matter influences fertility and other key soil properties, and thus is important independent of its role in the global C cycle. Most work on C dynamics is limited to upland soils, and more is needed to investigate C dynamics in poorly drained soils. Work is also needed to relate cycles of C with water, N, P, and other elements.

Citation: Trumbore, S., and P. Barbosa de Camargo (2009), Soil carbon dynamics, in Amazonia and Global Change, Geophys. Monogr. Ser., vol. 186, edited by M. Keller et al., pp. 451–462, AGU, Washington, D. C., doi:10.1029/2008GM000741.

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