Influence of soil texture on carbon dynamics and storage potential in tropical forest soils of Amazonia

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Read Full Article (file size: 440187 bytes) Cited by GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 17, NO. 2, 1040, doi:10.1029/2002GB001953, 2003 Influence of soil texture on carbon dynamics and storage potential in tropical forest soils of Amazonia Everaldo de Carvalho Conceição Telles Laboratorio de Ecologia Isotópica, Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, São Paulo, Brazil Plínio Barbosa de Camargo Laboratorio de Ecologia Isotópica, Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, São Paulo, Brazil Luiz A. Martinelli Laboratorio de Ecologia Isotópica, Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, São Paulo, Brazil Susan E. Trumbore Department of Earth System Science, University of California, Irvine, Irvine, California, USA Enir Salazar da Costa Department of Earth System Science, University of California, Irvine, Irvine, California, USA Joaquim Santos Instituto Nacional de Pesquisa da Amazônia (INPA), Manaus, Amazonas, Brazil Niro Higuchi Instituto Nacional de Pesquisa da Amazônia (INPA), Manaus, Amazonas, Brazil Raimundo Cosme Oliveira Jr. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA), Amazônia Oriental, Santarém, Brazil Abstract Stable and radiocarbon isotopes were used to investigate the role of soil clay content in the storage and dynamics of soil carbon in tropical forest soils. Organic matter in clay-rich Oxisols and Ultisols contains at least two distinct components: (1) material with light δ¹³C signatures and turnover times of decades or less; and (2) clay-associated, ¹³C-enriched, carbon with turnover times of decades at the surface to millennia at depths >20 cm. Soil texture, in this case clay content, exerts a major control on the amount of slowly cycling carbon and therefore influences the storage and dynamics of carbon in tropical forest soils. Soils in primary tropical forest have been proposed as a potentially large sink for anthropogenic carbon. Comparison of carbon stocks in Oxisols sampled near Manaus, Brazil, shows no measurable change in organic carbon stocks over the past 20 years. Simple models estimating the response of soil carbon pools to a sustained 0.5% yr⁻¹ increase in productivity result in C storage rates of 0.09 to 0.13 MgC ha⁻¹ yr⁻¹ in soil organic matter, with additional potential storage of 0.18 to 0.27 MgC ha⁻¹ yr⁻¹ in surface litter and roots. Most storage occurs in organic matter pools with turnover times less than a decade. Export of carbon in dissolved form from upland terra firme Oxisols likely accounts for <0.2 MgC ha⁻¹ yr⁻¹, but more work is required to assess the export potential for periodically inundated Spodosols. Published 2 May 2003. Index Terms: 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions; 0330 Atmospheric Composition and Structure: Geochemical cycles; 0322 Atmospheric Composition and Structure: Constituent sources and sinks; 1040 Geochemistry: Isotopic composition/chemistry. Read Full Article (file size: 440187 bytes) Cited by Citation: Telles, E. de C. C., P. B. de Camargo, L. A. Martinelli, S. E. Trumbore, E. S. da Costa, J. Santos, N. Higuchi, and R. C. Oliveira Jr. (2003), Influence of soil texture on carbon dynamics and storage potential in tropical forest soils of Amazonia, Global Biogeochem. Cycles, 17(2), 1040, doi:10.1029/2002GB001953. Copyright 2003 by the American Geophysical Union.

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