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

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...

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Bibliographic Details
Published in:Global biogeochemical cycles 2003-06, Vol.17 (2), p.9.1-n/a
Main Authors: Telles, Everaldo de Carvalho Conceição, de Camargo, Plínio Barbosa, Martinelli, Luiz A., Trumbore, Susan E., da Costa, Enir Salazar, Santos, Joaquim, Higuchi, Niro, Oliveira Jr, Raimundo Cosme
Format: Article
Language:English
Subjects:
14C
carbon cycle
decomposition
Earth sciences
Earth, ocean, space
Exact sciences and technology
Geochemistry
Isotope geochemistry
Isotope geochemistry. Geochronology
radiocarbon
Soil and rock geochemistry
soil carbon
soil texture
Soils
Surficial geology
tropical soil
turnover
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Summary: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
ISSN:0886-6236
1944-9224
DOI:10.1029/2002GB001953