Soil carbon dynamics following afforestation of a tropical savannah with Eucalyptus in Congo
Soil organic matter is a key factor in the global carbon cycle, but the magnitude and the direction of the change in soil carbon after afforestation with Eucalyptus in the tropics is still a matter of controversy. The objective of this work was to understand the dynamics of soil carbon in intensively managed Eucalyptus plantations after the afforestation of a native savannah. The isotopic composition (?) of soil carbon (C) and soil CO2 efflux (F) were measured on a four-age chronosequence of Eucalyptus and on an adjacent savannah. ?F was used to partition F between a C3 component and a C4 component, the latter corresponding to the decomposition of a labile pool of savannah-derived soil carbon (CSL). The mean residence time of CSL was 4.6 years. This further allowed us to partition the savannah-derived soil carbon into a labile and a stable (CSS) carbon pool. CSL accounted for 30% of soil carbon in the top soil of the savannah (0-5 cm), and only 12% when the entire 0-45 cm soil layer was considered. The decrease in CSL with time after plantation was more than compensated by an increase in Eucalyptus-derived carbon, and half of the newly incorporated Eucalyptus-derived carbon in the top soil was associated with the clay and fine silt fractions in the 14-year-old. stand. Increment in soil carbon after afforestation of tropical savannah with Eucalyptus is therefore expected despite a rapid disappearance of the labile savannah-derived carbon because a large fraction of savannah-derived carbon is stable.
| Main Authors: | , , , , , |
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| Format: | article biblioteca |
| Language: | eng |
| Subjects: | P33 - Chimie et physique du sol, K10 - Production forestière, Eucalyptus, sol tropical, plantations, zone tropicale, matière organique du sol, carbone, savane, plantation forestière, extension forestière, http://aims.fao.org/aos/agrovoc/c_2683, http://aims.fao.org/aos/agrovoc/c_7978, http://aims.fao.org/aos/agrovoc/c_5990, http://aims.fao.org/aos/agrovoc/c_7979, http://aims.fao.org/aos/agrovoc/c_35657, http://aims.fao.org/aos/agrovoc/c_1301, http://aims.fao.org/aos/agrovoc/c_6825, http://aims.fao.org/aos/agrovoc/c_3048, http://aims.fao.org/aos/agrovoc/c_162, http://aims.fao.org/aos/agrovoc/c_1811, |
| Online Access: | http://agritrop.cirad.fr/552329/ http://agritrop.cirad.fr/552329/1/document_552329.pdf |
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