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2017
- handle: 10670/1.ilm2fj
- hal: hal-02629172
- doi: 10.1111/gcb.13573
- PRODINRA: 404130
- PUBMED: 27966250
- WOS: 000404863300035
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info:eu-repo/semantics/altIdentifier/doi/10.1111/gcb.13573
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info:eu-repo/semantics/altIdentifier/pmid/27966250
info:eu-repo/semantics/OpenAccess
Mots-clés
cn coupling carbon storage deep soil mixed-grass pasture native forest -bio] -bio]/Vegetal BiologySujets proches
Grassland farming Paddocks (Pastures) PasturelandCiter ce document
Clement Stahl et al., « Continuous soil carbon storage of old permanent pastures in Amazonia », HALSHS : archive ouverte en Sciences de l’Homme et de la Société, ID : 10.1111/gcb.13573
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Résumé
Amazonian forests continuously accumulate carbon (C) in biomass and in soil, representing a carbon sink of 0.42-0.65 GtC yr-1 . In recent decades, more than 15% of Amazonian forests have been converted into pastures, resulting in net C emissions (~200 tC ha-1 ) due to biomass burning and litter mineralization in the first years after deforestation. However, little is known about the capacity of tropical pastures to restore a C sink. Our study shows in French Amazonia that the C storage observed in native forest can be partly restored in old (≥24 year) tropical pastures managed with a low stocking rate (±1 LSU ha-1 ) and without the use of fire since their establishment. A unique combination of a large chronosequence study and eddy covariance measurements showed that pastures stored between -1.27 ± 0.37 and -5.31 ± 2.08 tC ha-1 yr-1 while the nearby native forest stored -3.31 ± 0.44 tC ha-1 yr-1 . This carbon is mainly sequestered in the humus of deep soil layers (20-100 cm), whereas no C storage was observed in the 0- to 20-cm layer. C storage in C4 tropical pasture is associated with the installation and development of C3 species, which increase either the input of N to the ecosystem or the C:N ratio of soil organic matter. Efforts to curb deforestation remain an obvious priority to preserve forest C stocks and biodiversity. However, our results show that if sustainable management is applied in tropical pastures coming from deforestation (avoiding fires and overgrazing, using a grazing rotation plan and a mixture of C3 and C4 species), they can ensure a continuous C storage, thereby adding to the current C sink of Amazonian forests.