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L'agriculture pratique des pays chauds : Cultures - Elevage, Productions Naturelles, Végétales et Animales. Treizième année
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Comprehensive assessment of carbon productivity, allocation and storage in three Amazonian forests
Auteur(s) : Malhi, Yadvinder Aragao, Luiz Eduardo O. C. Metcalfe, Daniel B. Paiva, Romilda Quesada, Carlos A. Almeida, Samuel Anderson, Liana Brando, Paulo
Auteurs secondaires : School of Geography and the Environment, Environmental Change Institute ; University of Oxford [Oxford] Department of Forest Ecology and Management ; Swedish University of Agricultural Sciences School of Geography, Earth and Biosphere Institute ; University of Leeds Coordenaçao de Botânica ; Museu Paraense Emilio Goeldi Department of Botany and School of Natural Resources and Environment ; University of Florida [Gainesville] Ecology and Evolutionary Biology, Tulane University ; University of New Orleans Centro de Geociencias ; Universidade Federal do Pará Urban Design and Planning ; University of Washington [Seattle]

Éditeur(s) : HAL CCSD Wiley
Résumé : The allocation and cycling of carbon (C) within forests is an important component of the biospheric C cycle, but is particularly understudied within tropical forests. We synthesise reported and unpublished results from three lowland rainforest sites in Amazonia (in the regions of Manaus, Tapajos and Caxiuana), all major sites of the Large-Scale Biosphere-Atmosphere Programme (LBA). We attempt a comprehensive synthesis of the C stocks, nutrient status and, particularly, the allocation and internal C dynamics of all three sites. The calculated net primary productivities (NPP) are 10.1 +/- 1.4 Mg C ha(-1) yr(-1) (Manaus), 14.4 +/- 1.3 Mg C ha(-1) yr(-1) (Tapajos) and 10.0 +/- 1.2 Mg C ha(-1) yr(-1) (Caxiuana). All errors bars report standard errors. Soil and leaf nutrient analyses indicate that Tapajos has significantly more plant-available phosphorus and calcium. Autotrophic respiration at all three sites (14.9-21.4 Mg C ha yr(-1)) is more challenging to measure, with the largest component and greatest source of uncertainty being leaf dark respiration. Comparison of measured soil respiration with that predicted from C cycling measurements provides an independent constraint. It shows general good agreement at all three sites, with perhaps some evidence for measured soil respiration being less than expected. Twenty to thirty percent of fixed C is allocated belowground. Comparison of gross primary productivity (GPP), derived from ecosystem flux measurements with that derived from component studies (NPP plus autotrophic respiration) provides an additional crosscheck. The two approaches are in good agreement, giving increased confidence in both approaches to estimating GPP. The ecosystem carbon-use efficiency (CUEs), the ratio of NPP to GPP, is similar at Manaus (0.34 +/- 0.10) and Caxiuana (0.32 +/- 0.07), but may be higher at Tapajos (0.49 +/- 0.16), although the difference is not significant. Old growth or infertile tropical forests may have low CUE compared with recently disturbed and/or fertile forests.
ISSN: 1354-1013

hal-01032150
https://hal.archives-ouvertes.fr/hal-01032150
DOI : 10.1111/j.1365-2486.2008.01780.x

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