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Contribution à l'étude de la variabilité spatiale des composantes du bilan de carbone d'un sol de forêt tropicale humide (Paracou, Guyane française)

Abstract : The aim of this study was to define the spatial variability of the C balance components of the soil in a tropical rain forest. This work was conducted in French Guiana in the Guyaflux experimental forest and in a close plantation of monospecific plots. Two approaches were used in this investigation. The first one aimed to analyze the effects of the environmental factors (i.e. soil texture, soil moisture or forest structure) on the spatial and interspecific variability in several components in situ. Among these components, the root biomass, the fine roots (Ø < 2 mm) production and the soil respiration (Rsol) measurements underlined a large spatial variability within plot. At this scale, there was a significant empirical relationship between the tree basal area and soil respiration. Interspecific variations in fine root elongation and decomposition rate have been jointly estimated for five and eight tropical tree species, respectively. The second approach classified the factors according to the magnitude of their effects on spatial variability of Rsol. Rsol is derived from both heterotrophic respiration by microorganisms (Rh) that decompose ground surface organic matter and autotrophic respiration by roots (Ra). Datasets from two years experiments of Rsol were used to evaluate the performance of semi-mechanistic model on the Guyaflux site. A soil organic matter model, CENTURY, simulating Rh component was coupled with the McCree model, which simulates the Ra of Rsol. The results of a parametric sensitivity analysis on the different predictions proved that the litter quality (e.g. lignin content) and the soil moisture were the two main factors responsible for the spatial variation of the CO2 flux on the soil. In this study, we showed that the use of simulation models linked to experimental field results is a promising approach to understand the impact of the biotic and abiotic factors on the processes deeply complex in tropical forest.
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Submitted on : Thursday, March 29, 2018 - 11:31:58 AM
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  • HAL Id : tel-01748333, version 1



Laëtitia Bréchet. Contribution à l'étude de la variabilité spatiale des composantes du bilan de carbone d'un sol de forêt tropicale humide (Paracou, Guyane française). Sylviculture, foresterie. Université Henri Poincaré - Nancy 1, 2009. Français. ⟨NNT : 2009NAN10105⟩. ⟨tel-01748333⟩



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