A process-based model of nitrogen cycling in forest plantations. Part I. Structure, calibration and analysis of the decomposition model

Corbeels Marc, McMurtrie Ross E., Pepper David A., O'Connell Anthony M.. 2005. A process-based model of nitrogen cycling in forest plantations. Part I. Structure, calibration and analysis of the decomposition model. Ecological Modelling, 187 (4) : 426-448.

Autre titre : Un modèle mécaniste de cycle de l'azote dans des plantations forestières. 1ère partie : structure, calibration et analyse du modèle de décomposition

Liste HCERES des revues (en SHS) : oui

Thème(s) HCERES des revues (en SHS) : Economie-gestion

Résumé : We present a new decomposition model of C and N cycling in forest ecosystems that simulates N mineralisation from decomposing tree litter. It incorporates a mechanistic representation of the role of soil organisms in the N mineralisation-immobilisation turnover process during decomposition. We first calibrate the model using data from decomposition of 14C-labelled cellulose and lignin and 14C-labelled legume material and then calibrate and test it using mass loss and N loss data from decomposing Eucalyptus globulus residues. The model has been linked to the plant production submodel of the G'DAY ecosystem model, which previously used the CENTURY decomposition submodel for simulating C and N cycling. The key differences between this new decomposition model and the previous one, based on the CENTURY model, are: (1) growth of microbial biomass is the process that drives N mineralisation-immobilisation, and microbial succession is simulated; (2) decomposition of litter can be N-limited, depending on soil inorganic N availability relative to N requirements for microbial growth; (3) 'quality' of leaf and fine root litter is expressed in terms of biochemically measurable fractions; (4) the N:C ratio of microbial biomass active in decomposing litter is a function of litter quality and N availability; and (5) the N:C ratios of soil organic matter (SOM) pools are not prescribed but are instead simulated output variables defined by litter characteristics and soil inorganic N availability. With these modifications the model is able to provide reasonable estimates of both mass loss and N loss by decomposing E. globulus leaf and branch harvest residues in litterbag experiments. A sensitivity analysis of the decomposition model to selected parameters indicates that parameters regulating the stabilisation of organic C and N, as well as those describing incorporation of soil inorganic N in Young-SOM (biochemical immobilisation of N) are particularly critical for long-term applications of the model. A parameter identifiability analysis demonstrates that simulated short-term C and N loss from decomposing litter is highly sensitive to three model parameters that are identifiable from the E. globulus litterbag data.

Mots-clés Agrovoc : Eucalyptus globulus, Medicago, cycle de l'azote, plantation forestière, modèle de simulation, litière forestière, minéralisation, biodégradation, micro-organisme du sol

Classification Agris : P35 - Fertilité du sol
U10 - Informatique, mathématiques et statistiques

Champ stratégique Cirad : Axe 1 (2005-2013) - Intensification écologique

Auteurs et affiliations

• Corbeels Marc, CIRAD-CA-GEC (BRA)
• McMurtrie Ross E., UNSW Sidney (AUS)
• Pepper David A., UNSW Sidney (AUS)
• O'Connell Anthony M., CSIRO (AUS)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/535632/)

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