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Passage d'un modèle individuel à un modèle de distribution de la dynamique forestière. Application à une forêt dense tropicale humide de Guyane française

Abstract : A model of forest dynamics, considered as tool for forest management, can rely on different levels of stand description: tree, distribution or stand level. An approach is sought to build a model at an intermediary level between tree and stand, using the data from the experimental site at Paracou in French Guiana. First, the possibility to build a gap model is investigated from two points of view: by assessing whether the interaction variable used in gap models permits to explain the diameter increments observed at Paracou, and by assessing, on the other hand, whether the forest stand can be divided into independent cells. In both cases, results do not validate the gap model approach. However an individual-based distance-dependent model, that depends only on tree competition for light is obtained. This model is able to reproduce the joint diameter and height distribution observed at Paracou, as well as the tree spatial pattern on small distances (< 10 m). In a second stage, methods to change the level of description are defined, following two approaches. The first one is a theoretical approach that transposes the equations of a tree model into a distribution-based model using techniques for physics (Liouville theorem, mean-field approximation, moment method). This method is applied to the tree model that was built in the first stage. It appears that space plays for this model a role that cannot be circumvented. In a second approach, a model that mixes the tree level and the distribution level is built, the shift from the distribution-based component to the individual-based component occurring at 40 cm diameter. This model highlights the stochastic variability bound to the demography of large trees.
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https://tel.archives-ouvertes.fr/tel-00145095
Contributor : Nicolas Picard <>
Submitted on : Monday, May 7, 2007 - 5:48:10 PM
Last modification on : Monday, October 19, 2020 - 4:24:01 PM
Long-term archiving on: : Tuesday, April 6, 2010 - 11:25:07 PM

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  • HAL Id : tel-00145095, version 1

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Nicolas Picard. Passage d'un modèle individuel à un modèle de distribution de la dynamique forestière. Application à une forêt dense tropicale humide de Guyane française. Ecologie, Environnement. ENGREF (AgroParisTech), 1999. Français. ⟨tel-00145095⟩

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