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Etude des stratégies biomécaniques de croissance des jeunes arbres en peuplement hétérogène tropical humide

Abstract : The functioning of ecosystems is based on the functional diversity, which is the complementto the species diversity. In the tropical rain forest, the saplings grow in the dense and stratifiedunderstorey. This thesis deals with the diversity of realisation of the support function by thesaplings in this context. The hypotheses are that the race through higher and so brighter levelsconstrains the mechanical security of the saplings with necessary biomass saving and need ofreorientation (gravitropism) and acclimation (mecanoperception and response) processes andthat diversity is thus structured by the species light-demand and affinity for the risk. Using awide sample of 16 species, at the Paracou station, relevant functional traits - risk of not-selfsupportingand gravitropic performance - are defined through adapted modellings whichcombine trunk shape, biomass distribution and wood properties. The traits values varybetween species and also with ontogeny and saplings environment. These variations are dueto elementary traits (shape, biomass, wood) with strong geometrical effects. The less selfsupportingspecies (low mechanical security) have the highest gravitropic performances andare also the most light-demanders. A species, Tachigali melinonii, distinguishes itself bystrong slendernesses and a frequent not-self-supporting habit letting suppose a strongadaptability to its mechanical environment. An experiment (growth response to staking),however, did not provide the expected results whereas the species with lower risks, Dicoryniaguianensis, reacted more.
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Contributor : Gaëlle Jaouen <>
Submitted on : Thursday, April 10, 2008 - 7:28:28 PM
Last modification on : Thursday, November 5, 2020 - 7:06:02 PM
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  • HAL Id : tel-00272100, version 1
  • PRODINRA : 318420



Gaëlle Jaouen. Etude des stratégies biomécaniques de croissance des jeunes arbres en peuplement hétérogène tropical humide. Biologie végétale. Université Henri Poincaré - Nancy I, 2007. Français. ⟨tel-00272100⟩



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