Diversité anatomique et efficience du bois de tension des arbres de forêt tropicale humide

Abstract : Tension wood is a tissue developed by angiosperms to upright or maintain their vertical position. This tissue generates a strong tensile stress able to curve the stem upwards. In the literature, tension wood anatomy is characterized by the presence of an unlignified gelatinous layer (G-layer) in the fibre cell wall. The aims of this thesis are to study the anatomical diversity of tension wood as well as the associated mechanisms of tensile stress generation and eventual variations of uprighting efficiency in order to understand how trees upright. This thesis relies on anatomical observations of 291 tropical species, on estimations of maturation strain on adult trees and on estimations of maturation strain on artificially tilted young trees tied to a pole in a greenhouse. Our results show that the G-layer is present in the majority of the species, although it is mainly hidden by lignin. The G-layer is absent in tension wood of a few number of species. In these species, the mechanism of tensile stress generation involves the interaction of wood and bark. Although tensile stress is generated in separated tissues (wood and/or bark), these two mechanism of tensile stress generation show a similar efficiency of uprighting in juvenile trees. Results of this study open new prospects of research, including on functional role of lignin in the G-layer.
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Barbara Ghislain. Diversité anatomique et efficience du bois de tension des arbres de forêt tropicale humide. Ecologie, Environnement. Université de Guyane, 2017. Français. ⟨NNT : 2017YANE0012⟩. ⟨tel-02003389⟩

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