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The decreasing radial wood stiffness pattern of some tropical trees growing in the primary forest is reversed and increases when they are grown in a plantation

McLean J.P., Zhang T., Bardet S., Beauchêne J., Thibaut A., Clair B., Thibaut B.. 2011. Annals of Forest Science, 68 (4) : p. 681-688.

Background. This study examines the radial trend in wood stiffness of tropical rainforest trees. The objective was to determine if the type of growing environment (exposed plantation or dense primary forest) would have an effect on this radial trend. Methods. The axial elastic modulus of wood samples, representing a pith to bark cross-section, of six trees from several French Guianese species (two of Eperua falcata, one of Eperua grandiflora, two of Carapa procera and one of Symphonia gloubulifera) was measured using a dynamic "forced vibration" method. Results. Primary forest trees were observed to have a decrease in wood stiffness from pith to bark, whereas plantation trees, from the same genus or species, displayed a corresponding increase in wood stiffness. Juvenile wood stiffness appears to vary depending on the environment in which the tree had grown. Conclusion. We suggest that the growth strategy of primary forest trees is to produce wood resistant to self-buckling so that the height of the canopy may be obtained with the maximum of efficiency. In contrast, the growth strategy of the trees growing in an exposed plantation is to produce low-stiffness wood, important to provide flexibility in wind. Further experiments to study the behaviour of more species, with more individuals per species, growing across a range of physical environments, are required.

Mots-clés : bois tropical; forêt primaire; meliaceae; symphonia; eperua; eperua falcata; accroissement du diamètre; plantation forestière; propriété physicochimique; bois; forêt tropicale humide; guyane française; carapa procera; carapa grandiflora; symphonia globulifera; eperua grandiflora

Thématique : Anatomie et morphologie des plantes; Physiologie végétale : croissance et développement; Technologie des produits forestiers

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