C. Stahl1,3, Y. Aimene2, D. Bonal1 and B. Thibaut3
1INRA - Ecofog, Guyane; 2UAG - Ecofog, Guyane; 3CNRS - Ecofog, Guyane
Abstract
Tree trunk diameter changes during the day and the night and along full year with both a rainy and a dry season. In fact, a diminution in tree trunk diameter was observed in dry season whereas a large augmentation was observed in the onset of rainy season.
Change in tree trunk diameter is due to different phenomena those operated in different successive layers. In fact, superimposing to the radial growth due to cambium activity, there was clear decrease of tree trunk diameter during the dry season.
Aside of cambial growth, tree trunk diameter changes is the combination of successive layers contribution: purely passive mechanical strains of the heartwood, change in hydrostatic pressure in the sapwood and in the living phloem changes in the maturation stress during the year, swelling or shrinkage of dead outer bark due to change in relative humidity of surrounding air.
Specific experiments and a simple model of diameter changes are presented in order to understand these observed variations.