Jana Dlouh'a 1, 2, Tancr`ede Alm'eras1, Bruno Clair1 and Joseph Gril 1

1 Laboratoire de M'ecanique et G'enie Civil (LMGC), Universit'e Montpellier 2, CNRS UMR-5508, cc 048 - Place Eug`ene Bataillon, 34095 Montpellier Cedex 5 France.

2 Mendel University of Agriculture and Forestry in Brno (MZLU v Brne), Department of Wood Science, Zemedelsk'a 3, Brno, 602 00 Czech Republic.



Tropical rainforest represents highly competitive environment because of the density of the forest cover and low availability of the light. Thus, a number of growth strategies has been developed from the opportunist pioneer species to the patient shade tolerant species waiting for years in the under storey for the occasion to reach the light. Different growth dynamics result in different mechanical requirements during each stage of the tree life.
We investigated wood mechanical properties (dynamic Young's modulus and damping coefficient measured with a vibration test) of a selection of tropical species representing a wide range of growth strategies. We focused on the trees in juvenile stage where the competition for height growth is a critical constraint. The aim was to see if different biomechanical requirements related to the growth strategy of tropical species are reflected in a diversity of wood mechanical properties. Moreover, relation between mechanical properties and structural features (micro-fibril angle and density) was investigated in order to check for the validity of usual mechanistic models and search for a structural determinant of mechanical properties