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

Abstract

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. (Résumé d'auteur

Effect of early release from intense competition within high density natural regeneration on the properties of juvenile and mature wood of 40-year-old Sitka spruce (Picea sitchensis (Bong.) Carr.)

“…The juvenile wood formed in the control trees under these conditions had values of density, MOE and MOR similar to those of the mature wood (Table 2), whereas density and MOE of the juvenile wood of the re-spaced trees were inferior to those of the mature wood. McLean et al (2011) observed a broadly similar effect in a study on the wood properties of several naturally regenerated tropical species from primary forest and the same species growing under more widely spaced plantation conditions. Given that grain angle was too low in both treatments to significantly influence strength (e.g.…”

Patterns of within-stem variations in wood specific gravity and water content for five temperate tree species

“…Zobel and Sprague 1998;Woodcock and Shier 2002;Lachenbruch et al 2011;Plourde et al 2015) and typical radial patterns (TRP) of variations of functional or material properties of wood have been reported (Lachenbruch et al 2011). However, some radial trends may be strongly modified by changing growth conditions for the same species (McLean et al 2011).…”

The Evolutionary Fate of Phenotypic Plasticity and Functional Traits under Domestication in Manioc: Changes in Stem Biomechanics and the Appearance of Stem Brittleness

“…This differs from most tree species but is consistent with the mechanical strategy among climbing plants [17], [73], where early juvenile stages of growth are nearly always optimised for stiff “searching” behaviour and older stages of growth are comprised of more flexible material, once the plant has attached to its support. A recent study has also found a decrease in stiffness from the inside to outside of the stem in tropical tree species grown in closed forest conditions [74], implying that MFA can change in response to open or closed environmental conditions in tree species.…”