mechanical analysis of the relationship between free oscillations of Pinus pinaster Ait. saplings and their aerial architecture

• Published in: Journal of experimental botany Vol. 56; no. 416; pp. 1563 - 1573
• Main Authors: Sellier, Damien, Fourcaud, Thierry
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.06.2005; Oxford Publishing Limited (England); Oxford University Press (OUP)
• Subjects: Aerial architecture; Agronomy. Soil science and plant productions; anatomy & histology; Architecture; Biological and medical sciences; Biomechanical Phenomena; Botanics; Branches; Damping; Deformation; Economic plant physiology; Foliage; forest trees; France; Free vibration; frequency; Fundamental and applied biological sciences. Psychology; Gauges; Growth and development; Leaves; Life Sciences; loads; mechanical properties; mechanical stress; Morphogenesis, differentiation, rhizogenesis, tuberization. Senescence; Motion; Oscillation; oscillations; physiology; Pine trees; Pinus; Pinus - anatomy & histology; Pinus - physiology; Pinus pinaster; plant architecture; Plant Components, Aerial; Plant Components, Aerial - anatomy & histology; Plant Components, Aerial - physiology; Plant Stems; Plant Stems - anatomy & histology; Plant Stems - physiology; Research Papers; Saplings; seasonal variation; Swaying; Topology; tree age; tree biomechanics; tree crown; tree trunk; Trees; Vegetal Biology; France; Pinus pinaster; Branching; tree biomechanics; Aerial architecture; Gymnospermae; Coniferales; Spermatophyta; damping; oscillations; Stem; PIN MARITIME
• DOI: 10.1093/jxb/eri151
• ISSN: 0022-0957

The aim of this study was to investigate the influence of aerial architecture on the dynamic characteristics of young maritime pines (Pinus pinaster Ait.) using a mechanistic approach. For this purpose, three 4-year-old saplings with prominent differences in their branching patterns were submitted to free oscillation tests. The tests were carried out with different methods and directions of mechanical loading in order to initiate the movement of each sapling. The oscillations of the different architectural elements, i.e. stem and branches of different topological order, were measured with inclinometers and strain gauges fixed to saplings. Successive pruning of the architectural elements was carried out to evaluate their relative influence on the dynamic characteristics of the trees. The aerial systems were digitized before the mechanical tests in order to use 3D visualization techniques and to make architectural analyses of the crown structure. Two distinct modes of deformation were detected during free oscillations. The natural swaying frequency ranged from 0.6–0.8 Hz for the saplings tested at the same period of the year. The frequency variations were partly explained by the morphological differences of the experimental subjects. The motions of the axes were found to depend on their topology, i.e. the movement of the axes of a given branching order was forced by the movement of their respective bearing axis. The axes of third branching order had a significant and negative effect on the damping of the natural deformation mode. Results point out the major role played by foliage, qualitatively and quantitatively, on the damping of tree motions and on coupling the motions of the crown components.