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Abstract. Wood rays of beech trees were isolated with the aid of a new kind of milling technique, and their strength was directly measured using microtensile testing. The unexpectedly high tensile strength of approximately 75MPa in dry conditions leads to the supposition that, besides the known physiological functions of substance storage and conduction, the ray parenchyma also makes a contribution...
Abstract. Stem orientation is an important factor for fruit tree growth and branching habit since it influences fruit production as well as training practices. A mechanical model of the bending of a stem under axillary load was written and evaluated using experimental data on apricot trees (Prunus armeniaca L.). A set of 15 1-year-old stems of various shapes was observed during the early stage of...
Abstract. Radially oriented ray tissue is important for regulating radial strength of wood. The present study was undertaken in order to assess whether radial rays influence ring shake occurrence in chestnut wood (Castanea sativa Mill.), a species very prone to ring shake. Ray volume fraction was measured on tangential samples from two sets of wood discs, either with or without ring shake, collected...
Abstract. Biomechanical responses of stems of 6- to 7-year-old spruce [Picea abies (L.) Karst.] and beech (Fagus sylvatica L) trees were studied after 4years of growth in elevated atmospheric CO2 in combination with a nitrogen treatment and on two different soil types. At the end of the treatment, stems were harvested and tested in fresh and air-dried status. Bending characteristics of juvenile wood...
Abstract. The main objective of this paper is to present the results of a study of the interactions between the growth and design of a tree with regards to biomechanical factors at the plant level. A numerical incremental model dedicated to the calculation of tree mechanical behaviour has been integrated in the plant architecture simulation software AMAPpara. At any stage of tree growth, a new equilibrium...
Abstract. This paper is the first of a series focusing on the biomechanical analysis of live trees. The finite element method (fem) is the most common method used for the analysis of complex mechanical structures. Several fem industrial codes exist, but they need to be adapted to calculate the mechanical behaviour of growing trees. A general incremental model has been developed for this specific application...
The effects of temperature and water content on the viscoelasticity of living and dehydrated Tilia americana sapwood were examined using transient creep (time- and load-dependent deformation) tests under sustained bending loads. Creep tests were performed at 21.1C and 20.5C to determine the magnitudes and types of strains in living and dehydrated samples. Temperature had no effect on the creep rate...
Active mechanisms of re-orientation are necessary to maintain the verticality of tree stems. They are achieved through the production of reaction wood, associated with circumferential variations of three factors related to cambial activity: maturation strain, longitudinal modulus of elasticity (MOE) and eccentric growth. These factors were measured on 17 mature trees from different botanical families...
Within Rosa section Caninae (dogroses) two different growth types exist, arching (L-type) and erect (D-type). Due to the specific mode of chromosome allocation during meiosis, character inheritance in dogroses is maternally skewed. In this paper we try to assess the mode of inheritance of the ‘growth form’ in reciprocal hybrids of R. canina L. and R. rubiginosa L. to predict possible ecological niches...
Eugenia grandis (Wight) is grown in urban environments throughout Malaysia and root systems are often damaged through trenching for the laying down of roads and utilities. We investigated the effect of root cutting through trenching on the biomechanics of mature E. grandis. The force necessary to winch trees 0.2 m from the vertical was measured. Trenches were then dug at different distances (1.5,...
Thigmomorphogenesis is a well-studied process in agricultural crops and coniferous trees. Nevertheless, the effects on both shoot and root characteristics for deciduous woody species received little attention so far. In this study, the objective was to understand the effect of aboveground flexing treatments on the development of structural, mechanical and physiological root and shoot characteristics...
The effect of the self-weight increment, caused by annual growth, can be one of the principal processes affecting the development of growth stresses linked to the formation of reaction wood. This paper presents a preliminary study focusing on the relationship between the whole weight of the crown and the trunk displacement it creates. A mechanical beam model is proposed and tested theoretically, as...
Obtaining representative values of green wood properties is essential for studies investigating the biomechanical aspects of tree development and ecology. Here, we compare the biomechanical properties of wood stored in various conditions between their collection in the field and their measurement. The study was performed on a large sample of wood specimens from different tropical species and different...
In tropical dry forests, spatial heterogeneity in soil water availability is thought to determine interspecific differences in key components of resource use strategies, such as leaf phenology and xylem function. To understand the environmental drivers of variation in leaf phenology and xylem function, we explored the relation of soil water potential to topographic metrics derived from a digital elevation...
Key messageThe level of stresses of tension wood changes during the gravitropic movement. These changes are induced by the perception of strains experienced by the tree during reorientation to the upright position. Abstract In most hardwood species, tension wood is produced to ensure tropic movements in radially growing organs. Tension wood exhibits internal tensional forces (autostresses)...
Key messageStem guying to prevent wind-induced swaying of radiata pine trees resulted in significant changes in radial growth, but did not affect the frequency of compression wood or resin features. Abstract Mechanical stress resulting from wind forces acting on trees can cause a number of direct and indirect effects ranging from microscopic changes in...
Key messageStraight-stemmed populations ofPinus pinasterunder mechanical stress allocate more biomass to the stem relative to the branches and show greater variability in the roots than twisted-stemmed populations. Abstract Pinus pinaster Ait. has a tendency to exhibit stem flexuosity that negatively affects the quality of its wood and its productivity. There is a wide geographical variability...
Key messageMechanical properties of wood constrain most conifers to an excurrent form and limit the width of tree crowns. Development of support tissue alters allometric relations during ontogeny. Abstract Biomechanical constraints on tree architecture are explored. Torque on a tree branch is a multiplicative function of mass and moment arm. As such, the need for support rises faster than branch...
Key Message Wood maturation strains can be estimated from the change in curvature that occurs when a stem grown staked in tilted position is released from the stake. Abstract Trees have a motor system to enable upright growth in the field of gravity. This motor function is taken on by reaction wood, a special kind of wood that typically develops in leaning axes and generates mechanical force during...
Key message Interlocked grain and basic density increase from pith to bark in Bagassa guianensis and greatly improve trunk torsional stiffness and wood tenacity in the radial plane. Abstract Trees modulate their building material, wood, throughout their lifetime to meet changing mechanical needs. Basic density, a widely studied wood property, has been proved to be negatively correlated to growth...
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