Loïc Brancheriau

Cirad - La recherche agronomique pour le développement | CIRAD · Unité Propre de Recherche Biomasse, Bois, Énergie, Bioproduits (BioWooEB)

Wood characteristics of trees grown in agroforestry systems are still little studied, while their growth conditions are different from conventional stands. This work focused on the impact of the agroforestry system on the lignin/cellulose ratio of hybrid poplar trees. One disk sample was harvested on 6 agroforestry (AF) and 6 forest control (FC) po...

Objectives Carbon fixed during photosynthesis is exported from leaves towards sink organs as non-structural carbohydrates (NSC), that are a key energy source for metabolic processes in trees. In xylem, NSC are mostly stored as soluble sugars and starch in radial and axial parenchyma. The multi-functional nature of xylem means that cells possess sev...

Wood characteristics of trees grown in agrofor-estry systems are little studied, even if growth conditions are different from conventional stands. This work aimed to determine the impact of the agroforestry system on the heartwood formation process of hybrid walnut (Juglans regia × nigra) trees, especially the resulting extractive contents. Ethanol...

Functional-structural plant modelling approaches (FSPM) explore the relationships between the 3D structure and the physiological functioning of plants in relation to environmental conditions. In this study, we present a methodological approach that integrated architectural responses to planting design in an oil palm FSPM, and test the impact of pla...

Walnut agroforestry systems require regular tree pruning, generating a large volume of biomass residues which are mainly valorized as wood-energy, Ramial Chipped Wood (RCW) or animal litter. However, walnut is recognized as a rich source of different chemical compounds, which could be recovered as valuable chemicals. This study aims to improve the...

Key message Increment cores can provide improved predictive capabilities of the modulus of elasticity (MOE) of sawn boards. Multiple increment cores collected at different heights in a tree provide marginally increased accuracy over a single breast-height core, with higher labour costs. Approximately 50% of the variability of the static bending MOE...

Agroforestry practices like pruning trees to control the light flux to crops produce every year a large volume of branches which is valorized by farmers as mulching or energy fuel. However, according to the literature, the wood of branches shows higher rates of polyphenols than stem wood and this can open some new perspectives for branch exploitati...

• Key message A novel non-destructive method has been developed to predict modulus of elasticity (MOE) of logs using measurements taken from cores extracted from discs. The trees were felled and cut into logs to allow validation of our method; however, similar results would be obtained if the cores were extracted from standing trees. The method sho...

The original article was published with an erroneous affiliation details for co-author, David J. Lee. The correct affiliation for the author is Forest Industries Research Centre, University of the Sunshine Coast, Locked Bag 4, Maroochydore DC, QLD, 4558, Australia. The original article has been corrected

Transverse modal analysis of timber panels is a proven effective alternative method for approximating a material's elastic constants. Specific testing configurations, such as boundary conditions (BC) and location of sensor and impact, play a critical role in the accuracy of the results obtained from the experimental assessment. This article investi...

Key message Considering anisotropy in image reconstruction algorithm for ultrasound computed tomography of trees resulted in a more accurate detection of defects compared to common approaches used. ContextUltrasound computed tomography is a suitable tool for nondestructive evaluation of standing trees. Until now, to simplify the image reconstructio...

The properties of wood charcoal layers have an effect on the performance of small-scale blast furnaces. In order to characterize the mechanical behavior of a fixed bed of eucalyptus charcoal, a specific uniaxial compression test was designed and used with charcoal layers of different characteristics. This layer test has the potential to be standard...

When biomass is thermally treated, the enrichment of carbon in the remaining “green coal” is correlated with the temperature and duration. Other properties related to the energetic properties of the torrefied biomass are closely related to chemical modifications and correlated to the material mass loss occurring during the thermal degradation. The...

A method for the reconstruction of 2D tomographic images adapted to wood was presented, aiming to perform a nondestructive evaluation of standing trees. The proposed method takes into account the orthotropy property of wood material, performing an iterative process that approximated the curved rays. A slowness function was defined for every cell an...

The determination of natural rubber and resin contents of guayule (Parthenium argentatum) requires a long and destructive methodology to be implemented in the laboratory. In order to achieve a large number of measurements, it is necessary to determine the contents directly in the field in a fast and non-destructive way. The recent emergence of port...

Water and potassium are limiting factors for tree growth. Their influence on morphology and anatomy are well known, but their combined effects on tree growth remain to be clarified. A single clone of Eucalyptus grandis was analyzed under different treatments of rainfall exclusion and fertilization. Eight trees per treatment were sampled to investig...

The accurate assessment of the mechanical properties of timber from standing trees is beneficial for the growers and processors. Modulus of elasticity (MOE) is one of the most important mechanical properties for solid timber which determines the structural performance and market value of a sawn piece timber. MOE of boards sawn from a single log can...

Ultrasound Computed Tomography is a widely used technique for nondestructive control of materials. One application is the evaluation of the inner state of standing trees in urban areas. The quality of the tomographic image depends on several factors, such as the number of probes used and the image reconstruction algorithm. Here we are interested in...

Ultrasonic nondestructive imaging methods allow analyzing the inner structures of trees, without altering their condition. In this study, we are interested in evaluating the influence of anisotropy condition in the wood on the ultrasonic waves time-of-flight (TOF) estimation, by means of a raytracing approach. This technique is used particularly in...

Six different hybrid composites with various hybrid fiber mixing ratio were fabricated using the pultrusion technique. The effect of fibers hybridization and fibers configuration with respect to the loading axis were studied on flexural dynamic and static properties. In low fiber mixing ratio of about 0.09, the radial configuration of kenaf yarns i...

Background and aimsIn temperate conifer forests, soil temperature is an important driver of fine root growth and winter root growth can occur during aerial dormancy. We hypothesize that in conifers, stocks of non-structural carbohydrates (NSC) in fine roots are high enough to provide energy for root growth and production throughout the year, even w...

Time-of-flight measurement is a critical step to perform ultrasonic non-destructive testing of standing trees, with direct influence on the precision of defect detection. Aiming to increase the accuracy on the estimation, the characteristics of the ultrasonic measurement chain should be adapted to the constraints of wood testing in living condition...

Ultrasound computed tomography (USCT) using the transmission mode is a way to detect and assess the extent of decay in wood structures. The resolution of the ultrasonic image is closely related to the different anatomical features of wood. The complexity of the wave propagation process generates complex signals consisting of several wave packets wi...

Background and aims: For a given genotype, the observed variability of tree forms results from the stochasticity of meristem functioning and from changing and heterogeneous environmental factors affecting biomass formation and allocation. In response to climate change, trees adapt their architecture by adjusting growth processes such as pre- and n...

A number of studies have shown the ability of the vibration resonant method (VRM) to measure the modulus of elasticity (MOE) and the damping ratio (\(\xi\)) of calibrated wooden samples of various dimensions. This method based on free transverse vibrations was also studied to assess the decay extent in small stakes. Nevertheless, a need for investi...

To perform a non-destructive evaluation of wood, the Christoffel equation is frequently used to describe the relationship between the ultrasonic wave velocity and the mechanical parameters. In the context of acoustical tomography imaging of standing trees, the key contribution of this numerical study is to determine the influence of mechanical para...

Comparison between flexural wood strength values obtained from three-point and four-point bending tests in wood were only reported in few previous works, but remains unclear. Thus, the aim of this study was to determine the relationship between wood strength (MOR) obtained by 4-point and 3-point bending tests in Eucalyptus. Two or three specimens w...

The management of ecological engineering structures making up a timber structure requires periodical evaluations, including the level of decay of the constituent parts of the timber structure. Methods exist to measure the level of decay in the laboratory or in the field. However, they are rarely suitable for the conditions of ecological engineering...

In this work, we present a dataset, which provides information on the structural diversity of some endemic tropical species in Madagascar. The data were from CIRAD xylotheque (since 1937), and were also collected during various fieldworks (since 1964). The field notes and photographs were provided by French botanists; particularly by Francis Hallé....

In the European Union, timber is used in structural applications and must be graded with a Conformité Européene (CE) mark. To achieve standard, machine strength grading is used. A common technology for these machines is based on using the vibrational response of each wood board to estimate the timber modulus of elasticity and modulus of rupture. Th...

Trees play a major ecological and sanitary role in modern cities. Nondestructive imaging methods allow to analyze the inner structures of trees, without altering their condition. In this study, we are interested on evaluating the influence of anisotropy condition in wood on the tomography image reconstruction using ultrasonic waves, by time-of-flig...

Bing is a non-destructive testing technology for evaluating mechanical quality of wood and other materials by vibratory analysis, developed by CIRAD. Bing provides for any rigid material its elastic characteristics (longitudinal modulus of elasticity MOE and transverse shear modulus) and non-elastic (internal friction associated with each resonance...

Tropix software presents hundreds of tropical wood species, and provides a set of technological characteristics for each of them. The data come from CIRAD’s wood database which contains all the results of characterization tests conducted by our laboratories and machining centre over decades. Tropix software was first released in 1997. Current versi...

In the assessment of standing trees, an acoustic tomographic device is a valuable tool as it permits to acquire data from the inner part of the trees without causing them to fall down unnecessarily. The interpretation of the images produced by these devices is part of the diagnosis process for urban trees management. This paper presents a segmentat...

Cet ouvrage présente les principales caractéristiques technologiques de 283 essences forestières tropicales et 17 tempérées les plus usitées en Europe associées à leurs principales utilisations. Les opérateurs de la filière bois en seront les principaux utilisateurs, qu'ils soient producteurs ou consommateurs. Cet atlas constitue un outil pédagogiq...

Key message Sloped terrains tend to produce trees with higher radial variation in wood density while at high wind speeds, the wood tends to present higher stiffness and lower MFA in Eucalyptus. Abstract Few studies have investigated the influence of environmental conditions on the within-tree variation in Eucalyptus wood traits. The genotype and en...

The influence of wood properties, such as basic density, moisture content, dimensions of the pieces, chemical composition, anatomy, as well as parameters of the carbonization process, like final peak temperature, heating rate and pressure on the mechanics of charcoal used as a reductant in iron blast furnaces, was reviewed. The quality of charcoal...

Charcoal can replace coke in blast furnaces avoiding the use of reducing agents derived from fossil fuels. However, the main limitation of charcoal is its lower strength, which is essential for supporting the iron ore load inside the blast furnaces. In order to improve and control the charcoal quality, the objectives were then to study (i) the infl...

Key messageA retrospective architectural analysis performed on planted teaks in Togo showed that the variation of wood radial properties were linked with tree ontogeny, and that these relationships depended on thinning practices and provenance.ContextVariability in growth, flowering and forking in individual trees according to origin and/or thinnin...

• Context The quality of acoustic tomographic images in standing trees is mainly function of the accuracy of the acoustic velocity computation. Improving the acoustic velocity determination is, furthermore, of great interest because acoustic tools are widely used in nondestructive testing of wood. • Aims Four different signal processing algorith...

Key message Ultrasounds overestimate the MOE value. This paper analyses the causes of this difference and opens the perspective for a novel method allowing the calculation of the correct MOE from ultrasounds or NIRS measurements on cores. Context Standardized methods for determining wood modulus of elasticity (MOE) are destructive and require many...

In the present study, six different combinations of pultruded hybrid kenaf/glass composites were fabricated. The number of kenaf and glass rovings was specifically selected to ensure constant local fiber volume fractions in the composites. The volumetric composition of the composites was determined by using a gravimetrically based method. Optical m...

The acoustic tomographic technique is used in the diagnosis process of standing trees. This paper presents a segmentation methodology to separate defective regions in cross-section tomographic images obtained with Arbotom® device. A set of experiments was proposed using two trunk samples obtained from a eucalyptus tree, simulating defects by drilli...

Key message The surface area and dry biomass of leaves can be satisfactorily estimated from simple dimension measurements. These data are useful for estimating carbon allocation in trees using functional-structural growth models. Abstract Leaf area and leaf dry biomass are key parameters linked to plant production and they are used in functional-st...

Methods for measuring ultrasonic wave velocity in an elastic material require knowledge of the thickness of the sample. In general, the precision of this knowledge determines the accuracy of the experimental technique for measuring velocity. With the same restriction, measuring thickness of a material require a knowledge of the time-of-flight of th...

Studying the influence of defect on the dynamic behavior of wood in order to detect the local heterogeneities is of great importance in non-destructive testing of wood. The natural heterogeneities in wood are oriented in a volume. However, one-dimensional models are still used in dynamic characterization of wooden beams. The aim of this study was t...

Key message High-resolution imaging is possible if high-frequency sensors are used together with a signal-processing and inversion algorithm that is well suited to a low signal-to-noise ratio and the effect of wood anisotropy. Abstract Wood is a biological growth medium, and given that standing trees adapt themselves in their growth to environme...

The quality of the Ultrasonic Computed Tomography (UCT) imaging device, in term of spatial resolution, sensitivity or dynamic, is a function of the wavelength, the number of transducers, the ultrasonic field generated and the inversion algorithm. This latter factor was studied using four inversion techniques for the tomography of trees. Two new met...

An alternative inversion solution is presented to compute the elastic parameters based on the Timoshenko equation of motion in free flexural vibration. The interest of this solution was its relatively simple formulation and its validity domain, which was not restricted to the initial frequencies and a certain range of length-to-height ratio. The un...

The study analyses the relationship between local and global modulus of elasticity and develops and evaluates different models to predict local from global modulus measurements. The mechanical tests were performed on four species commonly used in Italy for structural purposes: fir, Douglas-fir, Corsican pine and chestnut. Two or three cross-section...

This work is part of a program that aims at studying the burr wood of thuja (Tetraclinis articulata). The goal of this work is to identify material symmetries of burr wood to improve its machining. To have a sufficient number of data and to limit the variability between samples, an ultrasonic experimental device, in direct contact on spherical samp...

Wood is an orthotropic material and its properties depend on its age but also depend on environmental growing conditions. An important feature of property alteration is reaction wood formation. Reaction wood forms when part of a tree is subjected to mechanical stress, and helps to bring parts of the plant into an optimal position. This article aims...

Xylophone belongs to the idiophone group of instruments which is very present in the African traditional and popular music. Its sound percussion quality is related to the resonance and the intrinsic properties of used wood. In spite of numerous studies of the acoustic properties of wood, very few works are available on Pterocarpus species in genera...

The cellulose microfibril angle (MFA) in the cell wall is known to have major effects on wood stiffness and shrinkage. However, its influence on juvenile wood traits is not fully understood, especially in Eucalyptus. The aim of this study was to evaluate the relationships among MFA, density (rho), dynamic modulus of elasticity (E), modulus of ruptu...

The aim of ARB'UST project is to develop an ultrasonic device for parametric imaging of standing trees. The device is designed to perform both transmission and reflection measurements, used for quantitative tomographic imaging. It allows various automatic acquisitions since the angular position of sensors can be precisely adjusted. The electronics...

Wood and composite characterization by the use of mechanical waves is the aim of the works presented. This characterization is achieved by the union of several scientific disciplines: Physics of elastic waves, wood science, signal processing, applied mathematics, statistics, and physical measurements. From a fundamental point of view, it comes then...

The aim of this study was to establish the relationship between the stiffness of scantlings, approaching structural size materials, and small specimens of 6-year-old Eucalyptus urophylla × grandis wood using a resonance technique. The correlation between the elastic modulus (E) of the scantlings in longitudinal vibration and small specimens in flex...

Developed by the CIRAD’s Biomass, Wood, Energy, Bioproducts Research Unit, the 7th release of TROPIX software introduces new features and properties in a friendly interface. It was designed from our “Tropical woods” database and compiles all the results of technological characterization tests performed by our staff, laboratories and machining cente...

Many woody plants persist in a temporal ‘persistence’ niche, through resprouting after disturbance events. Will multi-stemming (as a consequence of resprouting or life form) and biomechanical traits enable certain species to survive disturbance and occupy a persistence niche? A 1200-m long avalanche corridor in the French Alps, with disturbance eve...

Wood is a biological growth medium. It is orthotropic with longitudinal, radial and tangential axes. Furthermore, standing trees adapt themselves to environmental growth conditions, and their material properties vary with age. These changes result in variations that are much more complex than anisotropy. Studying wood quality and intraspecific vari...

This work was designed to provide the Australian structural radiata pine processing industry with some indications for improving stress grading methods and/or technologies to give an increase in structural grade yields, and significantly reduce processing costs without compromising product quality. To achieve this, advanced statistical techniques w...