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Wood characteristics of trees grown in agroforestry 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 and water extractions were successively performed on wood samples taken across the diameter of the trunk of agroforestry (AF) and forest (FC) walnut trees to get the radial distribution of the extractive contents. All the samples were analyzed by NIR-spectroscopy and NIR-hyperspectral imaging. Statistical discriminant models were developed to classify the samples from both different forestry systems, according to their chemical composition. The results indicated no significant differences between the values of extractive contents of AF and FC walnut woods, whatever the radial position. At the intra-tree scale, the quantity of extractives does not increase significantly with the radial position. However, partial least squares-discriminant analysis (PLS-DA) regression models, developed with NIRS measurements, showed that significant chemical differences exist between AF and FC trees, especially for extractives composition and lignin content. This allowed to classify wood specimens from both forestry systems. These results were confirmed by hyperspectral camera analyses.

Les bois de Juniperus oxycedrus subsp. oxycedrus étudiés sont issus de deux provenances du Nord-Ouest algérien aux conditions climatiques et édaphiques différentes (régions de Sidi Bel Abbès et de Tiaret). Les extractibles et les polyphénols totaux du duramen ont été quantifiés et caractérisés. La durabilité naturelle du duramen a été évaluée vis-à-vis de deux champignons de pourriture brune (Rhodonia placenta et Coniophora puteana) et de termites (Reticulitermes flavipes). Les taux d’extractibles les plus élevés sont ceux obtenus pour les bois de Sidi Bel Abbès. L’extraction au mélange toluène-éthanol a permis d’obtenir des taux plus élevés que l’extraction à l’eau, respectivement 14,17 % et 1,35 % pour les bois de Sidi Bel Abbès contre 9,84 % et 1,19 % pour ceux de Tiaret. Les analyses par chromatographie en phase gazeuse couplée à la spectrométrie de masse (GC/MS) montrent que les familles chimiques majoritairement identifiées dans les extraits aqueux sont les sesquiterpénoïdes, les acides gras et les stérols. Dans les extraits au toluène-éthanol, les sesquiterpènes et les sesquiterpénoïdes sont les composés majeurs. La composition en sesquiterpènes et sesquiterpénoïdes est différente en fonction de la provenance des bois, mais reste très similaire quantitativement. La teneur en polyphénols totaux des extraits au méthanol de la provenance Sidi Bel Abbès est supérieure à celle de Tiaret. Aucune différence significative n’est observée entre les deux provenances pour la durabilité naturelle vis-à-vis de C. puteana. En revanche, la résistance à R. placenta est significativement plus élevée pour la provenance Sidi Bel Abbès. Pour les deux provenances, le bois de J. oxycedrus subsp. oxycedrus est très durable vis-à-vis des champignons de pourriture. Il est aussi répulsif et résistant aux attaques de termites. Une analyse ciblée des relations entre la composition chimique et la durabilité naturelle permettra de mettre en évidence la nature du ou des constituants responsables de la durabilité́ naturelle du bois de J. oxycedrus subsp. oxycedrus, tant vis-à-vis des champignons lignivores que des termites.

In spite of different studies describing the effect of interspecific variability on wood thermal degradation, no study describes the effect of intraspecific variability of wood. As physical properties as well as chemical composition of wood can vary between stands and even within tree, the effect of radial position of European oak wood (Quercus petraea Liebl.) on its thermal stability was investigated. Samples of heartwood, sapwood, juvenile wood, earlywood or latewood taken from the radii of two trees were ground to fine sawdust before subjecting to thermogravimetric analysis (TGA) at 220 °C for 2 h. At the same time, holocellulose, cellulose and extractives as well as extracted heartwood and sapwood were also subjected to TGA using the same procedure. Results indicated that heartwood was more sensitive to heat than sapwood, the inner side of heartwood being more sensitive than the outer side. Differences were also noticed between native and extracted wood, the latter being less sensitive to thermal degradation. These results were consistent with the stability of each wood cell wall component indicating that extractives were more susceptible to thermal degradation than holocellulose, holocellulose being more susceptible than cellulose. At the ring level, earlywood was shown to be more sensitive to thermal degradation than latewood.

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International audience; Increasing or decreasing wood density (WD) from pith to bark is commonly observed in tropical tree species. The different types of WD radial variations, long been considered to depict the diversity of growth and mechanical strategies among forest guilds (heliophilic vs. shade-tolerant), were never analyzed in the light of heartwood (HW) formation. Yet, the additional mass of chemical extractives associated to HW formation increases WD and might affect both WD radial gradient (i.e., the slope of the relation between WD and radial distance) and pattern (i.e., linear or nonlinear variation). We studied 16 legumes species from French Guiana representing a wide diversity of growth strategies and positions on the shade-tolerance continuum. Using WD measurements and available HW extractives content values, we computed WD corrected by the extractive content and analyzed the effect of HW on WD radial gradients and patterns. We also related WD variations to demographic variables, such as sapling growth and mortality rates. Regardless of the position along the shade-tolerance continuum, correcting WD gradients reveals only increasing gradients. We determined three types of corrected WD patterns: (1) the upward curvilinear pattern is a specific feature of heliophilic species, whereas (2) the linear and (3) the downward curvilinear patterns are observed in both mid- and late-successional species. In addition, we found that saplings growth and mortality rates are better correlated with the corrected WD at stem center than with the uncorrected value: taking into account the effect of HW extractives on WD radial variations provides unbiased interpretation of biomass accumulation and tree mechanical strategies. Rather than a specific feature of heliophilic species, the increasing WD gradient is a shared strategy regardless of the shade tolerance habit. Finally, our study stresses to consider the occurrence of HW when using WD

Angélique (Dicorynia guianensis Amsh.) is a tree species in French Guiana that is heavily exploited for its wood, but it is known to have variable natural durability, which can be of severe consequences for the user. In this thesis we wanted to understand the origin of the natural durability of Angelique heartwood in order to understand its variability, to beter predict it. This multidisciplinary work combines wood sciences, natural products chemistry and microbiology. First, we implemented a sampling strategy based on the architectural profile of tree individuals to understand the variability of natural durabilityn which was confirmed by biological assays. We then assessed the influence of potential natural durability factors that we measured in the wood samples. As such, the role of metabolies was investigated using targeted and untargeted metabolomics, coupled with a dereplication strategy. Lignin and infradensity have also been tested as factors of durability for Angelique heartwood. Finally, factors that are related to tree ontogeny have been taken into account and the results highlight the importance of the stage development and the environment of tree individuals. Lastly, we have proposez esasy, fast and reliable spectroscopie tools (medium and near infrared) to predict the nartural durability. These results are encouraging and suggest their potential use by the timber industry to predict durability of Angélique heartwood.; L'Angélique (Dicorynia guianensis Amsh.) est une espèce forestière de Guyane très exploitée pour son bois mais ce dernier est connu pour présenter une durabilité naturelle variable, dont les conséquences peuvent être très lourdes pour l'utilisateur. Dans le cadre de cette thèse nous avons souhaité comprendre l'origine de la durabilité naturelle du duramen se l'Angélique afin d'appréhender sa variabilité pour mieux la prédire. Dans un premier temps, nous avons mis en oeuvre une stratégie d'échantillonnage basée sur l'étude architecturale de l'arbre pour appréhender la variabilité de la durabilité naturelle, ce qui a été confirmé par les essais biologiques réalisés. Nous avons par la suite évalué l'influence de potentiels facteurs mesurés dans le bois sur la durabilité naturelle. A ce titre, le rôle des extractibles a été évalué par des approches métaboliques ciblées et non ciblées, couplées à une stratégie de déréplication. La lignine et l'infradensité ont également été retenues comme facteurs de durabilité naturelle de l'Angélique. Enfin, ses caractéristiques propres à l'ontogénie se l'arbre ont été pris en compte et les résultats mettent en lumière l'importance du stade de développement de l'arbre ainsi que son environnement. Enfin, nous avons proposé ses outils spectroscopiques (moyen et proche infrarouge) simples, rapides et fiables pour prédire la durabilité naturelle. Ces résultats sont encourageants et suggèrent leur utilisation potentielle pour la filière bois pour prédire la durabilité naturelle du bois de l'Angélique.

Plant architecture can be used to study plant development retrospectively thanks to time-dependent morphological markers, particularly those corresponding to the winter break in temperate regions. The Aleppo Pine and the Turkish Pine are polycyclic species, thus they usually develop several consecutive growth units per year, making it sometimes difficult to date them. In this study, we show that keeping track of the pith diameter profile, to date each shoot, is an efficient method. The pith diameter is larger on the first growth unit than on the last growth unit of the year. Moreover, a pairwise comparison showed that the pith diameter undergoes a decrease along the annual shoot from the first growth unit to the last. As pith diameter decreases upwards the annual shoot, it can be used for dating. Pith diameter progresses from 1 year to another too: there is an increase in the early years of life, corresponding to the tree's establishment phase. Lastly, we found a positive relationship between the basal pith diameter of an annual shoot and its length. The variability around this relationship could reflect environmental conditions, especially climate conditions.

Most of the defects affecting heat-treated wood quality are often attributed to heterogeneous heat transfers in industrial kilns. Even if interspecific variability of wood has been reported to affect thermal degradation of the material, little has been reported on the effects of intraspecific variability. The aim of this work was to study the effect of intraspecific variability of silver fir (Abies alba Mill.) wood on its thermal degradation. For this purpose, wood samples were sampled along the radius of cross-sections to estimate the effect of radial position on wood thermal degradation. Sampling was carried out on discs of four trees, two resulting from dynamic growth stand and two from standard growth stand. The study was performed at different scales: at wood compartments scale involving juvenile and mature heartwood, transition zone between heartwood and sapwood and sapwood as well as at intra-ring scale. Wood samples were ground to sawdust and subjected to thermogravimetric analysis and chemical analysis. Juvenile heartwood was shown to be more sensitive to thermal degradation than other compartments. The thermal behavior of sapwood was not particularly different from that of heartwood, and the presence of extractives did not influence significantly thermal degradation. Earlywood was more sensitive to thermal degradation than latewood explaining the higher susceptibility of fast growing heartwood containing larger rings with higher contents of earlywood.

International audience; Driven by a necessity for confident molecular identification at high spatial resolution, a new time-of-flight secondary ion mass spectrometry (TOF-SIMS) tandem mass spectrometry (tandem MS) imaging instrument has been recently developed. In this paper, the superior MS/MS spectrometry and imaging capability of this new tool is shown for natural product study. For the first time, via in situ analysis of the bioactive metabolites rubrenolide and rubrenolide in Amazonian tree species Sextonia rubra (Lauraceae), we were able both to analyze and to image by tandem MS the molecular products of natural biosynthesis. Despite the low abundance of the metabolites in the wood sample(s), efficient MS/MS analysis of these gamma-lactone compounds was achieved, providing high confidence in the identification and localization. In addition, tandem MS imaging minimized the mass interferences and revealed specific localization of these metabolites primarily in the ray parenchyma cells but also in certain oil cells and, further, revealed the presence of previously unidentified gamma-lactone, paving the way for future studies in biosynthesis.

International audience; Heartwood/sapwood profile and the tradeoff between trunk and crown increment in a natural forest: the case study of a tropical tree (Dicorynia guianensis Amsh., Fabaceae) Key message Sapwood area and the radial growth rate of the trunk follow the same pattern at breast height, with an initial increase and subsequent constant value, resulting from the increasing growth allocation toward the crown rather than tree decline. Heartwood area and heartwood volume in the trunk increase more rapidly after this shift occurs. Abstract Sapwood (SW) and heartwood (HW) are two functionally distinct classifications of wood in perennial stems for which quantities can vary greatly in tropical trees. Numerous positive correlations have been found between the radial growth rate (RGR) and SW quantity; however, variations in the SW/HW quantities have not been studied in light of the ontogenetic variation of RGR. Wood core sampling, intensive measurements of tree structure (number of branches, stem volumes), and radial growth monitoring were performed on an abundant and highly exploited tree species in French Guiana (Dicorynia guianensis) to investigate the relationship between RGR, SW/HW quantity, tree structure, and their variations on the course of a tree's ontogeny. SW area and RGR followed the same pattern of variation throughout tree development, both increasing first and reaching a steady state after 50 cm DBH (diameter at breast height). After this value, we observed a strong increase in both the HW area and HW volume increment, concomitant with a more rapid increase in crown volume. The stabilization of RGR for trees with DBH >50 cm was related not to a tree's decline but rather to an increasing wood allocation to the crown, confirming that RGR at breast height is a poor indicator of whole-tree growth for bigger individuals. We also confirmed that HW formation is an ontogenetic process managing SW quantity that is continuously and increasingly produced within the crown as the tree grows. This study highlights the effect of growth-mediated ontogenetic changes on the localization of water and carbohydrate storage within a tree, resulting from SW and HW dynamics throughout tree ontogeny.

En lien avec la notice : http://prodinra.inra.fr/?locale=fr#!ConsultNotice:355849; National audience

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A new naphthoquinone derivative was isolated from the heartwood of the teak stem. The chemical structure of this new compound, 40,50-dihydroxy-epiisocatalponol, was determined using 1-D and 2-D nuclear magnetic resonance experiments, vibrational circular dichroism, HRMS, and optical rotation. We showed that this new naphthoquinone derivative plays a key role in the variability of decay resistance in teak wood. A high negative correlation was found between its concentration and the mass losses of the wood samples after exposure to the brown rot Antrodia sp., the fungus that is the most virulent against teak (R ¼ _0.9; r < 0.0001). In-vitro bioassays allowed us to demonstrate that 40,50-dihydroxyepiisocatalponol acted as a fungicide against Trametes versicolor (white rot) at 58 mg ml-1 (0.22 mM). Overall, our results demonstrated that the concentration of 40,50-dihydroxy-epiisocatalponol could be used as a new tool to evaluate teak wood durability.

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International audience; Challenging evaluation of tropical forest biodiversity requires the reporting of taxonomic diversity but also the systematic characterization of wood properties in order to discover new promising species for timber industry. Among wood properties, the dimensional stability is regarded as a major technological characteristic to validate whether a wood species is adapted to commercial uses. Cell structure and organization are known to influence the drying shrinkage making wood density and microfibrils angle markers of choice to predict wood dimensional stability. On the contrary the role of wood extractive content remains unclear. This work focuses on the fast-growing tropical species Bagassa guianensis and we report herein a correlation between heartwood drying shrinkage and extractive content. Chemical extractions and shrinkage experiments were performed on separate wood twin samples to better evaluate correctly how secondary metabolites influence the wood shrinkage behaviour. Extractive content were qualitatively and quantitatively analysed using HPLC and NMR spectroscopy. We found that B guianensis heartwood has a homogeneous low shrinkage along its radius that could not be explained only by its basic density. In fact the low drying shrinkage is correlated to the high extractive content and a corrected model to improve the prediction of wood dimensional stability is presented. Additionally NMR experiments conducted on sapwood and heartwood extracts demonstrate that secondary metabolites biosynthesis occurs in sapwood thus revealing B. guianensis as a Juglans-Type heartwood formation. This work demonstrates that B. guianensis, a fast-growing species associated with high durability and high dimensional stability, is a good candidate for lumber production and commercial purposes.

National audience; Dans le cadre de recherches génériques sur les déterminants génétiques, moléculaires et biochimiques de la qualité du bois, il a été mis en évidence d’intéressantes propriétés biologiques et colorantes au niveau de deux types d’extraits de bois de robinier (Robinia pseudoacacia). Bien représentée en métropole et en région Centre, cette essence fixe naturellement l’azote atmosphérique, s’accommode de sols peu fertiles et est tolérante au stress hydrique. Elle représente de ce fait une espèce de choix pour la production de biomasse et la séquestration de carbone sur des friches non-agricoles qui ne peuvent être valorisées par d’autres espèces pérennes généralement plantées dans ces buts comme le peuplier ou le saule. Vu la proportion importante de bois de coeur présente chez le robinier, la mise en place, d’unités de production d’extraits ou de molécules de haute valeur ajoutée à partir de cette ressource locale semble judicieuse en complément des filières d’utilisation classiques de ce bois (bois-énergie, fabrication de piquets et de menuiseries extérieures). En relation avec des partenaires régionaux fortement impliqués dans les filières cosmétiques et phytosanitaires potentiellement utilisatrices de ces nouveaux produits issus du bois, le projet ValRob vise à confirmer la nature et l’activité des deux molécules en jeu, à estimer la variabilité génétique de leurs teneurs au sein des ressources génétiques françaises de robinier et finalement, à concrétiser leur production et leur valorisation au niveau industriel en tenant compte des données socio-économiques de la filière bois-forêt bien implantée au niveau régional.

Wood is a multifunctional tissue involved in sap conduction, storage of water and reserves as well as mechanical support. Tree during its development experiments various constraints due to its environment and its growing size. In response to these constraints, wood functional performances are adjusted by variations of property values, which are dependent on the xylogenesis product. However, wood properties may be modified by the deposition of chemical extractives during heartwood formation. Thus heartwood properties are the result of xylogenesis, heartwood formation and their interactions. This work gave rise to the term 'wood profile', designating all variations of wood properties at different scales and in an ontogenetic dimension, resulting from both processes described above. The diversity of shade tolerance (heliophilic to sciaphilic) strategies species suggests a diversity of wood profile expressions. The description of these different expressions could be a way to better understand plant strategies. Understanding and characterizing wood profile and variations in heartwood quantity in tree, is an economical issue since the Guyanese timber industry has been identified as a promising sector. The analysis of the diversity of wood profile—using a bottom-up approach, from the individual level to the interspecific level—proves to discriminate shade tolerance strategies efficiently. Wood specific gravity variation is especially relevant. However, its relevance is based on (1) combinations of both radial and vertical variations and (2) integration of heartwood that may impact range and direction of the gradient and shape of the profile as well. Effect of heartwood formation on wood specific gravity variations is suggestive of shade tolerance strategy as well as quality and/or quantity of chemical extractives. Relevant characterization of shade tolerance strategies by wood profile is the result of the integration of diverse processes and properties. To the view of growth allocation shift (from trunk to crown) observed in Dicorynia guianensis and of previous studies on tree growth, a potential link between wood profile diversity and growth allocation strategies may exist.; Le bois est un tissu plurifonctionnel permettant la conduction de la sève brute, le stockage de l’eau et des sucres ainsi que le soutien mécanique de la plante. L’arbre au cours de son développement expérimente différentes contraintes liées à son environnement et à sa taille croissante. En réponse à ces contraintes, les performances fonctionnelles du bois sont ajustées par des variations de valeurs de propriétés, elles-mêmes dépendantes du produit de la xylogénèse. Cependant les extrais chimiques déposés lors du processus de duraminisation, entraine la modification des propriétés du bois. Les propriétés du duramen sont le fruit de la xylognénése et de la duraminisation ainsi que de leurs interactions. Ce travail de thèse a donné naissance au terme ‘profil ligneux’, désignant l’ensemble des variations des propriétés du bois à différentes échelles et dans une dimension ontogénique résultant des deux processus cités précédemment. La diversité de tempéraments vis-à-vis de la lumière (héliophilie à sciaphilie) des essences tropicales suggère une diversité d’expressions du profil ligneux.La description de ces différentes expressions serait gage d’une meilleure compréhension du tempérament.Comprendre et caractériser le profil ligneux et la variation de la quantité de bois de coeur dans l’arbre, représentent également un enjeu économique puisque l’industrie du bois Guyanaise a été identifiée comme une filière d’avenir. L’analyse de la diversité du profil ligneux—par une approche ascendante, de l’échelle individuelle à l’échelle interspécifique—a prouvé son efficacité dans la discrimination du degré d’affinité à la lumière. La variation de densité est particuliérment pertinente. Néanmoins, sa pertinence réside dans (1) la combinaison du gradient radial et vertical et (2) la prise en compte du duramen qui modifie parfois, l’amplitude et la direction du gradient ainsi que la forme du profil. L’effet de la duraminisation sur la variation de densité devient alors évocateur du tempérament de l’espèce au même titre que la qualité et/ou la quantité d’extraits chimiques mis en jeu. La pertinence du profil ligneux dans la caractérisation du tempérament écologique est due à son aspect intégrateur de divers processus et propriétés. En regard du changement de l’allocation de croissance (i.e. du tronc vers la couronne) observé chez Dicorynia guianensis et de travaux précédents sur la croissance des arbres, un lien potentiel entre la diversité du profil ligneux et la stratégie d’allocation de la croissance pourrait exister.

International audience; Fast and accurate methods are needed to measure durability related chemical characteristics from solid wood. In the field of forest tree breeding the measurements would be performed from increment core samples collected from standing trees. In this study we have assessed the potential of Near Infrared Spectroscopy (NIRS) for evaluating the content of stilbenes (STB) pinosylvin (PS) and its monomethyl ether (PSM) from heartwood samples of Scots pine, Pinus sylvestris L. Gas chromatography mass spectrometry (GC-MS) was used as a reference method. Increment core samples originating from a Scots pine progeny trial were divided into calibration and validation sets. Predictive models were developed for the calibration set using partial least-square regression. Prediction accuracy of the models was evaluated using the validation set. The best model was characterized by a R² of 0.87 for the validation set, demonstrating the usefulness of NIRS for evaluating the content of stilbenes. Also a technology based on UV-fluorescence of stilbenes will be briefly discussed.

International audience; The chemical investigations of Dicorynia guianensis heartwood led to the isolation of four new indole alkaloids for the first time in this plant. Compound (1) identified as spiroindolone 2',3',4',9'-tetrahydrospiro [indoline-3,1'pyrido[3,4-b]-indol]-2-one, and compound (3) described as nitrone 1-methyl-4,9-dihydro-3H-pyrido [3,4-b] indole 2-oxide and were isolated for the first time as natural products. ABTS antioxidant activity guided their isolation. (C) 2015 Phytochemical Society of Europe.

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Radial variations in wood mineral element concentrations (N, P, Ca, Mg, K, Mn, Al) were investigated in 5 oak trees (a ring-porous species with typical heartwood) and 5 beech trees (a diffuse-porous to semi-ring porous wood species lacking typical heartwood) growing on an ochreous brown earth in the Belgian Ardennes. Differences in concentration profiles were consistent with the difference in wood structure. Specifically, oak had markedly higher concentrations in sapwood, suggesting that nutrients are actively resorbed from senescing wood rings, resulting in very low elemental concentrations in heartwood. Similarities between the two species, including outwardly decreasing cation concentrations and a recent increase in Al concentration, might be ascribed to a common environmental influence, i.e. soil leaching by acid rain. However, the decrease in Mn concentration in both species is not consistent with a scenario of decreasing soil pH. Alternative explanations are discussed., info:eu-repo/semantics/published

As the proportion of sapwood (SW) transformed into heartwood (HW) is irregular both radially and longitudinally in trunks of Maritime pine (#Pinus pinaster# Ait.), it has been suggested that HW formation is a developmental process, regulated internally within the tree. In trees where stem growth is eccentric due to stem lean or wind action, the number of annual growth rings of SW transformed into HW is greater on the compressed side of the tree. To determine the contribution to bending stiffness, if any, of this prematurely formed HW, four point bending tests were carried out on fresh HW and SW samples taken from the same growth ring, or neighbouring growth rings, at different cross-sectional positions at a height of 2 m from six 52-year-old Maritime pines. The mean (± s.e.) modulus of elasticity (E) was 7.6 ± 0.3 GPa (longitudinal direction) for all samples. No significant differences in E were found between HW and SW; thus HW does not play a significant mechanical role in bending stiffness. To test a second hypothesis that early HW formation on the compressed side of trees may maintain a constant, optimal volume of SW around the tree, the Pipe Model Theory was applied to 12 52-year-old leaning Maritime pines (angle of lean varied from 0-22°). The surface area (S) of the SW was determined at different heights up the trunk and correlated with crown surface area (S crown). Regressions between Ssw and S crown were highly significant, thereby supporting the theory that HW formation and extension is controlled internally in Maritime pine. HW formation in Maritime pine then serves to maintain an optimal proportion of functional SW which is an important criterion for survival in a species often subjected to severe drought for long periods.

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Présentation de l'éditeur : PROTA 7 porte sur les arbres à bois d'oeuvre de l'Afrique tropicale. La base de données PROTA "SPECIELIST" répertorie 2352 espèces utilisées comme telles. 1204 parmi elles sont des bois d'oeuvre dont c'est l'usage primaire, et seules ces espèces ont été retenues pour le volume 7, qui est divisé en 2 tomes. PROTA 7 (1) a décrit 511 espèces appartenant à une sélection de 25 familles botaniques. Les 693 autres espèces dont l'usage primaire est le bois d'oeuvre sont traitées dans PROTA 7 (2), dans laquelle aussi les 1148 plantes qui sont listées comme "Bois d'oeuvre ayant un autre usage primaire" et sont renvoyées à d'autres volumes de l'encyclopédie. Dans PROTA 7 (2), les 693 bois d'oeuvre retenus sont décrits au sein de 314 articles de synthèse, ce qui implique que 379 espèces ne sont que mentionnées et brièvement décrites dans les articles sur les espèces apparentées plus importantes ; elles ne font pas l'objet d'un article séparé par manque de données

Le projet GESFORCOM devait participer à la mise en place de l'aménagement forestier de la forêt d'Ambohilero. Cet aménagement, fondé sur le transfert de gestion des ressources forestières des "kijana" à hauteur de surfaces représentant moins de 30% des surfaces de ces terroirs, devait permettre de renforcer l'aménagement mis en place précédemment par le projet FFEM-Biodiversité (2002-2007). L'exploitation concertée des ressources ligneuses de ce massif est un des principaux axes de cet aménagement. En ce sens, il s'oppose à la mise en place des contrats GCF par l'ONG Conservation International (CI) où toute exploitation est prohibée. L'article présente de façon historique les interventions de l'Etat, appuyé ou non par des organismes. Il montre comment d'année en année, on est passé d'un cadre où l'exploitation était autorisée par des permis d'exploitation de gré à gré, à un système où l'exploitation est prohibée, y compris au niveau des VOl à l'image de ceux installés parle projet FFEM-Biodiversité. Il montre comment l'exploitation illicite ou "drodaka" est présente dans le massif depuis une cinquantaine d'années et répond à des causes à la fois économiques (la pauvreté des populations forestières) et socio-culturelles. Face à cette situation, il paraît difficile de vouloir décréter un arrêt de ces exploitations illicites. Les contrats de conservation GCF ne sont pas en mesure d'empêcher cette exploitation. Le projet GESFORCOM, en relation avec le projet FFEM-COGESFOR, aborde la question en considérant que, si les moyens de l'Etat ne lui permettent pas d'empêcher le drodaka, il convient de mettre en place les conditions d'information et de formation des VOl et des bûcherons qui puissent, en prenant en considération leurs contraintes, notamment liées à la pauvreté, arrêter un cadre d'exploitation raisonné où les volumes commercialisés restent conformes aux capacités des kijana du massif.

Présentation de l'éditeur : PROTA 7 deals with the timbers of Tropical Africa. Because the group is very large, it has been subdivided into 2 volumes. In PROTA 7(1) 511 "primary use" timbers, belonging to a selection of 25 botanical families, were described in 280 review articles (2008). This volume, PROTA 7(2) describes 693 "primary use" timbers in 314 review articles. All articles are illustrated with a geographic distribution map and many with a line drawing of the habit. The accompanying CD-Rom allows for easy searching through the texts and contains in addition numerous photographs (a.o. on wood anatomy)

International audience; • Introduction Non-structural carbohydrates and phenolic compounds are implicated in the natural durability of wood. In order to find the chemical traits of natural durability in teak wood, the radial distribution of phenolics compounds and non-structural carbohydrates were studied in trees ranked by contrasting natural durability class against Antrodia sp. • Methods Non-structural carbohydrates were analyzed by spectrophotometry after enzymatic assays and phenolics compounds using HPLC. • Results High concentrations of starch, sucrose, glucose, and fructose were found in the sapwood, whereas only trace amounts were found in the heartwood. In the sapwood, low concentrations of H1 (a hydroxycinnamic acid derivative) were specifically detected. Tectoquinone was also detected in the sapwood but its content increased dramatically in the heartwood. 2-(Hydroxymethyl)anthraquinone and P1, an unidentified compound, were only detected in the heartwood and at high concentrations (>3 mg equivalent 5-methoxyflavone g−1 dry weight. Lower concentrations of 1,4-naphthoquinone, anthraquinone-2-carboxylic acid, and lapachol were also only detected in the heartwood. H1 and tectoquinone present in the sapwood could be considered as phenolic precursors of the synthesis of heartwood toxic phenolics in the heartwood. • Conclusion Correlations between natural durability and chemical composition of heartwood (quinone derivatives, P1, and non-structural carbohydrates) suggest that P1, 2-(hydroxymethyl)anthraquinone and tectoquinone could be natural durability traits. Heartwood extractives, mainly quinone derivatives, were formed from non-structural carbohydrates which were weakly correlated to natural durability.

International audience; Wood colour of Tectona grandis produced from fast-growth plantations is highly variable and the causes of this variation are relatively unknown.* With the purpose of understanding the colour variation, different fast-growth plantations were sampled with different growth rates, tree ages, and sites.* Wood colour was measured with a CIELab system, where three variables are estimated: coordinate L* for lightness, coordinate a* defines redness and coordinate b* defines yellowness.* Results showed only a negative correlation between L* and a*. L* and a* were negatively and positively respectively correlated with pith distance in heartwood, but not for b*. No correlations were found between L* and b* in sapwood and plantation characteristics, while a* was positively correlated with age and height of tree and growth rate. In heartwood, tree age and diameter at breast height were correlated with all colour parameters, but tree height and plantation density were correlated with a* and b*. Cluster site had correlation with L*. Multiple correlation analysis showed that the heartwood is increasing darker (L*) and redder (a*) when the trees are older and bigger. Correlation coefficient shown that sapwood and heartwood with lighter colour (L*) is less resistance to fungal attack, but redness colour (a*) increasing decay resistance.; Il y a une grande variabilité de la couleur du bois de Tectona grandis produit à partir de plantations à croissance rapide et les causes de ces variations sont relativement inconnues.* Pour comprendre l'origine des variations de couleur nous avons échantillonné dans des plantations à croissance rapide qui diffèrent entre elles en termes de vitesse de croissance, d'âge et de site.* La couleur du bois a été mesurée avec le système CIELab qui permet la mesure de trois variables colorimétriques: la luminance L* allant du noir au blanc, a* et b* allant respectivement du vert au rouge et du bleu au jaune.* Les résultats montrent une corrélation négative entre L* et a*. Dans le bois le cœur il y a une corrélation négative entre L* et la distance à la moelle et une corrélation positive entre a* et la distance à la moelle: aucune corrélation n'apparaît pour b*. Dans l'aubier, on ne trouve aucune corrélation entre L* et b* et les caractéristiques des plantations. Cependant a* est corrélé positivement avec l'âge, la hauteur et la vitesse de croissance des arbres. Dans le bois de cœur, l'âge et le diamètre à 1,3 m des arbres sont corrélés avec les trois coordonnées chromatiques mais la hauteur des arbres et la densité de plantation sont corrélées avec a* et b*. Il y a une corrélation entre le site et L*. On montre que le bois de cœur est d'autant plus sombre et rouge que les arbres sont plus vieux et plus gros. Les corrélations obtenues montrent que les bois d'aubier et de cœur qui sont les plus clairs résistent moins bien aux attaques fongiques et que les bois de tendance plus rougeâtre ont une meilleure résistance aux pourritures.

International audience; OSB panels were manufactured with a mixture of pine and cypress heartwood and lignin and tannin based resins in order to propose an eco-friendly wood composite. The resistance of OSB panels against Reticulitermes santonensis was tested according to EN 118 and EN 117 as well as in a field test. OSB made from cypress showed more resistance against the tested termite, the resistance decreased as the percentage of pine increased. The degree of attack differed according to the choice of standard procedure. The field test results revealed that in outdoor conditions and when the termites had a feeding choice, all mixtures showed the same behaviour. The decay resistance was assessed according to EN 12038, and the results revealed that the resistance increases when the percentage of cypress increases.

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