References of "Hebert, Jacques"
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See detailG-Cube 2.0 : Un logiciel de cubage et de constitution de lots de bois
Handerek, Daphné ULg; Quevauvillers, Samuel ULg; Hebert, Jacques ULg et al

in Forêt Wallonne (2013), (124), 20-27

G-Cube, le logiciel de cubage et de constitution de lots de bois développé par Gembloux Agro-Bio Tech, fait peau neuve. Cette version 2.0 voit arriver des nouveautés parmi lesquelles : la géolocalisation ... [more ▼]

G-Cube, le logiciel de cubage et de constitution de lots de bois développé par Gembloux Agro-Bio Tech, fait peau neuve. Cette version 2.0 voit arriver des nouveautés parmi lesquelles : la géolocalisation des arbres cubés, le croisement des données avec des listes de prix personnelles ou standardisées, ou encore l’abandon de l’environnement Excel au profit d’une interface autonome. [less ▲]

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See detailModeling recent bark stripping by red deer (Cervus elaphus) in South Belgium coniferous stands
Ligot, Gauthier ULg; Gheysen, Thibaut; Lehaire, François ULg et al

in Annals of Forest Science : a Multidisciplinary and International Journal (2013), 70(3),

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See detailEffect of growth rate on the natural durability of Douglas-fir in western Europe
Pollet, Caroline; Henin, Jean-Marc; Hebert, Jacques ULg et al

in Canadian Journal of Forest Research = Journal Canadien de la Recherche Forestière (2013), 43(10), 891-896

Douglas-fir is a relatively recent species in the central European forest landscape. It is not clear how its natural durability is influenced by silviculture. We therefore investigated how the natural ... [more ▼]

Douglas-fir is a relatively recent species in the central European forest landscape. It is not clear how its natural durability is influenced by silviculture. We therefore investigated how the natural durability of the (Pseudotsuga menziesii (Mirb.) Franco) Douglas-fir varies according to tree growth rate; subsequently, the influence of the nature of the wood (juvenile or mature) and radial position was also analyzed. For this purposes, a total of 60 trees grown in Wallonia (Southern Belgium) was felled: these consisted of 6 trees in each of 10 stands where the average tree girth was approximately 150 cm. Since the age of these plantations ranged from 40 to 69 years, the radial tree growth rate ranged between approximately 3 and 7 mm. In all the trees, standardized heartwood test specimens were taken from different radial positions in the butt log. The mass losses caused by the fungi Poria placenta and Coniophora puteana were assessed according to CEN/TS 15083-1 (2005). Poria placenta exhibited a higher decaying efficiency than C. puteana, leading to classify Douglas-fir wood as slightly durable (class 4). No difference was observed between the durability against P. placenta of juvenile and mature wood. Similarly, growth rate seemed to have no direct impact on durability. Durability was, however, significantly correlated with wood density. The effect of site and tree on the natural durability of the wood was also examined. [less ▲]

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See detailAnalyse de l'évolution de la surface de la forêt wallonne par interprétation d'images aériennes : un outil complémentaire à l'inventaire forestier régional
Lejeune, Philippe ULg; Alderweireld, Matthieu ULg; Lecomte, Hugues et al

in Forêt Wallonne (2013), (125), 27-35

L'analyse des images aériennes vient en complément des données recueillies par l'inventaire permanent des ressources forestières. L'objectif est d'obtenir des données plus fréquemment actualisées en ce ... [more ▼]

L'analyse des images aériennes vient en complément des données recueillies par l'inventaire permanent des ressources forestières. L'objectif est d'obtenir des données plus fréquemment actualisées en ce qui concerne les proportions et les surfaces de mises à blanc, l'âge d'exploitation et les surfaces de plantation. [less ▲]

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See detailVon Rittinger theory adapted to wood chip and pellet milling, in a laboratory scale hammermill
Temmerman, Michaël ULg; Daugbjerg Jensen, Peter; Hebert, Jacques ULg

in Biomass & Bioenergy (2013)

The study draws upon the milling theories developed for the ore processing industry (Von Rittinger, Kick and Bond theories) in order to define a method for characterising wood chip and pellet energy ... [more ▼]

The study draws upon the milling theories developed for the ore processing industry (Von Rittinger, Kick and Bond theories) in order to define a method for characterising wood chip and pellet energy consumption during milling. Energy consumption during wood milling depends on three main factors: the material moisture content, the particle size difference between the feed and the milled product, and the material itself. The latter may be characterised by a single parameter based on an adaptation of Von Rittinger’s constant. A relation characterising wood pellet energy consumption as a function of the particle size distribution of the pellet ingredients and the milled pellets is proposed. This is characteristic of each type of pellet for each moisture content value considered. [less ▲]

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See detailTraitement phytosanitaire des bois d'emballage par micro-ondes
Leyman, Michaël; Hebert, Jacques ULg; Jourez, Benoît ULg et al

Report (2012)

Only two treatments of wood packaging material are approved in the International Standard of Phytosanitary Management (ISPM) 15: fumigation with methyl bromide and heat treatment. Methyl bromide ... [more ▼]

Only two treatments of wood packaging material are approved in the International Standard of Phytosanitary Management (ISPM) 15: fumigation with methyl bromide and heat treatment. Methyl bromide fumigation is being phased out, which makes heat treatment the only sanitation method available for the industry. Other treatments are however about to be approved. One of these is the microwave irradiation treatment (MIT). According to the FAO, the target organisms are eradicated if 60°C (or more) is maintained during 60 seconds throughout the profile of the wood (i.e. 60°C/60s). A study was funded by the SPW - Service Publique de Wallonie (DGO3) – in collaboration with the ULg - Gembloux Agro-Bio Tech - to identify, using pallet boards, the treatment program needed to achieve 60°C/60s. A 4m-long industrial 2.45GHz tunnel oven delivering a maximum power of 28.8 kW was used to make the experiments. Temperature was measured with a VarioCAM® infrared camera. The three most relevant results of this study are : (i) Reaching at least 63.2 °C (Populus sp.) or 64.8°C (Pinus sylvestris L.) on the upper surface of 22mm-thick boards warrants 60°C/60s throughout the profile of the wood, whatever its moisture content, density and initial temperature; (ii) Using a Gompertz distribution, the upper surface temperature needed to achieve 99.9968% mortality (Probit 9) of the most microwave-resistant life stage of Hylotrupes bajulus L. (i.e. the >150mg larvae) was estimated to be 47°C and 55°C, respectively for wood with >20% and <20% moisture content; (iii) From a technical point of view, MIT can be integrated into an automatic assembly line of pallets. The profitability of the MIT is difficult to estimate and depends on timber and oven characteristics, cost of energy, etc. Nevertheless, the treatment costs seem to be similar as for conventional heat treatment. However, if the drying of the timber is required (apart from a sanitary treatment), the profitability of the MIT could be doubtful. This study contributes to a better knowledge of the MIT and will help the Belgian National Plant Protection Organization to implement treatment guidelines and programs in order to comply with ISMP15. [less ▲]

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See detailAssessing and Harmonizing Lying Deadwood Volume with Regional Forest Inventory Data in Wallonia (Southern Region of Belgium)
Ligot, Gauthier ULg; Lejeune, Philippe ULg; Rondeux, Jacques ULg et al

in Open Forest Science Journal (2012), 5

Using lying deadwood or coarse woody debris (CWD) is on the rise among national and local forest inventories. We compared two generally recommended methods for lying deadwood: line intersect sampling and ... [more ▼]

Using lying deadwood or coarse woody debris (CWD) is on the rise among national and local forest inventories. We compared two generally recommended methods for lying deadwood: line intersect sampling and fixed area sampling. We assessed both methods in plots of the regional forest inventory of Wallonia (southern region of Belgium) and we developed bridging functions that converts CWD volume estimates to estimates that would have been obtained with different thresholds. [less ▲]

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See detailMicrowave-treatment of frozen wood packaging material
Henin, Jean-Marc; Bauduin, Aline; Leyman, Michaël ULg et al

Conference (2012, July 12)

As part of the wood packaging material (WPM) regulation in international trade, the dielectric heating (DH) is soon to be included in ISPM15 (IPPC 2009) as an approved phytosanitary treatment. It has been ... [more ▼]

As part of the wood packaging material (WPM) regulation in international trade, the dielectric heating (DH) is soon to be included in ISPM15 (IPPC 2009) as an approved phytosanitary treatment. It has been considered that when using dielectric radiation (i.e. microwaves or radiofrequencies), reaching 60°C or more throughout the entire profile of the wood during at least 60s (i.e. 60°C/60s) ensures the eradication of any noxious organism present in the wood. Regarding the treatment itself, the main requirements mentioned in the draft of ISPM15 Annex 1 (IPPC 2011) concern the way to achieve “uniformity of heating” as well as the treatment duration, which must not exceed 30min. Concerning wood characteristics, the only restriction to the DH concerns the thickness of the wood pieces, which must not exceed 20cm; no other restriction exists regarding wood moisture content, density or initial temperature. As reported in the draft of ISPM15 Annex 1, it is generally considered that “when using microwaves as a heating source, the coldest part of the wood is the surface”. This statement implies that achieving 60°C (or more) during 60s at the surface of the wood should guarantee compliance with IPPC requirements (i.e. 60°C throughout the profile of the wood). However, since ice and liquid water exhibit very different properties towards microwaves, initially frozen wood (9cmX9cm and 17cmX17cm in cross-section) was irradiated in a 28.8 kW microwave oven (2.45GHz) in order to assess whether achieving 60°C/60s at the surface of less than 20cm-thick planks ensures higher core temperatures. The temperature pattern observed after the treatment was compared with the one observed after the treatment of initially thawed wood pieces. It was observed that, in some conditions, initially frozen pieces exhibit inside temperature (much) lower than 60°C, despite complying with 60°C/60s all over the surface of the wood. These results show that when wood is heated with microwaves, its coldest part may not be the surface. Our results also strongly suggest that the impact of wood properties on post-treatment temperature pattern should be further investigated in order to better identify the limits of the DH (at least on frozen wood). [less ▲]

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See detailEffect of growth rate and radial position on the natural durability of Douglas-fir
Pollet, Caroline; Henin, Jean-Marc; Jourez, Benoît ULg et al

Conference (2012, July 11)

In terms of natural durability, Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) fame owns to the favourable characteristics of centuries-old trees harvested in old-growth North American forests. The ... [more ▼]

In terms of natural durability, Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) fame owns to the favourable characteristics of centuries-old trees harvested in old-growth North American forests. The properties of wood coming from plantations harvested between 50 and 100 years-old are likely to be different. In such stands, plantation density and thinning intensity may have a large impact on the trees growth rate. Since this parameter is known to affect some properties of the wood, it was decided to assess to what extent an increase in Douglas fir growth rate affects the natural durability of its wood. This issue is indeed poorly documented in the scientific literature. This parameter was evaluated on standardized heartwood specimens taken from 60 trees originating from 10 stands in Wallonia (Southern Belgium). In all these stands, the average girth of the trees ranged between 140 and 160cm, whilst their age (from plantation) ranged from 38 to 66 years old: These stands are thus representative of very contrasted silvicultural management practices. In terms of individual growth, the Mean Ring Width of the trees ranges between ca 3 and 7mm. Globally, 600 tests specimens were taken from two radial positions in the heartwood of each tree. Half of the specimens were taken in the heartwood at the border of the sapwood; the other half encloses the 20 years old ring, counting from the pith. The mass losses caused by the wood decaying fungus Poria placenta were assessed according to Cen/ts 15083-1 (2005).The natural durability of the wood is discussed as affected by sites, trees, radial positions in tree and tree growth rate. [less ▲]

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See detailPhysical and mechanical properties of black locust (Robinia pseudoacacia) wood grown in Belgium
Pollet, Caroline; Verheyen, Cécile; Hebert, Jacques ULg et al

in Revue canadienne de recherche forestière (2012), 42(5), 831-840

The objective of this study was to characterize black locust (Robinia pseudoacacia L.) wood on the basis of its physical and mechanical properties. The results are compared with those reported in the ... [more ▼]

The objective of this study was to characterize black locust (Robinia pseudoacacia L.) wood on the basis of its physical and mechanical properties. The results are compared with those reported in the literature for English oak (Quercus robur L.), teak (Tectona grandis L. f.), and afzelia (Afzelia sp.), since black locust is likely to be used for the same purposes as the former species. The variations between sites, trees, and radial positions in the trunk were also studied. The physical and mechanical properties of black locust wood were evaluated on clear wood specimens taken from 27 trees distributed over five sites in Wallonia (Belgium) according to Belgian and French standards. Most of the black locust’s mechanical properties are higher than those of oak and teak. The black locust is classified as a “mid-heavy” (734 kg·m–3) and “half-hard” (5.22) wood type with very high resilience (17.2 J·cm–2), modulus of elasticity (15 700 MPa), and tensile strength in static bending (138 MPa). Its resilience is exceptional, higher than that of teak and afzelia, while its modulus of elasticity and bending strength, which surpass those of teak, are comparable with those of afzelia. Black locust shows high total volumetric shrinkage (16%), placing it in the “nervous” class, average tangential (8.8%) and radial shrinkage (5.5%) as well as average axial compressive (63 MPa) and splitting strength (17.8 N·mm–1). No technological incompatibilities would prevent the use of this wood for many value-added purposes (floor, deck, exterior woodwork, and furniture); however, significant shrinkage makes it necessary to condition the wood to its service moisture. [less ▲]

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See detailHarmonized Growth Models and Simulations of the Evolution of Pure Stands of Norway spruce, Larches and Douglas-fir for Southern Belgium (Wallonia).
Perin, Jérôme ULg; Ligot, Gauthier ULg; Cerisier, François ULg et al

Poster (2012, March 02)

In order to compare different silvicultural scenarios we have undertaken the development of a software that can simulate stand evolution in regards to their species composition, site characteristics and ... [more ▼]

In order to compare different silvicultural scenarios we have undertaken the development of a software that can simulate stand evolution in regards to their species composition, site characteristics and silvicultural operations. As a first approach we limited the scope of our work to even-aged and pure coniferous stands of the three most important coniferous species in Wallonia (southern part of Belgium): Norway spruce (Picea abies), douglas-fir (Pseudotsuga menziensii) and larches (Larix sp.). This presentation introduces carried out simulations and compare their outcomes. First we gathered data sets from the permanent regional inventory, from observation networks and experimental plots throughout Wallonia. Then we adjusted, for these species, harmonized and distance-independent models of dominant-height growth, tree diameter growth, mortality, and the distribution of tree diameter frequency before the first thinning. Next we implemented those models in the Capsis platform, and we simulated, for the three species, the evolution of virtual stands using different scenarios. On one hand the evolution was performed without thinning, and on the other hand we applied silvicultural scenarios that are commonly used in Wallonia. As a result these models highlight, for example, the great juvenile growth and sensibility to stands density of larches whereas Norway spruce behaves the opposite. Further work is however needed to predict and simulate wood quality and value. Once this will be achieved we will attempt to optimize silvicultural scenarios for the three species. [less ▲]

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See detailMise au point d’une méthode de traitement par micro-ondes des bois d’emballage destinés à l’exportation comme alternative aux mesures phytosanitaires actuellement appliquées (bromure de méthyle et traitement thermique).
Leyman, Michaël ULg; Bauduin, Aline; Henin, Jean-Marc et al

Report (2012)

La convention RF 09/6216 WOODPACKTREAT, subventionnée par le Service Public Fédéral, c’est déroulée du 01-02-2010 au 31-03-2012. L’objectif de ce projet consistait à élaborer une méthode standardisée de ... [more ▼]

La convention RF 09/6216 WOODPACKTREAT, subventionnée par le Service Public Fédéral, c’est déroulée du 01-02-2010 au 31-03-2012. L’objectif de ce projet consistait à élaborer une méthode standardisée de traitement sanitaire des bois d’emballage à l’aide de micro-ondes en déterminant, en fonction des caractéristiques du bois, les modalités du traitement requis afin de garantir une mortalité de 100% des ravageurs/pathogènes présents. De manière plus spécifique, les objectifs étaient au nombre de quatre : 1. étudier la relation existante entre la température de surface (Ts), facilement contrôlable, et la température au coeur du bois (Tc) lorsque les caractéristiques de planches varient (épaisseur, humidité, masse volumique et température initiale) ; 2. vérifier la stabilité de la relation Tc-Ts en fonction de la puissance du rayonnement, de la durée de l’exposition et de la charge de bois dans le four ; 3. contrôler le taux de mortalité des organismes placés dans les conditions de Ts qui garantissent 60° C à coeur pendant 60 secondes à l’issue du traitement ; 4. s’assurer de la faisabilité technique du procédé qui sera mis au point, de sa rentabilité, ainsi que son potentiel d’intégration dans une chaîne de fabrication. Un four à micro-ondes de 2,5 GHz dont la puissance pouvait variée de 0 à 28,8 kW fut utilisé. Les planches prises pour les expériences mesuraient 80 X 20 X 2,2 cm. L’ensemble des objectifs n’ont pas pus être menés à bien en raisons de problèmes survenus au four (notamment la découverte d’une répartition non homogène des micro-ondes). Toutefois, un certain nombre de résultat ont put être trouvés, dont voici les principaux: 1. La relation entre les Ts et les Ts n’est significativement influencée que par le type d’essence (la température et l’humidité initiale n’ont pas d’influences significatives). La Ts nécessaire pour avoir dans 99 % des cas une Tc au minimal de 60 °C est de 68 °C pour le peuplier et de 72,5 °C pour le pin. 2. Pour une même énergie incidente, l’élévation de la T est influencée par la durée d’exposition aux rayonnements. Plus la durée est importante, plus le rendement est meilleur. Ce dernier atteint au bout d’un certain temps une valeur limite. La charge du four influence également le rendement. Plus il y a de masse dans le four, plus le rendement est élevé. 3. Le stade de développement d’ Hylotrupes bajulus L. (espèce de référence en matière d’essais de traitement biocide préventif ou curatif du bois) le plus résistant aux micro-ondes ainsi que sa température létale ont été déterminés. Les larves de plus de 150 mg sont les plus résistantes. Une température de 69,7°C garanti 99,99683% de mortalité (taux imposé par l’annexe 1 de l’ISPM 15). 4. Le procédé semble techniquement réalisable. Il semble, par contre, financièrement peu rentable. Toutefois, cette situation pourrait changer avec un durcissement des normes. Suite à ces constatations, il est prévu, au cours d’une convention SPW & ULg: de mettre au point et de valider, en fonction des caractéristiques du bois, le programme de traitement (60°C pendant 60 secondes) ; de vérifier sur des larves d’H. bajulus la létalité du traitement micro-onde établi ; d’évaluer la possible intégration du processus dans une chaîne de production industrielle. [less ▲]

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See detailStorm-damage management and decision-making process in Wallonia (Belgium)
Riguelle, Simon ULg; Hebert, Jacques ULg; Jourez, Benoît ULg

Conference given outside the academic context (2012)

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See detailLe plan chablis : un outil de planification d'urgence et de gestion de crise pour la forêt wallonne.
Riguelle, Simon ULg; Hebert, Jacques ULg; Jourez, Benoît ULg et al

in Forêt Wallonne (2011), (111), 3-9

La DGARNE, souhaitant anticiper une éventuelle tempête de grande ampleur en forêt wallonne, a mis au point un plan de gestion des crises chablis en vue de pouvoir intervenir de manière coordonnée et ... [more ▼]

La DGARNE, souhaitant anticiper une éventuelle tempête de grande ampleur en forêt wallonne, a mis au point un plan de gestion des crises chablis en vue de pouvoir intervenir de manière coordonnée et réduire les impacts négatifs pour la filière bois. Cet article fait suite à des formations sur la phase d'inventaire rapide du plan chablis données dans tous les cantonnements du DNF. [less ▲]

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See detailA Regional Inventory and Monitoring Setup to Evaluate Bark Peeling Damage by Red Deer (Cervus Elaphus) in Coniferous Plantations in Southern Belgium
Gheysen, Thibaut; Brostaux, Yves ULg; Hebert, Jacques ULg et al

in Environmental Monitoring & Assessment (2011), 181(1-4), 335-45

Bark peeling by red deer (Cervus elaphus L.) has become a serious issue for productive forests in western Europe. The damage is particularly severe on species such as spruce, as these become vulnerable to ... [more ▼]

Bark peeling by red deer (Cervus elaphus L.) has become a serious issue for productive forests in western Europe. The damage is particularly severe on species such as spruce, as these become vulnerable to fungus attacks that result in considerably depreciated timber. This article presents a monitoring setup for recent bark peeling damage in spruce plantings in Wallonia (southern part of Belgium). This setup implies to collect data annually from a survey involving cluster sampling. It has been employed since 2004 in coniferous stands amounting to 165,000 ha of land, where Norway spruce is the predominant species. The study area was divided into blocks delineated along features preventing deer migrations. A set of indicators was computed either at the whole study area level or at block level. The resulting set of indicators enabled forest managers to follow up debarking intensity in productive forests. Additional analyses were carried out in order to assess the relationship between the social position of trees in the stand and the debarking probability on the one hand, and the relationship between the variation in damage magnitude and seasonality, namely summer versus winter, on the other hand. [less ▲]

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See detailL'épinette de Norvège : sylviculture et qualité du bois
Hebert, Jacques ULg

Scientific conference (2010, November 11)

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See detailForesterie en Wallonie: une source d'inspiration ?
Hebert, Jacques ULg

Scientific conference (2010, November 10)

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