Status of Trichoferus campestris invasion (Faldermann, 1835) internationally and réflexionon its first interceeption in Belgium (Coleoptera, Cerambycidae, Cerambycinae, Hesperophanini)

peer reviewedPlusieurs interceptions ou signalements inédits d’un cérambycide d’origine asiatique, Trichoferus campestris (Faldermann, 1835), ont été effectués très récemment en Europe, notamment en France et pour la première fois en Belgique. L’établissement de cette espèce envahissante a déjà été constaté dans plusieurs pays européens ainsi qu’au Canada et aux États-Unis. Une synthèse des informations géographiques, biologiques et comportementales, ainsi qu’une liste des plantes hôtes de T. campestris, sont données. Le contexte de son interception en Belgique est exposé et discuté plus largement.Several interceptions or new reports of a cerambycid of Asian origin, Trichoferus campestris (Faldermann, 1835), have been made very recently in Europe, particularly in France and for the first time in Belgium. The establishment of this invasive species has already been observed in several European countries as well as in Canada and the United States. A summary of geographical, biological and behavioral information, as well as a list of host plants of T. campestris, are given. The context of its interception in Belgium is exposed and discussed more widely

Impact of growth rate on the distribution of visually strength-graded West-European Douglas-fir boards

Douglas-fir is a relatively new species within the forest landscape of Wallonia (Southern Belgium). Consequently, some uncertainties remain regarding how to keep full advantage of its high productivity as well as of the good properties of its wood. Moreover, the recent implementation of the timber strength grading (Council Directive 89/106/EEC) is likely to sensitize forest managers and the sawing industry to the impact of sylviculture on the resource quality. In that context, this research aimed at assessing to what extent the ring width of the trees (RWtree) and the mean girth increment of the stands (MGI) influences, in the frame of a visual strength grading, the distribution of the boards they produce. The experimental material was derived from 33 trees (girth range of between 120cm and 170cm) originating from 11 Douglas-fir stands (age range of between 41 and 69 y.o.) representative of contrasting sylvicultural management practices: RWtree ranged from 3 to 6 mm. From a bolt located 6 to 8.2m height in the standing trees, boards (38X100X2100mm³) were sawn and graded according to the Belgian Standard NBN B 16-520. This research evidenced that: - Only the Knot Area Ratio (KAR) impedes boards to be employed in structural uses. Practically, no board having a KAR allowing S10 grading (S10 corresponds to C30 as defined in EN338) exhibits a ring width higher than 6mm, which is the maximum value accepted for S10 grading (according to NBN B 16-520). These observations demonstrate the highly prevailing character of the knottiness regarding the boards’ grading; - 87% of the boards produced by trees from RWtree≥5mm can be used in structural uses, but only 7% can be classified into S10 strength class. In comparison, trees with RWtree<4.5mm also provided 87% of boards which can be used in structure, but 18% of the boards can be graded into S10 strength class; - 89% of the boards produced by stands with MGI>3cm/year are accepted for structural uses, but only 9% are graded into S10 class. Regarding the stands with MGI≤3cm/year, these values are 89% and 24%, respectively. Growth rate thus doesn’t seem to affect the percentage of Douglas-fir boards fit for structural uses. Dynamic sylviculture however significantly decreases the percentage of boards graded into S10 strength class: although it should be supported by financial assessments, early pruning thus seems highly advisable in a context of dynamic sylviculture.ETUDE DES RELATIONS SYLVICULTURE-QUALITE DU BOIS CHEZ LE DOUGLA

Impact of Tree Growth Rate on the Mechanical Properties of Douglas Fir Lumber in Belgium

In the context of questioning the relevance of making Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) silviculture more dynamic in Wallonia, we evaluated the influence of growth rate on the potential of Douglas-fir lumber for structural uses. Therefore, six trees 120 to 180 cm in circumference at 1.5 m were felled in 11 stands whose age varied from 40 to 69 years (mean circumference of the trees &asymp;150 cm; initial planting density from &asymp;2200 to 4400 seedlings/ha). In total, 706 boards (38 &times; 100 mm&sup2; and 70 &times; 180 mm&sup2; in cross section) were cut from these trees, whose average ring width ranged between 3 and 7 mm. The density of the wood (&rho;) always appeared compatible with the mechanical class C30, regardless of the growth rate of the trees from which the lumber originated. The modulus of elasticity (E) and the modulus of rupture (fm) displayed by the 38 &times; 100 mm&sup2; boards cut from corewood were respectively 30% and 41% lower than those observed in outerwood. The latter did not seem affected by growth rate: E and fm characteristic values remained compatible with structural use, regardless of the mean ring width. Growth rate considerably affects the characteristic values of these mechanical properties when boards are made from corewood. Juvenile growth should therefore be limited

Impact of growth rate on the mechanical properties of Douglas-fir grown in Wallonia (Southern Belgium)

Timber is traditionally the main purpose of Douglas-fir in Europe. However, some uncertainties remain concerning the sylviculture that should be applied in order to maximise girth growth rate (GR) without affecting the good mechanical properties of the wood. So, the present study aimed at assessing to what extent the GR of Douglas-firs grown in Wallonia influences the mechanical properties of wood clear samples. The modulus of elasticity (E) and static bending strength (σf) were measured according to NF B51-016 and NF B51-008 and are discussed according to the ring width measured on the samples, as well as on the growth rate of the trees and of the stands, for both juvenile and mature wood. This assessment will help to provide sylviculture guidelines for foresters. The experimental material was derived from 11 Douglas-fir stands distributed all over Wallonia, Southern Belgium. At the time of felling, the age of the stands ranged from 41 to 69 years old. In each stand, six trees were felled, their girth varying from 120cm to 179 cm. As a consequence of the sampling methodology the growth rate of the trees ranged from 3 mm to 7 mm. From the 66 butt logs, 274 and 884 clear samples were taken in the juvenile and mature wood respectively. This research evidenced that: - Whatever the GR, the mean values of E and σf in the juvenile wood are 20% lower than those in the mature wood; - At the tree level, the mean E and σf of the samples taken from trees with ring width>5mm are about 10% lower than those of the samples taken from trees with ring width<5mm, whether considering juvenile or mature wood; - At the stand level and regardless to the type of wood (juvenile/mature), the mean E and σf of the samples originating from stands with mean girth increment>3cm/year are respectively 5% and 9% lower than those of the samples originating from stands with mean girth increment <3cm/year. This observation should lead the forest manager to consider carefully sylvicultural practices that would induce a too fast juvenile growth; high growth rate in the mature wood do not appear to be a problem considering the properties studied here. One should however take into account the impact of the growth rate on the singularities of the boards.ETUDE DES RELATIONS SYLVICULTURE-QUALITE DU BOIS CHEZ LE DOUGLA

Influence de la vitesse de croissance sur le classement de lames de bardage de Douglas wallon (Belgique)

Relation sylviculture - qualité du boi

Phytosanitary treatment of European pallets by microwave: developing a program to ensure compliance with ISPM 15 and monitoring its efficacy on the house longhorn beetle (Hylotrupes bajulus L.)

Microwave heating was recently approved by the FAO as a significantly effective phytosanitary treatment for wood packaging material. According to ISPM 15 (FAO 2009), the target organisms are eradicated if a temperature higher than 60 °C is maintained for 60 s across the entire profile of the board (i.e. 60 °C/60 s). A study using pallet boards was carried out in order to set up a treatment program that would meet ISPM 15 requirements in terms of wood temperature and insect mortality. A 4 m-long industrial tunnel oven (maximum power of 28.8 kW) was used to carry out the experiments. Temperature was measured by means of a VarioCAM® infrared camera. The most relevant results we found were: (i) achieving a temperature of 63.2 °C (Populus sp.) or 64.8 °C (Pinus sylvestris L.) on the upper surface of 22 mm-thick boards enabled compliance with FAO requirements (i.e. 60 °C/60 s), whatever the moisture content, basic density and initial temperature of the wood (provided the latter exceeded 0 °C); (ii) larvae >150 mg represented the most microwave-resistant life stage of Hylotrupes bajulus L.; (iii) the mortality rate of the larvae was influenced by the moisture content of the boards. Using the Gompertz model, we estimated the upper surface temperature that would be needed to achieve a 99.99683% mortality rate (the Probit 9 mortality level of efficacy) for the most microwave-resistant life stage of H. bajulus. This temperature was estimated to be 46.8 °C and 57 °C for wood with >50 and <25% moisture content, respectively.Mise 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)

Le traitement phytosanitaire du bois dans le cadre de la prévention des invasions biologiques

Les invasions biologiques constituent une menace de premier ordre pour les forêts du monde entier. Leur intégrité et leur persistance peuvent être mises à mal par l’introduction fortuite d’espèces exotiques envahissantes. Nombre de ces dernières ont été et sont encore potentiellement disséminées d’un continent à l’autre via divers produits en bois, parmi lesquels on peut citer les bois d’emballage ou les plaquettes de bois (chips). Dans ce contexte, le Laboratoire de Technologie du Bois (LTB) et l’Axe de Gestion des Ressources forestières de Gembloux Agro-Bio Tech (GABT) ont contribué à la mise au point de processus originaux de traitement phytosanitaire du bois. S’appuyant notamment sur un élevage de capricornes des maisons (Coléoptère longicorne) unique en Belgique, les recherches décrites ici ont permis d’améliorer la compréhension du chauffage par micro-ondes de palettes et de valider, en collaboration avec un partenaire industriel wallon, un four de traitement de plaquettes de bois. L’importance économique du secteur de l’emballage est telle que la production annuelle de palettes en bois est considérée comme un indicateur de l’activité marchande d’un pays ou d’une région. Par ailleurs, qu’elles soient destinées à la production de papier, de panneaux ou d’énergie, l’importance des mouvements intercontinentaux des plaquettes en bois est à la mesure du risque phytosanitaire qu’elles représentent. Ainsi qu’en atteste leur intégration dans les normes internationales, les résultats présentés ici ont une portée qui dépasse largement les frontières de la Wallonie