References of "Lejeune, Philippe"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailKeep the nest clean: survival advantages of corpse removal in ants
Diez, Lise; Lejeune, Philippe ULg; Detrain, Claire

in Biology Letters (2014), 10(7),

Sociality increases exposure to pathogens. Therefore, social insects have developed a wide range of behavioural defences, known as ‘social immunity’. However, the benefits of these behaviours in terms of ... [more ▼]

Sociality increases exposure to pathogens. Therefore, social insects have developed a wide range of behavioural defences, known as ‘social immunity’. However, the benefits of these behaviours in terms of colony survival have been scarcely investigated. We tested the survival advantage of prophylaxis, i.e. corpse removal, in ants. Over 50 days, we compared the survival of ants in colonies that were free to remove corpses with those that were restricted in their corpse removal. From Day 8 onwards, the survival of adult workers was significantly higher in colonies that were allowed to remove corpses normally. Overall, larvae survived better than adults, but were slightly affected by the presence of corpses in the nest. When removal was restricted, ants removed as many corpses as they could and moved the remaining corpses away from brood, typically to the nest corners. These results show the importance of nest maintenance and prophylactic behaviour in social insects. [less ▲]

Detailed reference viewed: 8 (4 ULg)
Full Text
See detailSIMMEM comme outil d'aide à la gestion : exemple d'application à une forêt communale en Ardenne belge
Dedry, Laurent ULg; Perin, Jérôme ULg; De Thier, Olivier ULg et al

Scientific conference (2014, April 08)

SIMMEM est un module informatique intégré à CAPSIS permettant de simuler l'évolution des forêts sur des périodes allant jusqu'à plusieurs dizaines d'années

Detailed reference viewed: 23 (15 ULg)
Full Text
See detailG-Cube version 2.3.1 - Logiciel de cubage et de lotissement d'arbres
Lejeune, Philippe ULg; Quevauvillers, Samuel ULg; Handerek, Daphné ULg

Software (2014)

This software is dedicated to the volume estimation of tree list using as set of volume equations adapted to belgian forest species. A specific module takes in charge the creation and the price ... [more ▼]

This software is dedicated to the volume estimation of tree list using as set of volume equations adapted to belgian forest species. A specific module takes in charge the creation and the price calculation of trees assortments [less ▲]

Detailed reference viewed: 1320 (103 ULg)
Full Text
See detailNouvelles courbes de productivité harmonisées pour le douglas, l'épicéa et les mélèzes en wallonie
Perin, Jérôme ULg; De Thier, Olivier ULg; Claessens, Hugues ULg et al

in Forêt Wallonne (2014), 129(mars/avril),

Les courbes de productivité sont des outils de diagnostic précieux en gestion forestière. Elles permettent d'estimer le potentiel de production d'un peuplement de structure équienne d’âge connu à partir d ... [more ▼]

Les courbes de productivité sont des outils de diagnostic précieux en gestion forestière. Elles permettent d'estimer le potentiel de production d'un peuplement de structure équienne d’âge connu à partir d'une mesure ponctuelle de la hauteur dominante. Une nouvelle génération de modèles de productivité plus fiables ont été développés pour l'épicéa, le douglas et les mélèzes en Wallonie et ont été intégrés au sein d'un outil informatique de diagnostic simple et rapide d'utilisation. [less ▲]

Detailed reference viewed: 17 (9 ULg)
Full Text
Peer Reviewed
See detailVers une synthèse de la conception et une définition des zones dans le gradient urbain-rural
Andre, Marie ULg; Mahy, Grégory ULg; Lejeune, Philippe ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2014), 18(1), 61-74

The increasing footprint of urbanization on landscapes justifies the study of cities and the zones surrounding them. Paradoxically, the concepts relating to these zones remain unclear. Scientists from ... [more ▼]

The increasing footprint of urbanization on landscapes justifies the study of cities and the zones surrounding them. Paradoxically, the concepts relating to these zones remain unclear. Scientists from different disciplines diverge when defining these zones or their limits; they even often mention the zones without any definition. This practice excludes comparison between studies. By means of bibliographic research, the variety of terms used to describe the different zones composing the urban-rural gradient has been evidenced, as well as the characteristics of the zones themselves. They have been evaluated according to their relative importance and according to a series of criteria. Finally, new definitions for the different zones have been proposed in order to enable their identification in the field. [less ▲]

Detailed reference viewed: 89 (22 ULg)
Full Text
See detailThe end of roaming in the forest causes a loss of timber resources: the paradox of slash-and-burn agriculture
Morin-Rivat, Julie ULg; Fayolle, Adeline ULg; Favier, Charly et al

Conference (2014, February 27)

Tropical forests are not believed as pristine anymore. Their structure and specific composition are induced by past climatic and human disturbances over years. In the African moist forests, the emergent ... [more ▼]

Tropical forests are not believed as pristine anymore. Their structure and specific composition are induced by past climatic and human disturbances over years. In the African moist forests, the emergent trees are mainly light-demanding. These trees are considered to derive from the recent disturbances of the last centuries. Most of them are exploited for their timber. However, several of these tree species are currently suffering from a lack of regeneration that threatens the specific diversity of the forests and the sustainability of timber exploitation. Through dendrometric and radiocarbon analyses we found that the majority of the trees of the Congo Basin are not older than 160 years. This corresponds to about the year 1850 when the Europeans colonized the inner regions of Central Africa. By reassembling people along the road axes, the colonial administration reduced the forest roaming. Former activities such as slash and burn agriculture created large openings in the canopy that allowed light-demanding tree species to establish. Currently we observed that timber logging does not provide openings large enough for the recruitment of these species. We thus anticipate that adjustments in forest management strategies shall be made to preserve the forest resources, for instance by recreating the conditions of slash and burn agriculture. [less ▲]

Detailed reference viewed: 55 (7 ULg)
Full Text
Peer Reviewed
See detailSpeciation slowing down in widespread and long-living tree taxa : insights from the tropical timber tree genus Milicia (Moraceae)
Daïnou, Kasso ULg; Mahy, Grégory ULg; Duminil, Jérôme et al

in Heredity (2014)

The long generation time and large effective size of widespread forest tree species can result in slow evolutionary rate and incomplete lineage sorting, complicating species delimitation. We addressed ... [more ▼]

The long generation time and large effective size of widespread forest tree species can result in slow evolutionary rate and incomplete lineage sorting, complicating species delimitation. We addressed this issue with the African timber tree genus Milicia that comprises two morphologically similar and often confounded species: M. excelsa, widespread from West to East Africa, and M. regia, endemic to West Africa. We combined information from nuclear microsatellites (nSSRs), nuclear and plastid DNA sequences, and morphological systematics to identify significant evolutionary units and infer their evolutionary and biogeographical history. We detected five geographically coherent genetic clusters using nSSRs and three levels of genetic differentiation. First, one West African cluster matched perfectly with the morphospecies M. regia that formed a monophyletic clade at both DNA sequences. Second, a West African M. excelsa cluster formed a monophyletic group at plastid DNA and was more related to M. regia than to Central African M. excelsa, but shared many haplotypes with the latter at nuclear DNA. Third, three Central African clusters appeared little differentiated and shared most of their haplotypes. Although gene tree paraphyly could suggest a single species in Milicia following the phylogenetic species concept, the existence of mutual haplotypic exclusivity and nonadmixed genetic clusters in the contact area of the two taxa indicate strong reproductive isolation and, thus, two species following the biological species concept. Molecular dating of the first divergence events showed that speciation in Milicia is ancient (Tertiary), indicating that long-living tree taxa exhibiting genetic speciation may remain similar morphologically. [less ▲]

Detailed reference viewed: 19 (12 ULg)
Full Text
Peer Reviewed
See detailPrerequisites for a Black locust genomic selection program
Verdu, Cindy ULg; Mengal, Coralie ULg; Henrotay, Frédéric ULg et al

Poster (2014, February 07)

The use of renewable resources as an alternative to fossil fuels has become a priority. Efficient use of forest as a resource for energy and green chemistry purposes require the development of suitable ... [more ▼]

The use of renewable resources as an alternative to fossil fuels has become a priority. Efficient use of forest as a resource for energy and green chemistry purposes require the development of suitable selected genotypes that are competitive and ready to meet the challenges of global change. In this context, the black locust, Robinia pseudoacacia L., is a very promising species which has many advantages in the context of current global change: high phenotypic plasticity, drought resistance, high biomass production and fixation of atmospheric nitrogen. The genetic improvement of woody species using traditional methods can take between 20 to 30 years. These times can be greatly reduced with the development of new selection methods such as genomic selection. Before starting a genomic selection program, it is necessary to 1) develop new molecular markers to achieve a very dense genetic map for genomic selection, 2) study the genetic diversity of the species present in Belgium and compare it with that of the native area, 3) study the structure and the relatedness of different populations, 4) establish a core collection gathering the most genetically diverse individuals, and 5) as black locust is an exotic species, verify its invasiveness in Belgium. These 5 steps will be detailed and the first results obtained will be discussed. [less ▲]

Detailed reference viewed: 25 (7 ULg)
Full Text
See detailA diachronic analysis of the dynamic of two cities: Kisangani and Lubumbashi (Democratic Republic of Congo): How do the extension and/or of the densification of these cities impact the urban internal and peripheral ecosystems?
Andre, Marie ULg; Mahy, Grégory ULg; Lejeune, Philippe ULg et al

Poster (2014, February 07)

The dynamics of two cities between two years (2002 and 2010 for Kisangani; 2002 and 2008 for Lubumbashi, both part of the Democratic Republic of Congo) have been examined in order to estimate how their ... [more ▼]

The dynamics of two cities between two years (2002 and 2010 for Kisangani; 2002 and 2008 for Lubumbashi, both part of the Democratic Republic of Congo) have been examined in order to estimate how their extension and/or of the densification have impacted the urban internal and peripheral ecosystems. This study singularizes itself from the subjective ones by its quantified and objective approach based on landscape ecology. This discipline assumes that the landscape pattern description is important because, according to its central hypothesis called “pattern-process paradigm”, the ecological processes influence landscape structure and vice versa. Composition metrics, which are commonly used in landscape ecology, describe the pattern among other things in quantifying the presence and the number of patches from the various classes within the landscape. For each city two SPOT 5 images were classified with a oriented-object supervised approach; then built area proportion index, a composition landscape metric, has been evaluated in order to 1) identify the extent of each area (urban, suburban, rural) within the urban-rural gradient, 2) quantify the dynamic of the different areas in the urban-rural gradient during the last decade and 3) quantify the effect of a decade of urban and suburban growth on ecosystems. The similarities and differences between these cities, relevance and gaps in the method have then been identified and discussed. [less ▲]

Detailed reference viewed: 22 (4 ULg)
Full Text
See detailQuantifier la ressource forestière grâce au LiDAR - Quelques applications concrètes
Bonnet, Stéphanie ULg; Dedry, Laurent ULg; Bauwens, Sébastien ULg et al

Conference given outside the academic context (2014)

Après l’avènement des Systèmes d’Information Géographique et l’utilisation de plus en plus répandue des images aériennes et satellitaires, le LiDAR constitue une nouvelle avancée dans la quantification et ... [more ▼]

Après l’avènement des Systèmes d’Information Géographique et l’utilisation de plus en plus répandue des images aériennes et satellitaires, le LiDAR constitue une nouvelle avancée dans la quantification et le monitoring des ressources naturelles en général et forestières en particulier. Le LiDAR est une technologie d’acquisition d’information en trois dimensions. Collectées le plus souvent à partir d’un avion, les données LiDAR prennent la forme de nuages de points plus ou moins denses qui décrivent finement les structures tridimensionnelle des zones observées et donc du couvert végétal dans le cas de zones forestières. Même si, à l'heure actuelle, l’acquisition des données reste encore relativement coûteuse et leur traitement apparemment complexe, les perspectives d’utilisation de ces données apparaissent très prometteuses au plan de la gestion forestière. [less ▲]

Detailed reference viewed: 56 (22 ULg)
Full Text
Peer Reviewed
See detailDendrochronological analysis of large tropical trees: a new approach combining photogrammetry, image processing and GIS tools
Latte, Nicolas ULg; Bauwens, Sébastien ULg; Bonnet, Stéphanie ULg et al

Conference (2014, January 17)

Tree-ring analysis of tropical trees is especially time-consuming for the largest trees. Because of large dimensions and irregular shapes, the tree-ring measurements are generally achieved (semi-)manually ... [more ▼]

Tree-ring analysis of tropical trees is especially time-consuming for the largest trees. Because of large dimensions and irregular shapes, the tree-ring measurements are generally achieved (semi-)manually directly from wood samples. The aim of this study is to present a new approach of tree-ring measurements combining photogrammetry, image processing and GIS tools that is appropriate for very large wood samples. Disks are sawed from felled trees above buttress. Small diameters holes are drilled to the disk surface to be later used as control points. Images are taken with an off-the-shelf camera and assembled with PhotoScan in order to produce an orthoimage of the green disk surface. After drying, disks are sanded (grain 80-400) and scanned with a flatbed scanner (A3 size) at high resolution (1200-2400 dpi). The scans are then mosaicked together with Autopano into one single image. Based on the control points of the green orthoimage, the ‘dry’ image is georeferenced and rectified. Using a GIS environment, tree-rings are delimited and ring widths and/or areas measured. Disks are entirely digitalized into high resolution images (0.02-0.04mm per pixel) offering a wide range of analysis possibilities. The image-based procedure reduces cost of disk handling and transportation, facilitates data processing and transfer and, is adaptable to any type of wood samples. [less ▲]

Detailed reference viewed: 110 (32 ULg)
Full Text
Peer Reviewed
See detailUn complexe d’espèces d’Afzelia des forêts africaines d’intérêt économique et écologique (synthèse bibliographique)
Donkpegan, Segbedji ULg; Hardy, J. Olivier; Lejeune, Philippe ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2014), 18(2),

The purpose of this review is to provide a knowledge update and a comprehensive literature review of the genus Afzelia, a complex of sister species exploited for their timber in Central Africa. The ... [more ▼]

The purpose of this review is to provide a knowledge update and a comprehensive literature review of the genus Afzelia, a complex of sister species exploited for their timber in Central Africa. The distribution of Afzelia species in Africa suggests that the tree has made various adaptations due to ecological factors. However, on the basis of only vegetative criteria, it is difficult to distinguish species in forest inventory, and this could compromise the sustainable management approach promoted by the populations of Central African countries. We show that the genus remains generally understudied, although some of its species are considered by the IUCN as being under threat. Therefore, the ecological and genetic aspects of our investigations should prove relevant to the future cultivation of Afzelia. [less ▲]

Detailed reference viewed: 16 (4 ULg)
Full Text
Peer Reviewed
See detailLes indicateurs de la pression du cerf élaphe sur la végétation du sous-bois en forêts feuillues tempérées : synthèse bibliographique
Lehaire, François ULg; Ligot, Gauthier ULg; Morelle, Kevin ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2014), 18(2), 262-272

During the last decades, the populations of large herbivores have increased. Consequently, their pressure on forest vegetation has been exacerbated and has reached in some forests levels that reduced the ... [more ▼]

During the last decades, the populations of large herbivores have increased. Consequently, their pressure on forest vegetation has been exacerbated and has reached in some forests levels that reduced the diversity of forest ecosystem services. Assessing the balance between timber production and hunting remains a crucial question for forest users (foresters, hunters) and requires reliable tools such as ecological indicators. This paper reviews the ecological indicators that characterize the pressure of red deer (Cervus elaphus L.) on understory vegetation in temperate deciduous forest. Such indicators monitor the cover, height, stem density, biomass and species diversity of different indicator plant groups. These plant groups embrace species belonging to herbaceous stratum, forest regeneration or particular species such as bilberry (Vaccinium myrtillus L.) and bramble (Rubus fruticosus L.). The choice of indicator plants, as it affects considerably the performance of the ecological indicator of deer pressure on understory vegetation, must be carried out with caution taking into account plant abundance and palatability. The reviewed indicators help to understand the relationships between biodiversity, carrying capacity and deer populations. They are intended to forest managers that would like to monitor red deer pressure in regards to forest management goals and forest sustainability. [less ▲]

Detailed reference viewed: 18 (7 ULg)