References of "Lejeune, Philippe"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailWill Elephants Soon Disappear from West African Savannahs?
Bouché, Philippe ULg; Douglas-Hamilton, Iain; Wittemyer, George et al

in PLoS ONE (2011), 6(6), 1-11

Precipitous declines in Africa’s native fauna and flora are recognized, but few comprehensive records of these changes have been compiled. Here, we present population trends for African elephants in the 6 ... [more ▼]

Precipitous declines in Africa’s native fauna and flora are recognized, but few comprehensive records of these changes have been compiled. Here, we present population trends for African elephants in the 6,213,000 km2 Sudano-Sahelian range of West and Central Africa assessed through the analysis of aerial and ground surveys conducted over the past 4 decades. These surveys are focused on the best protected areas in the region, and therefore represent the best case scenario for the northern savanna elephants. A minimum of 7,745 elephants currently inhabit the entire region, representing a minimum decline of 50% from estimates four decades ago for these protected areas. Most of the historic range is now devoid of elephants and, therefore, was not surveyed. Of the 23 surveyed elephant populations, half are estimated to number less than 200 individuals. Historically, most populations numbering less than 200 individuals in the region were extirpated within a few decades. Declines differed by region, with Central African populations experiencing much higher declines (276%) than those in West Africa (233%). As a result, elephants in West Africa now account for 86% of the total surveyed. Range wide, two refuge zones retain elephants, one in West and the other in Central Africa. These zones are separated by a large distance (,900 km) of high density human land use, suggesting connectivity between the regions is permanently cut. Within each zone, however, sporadic contacts between populations remain. Retaining such connectivity should be a high priority for conservation of elephants in this region. Specific corridors designed to reduce the isolation of the surveyed populations are proposed. The strong commitment of governments, effective law enforcement to control the illegal ivory trade and the involvement of local communities and private partners are all critical to securing the future of elephants inhabiting Africa’s northern savannas. [less ▲]

Detailed reference viewed: 454 (52 ULg)
Full Text
Peer Reviewed
See detailPotentialities of using ASTER & SRTM DEM for road planning in Central African sustainable forest logging context. A case study in East Gabon
Philippart, Julien ULg; Handerek, Daphné ULg; Lejeune, Philippe ULg et al

Poster (2011, June 02)

Slope is the main constraint for sustainable forest road planning in Central Africa. Remote sensing now provides free and downloadable Data Elevation Model (DEM) covering most of appeared lands. In this ... [more ▼]

Slope is the main constraint for sustainable forest road planning in Central Africa. Remote sensing now provides free and downloadable Data Elevation Model (DEM) covering most of appeared lands. In this study, we evaluate potentialities and limitations of Shuttle Radar Topography Mission (SRTM) DEMs, derived from radar interferometry and Advanced Spaceborn Thermal Emission and Reflection Radiometer (ASTER) DEMs, themselves derived from digital photogrammetry for slope evaluation. Assessment is presented for hilly (Milole) and flat (Okondja) areas. Three elevation maps were derived from initial ASTER 30-m and SRTM 90-m DEMs : a SRTM 30-m resampled from SRTM 90-m and two ASTER 30-m where absurd values (artifacts) were corrected with SRTM 90-m and resampled SRTM 30-m respectively. We qualitatively and quantitatively assess the accuracy of all elevation maps compared to 992 (698) slope measures on field along transects of 10.5 (7.5) km in Milolé (Okondja). We estimated root mean square error (RMSE) for slope estimation at 7.8 (10.7), 8.1 (10.1), 11.7 (11.2), 10.1 (11.2) and, 9.3° (11.0°) for SRTM 90-m, SRTM 30-m, ASTER 30-m, ASTER 30-m CORR 90 and ASTER 30-m CORR 30 respectively in Milolé (Okondja). We also use a classification error matrix to assess Global Accuracy (GA) and User’s Accuracy (UA) of elevation maps by classifying ground slopes in two categories: lower or equal and higher than maximum slope limitation of 12% (30%) for primary (secondary) roads. All DEMs show a greater GA in hilly area (Milolé) than in flat area (Okondja) and SRTM derived DEMs show a higher UA for secondary roads constraint. UA for the lower or equal category varies between 55.5 and 75.2% (63.9 and 91.7%) for primary (secondary) roads. The use of corrected aster DEMs increases initial ASTER UA from 0.1 to 18.8% depending on category and slope limitation. Despite a relatively high RMSE for slope grade, all of the DEMs tested were found to be consistent for consideration of maximum slope constraint aiming at sustainable road planning for forest logging in Central Africa. [less ▲]

Detailed reference viewed: 65 (25 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 97 (52 ULg)
Full Text
See detailPrincipes de base de la télédétection et ses potentialités comme outil de caractérisation de la ressource forestière. I. Images aériennes et satellitaires
Bonnet, Stéphanie ULg; Toromanoff, François ULg; Fourneau, François ULg et al

in Forêt Wallonne (2011), (114), 45-56

Face aux enjeux pesant sur la forêt, la caractérisation de cette ressource multifonctionnelle est primordiale pour une gestion efficace et raisonnée. Cependant, la réalisation d'inventaires forestiers ... [more ▼]

Face aux enjeux pesant sur la forêt, la caractérisation de cette ressource multifonctionnelle est primordiale pour une gestion efficace et raisonnée. Cependant, la réalisation d'inventaires forestiers représente un travail substantiel en termes de temps et de budget. Dans ce contexte, les images aériennes et satellitaires deviennent, après l'avènement des Systèmes d'Information Géographique (SIG), des outils indispensables pour analyser la composition et l'évolution de nos forêts. Cet article présente synthétiquement les grands principes de télédétection et les services qu'elle peut rendre au forestier. [less ▲]

Detailed reference viewed: 167 (35 ULg)
Full Text
See detailTaille des placeaux de caractérisation des teckeraies à sylviculture paysanne au Sud-Bénin
Atindogbe, Gilbert; Aoudji, Augustin Kossi; Fonton, Noël Houédougbé et al

in Bois et Forêts des Tropiques (2011), 310(4), 69-78

Success of teak, Tectona grandis, plantations in State forests has encouraged involvement of private landowners in this sector, with inadequate planting method and a management system livelihood ... [more ▼]

Success of teak, Tectona grandis, plantations in State forests has encouraged involvement of private landowners in this sector, with inadequate planting method and a management system livelihood-improvement oriented. Any assessment and characterisation of this resource therefore demands a study on the representativeness of the sampling units. Three sampling types and twelve sampling units were compared: plots defined by area (100 m2, 200 m2, 400 m2 and 600 m2); plots with a fixed number of trees (7, 9, 11, 13 and 15 trees) and strip sampling (5, 10 and 15 trees). The units were established randomly and a full inventory conducted, with one to four reiterations in each of the eighteen plantations of different ages managed as high stands and coppices. The dendrometric parameters calculated for each observation unit and for the full inventory are as follows: density (Na/ha), basal area (G), arithmetical average diameter of stems (dg), average basal area of stems. The criterion for comparison is the root mean square error relative (RRMSE) to the reference value: from the full inventory. The analysis of results shows that RRMSE can be as high as 36 %, and even more in high stand plantations. Plots with a fixed surface area produce the best estimations for characterising plantations, with approximately equivalent efficiency for 400 and 600 m2 plots, with a RRMSE of 10 % (Na/ha), 13 % for (G) and 7 % for (dg). Strip sampling produced better results than plots with a fixed number of trees, with a better (dg) estimation of 10 % to 12 %. Given the cost of the inventory, 400 m2 sampling plots may be recommended to improve the charaterisation of teak plantations under farm silviculture. [less ▲]

Detailed reference viewed: 21 (5 ULg)
Full Text
Peer Reviewed
See detailMéthode pragmatique d’évaluation de la réserve en eau des stations forestières et cartographie à l’échelle régionale (Wallonie, Belgique)
Ridremont, François ULg; Lejeune, Philippe ULg; Claessens, Hugues ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(S2), 727-741

The assessment of the forest sites water availability constitutes a growing concern following the awareness of the potential impact of climate change on the soil moisture regime. At the present time, the ... [more ▼]

The assessment of the forest sites water availability constitutes a growing concern following the awareness of the potential impact of climate change on the soil moisture regime. At the present time, the forest managers lack tools for a quantitative estimation of the soil water reserve. This paper presents a simple estimation method that can be adopted on field by foresters. A map of this soil water reserve at the forest site scale has been established for the Southern Belgium. After the inventory of the possible techniques, the “textural method”, based on the pedotransfert classes of Jamagne et al. (1977), has been used. The soil profiles from the Aardewerk database have eased the translation of the Jamagne et al. (1977)’s results in the Belgian textural system. Moreover, the geodatabase of the Digital Soil Map of Wallonia (DSMW), through the typology of the major soil types, has been used as mapping support of the water reserve at the regional scale. Like a first attempt of validation, the result has been compared with the bioindicator character of forest understory vegetation. The regression results show a significant relationship between the soil water reserve and the vegetation estimate, but they also indicate that the water reserve does not explain alone the moisture level expressed by the flora. It emerges that the characterization of the Walloon parent materials will constitute an undeniable support for the development of the proposed method, the transposition of foreign results leading to some bias. The use prospects of this thematic map are multiple: integration as inputs for the autecological modelling, assessment of the moisture regime for the water availability of forest sites and building of sites catalogs; as many tools to guide forest managers in their planning measures. [less ▲]

Detailed reference viewed: 66 (21 ULg)
Full Text
See detailL'inventaire des dégâts frais d'écorcement dans les peuplements résineux en Wallonie : bilan et perspectives
Lejeune, Philippe ULg; Gheysen, Thibaut ULg; Arnal, Delphine et al

in Forêt Wallonne (2011), (114), 3-16

Depuis 2003, un inventaire des dégâts d'écorcement est en place dans les jeunes peuplements d'épicéa et de douglas des forêts wallonnes. L'originalité de cet inventaire tient dans la très large superficie ... [more ▼]

Depuis 2003, un inventaire des dégâts d'écorcement est en place dans les jeunes peuplements d'épicéa et de douglas des forêts wallonnes. L'originalité de cet inventaire tient dans la très large superficie qu'il couvre ainsi que dans sa durée. Ce premier article présente succintement la méthode et quelques résultats disponibles. [less ▲]

Detailed reference viewed: 56 (29 ULg)
Full Text
See detailIdentification des zones déficitaires en desserte forestière à l'échelle d'un territoire communal
Colson, Vincent; Braun, Matthieu; Debaty, Joëlle et al

in Forêt Wallonne (2011), (114), 26-36

La voirie forestière est un des éléments permettant la bonne mobilisation des bois. Encore faut-il qu'elle soit suffisante et bien répartie. Afin d'évaluer ces deux aspects, une technique est à l'essai ... [more ▼]

La voirie forestière est un des éléments permettant la bonne mobilisation des bois. Encore faut-il qu'elle soit suffisante et bien répartie. Afin d'évaluer ces deux aspects, une technique est à l'essai actuellement dans quelques communes pilotes. [less ▲]

Detailed reference viewed: 37 (22 ULg)
Full Text
See detailLa Carte numérique d’Occupation du Sol de Wallonie version 2_07
Gheysen, Thibaut; Lejeune, Philippe ULg

Conference (2010, October 20)

La version 1 de la carte numérique d’occupation du sol de Wallonie (COSW) a été produite en 2007 pour les années de référence 2001, 2003 et 2005. Cette réalisation répondait à un besoin important de ... [more ▼]

La version 1 de la carte numérique d’occupation du sol de Wallonie (COSW) a été produite en 2007 pour les années de référence 2001, 2003 et 2005. Cette réalisation répondait à un besoin important de description de cette thématique sur l’ensemble du territoire wallon. En effet, à cette époque, la seule couche disponible était le plan d’occupation du sol (raster, 1:50 000) basé sur des données de la fin des années 80 ! La méthode utilisée pour produire cette carte repose sur l’utilisation d’une couche de base qui est le PLI (Plan de Localisation Informatique). Celui-ci est combiné avec la nature de la matrice cadastrale et croisé par géotraitements avec différentes couches décrivant certaines thématiques de l’occupation du sol : le parcellaire agricole (issu du SIGEC), les plans d’eau, les zones d’extraction, les terrils, les décharges, les Sites à Réaménager (SAR), les zones portuaires ou encore les aérodromes. Le principal inconvénient de cette méthode réside dans le fait que la partie non cadastrée du territoire, qui représente 5% en termes de surface, n’est pas décrite. De même, la carte hérite des imprécisions géométriques du PLI, qui peuvent s’avérer gênantes lorsque la carte est superposée à d’autres couches cartographiques comme les orthoimages. La version 2 de cette COSW est désormais disponible pour l’année de référence 2007. Elle intègre deux améliorations par rapport à la version précédente : 1° La description des espaces non cadastrés. 2° Deux nouvelles couches thématiques interviennent dans le processus de production pour la description des zones de campings et des parcs résidentiels. L’outil de production de cette carte a également été complètement revu, en s’appuyant sur une programmation en VB.NET et en utilisant les géotraitements de la version 9.3 d’ArcGIS. Les données sont désormais gérées dans le format file geodatabase, certaines données intermédiaires utiles aux différentes étapes du processus de production étant stockées dans des personnal geodatabases. La version 2_07 correspondant aux données du PLI et du parcellaire agricole (issu du SIGEC) de 2007 est déclinée en 5 couches correspondant aux 5 niveaux de la légende de la COSW. L’analyse de la précision thématique de la carte est basée sur la photo-interprétation de 1000 points répartis aléatoirement sur l’ensemble du territoire. Elle a concerné le niveau 3 de la légende. La précision globale obtenue pour ce niveau est de 89,1 %. Les confusions les plus fréquentes sont commises entre classes forestières (peuplements feuillus, résineux et mixtes, coupes rases, ..) qui représentent 35 % des erreurs de classification. Les confusions « territoires agricoles vs territoire artificialisés » et « territoires agricoles vs forêts » représentent respectivement 20 % et 17 % des erreurs détectées. L’analyse de la précision géométrique est basée sur la mesure ponctuelle (n = 1000) des discordances entre les limites cartographiées et les limites photo-inteprétées sur les orthoimages de 2006-2007. L’erreur moyenne est de 3,4 m. 70 % des points analysés présentent une erreur inférieure à 4 m. Les limites associées aux zones forestières présentent une erreur moyenne plus importante (5,2 m), par rapport aux limites des espaces agricoles (2,5 m) ou des territoires artificialisés (2,9 m). [less ▲]

Detailed reference viewed: 130 (10 ULg)
Full Text
See detailInventaire sur l’affectation des terres de la Belgique dans le cadre du Protocole de Kyoto et de la CCNUCC
Bauwens, Sébastien ULg; Hebert, Jacques ULg; Lejeune, Philippe ULg

Poster (2010, May)

La Belgique réalise annuellement un inventaire de ses émissions de gaz à effet de serre (GES) dans le cadre du Protocole de Kyoto et de la Convention Cadre des Nations Unies sur les Changements ... [more ▼]

La Belgique réalise annuellement un inventaire de ses émissions de gaz à effet de serre (GES) dans le cadre du Protocole de Kyoto et de la Convention Cadre des Nations Unies sur les Changements Climatiques (CCNUCC/UNFCCC). L’affectation des terres et le changement d’affectation des terres (LULUCF) forment l’un des cinq principaux secteurs qui doivent être rapportés dans cet inventaire national. Ce poster présente la méthode mise en œuvre au niveau de la Belgique pour réaliser le rapportage de ce secteur, ainsi que les résultats pour 1990 et 2008. [less ▲]

Detailed reference viewed: 32 (9 ULg)
Full Text
See detailLes inventaires forestiers par échantillonnage comme outil d’aide à la gestion : exemple d’application au Domaine royal de Ciergnon
Gheysen, Thibaut ULg; Arnould, Dominique; Nachtergaele, Quentin et al

Poster (2010, May)

Ce poster présente un exemple concret de mise en oeuvre d’inventaire forestier de gestion sur un massif d’environ 5000 ha de forêt situé en Wallonie. L’objectif est de fournir au gestionnaire un tableau ... [more ▼]

Ce poster présente un exemple concret de mise en oeuvre d’inventaire forestier de gestion sur un massif d’environ 5000 ha de forêt situé en Wallonie. L’objectif est de fournir au gestionnaire un tableau de bord rassemblant les principaux indicateurs décrivant l’état de son patrimoine forestier. Le plan d’échantillonnage est constitué d’une grille systématique comportant 1 point de sondage par 4 ha. Les points sont permanents et visités tous les 4 ans. Les informations, délivrées dans un rapport d’inventaire standardisé, concernent notamment : la surface terrière et le volume par ha, la structure, la composition, l’état de la régénération, le potentiel biomasse, la diversité spécifique et les accroissements. [less ▲]

Detailed reference viewed: 47 (9 ULg)
Full Text
See detailDevelopment of an Open Source GIS Based Decision Support System for locating Wind Farms in Wallonia (Sourthern Belgium)
Lejeune, Philippe ULg; Gheysen, Thibaut ULg; Ducenne, Quentin et al

in Delvin, Ger (Ed.) Decision Support Systems , Advances in (2010)

The Walloon Region - Southern Belgium – aims at significantly increasing its wind-power electricity production capacity by the end of 2020. Such a development requires a comprehensive body of reliable ... [more ▼]

The Walloon Region - Southern Belgium – aims at significantly increasing its wind-power electricity production capacity by the end of 2020. Such a development requires a comprehensive body of reliable procedures pertaining to land use and landscape issues and subsequent controversy arising from wind farms located in densely populated areas. These procedures should enable experts and decision-makers to perform robust impact assessment analyses. To this end, an analytical framework based on GIS functionalities has been developed to evaluate and contrast various constraints against suitability criteria regarding building wind farms. This system can perform exhaustive spatial analyses over the whole region, i.e. 17,000 km², using a 10-m resolution in a raster mode. The approach is two-fold. Firstly, the framework allows an aggregation of 40 criteria related to both environmental and landscape constraints. The aggregation process is derived from Boolean algebra. It results into a 3-level constraint scale, i.e. exclusion, highly sensitive and sensitive. Secondly, the framework involves a weighted linear combination aggregation method where criteria are standardized on a [0,1] scale prior to aggregation. Different weights are required to translate criteria into a preference scale. In this process, the constraint map can be used as a mask for further suitability analysis. The geo-database and analysis functionalities were developed in an open source GIS GRASS environment. These functionalities are used to either import or export data from other GIS platforms, to update constraint and suitability maps, to perform an analysis of sensitivity with regard to criteria-defining parameters, and to perform exhaustive appraisals of wind farm projects. Grass GIS-tools seem to offer a good alternative to commercial GIS software for the development of such a Decision Support System as they ensure an easier access to stakeholders involved in the development of wind energy in Wallonia. [less ▲]

Detailed reference viewed: 154 (19 ULg)
Full Text
See detailA Silvicultural Decision Support System to Compare Forest Management Scenarios for Larch Stands on a Multicriteria Basis
Rondeux, Jacques ULg; Hebert, Jacques ULg; Claessens, Hugues ULg et al

in Delvin, Ger (Ed.) Decision Support Systems, Advances in (2010)

Detailed reference viewed: 43 (14 ULg)
Full Text
See detailQGIS, une alternative open source à ArcGIS?
Bonnet, Stéphanie ULg; Gheysen, Thibaut; Lejeune, Philippe ULg

Learning material (2010)

Séminaire d'introduction au logiciel Quantum GIS, dispensé dans le cadre du cours de télédétection appliquée (18 février 2010) à Gembloux Agro-Bio Tech.

Detailed reference viewed: 158 (39 ULg)
Full Text
See detailModelling of Forest Trees Autecology. An applied research at the Walloon Region scale (Belgium).
Ridremont, François ULg; Claessens, Hugues ULg; Lejeune, Philippe ULg et al

in Hallet, Vincent; Vanclooster, Marnik (Eds.) ENVITAM and UNITER : PhD Student Day 2010 Proceedings (2010, January 12)

Detailed reference viewed: 34 (13 ULg)
Full Text
See detailModelling of Forest Trees Autecology. An applied research at the Walloon Region scale (Belgium)
Ridremont, François ULg; Claessens, Hugues ULg; Lejeune, Philippe ULg et al

Poster (2010, January 12)

Three reasons have urged the Walloon Forest Administration (Walloon Public Service) on to solicit the help of forest researchers to bring practical responses to the adaptation of its current forests ... [more ▼]

Three reasons have urged the Walloon Forest Administration (Walloon Public Service) on to solicit the help of forest researchers to bring practical responses to the adaptation of its current forests management: (i) the progression of research in applied autecology, (ii) the development of software for the management and the analysis of georeferenced data (GIS technologies) and, (iii) the awareness of the potential negative impacts of climate change on forests. To answer to this request, this research aims to model the autecology of the main forest tree species at the Walloon Region scale (Beech, Oak, Norway Spruce, Douglas-fir and valuable broadleaves species). The results will be used to update current practical tools to assess the adequacy of forest tree species on sites, especially in the climate change context. The research is built into three main steps: • update the autecology knowledge for the targeted forest tree species through a state of the art; • compile and create different ecological parameters that can explain the major part of trees growth such as climatic, topographic, geologic, edaphic and phytosociological data gathered from forest plots or geodatabases. In the context of climate change, a particular attention will be brought on bioclimatic and soil moisture conditions because of their narrow link with the potential risk of trees ecophysiological stress; • model tree species reaction to environmental conditions with tree growth indicators. Three types of indicators with different spatio-temporal scales are foreseen: stand site index (30-50 years), periodic diameter growth (5-10 years) and tree-ring growth (1-3 years). The use of these three scales is justified by the interest presented by their cross-validations which are necessary for an accurate extrapolation of results to the entire region. Results should indicate the tree species behaviour, especially towards stress conditions. The integration of climatic data, provided by global climate models based on IPCC's climate scenarios, in autecological models could be used to assess the behaviour of forest stands in future climate conditions. From those results, we expect to identify and assess accurately the risky “sites-species pairs” to avoid in the context of a sustainable silviculture. Finally, results will be used to provide autecological synthesis and practical tools to help forest managers and foresters to identify the best “site-species pairs” (tree-site adequacy maps, sites catalogue and computer platform). [less ▲]

Detailed reference viewed: 133 (42 ULg)