References of "Lejeune, Philippe"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailEvaluation de la ressource en teck, Tectona grandis L.f., des plantations privées du Sud-Bénin
Atindogbé, Gilbert; Fonton, Noël, Houédougbé; Lejeune, Philippe ULg

in Bois et Forêts des Tropiques (2013), (316(2)), 93-103

Private teak plantations in southern Benin have been established at an increasing rate in the last thirty years. To remedy the lack of reliable information on this resource, a methodological approach was ... [more ▼]

Private teak plantations in southern Benin have been established at an increasing rate in the last thirty years. To remedy the lack of reliable information on this resource, a methodological approach was designed to quantify and characterise private teak plantations and gain a better understanding of the private owners involved in teak production in Benin. The method involves “snowball sampling” among three categories of players: forestry service agents, village chiefs and the owners of teak plantations or their representatives. The data collected are the socio-economic profiles of the owners, an overall description of their plantations and dendrometric characterisations of these plantations. In order to assess its performance, the snowball sampling technique was tested by the quadrant method. Snowball sampling identified 1,002 owners and 861.10 ha of Tectona grandis L.f. plantations. Almost 69 % of the plantations were less than 6 years of age, of which 12.4 % were young plantations and 56.7 % coppice. Stands more than 20 years of age accounted for only a very small proportion of these teak resources (0.2 %). With a very low overall afforestation rate, estimated at 3.58 %, and a snowball sampling detection rate of 68.6%, the total area planted with teak was estimated at 1,255.3 ha, within confidence limits of 1,084.5 ha and 1,574.2 ha. The geodatabase built up during the snowball sampling campaign in the Toffo municipality is clearly a promising start for the development of a network of players involved in teak production. The value of snowball sampling in the context of small-scale sylviculture warrants its application to the other municipalities concerned. [less ▲]

Detailed reference viewed: 31 (10 ULg)
Full Text
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 ▲]

Detailed reference viewed: 38 (12 ULg)
Full Text
Peer Reviewed
See detailLiDAR derived ecological integrity indicators for riparian zones: Application to the Houille river in Southern Belgium/Northern France
Michez, Adrien ULg; Piégay, Hervé; Toromanoff, François ULg et al

in Ecological Indicators (2013), 34(0), 627-640

Riparian zones are central landscape features providing several ecosystem services and are exceptionally rich in biodiversity. Despite their relatively low area coverage, riparian zones consequently ... [more ▼]

Riparian zones are central landscape features providing several ecosystem services and are exceptionally rich in biodiversity. Despite their relatively low area coverage, riparian zones consequently represent a major concern for land and water resource managers confirmed within several European directives. These directives involve effective multi-scale monitoring to assess their conditions and their ability to carry out their functions. The objective of this research was to develop automated tools to provide from a single aerial LiDAR dataset new mapping tools and keystone riparian zone attributes assessing the ecological integrity of the riparian zone at a network scale (24 km reach). Different metrics were extracted from the original LiDAR point cloud, notably the Digital Terrain Model and Canopy Height Model rasters, allowing the extraction of riparian zones attributes such as the wetted channel (0.89 m; mean residual) and floodplain extents (6.02 m; mean residual). Different riparian forest characteristics were directly extracted from these layers (patch extent, overhanging character, longitudinal continuity, relative water level, mean and relative standard deviation of tree height). Within the riparian forest, the coniferous stands were distinguished from deciduous and isolated trees, with high accuracy (87.3 %, Kappa Index). Going further the mapping of the indicators, our study proposed an original approach to study the riparian zone attributes within different buffer width, from local scale (50 m long channel axis reach) to a network scale (ca 2 km long reaches), using a disaggregation/re-agraggation process. This novel approach, combined to graphical presentations of the results allow natural resource managers to visualise the variation of upstream-downstream attributes and to identify priority action areas. In the case study, results showed a general decrease of the riparian forests when the river crosses built-up areas. They also highlighted the lower flooding frequency of riparian forest patches in habitats areas. Those results showed that LiDAR data can be used to extract indicators of ecological integrity of riparian zones in temperate climate zone. They will enable the assessment of the ecological integrity of riparian zones to be undertaken at the regional scale (13000 km, completely covered by an aerial LIDAR survey in 2013). [less ▲]

Detailed reference viewed: 94 (23 ULg)
Full Text
Peer Reviewed
See detailTree allometry in Central Africa: Testing the validity of pantropical multi-species allometric equations for estimating biomass and carbon stocks
Fayolle, Adeline ULg; Doucet, Jean-Louis ULg; Gillet, Jean-François et al

in Forest Ecology & Management (2013), (305), 29-37

There is a lot of uncertainty in the amount and spatial variations of above-ground biomass in Africa, partly because very few allometric equations are available. The aim of this study was to assess the ... [more ▼]

There is a lot of uncertainty in the amount and spatial variations of above-ground biomass in Africa, partly because very few allometric equations are available. The aim of this study was to assess the validity of using pan-tropical multispecies allometric equations developed by Chave et al. (2005) for estimating the above-ground biomass of trees in Central Africa and/or to develop site-specific equations. The study was conducted in lowland tropical forests of South-eastern Cameroon, at the edge between evergreen and semi-evergreen forests. Data of above-ground woody biomass were obtained from destructive sampling of 138 trees belonging to 47 taxa across a huge range of diameter (5.30–192.50 cm) and wood specific gravity (0.284–1.152 g cm 3). A set of local site-specific multi- and single-species models relating above-ground biomass to tree diameter and wood specific gravity were fitted to the data. The best model was selected using information criterion. Both tree diameter and wood specific gravity were important predictor to consider for the estimation of above-ground biomass at tree scale. Single-species models were not necessarily better than multi-species models including wood specific gravity as a predictor. The best local multi-species model had the same structure and parameters as the pan-tropical equation developed by Chave et al. (2005) for moist forests. The estimates from the pan-tropical multi-species equation were nearly as good as those of the local multi-species equation. Using wood specific gravity from the global data base only slightly increased the estimation errors, because for the study taxa wood specific gravity was highly correlated to wood specific gravity from the global data base. In this study, we showed that the pantropical multi-species allometric equation developped for moist forests can be used to produce accurate estimates of biomass and carbon stocks from diameter measurement in forest inventory and wood specific gravity from global data base at species level. These findings are especially timely given the urgent need to quantify biomass and carbon stocks in the tropics, and given the spatial extent of moist forests in Central Africa. [less ▲]

Detailed reference viewed: 66 (16 ULg)
Full Text
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 ▲]

Detailed reference viewed: 139 (33 ULg)
Full Text
See detailLe Projet Léopard du Parc W : un Echange de Savoir Intra-Africain au Service de la Conservation de la Nature
Marchal, A.; Marchal, J.; Ouedraogo, M. et al

in Parcs & Réserves (2013), 67(4), 18-25

Detailed reference viewed: 123 (31 ULg)
Full Text
Peer Reviewed
See detailGame species monitoring using road–based distance sampling in association with thermal imagers: a covariate analysis
Morelle, Kevin ULg; Bouché, Philippe; Lehaire, François ULg et al

in Animal Biodiversity and Conservation (2012), 35(2), 253-265

Monitoring of game species populations is necessary to adequately assess culling by hunters in areas where natural large predators are absent. However, game managers have to control several species and ... [more ▼]

Monitoring of game species populations is necessary to adequately assess culling by hunters in areas where natural large predators are absent. However, game managers have to control several species and they often lack of an efficient and convenient survey design method. Monitoring several species at that same time over large areas could thus be cost– and time–effective. We tested the influence of several factors during monitoring of three common game species, (wild boar, roe deer and red fox, using road–based distance sampling in association with thermal imagers. This pilot survey based on 20 night counts in five contrasting sites studied the effect of several covariates (species, thermal imaging, observer, group size, and habitat type) on the detection probabilities. No differences were observed between thermal imagers and group sizes , but we found differences between observers . Expected differences were also observed between species and between habitat type. Our results show that the detectability of low cost thermal imaging equipment is similar to that of more expensive methods, highlighting new possibilities for the use of thermal imagery by game managers. Although adjustments should be made to the study design our findings suggest that large–scale multi–species monitoring could be an efficient method for common game species. [less ▲]

Detailed reference viewed: 136 (53 ULg)
Full Text
Peer Reviewed
See detailEcology of Pericopsis elata (Fabaceae), a Timber Species Considered as Endangered, in Southeastern Cameroon
Bourland, Nils ULg; Kouadio, Yao Lambert; Lejeune, Philippe ULg et al

in Biotropica (2012), 44(6), 840-847

Pericopsis elata (Fabaceae) is a tall tree of high commercial value of the moist semi-deciduous African forests. As a result of logging which started decades ago, it is considered as threatened and ... [more ▼]

Pericopsis elata (Fabaceae) is a tall tree of high commercial value of the moist semi-deciduous African forests. As a result of logging which started decades ago, it is considered as threatened and included on both IUCN Red List and CITES Appendix II even though essential biological parameters controlling its population dynamics remain unknown. This study aims at improving the knowledge of the species ecological parameters and at assessing the impact of selective logging on its populations in an 118,052 ha forest in Cameroon. After inventorying the species in 1,432 ha, mortality and growth were assessed over continuous 5- and 2-year periods in unlogged and logged areas, respectively. Phenology was monitored in the unlogged forest during 5 years. The population structure followed a bell-shaped curve. Mean annual diameter increments in both environments did not differ significantly between unlogged and logged areas. P. elata is a deciduous species that flowers at the end of the main dry season. The minimum reproduction and effective flowering diameters were, respectively, 32 and 37 cm. Fruit maturation took place during 7 months. With a minimum logging diameter of 90 cm, the recovery rate computed over a 30-year period was greater than 100%. Selective logging harvested only 12.1% of the total number of seed trees and had little influence on the species biological parameters. Securing sufficient regeneration as a post-logging action is probably the most important consideration for achieving long-term sustainability. Implications for the conservation status of the species are discussed at the regional level. [less ▲]

Detailed reference viewed: 187 (89 ULg)
Full Text
See detailLes équations allométriques pantropicales sont-elles valides en Afrique centrale
Fayolle, Adeline ULg; Ernst, Gaëtan; Bouissou, Christina et al

Scientific conference (2012, October 24)

Detailed reference viewed: 50 (12 ULg)
Full Text
See detailL'anthropisation du paysage et ses impacts sur les écosystèmes forestiers
Bogaert, Jan ULg; Andre, Marie ULg; Lejeune, Philippe ULg et al

Conference (2012, October 24)

Detailed reference viewed: 48 (15 ULg)
Full Text
See detailFeasibility study for elephant inventory with an Unmanned Aerial Vehicle
Lisein, Jonathan ULg; Vermeulen, Cédric ULg; Bouché, Philippe ULg et al

Scientific conference (2012, October 04)

Detailed reference viewed: 95 (9 ULg)
See detailFour Ws and one H: Movement ecology of wild boar
Morelle, Kevin ULg; Lejeune, Philippe ULg

Conference (2012, October 04)

Detailed reference viewed: 24 (5 ULg)
Full Text
Peer Reviewed
See detailOverview of animal related-accidents in one of the world’s densest road network region
Lehaire, François ULg; Morelle, Kevin ULg; Lejeune, Philippe ULg et al

Poster (2012, October)

With its 4.7 km/km² of public roads, Southern Belgium (Wallonia) has one of the densest road network of Western Europe. This network as well as the observed increase in main game species populations (red ... [more ▼]

With its 4.7 km/km² of public roads, Southern Belgium (Wallonia) has one of the densest road network of Western Europe. This network as well as the observed increase in main game species populations (red deer, roe deer and wild boar) make Wallonia an interesting region for studying the patterns of traffic accidents caused by animals. Moreover, compared to most of European countries, no statistics are available for this area. To shed light on the current situation of wildlife roadkills, the police database of traffic accident statement was thoroughly investigated. Those statements concern accidents that occurred between 2006 and 2010. Each record includes date, time, species involved and information about the location of the accident event. Based on this dataset, we have analysed (i) composition and percentage of involved species, (ii) the consequence (material damages / bodily injuries), (iii) the spatial (type of roads, proximity to landscape features, ‘hot spot’ map) and (iv) temporal (daily, weekly and seasonal) distribution of animal-related accidents. In conclusion future research perspectives are presented. [less ▲]

Detailed reference viewed: 54 (18 ULg)
Full Text
Peer Reviewed
See detailCreation of a Canopy Height Model from mini-UAV Imagery
Lisein, Jonathan ULg; Bonnet, Stéphanie ULg; Lejeune, Philippe ULg

Poster (2012, September 12)

The arrival of mini-UAV (Unmanned Aerial Vehicle), these small autonomous aircrafts, has opened the doors to a new environmental data acquisition’s approach. In forestry, low-altitude imagery from UAV can ... [more ▼]

The arrival of mini-UAV (Unmanned Aerial Vehicle), these small autonomous aircrafts, has opened the doors to a new environmental data acquisition’s approach. In forestry, low-altitude imagery from UAV can be used to characterize forest ecosystem structure through a Canopy Height Model (CHM). In this research, authors developed a new workflow for acquiring low-altitude aerial images with a mini-UAV and used them for the construction of a high resolution Canopy Height Model. An accuracy analysis is performed and shows that individual dominant tree height can be measured from (UAV-photo-) CHM with a precision of 2 meters. [less ▲]

Detailed reference viewed: 216 (34 ULg)
Full Text
Peer Reviewed
See detailFactors influencing wild boar presence in agricultural landscape: a habitat suitability modelling approach
Morelle, Kevin ULg; Lejeune, Philippe ULg

Conference (2012, September 04)

The wild boar (Sus scrofa L.) population has increased in most parts of Europe during the last three decades. As a consequence, population distribution ranges have shifted to more agricultural areas ... [more ▼]

The wild boar (Sus scrofa L.) population has increased in most parts of Europe during the last three decades. As a consequence, population distribution ranges have shifted to more agricultural areas. These newly colonized areas are characterized by highly fragmented forest cover and a preponderance of crop fields and grasslands, thus increasing the risk of problematic interactions with farming activities and small game species. Although plasticity of wild boar to various environmental conditions is well known, understanding the ecological patterns that promote the density distribution of the species within agricultural areas remains of importance for adapted management strategies within these landscapes. Inside a recently occupied area (between 10-30 years of wild boar regular presence) of southern Belgium, we studied the relation between occurences of wild boar population, estimated by hunting bag and crop damages, with a set of environmental, anthropic and landscape variables. We used Maximum Entropy (MaxEnt) approach to analyze the data. Considering the main factors known to favour wild boar distribution, we hypothesized that crop fields providing cover and food, deciduous forest (providing mast) and water stream density are the main factors influencing the wild boar density distribution. The results are used to derive a habitat suitability map of wild boar distribution in northern Wallonia where wild boar recently starts to spread. [less ▲]

Detailed reference viewed: 61 (7 ULg)
Full Text
Peer Reviewed
See detailDiagnosing structure and composition typologies in uneven-aged broad-leaved forests: a comparison of classification methods
Bonnet, Stéphanie ULg; Brostaux, Yves ULg; Claessens, Hugues ULg et al

Poster (2012, September)

Structure and composition of forest stands are crucial factors for forest planning and biodiversity management. In Belgium, typologies of structure and composition exist to support planning in uneven-aged ... [more ▼]

Structure and composition of forest stands are crucial factors for forest planning and biodiversity management. In Belgium, typologies of structure and composition exist to support planning in uneven-aged broadleaved forests (typically dominated by oak and beech). The principle of these typologies is to classify irregular stands with the percentage of small, medium, large, and very large trees (regarding dbh), and the percentage of basal area of oak and beech. This paper investigates the potential of LiDAR data processed with classification methods (k-nn, K-Means, CART, etc.) to allocate a forest structure and composition type. For this purpose several supervised and unsupervised classification methods are compared, as well as the impact of leaf-on (summer) and leaf-off (winter) data to discriminate the forest types. [less ▲]

Detailed reference viewed: 32 (16 ULg)
Full Text
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 ▲]

Detailed reference viewed: 56 (7 ULg)
Full Text
Peer Reviewed
See detailThe detection and characterization of broad-leaved forest canopy gaps: a regeneration perspective
Bonnet, Stéphanie ULg; Bauwens, Sébastien; Lehaire, François ULg et al

Poster (2012, September)

Canopy gaps are areas of high regeneration potential and, in uneven-aged forest, gaps are therefore places of particular care for the forest manager. Nevertheless the cartography and characterization of ... [more ▼]

Canopy gaps are areas of high regeneration potential and, in uneven-aged forest, gaps are therefore places of particular care for the forest manager. Nevertheless the cartography and characterization of canopy gaps are complex issues. This paper addresses the fundamental question of the canopy gap definition: what is the minimal area, the maximal height of vegetation, type of regeneration, etc? From a regeneration point of view, canopy gaps can be defined as holes in the forest cover where light conditions are suitable for recruitment. As an active sensor, LiDAR has made it possible to tackle the problems of shadows and penetration into the canopy, typical of aerial images. This study investigates the cartography and characterization of forest canopy gaps as areas of natural regeneration. [less ▲]

Detailed reference viewed: 42 (17 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 62 (22 ULg)
Full Text
Peer Reviewed
See detailCurrent Pericopsis elata (Fabaceae) patches in southeastern Cameroon: remnants of a long and rich Human-rainforest relationship?
Bourland, Nils ULg; Cerisier, François; Livingstone Smith, Alexandre et al

Poster (2012, June 23)

Pericopsis elata is one of the most valuable African timber species. This IUCN Red Listed tree suffers from a lack of regeneration, thus its current presence provokes questioning. Our work aimed at ... [more ▼]

Pericopsis elata is one of the most valuable African timber species. This IUCN Red Listed tree suffers from a lack of regeneration, thus its current presence provokes questioning. Our work aimed at understanding its origins so as to help securing its future. This study, lead away from engineering works, was conducted in four different sites located within the natural distribution area of the species and taking into account the different growing conditions were the species occurs. Our observations are based on an analysis of charcoal elements and pottery fragments discovered in subsurface layers of soils as well as current botanical and pedological surveys. Evidence of past human activities we found led to the assumption that this part of the Congo Basin was much more inhabited than previously thought. Some of the results obtained for P. elata could apply for other long lived light demanding species growing in the same environment [less ▲]

Detailed reference viewed: 29 (9 ULg)