References of "Bauwens, Sébastien"
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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 ▲]

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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 ▲]

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See detailLe LiDAR-t et la photogrammétrie pour modéliser des troncs irréguliers
Bauwens, Sébastien ULg

Scientific conference (2013, October 08)

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See detailDescription of a new procedure to estimate the carbon stocks of all forest pools and impact assessment of methodological choices on the estimates
Latte, Nicolas ULg; Colinet, Gilles ULg; Fayolle, Adeline ULg et al

in European Journal of Forest Research (2013), 132

Forest ecosystems play a major role in atmospheric carbon sequestration and emission. Comparable organic carbon stock estimates at temporal and spatial scales for all forest pools are needed for ... [more ▼]

Forest ecosystems play a major role in atmospheric carbon sequestration and emission. Comparable organic carbon stock estimates at temporal and spatial scales for all forest pools are needed for scientific investigations and political purposes. Therefore, we developed a new carbon stock (CS) estimation procedure that combines forest inventory and soil and litter geodatabases at a regional scale (southern Belgium). This procedure can be implemented in other regions and countries on condition that available external carbon soil and litter data can be linked to forest inventory plots. The presented procedure includes a specific CS estimation method for each of the following forest pools and subpools (in brackets): living biomass (aboveground and belowground), deadwood (dead trees and snags, coarse woody debris and stumps), litter, and soil. The total CS of the forest was estimated at 86 Tg (185 Mg ha-1). Soil up to 0.2 m depth, living biomass, litter, and deadwood CSs account, respectively, for 48, 47, 4, and 1 % of the total CS. The analysis of the CS variation within the pools across ecoregions and forest types revealed in particular that: (1) the living biomass CS of broadleaved forests exceeds that of coniferous forests, (2) the soil and litter CSs of coniferous forest exceed those of broadleaved forests, and (3) beech stands come at the top in carbon stocking capacity. Because our estimates differ sometimes significantly from the previous studies, we compared different methods and their impacts on the estimates. We demonstrated that estimates may vary highly, from -16 to ?12 %, depending on the selected methods. Methodological choices are thus essential especially for estimating CO2 fluxes by the stock change approach. The sources of error and the accuracy of the estimates were discussed extensively. [less ▲]

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See detailPrincipes de base de la télédétection et ses potentialités comme outil de caractérisation de la ressource forestière – II. LiDAR aérien
Bonnet, Stéphanie ULg; Toromanoff, François ULg; Bauwens, Sébastien ULg et al

in Forêt Wallonne (2013), (124), 28-41

La télédétection a déjà démontré, au travers de nombreuses études, son potentiel de caractérisation de la ressource forestière. En particulier, le développement du LiDAR aérien a ouvert la voie à de ... [more ▼]

La télédétection a déjà démontré, au travers de nombreuses études, son potentiel de caractérisation de la ressource forestière. En particulier, le développement du LiDAR aérien a ouvert la voie à de nouvelles perspectives. Cette technologie offre une vision tridimensionnelle de la forêt qui permet de récolter à large échelle des informations à l'intérieur même des peuplements. Après avoir présenté les grands principes de télédétection dans un premier article (Forêt Wallonne n°114), ce second volet présente quelques concepts de base pour se familiariser avec le LiDAR et illustre son intérêt pour la gestion des forêts et des milieux naturels aux travers de travaux de recherche menés sur une zone pilote constituée par le bassin versant de la Houille dans la région de Gedinne en Province de Namur. [less ▲]

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See detailLa photogrammétrie: un procédé pour mesurer les arbres à troncs irréguliers
Bauwens, Sébastien ULg; Fayolle, Adeline ULg; Nzenga, Alide Kidimbu et al

Conference (2013, April)

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See detailSimuler la ressource forestière à l'échelle d'un massif : application de SIMMEM et GYMNOS
Ligot, Gauthier ULg; Vallet, Patrick; Perin, Jérôme ULg et al

Conference (2012, April 02)

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See detailEstimation de l’impact de différents modes d’exploitation forestière sur les stocks de carbone en Afrique centrale
Durrieu de Madron, Luc; Bauwens, Sébastien ULg; Giraud, Adeline et al

in Bois et Forêts des Tropiques (2011), 308(2), 75-86

There has been little in-depth research to date on logging impacts in Central Africa in terms of carbon emissions. The REDD mechanism (Reducing Emissions from Deforestation and forest Degradation), has ... [more ▼]

There has been little in-depth research to date on logging impacts in Central Africa in terms of carbon emissions. The REDD mechanism (Reducing Emissions from Deforestation and forest Degradation), has brought this topic to the forefront, with the increase in managed logging concessions and the spread of low-impact logging methods. The aim of this study was to make a meta-analysis covering different experiences reported in the literature. The data collected were applied to a hypothetical logging operation in order to produce a theoretical assessment of its impact on carbon stocks. Our results show that, based on the assumptions used, managed forestry in a conventional logging concession with no forward planning would reduce carbon losses by one tenth, with 10 to 20 m3 of timber extracted per hectare. Most of the carbon savings would result from an increase in the minimum logging diameter. The other gains from low-impact logging would result from improving the design of logging roads, i.e., 5 to 8% of carbon losses due to conventional logging practice. These gains are higher than the error found for the nearest reality measurements made for clear-felled biomass in French Guiana. However, they are much lower than the errors calculated for biomass estimations in several studies available in the literature. In any case, introducing development planning and low-impact logging techniques in timber concessions are able to induce a favourable difference to carbon stocks in Africa’s dense forests. [less ▲]

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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 ▲]

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See detailExperiences on avoided degradation in Africa : Technical challenges in monitoring of carbon impacts of logging and the estimation of potential impact of SFM and RIL practices - state of the art of current research, results and future axes of research needed
Durrieu de Maderon, Luc; Bauwens, Sébastien ULg

Conference (2009, October 20)

Présentation des pratiques forestières en Afrique Centrale de leurs impacts en terme de carbone et proposition d'un protocole d’études

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See detailCaractérisation de l’agroforêt LIMBA-bananier de la Réserve de Biosphère de Luki (Mayumbe, Bas-Congo)
Bauwens, Sébastien ULg

Master's dissertation (2008)

Few studies have been realised about agroforestry systems including banana plants. The aim of this study is to carry out a better knowledge of the original agroforestry system: the limba – banana ... [more ▼]

Few studies have been realised about agroforestry systems including banana plants. The aim of this study is to carry out a better knowledge of the original agroforestry system: the limba – banana (Terminalia superba- Musa acuminate cult. ‘Gros Michel’). To achieve this aim, the attention has been put on three points: characterizing the woody component, estimating the yield of the banana understorey crop and evaluating the vegetal diversity of this system. The limbas’ plantation doesn’t show anymore its expected silvicultural potential. Its density is in average 26 limbas per hectare, which represents a volume of 136.71 m³/ha, that is to say the third of a limba’s plantation volume with the same age and with 86 limbas/ha. The botanical composition of this system does not fundamentally differ from a pure limba’s plantation. However, the woody vegetal diversity is reduced by a half. With a canopy closure at 60 %, the yield of 20-year old banana plantation is 25 % lower than a classic banana plantation yield of the province (Bas-Congo). This yield is suitable for a banana plantation of this age with no external input. Banana plantations in open field are usually abandoned after 10 years because of an unsufficient yield, and they are then lied fallow for 10 to 15 years. This agroforestry system appears to be sustainable and it suits perfectly the transition areas of the Biosphere Reserve of Luki. [less ▲]

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