Foreseeing a mutliscale statistical approach of the genetical heterogenity of the macroalgae Codium elisabethae and Codium bursa within Western Mediterrannean and Macaronesia: from benthic habitat connectivity to island isolation
Sirjacobs, Damien ; ; Demoulin, Vincent et al
Poster (2007, January)Detailed reference viewed: 20 (3 ULg)
Foreseeing nitrate concentration in groundwater: A review of available modelling approaches
Orban, Philippe ; Brouyère, Serge
Conference (2009, December 10)
In the scientific community, increasing concerns on groundwater quality and quantity have motivated the development of numerical models for groundwater management since the 1970’s. Mathematical and ... [more ▼]
In the scientific community, increasing concerns on groundwater quality and quantity have motivated the development of numerical models for groundwater management since the 1970’s. Mathematical and numerical models are, for example, promising tools for prediction of concentration and they can be used to make the dynamic link between nitrogen manure and the resulting evolution of nitrate concentration in groundwater. However, from a practical and managerial perspective, there have been very few real attempts of developing efficient calibrated and validated transport models in particular at the scale of the groundwater body, which is the management unit of groundwater resource in the European Union. Actually two main challenges remains, (1) performing numerical tools are not really available and (2) parametrisation of such transport models at the regional scale is difficult due to the large amount of data required. Generally speaking models can be grouped in different categories ranging from black box models to physically based distributed models. The black box models such as transfer function are simple but attractive because they require relatively less data but with the drawback that modelling result are not spatially distributed while the predictive capability of these models is questionable due to the semi-analytical nature of the process descriptions. On the contrary, physically based distributed model require more data but, due to a more advanced description of ongoing processes, such models are expected to have better predictive capabilities than the black box models. Black box model and physically based distributed model approaches have all proved their utilities and have all their justifications, advantages and disadvantages regarding the development of regional scale groundwater model. A new flexible methodology (the Hybrid Finite Element Mixing Cell method) has been developed that allows combining in a single model, and in a fully integrated way, different mathematical approaches of various complexities for groundwater in complex environment. This method has been implemented in the SUFTD, a finite element groundwater flow and solute transport numerical model. Combining on the one hand the use of a spatially distributed groundwater flow and solute transport model taking advantages of this Hybrid Finite Element Mixing Cell Approach method and on the other hand spatial datasets of tritium and nitrate contents, an illustration on the problem of nitrate trend assessment and forecasting for an important groundwater resource located in the Geer groundwater body (480 km²) in the Walloon Region of Belgium will be proposed. [less ▲]Detailed reference viewed: 4 (2 ULg)
Forest and garden: traces of wildness in a modernizing land, 1897-1949 (M.L. Simo).
in Landscape Journal (2004), 23(2), 174-176Detailed reference viewed: 14 (0 ULg)
Forest anomalies and human occupation in Central Africa during the last two millennia
; ; et al
Conference (2012, June 23)
Central African rainforests are no longer considered as pristine, but as the outcome of a long history of changes due mainly to climatic variation. For the later part of the Holocene it has been ... [more ▼]
Central African rainforests are no longer considered as pristine, but as the outcome of a long history of changes due mainly to climatic variation. For the later part of the Holocene it has been hypothesised that climate changes together with human activities triggered modifications in terms of distribution and botanical composition. While developing a research project to explore the mechanisms of forest change, new research avenues for the archaeology of rainforests became apparent. In this paper, we outline the results of this approach, implemented on a forest concession (Cameroon). We introduce our methodology based on the analysis of botanical inventories (focused on large trees of human linked species and light demanding species), coupled to systematic core boring and test pits. A sampling strategy for the collection of charcoal and its identification is developed and archaeological remains found in association are analyzed at the Royal Museum for Central Africa. [less ▲]Detailed reference viewed: 44 (7 ULg)
Forest canopy perforation in time and space in Amazonian Ecuador.
; Bogaert, Jan ; et al
in Acta Oecologica: International Journal of Ecology (2000), 21(4-5), 285-291Detailed reference viewed: 11 (1 ULg)
Forest fragmentation: causes, ecological impacts and implications for landscape management
Bogaert, Jan ; ; et al
in Li, C; Lafortezza, R; Chen, J (Eds.) Landscape Ecology and Forest Management: Challenges and Solutions in a Changing Globe (2011)Detailed reference viewed: 97 (17 ULg)
Forest growth data : capture, retrieval and dissemination
; Rondeux, Jacques
Book published by Faculty of Agriculture - First published in : Bulletin des Recherches Agronomiques de Gembloux,  volume 25 (1) and (2), pages 1-236 (1990)Detailed reference viewed: 12 (1 ULg)
Forest inventory with Terrestrial LiDAR: what about Hand-Held Mobile LiDAR?
Bauwens, Sébastien ; ; et al
Conference (2014, November 05)
For a decade, studies of the application of static Terrestrial Laser Scanner (TLS) in plotwise forest inventories are giving more and more effective results. In spite of the improvements occurring in ... [more ▼]
For a decade, studies of the application of static Terrestrial Laser Scanner (TLS) in plotwise forest inventories are giving more and more effective results. In spite of the improvements occurring in processing scan data to extract forest attributes, the occlusion effect is still limiting the processing efficiency. A multi-scan approach is recommended to reduce this effect. However, such approach needs pre-scan preparations (setting up the plot, targets positioning), it requires data registration and it comes at a higher data collection cost. In this study we explore the potential of a Hand-held mobile LiDAR System (HMLS) as new LiDAR tool to scan forest plots. HMLS data are compared to static TLS data (single and multi-scan) in terms of data acquisition, registration time and quality of automatic DBH extraction. The low weight, small size of the instrument and no targets requirements reduce the time of pre-scan preparations to the time needed for single scan which is 6 times less than scanning a plot with 5 scans. The registration time depends of the time spent to scan the plot and it is of the same magnitude than single scan. The resulting point cloud of the HMLS is noisier than TLS point clouds. Nevertheless, error on DBH estimations is similar to scanning a plot with a TLS positioned at 5 locations. RMSE is higher than multi-scan and close to single scan for trees detected by the both LiDAR technologies. This first study exhibits the high potential of HMLS by its simple use, which needs only one operator while presenting similar results in automatic DBH extraction than static TLS. Technology and registering method improvements of this type of mobile LiDAR will reduce the noise of the point cloud, which might reduce the DBH RMSE. [less ▲]Detailed reference viewed: 227 (29 ULg)
Forest radiative transfer models: which approach for which application?
Ligot, Gauthier ; ; et al
in Canadian Journal of Forest Research = Journal Canadien de la Recherche Forestière (2014), 44(5), 385-397Detailed reference viewed: 99 (34 ULg)
Forest refugia revisited: nSSRs and cpDNA sequences support historical isolation in a wide-spread African tree with high colonization capacity, Milicia excelsa (Moraceae)
Daïnou, Kasso ; Bizoux, Jean-Philippe ; Doucet, Jean-Louis et al
in Molecular Ecology (2010), 19
The impact of the Pleistocene climate oscillations on the structure of biodiversity in tropical regions remains poorly understood. In this study, the forest refuge theory is examined at the molecular ... [more ▼]
The impact of the Pleistocene climate oscillations on the structure of biodiversity in tropical regions remains poorly understood. In this study, the forest refuge theory is examined at the molecular level in Milicia excelsa, a dioecious tree with a continuous range throughout tropical Africa. Eight nuclear microsatellites (nuSSRs) and two sequences and one microsatellite from chloroplast DNA (cpDNA) showed a deep divide between samples from Benin and those from Lower Guinea. This suggests both that these populations were isolated in separate geographical regions, probably for several glacial cycles of the Pleistocene, and a poor mixture of gene pools despite M. excelsa’s wind-pollination syndrome. The divide can also be related to seed dispersal patterns, which should be largely determined by the migration behaviour of M. excelsa's main seed disperser, the frugivorous bat Eidolon helvum. Within Lower Guinea, a north-south divide, observed with both markers despite weak genetic structure (nuSSRs: FST=0.035, cpDNA: GST=0.506), suggested the existence of separate Pleistocene refugia in Cameroon and the Gabon/Congo region. We inferred a pollen-to-seed dispersal distance ratio of 1.76, consistent with wide-ranging gene dispersal by both wind and bats. Simulations in an Approximate Bayesian Computation framework suggested low nuSSR and cpDNA mutation rates but imprecise estimates of other demographic parameters, probably due to a substantial gene flow between the Lower Guinean gene pools. The decline of genetic diversity detected in some Gabonese populations could be a consequence of the relatively recent establishment of a closed canopy forest which may negatively affect M. excelsa's reproductive system. [less ▲]Detailed reference viewed: 65 (19 ULg)
Foresterie communautaire : les silences de la loi gabonaise
Conference (2008)Detailed reference viewed: 19 (2 ULg)
La foresterie communautaire au Cameroun en 2014. Bilan et perspectives 20 ans après la promulgation de la loi.
Conference (2014, April 03)Detailed reference viewed: 35 (6 ULg)
Foresterie communautaire au Cameroun et typologie du milieu chez les peuples forestiers: des représentations contradictoires?
Conference (1997)Detailed reference viewed: 18 (3 ULg)
La foresterie communautaire au Gabon : l'esprit de la loi
; ; et al
in Doucet, Jean-Louis; Vermeulen, Cédric (Eds.) Les premières forêts communautaires du Gabon : Récits d'une expérience pilote (2008)
Les forêts communautaires constituent une des innovations sociales les plus importantes de la nouvelle loi n° 016/01 portant code forestier au Gabon. Cet article détaille les différentes parties de la loi ... [more ▼]
Les forêts communautaires constituent une des innovations sociales les plus importantes de la nouvelle loi n° 016/01 portant code forestier au Gabon. Cet article détaille les différentes parties de la loi relatives à ces dernières et fournit une première interprétation de l’esprit de cette loi et de la volonté du législateur. Les grands thèmes qui y sont défendus tournent autour de la communauté locale, de la décentralisation de la gestion des ressources, de l’aménagement et de la gratuité. La volonté de l’état gabonais d’associer les populations à la gestion de la forêt dans l’optique de contribuer à la réduction de la pauvreté est évidente. [less ▲]Detailed reference viewed: 155 (13 ULg)
Foresterie en Wallonie: une source d'inspiration ?
Scientific conference (2010, November 10)Detailed reference viewed: 18 (5 ULg)
Foresterie sociale ou communautaire? Des approches complémentaires au Gabon
; ; et al
in Green Heart of Africa Bulletin (2011), (March), 12Detailed reference viewed: 94 (18 ULg)
ForEstimator : un nouvel outil cartographique pour mieux connaître la forêt wallonne
Dedry, Laurent ; De Thier, Olivier ; Perin, Jérôme et al
in Forêt-Nature (2015), (135), 40-46
Suite à l’acquisition par le Service public de Wallonie d’une couverture LiDAR de l’ensemble du territoire régional, et à l’établissement d’un modèle numérique de hauteur basé sur cette dernière, Gembloux ... [more ▼]
Suite à l’acquisition par le Service public de Wallonie d’une couverture LiDAR de l’ensemble du territoire régional, et à l’établissement d’un modèle numérique de hauteur basé sur cette dernière, Gembloux Agro-BioTech (GxABt) a mis au point un plugin QGIS, baptisé «ForEstimator», permettant aux gestionnaires et propriétaires forestiers de calculer facilement la hauteur dominante de leurs peuplements d’épicéas et de douglas équiennes. De plus, pour corriger l’ancienneté des données LiDAR, le plugin est couplé à un modèle de prédiction de la croissance de la hauteur dominante. Cette originalité permet d’actualiser l’estimation à une date postérieure à l’acquisition des données LiDAR. Parallèlement, l’équipe de GxABT a pu déterminer l’arbre le plus haut de Wallonie. Il s’agit d’un douglas de 61 mètres de haut au sein d’un peuplement mélangé de douglas et tsuga, planté en 1900, situé à Bouillon. ForEstimator permet aux gestionnaires forestiers de produire facilement des cartes de hauteur dominante, de productivité des peuplements, etc. [less ▲]Detailed reference viewed: 91 (27 ULg)