References of "Bogaert, Jan"
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See detailInterprétation paysagère du processus d’urbanisation à Lubumbashi (RD Congo): dynamique de la structure spatiale et suivi des indicateurs écologiques entre 2002 et 2008
Useni Sikuzani, Yannick; Andre, Marie ULg; Mahy, Grégory ULg et al

in Mahy, Grégory; Colinet, Gilles; Bogaert, Jan (Eds.) Anthropisation au Katanga (in press)

Lubumbashi is one of the fastest growing African cities with annual population growth rates of 5 %. Its urban population growth leads to a rapid urban growth associated with several environmental problems ... [more ▼]

Lubumbashi is one of the fastest growing African cities with annual population growth rates of 5 %. Its urban population growth leads to a rapid urban growth associated with several environmental problems. This study test hypothesis that rapid built-up growth is followed by natural habitats decrease and creates favorable conditions for the spread of Tithonia diversifolia, an invasive specie. From two SPOT satellite images from 2002 and 2008 supported by field visits, seven land cover classes were obtained and the accuracy of the classification was verified. Landscape dynamic has been demonstrated through a transition matrix, by calculating spatial pattern metrics and identification of spatial transformation processes. The results obtained show that built-up covering 32 % of the landscape in 2008 against 22.6 % of the landscape in 2002. Its growth, followed by Tithonia diversifolia and anthropogenic vegetation, operates to the detriment of natural classes. The effect of human impact was translated by the increase of disturbance index which increased from 1.9 to 3.3 in six years, confirming that in the study area, natural classes are removed parallel to aggregation and creating of anthropogenic classes. The study area has undergone significant changes related to urban growth, which implies establishing efficient urban planning and management policies to reverse this trend. [less ▲]

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See detailQuantification of anthropogenic effects in the landscape of Lubumbashi
Andre, Marie ULg; Vranken, Isabelle ULg; Boisson, Sylvain ULg et al

in Mahy, Grégory; Colinet, Gilles; Bogaert, Jan (Eds.) Anthropisation au Katanga (in press)

In order to understand the dynamic of the (sub)urbanisation and so, to quantify the anthropogenic effects of the rapid growth of tropical cities, it is crucial to find and apply valuable methods. In this ... [more ▼]

In order to understand the dynamic of the (sub)urbanisation and so, to quantify the anthropogenic effects of the rapid growth of tropical cities, it is crucial to find and apply valuable methods. In this contribution, the transferability of the Rüdisser et al. (2012) «Distance to Nature» hemeroby assessment method to the landscape surrounding the city of Lubumbashi (DRC) is evaluated. That methodology has the advantage of taking structural connectivity into account by computing the distance to natural habitats. As it had never been applied to an African city before, some adjustments (fitting of the local land uses types into the hemeroby levels designed to Austria) and amendments (suppression of the final classification into hemeroby level simplification) are proposed. Moreover, an analysis of the decanal (2002-2013) hemeroby dynamics is presented. Results suggest that the Distance to Nature methodology is transferable but requires good field knowledge to define reference habitats and identify them in the Landsat classified images. There was a dramatic decrease of the «natural» and «near-natural» levels in the study extent during the studied period. In addition, 32% of the land underwent anthropisation increase, mostly around cities and following a ribbon development. [less ▲]

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See detailOptimization of a cheap and residential small-scale production of edible crickets with local by-products as an alternative protein-rich human food source in Ratanakiri Province (Cambodia)
Caparros Megido, Rudy ULg; Alabi, Taofic ULg; Nieus, Clément et al

in Journal of the Science of Food and Agriculture (2016)

Background - Health status of the indigenous people of the Ratanakiri Province, Cambodia, is significantly lower compared to the rest of the nation. The domestication and mass production of insects may ... [more ▼]

Background - Health status of the indigenous people of the Ratanakiri Province, Cambodia, is significantly lower compared to the rest of the nation. The domestication and mass production of insects may represent a sustainable, cost effective and high quality alternative source of protein to traditional livestock. This study aimed to optimise a cheap and residential cricket breeding system based on unused wild resources. The cricket development, Teleogryllus testaceus (Walker), under seven diets composed of taro aerial parts, young cassava leaves, young cashew leaves and brown rice flour (with or without banana slices), versus a traditionally used broiler feed diet was studied. Results - Cricket mortality was low in all diets, except the two cashew-based diets. Total biomass was significantly higher under the broiler feed, in addition to the two diets containing a combination of cassava leaf powder and brown rice. Yet, crickets fed with the taro diet had the highest percentage of protein. Concerning the breeding system cost, units using cassava leaves were the cheapest ones. Conclusion – Diets based of cassava leaves seems to be the most promising ones. Nevertheless, to produce crickets with a high body mass and a high protein level, a new experiment must be realised in which the cassava leaf maturity will be adapted to fit with the cricket growth stage. Moreover, to reduce the cost of the breeding units, handmade local products should be used instead of purchased components. [less ▲]

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See detailTerritoires périurbains. Développement, enjeux et perspectives dans les pays du Sud.
Bogaert, Jan ULg; Halleux, Jean-Marie ULg

Book published by Presses agronomiques de Gembloux (2015)

Nous assistons actuellement au peuplement des zones périurbaines de la planète par des centaines de millions d’individus. Cette évolution pose de redoutables problèmes et des difficultés inédites pour les ... [more ▼]

Nous assistons actuellement au peuplement des zones périurbaines de la planète par des centaines de millions d’individus. Cette évolution pose de redoutables problèmes et des difficultés inédites pour les politiques publiques. Si les effets de la périurbanisation sont relativement bien connus dans les pays du Nord, les analyses dédiées aux pays du Sud sont bien moins développées. L’ouvrage « Territoires périurbains : développement, enjeux et perspectives dans les pays du Sud » permet de lever un coin du voile sur cette problématique et sur les grands défis que la périurbanisation pose pour le Sud en général et pour l’Afrique centrale en particulier. L’ouvrage débute en cherchant à clarifier ce qu’il faut exactement entendre par « territoire périurbain ». À la suite de cette mise en contexte, il se poursuit par cinq parties organisées autour des problématiques des ressources naturelles, de la sécurité alimentaire, de la santé publique, des services publics et de l’aménagement des territoires. Pour chacune de ces problématiques, des chercheurs spécialisés issus de disciplines variées apportent des contributions qui, tout en soulignant l’ampleur des défis, permettent la mise en avant de solutions innovantes pour améliorer la gouvernance et le bien-être des populations. Cet ouvrage s’adresse d’abord aux chercheurs préoccupés par les défis du développement. En parallèle, par les pistes pour l’action publique qu’il esquisse, il ne manquera pas d’également intéresser les décideurs et les praticiens qui opèrent dans le contexte des territoires périurbains des pays du Sud. [less ▲]

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See detailPeri-urban dynamics: landscape ecology perspectives
Bogaert, Jan ULg; Biloso, Apollinaire; Vranken, Isabelle et al

in Bogaert, Jan; Halleux, Jean-Marie (Eds.) Territoires périurbains: Développement, enjeux et perspectives dans les pays du sud (2015)

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See detailWood Specific Gravity Variations and Biomass of Central African Tree Species: The Simple Choice of the Outer Wood
Bastin, Jean-François ULg; Fayolle, Adeline ULg; Tarelkin, Yegor et al

in PLoS ONE (2015)

Context: Wood specific gravity is a key element in tropical forest ecology. It integrates many aspects of tree mechanical properties and functioning and is an important predictor of tree biomass. Wood ... [more ▼]

Context: Wood specific gravity is a key element in tropical forest ecology. It integrates many aspects of tree mechanical properties and functioning and is an important predictor of tree biomass. Wood specific gravity varies widely among and within species and also within individual trees. Notably, contrasted patterns of radial variation of wood specific gravity have been demonstrated and related to regeneration guilds (light demanding vs. shade-bearing). However, although being repeatedly invoked as a potential source of error when estimating the biomass of trees, both intraspecific and radial variations remain little studied. In this study we characterized detailed pith-to-bark wood specific gravity profiles among contrasted species prominently contributing to the biomass of the forest, i.e., the dominant species, and we quantified the consequences of such variations on the biomass. Methods: Radial profiles of wood density at 8% moisture content were compiled for 14 dominant species in the Democratic Republic of Congo, adapting a unique 3D X-ray scanning technique at very high spatial resolution on core samples. Mean wood density estimates were validated by water displacement measurements. Wood density profiles were converted to wood specific gravity and linear mixed models were used to decompose the radial variance. Potential errors in biomass estimation were assessed by comparing the biomass estimated from the wood specific gravity measured from pith-to-bark profiles, from global repositories, and from partial information (outer wood or inner wood). Results: Wood specific gravity profiles from pith-to-bark presented positive, neutral and negative trends. Positive trends mainly characterized light-demanding species, increasing up to 1.8 g.cm-3 per meter for Piptadeniastrum africanum, and negative trends characterized shade-bearing species, decreasing up to 1 g.cm-3 per meter for Strombosia pustulata. The linear mixed model showed the greater part of wood specific gravity variance was explained by species only (45%) followed by a redundant part between species and regeneration guilds (36%). Despite substantial variation in wood specific gravity profiles among species and regeneration guilds, we found that values from the outer wood were strongly correlated to values from the whole profile, without any significant bias. In addition, we found that wood specific gravity from the DRYAD global repository may strongly differ depending on the species (up to 40% for Dialium pachyphyllum). Main conclusion: Therefore, when estimating forest biomass in specific sites, we recommend the systematic collection of outer wood samples on dominant species. This should prevent the main errors in biomass estimations resulting from wood specific gravity and allow for the collection of new information to explore the intraspecific variation of mechanical properties of trees. [less ▲]

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See detailAnthropogenic landscape change: synthesis of the concepts and quantification methods
Andre, Marie ULg; Vranken, Isabelle ULg; Mahy, Grégory ULg et al

Conference (2015, August 26)

Anthropogenic disturbances impact the whole biosphere, at least indirectly, and are of major concern in various disciplines and policies. To tackle it, most studies, specific to their thematic, create ... [more ▼]

Anthropogenic disturbances impact the whole biosphere, at least indirectly, and are of major concern in various disciplines and policies. To tackle it, most studies, specific to their thematic, create their own reference framework without connection with related purposes in other disciplines. This results in a plethora of terms and concepts that in turn impedes addressing that issue on a comprehensive way as well as complementarity between studies. Here, we clarify and synthesize the most frequently employed terms to characterise human impact on the environment (anthropisation, naturalness, hemeroby, novel ecosystem, analogous ecosystem, climax, etc.), their synonyms, the nuances and relationships between each of them, as well as the concepts used to designate the responses given by humans to environmental disturbances (restoration, management, conservation). We go on reviewing the methods used to assess anthropogenic changes, exploring different branches of ecology and geography. The strengths and weaknesses of the existing approaches are then used as a basis to develop a new analytical framework: we propose an action-oriented type of naturalness, and we develop a general methodology to quantify landscape anthropisation. Our methodology combines object-oriented and gradient analyses. Moreover, it is based on the assessment of ecosystem disturbance, landscape configuration and dynamics as well as on easily acquired data sets. Our integrated approach of the concern could be at the basis of land planning, environmental restoration and management practices as well as policies. [less ▲]

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See detailSeeing Central African forests through their largest trees
Bastin, Jean-François ULg; Barbier, Nicolas; Réjou-Méchain, Maxime et al

in Scientific Reports (2015)

Large tropical trees and a few dominant species were recently identified as the main structuring elements of tropical forests. However, such result did not translate yet into quantitative approaches which ... [more ▼]

Large tropical trees and a few dominant species were recently identified as the main structuring elements of tropical forests. However, such result did not translate yet into quantitative approaches which are essential to understand, predict and monitor forest functions and composition over large, often poorly accessible territories. Here we show that the above-ground biomass (AGB) of the whole forest can be predicted from a few large trees and that the relationship is proved strikingly stable in 175 1-ha plots investigated across 8 sites spanning Central Africa. We designed a generic model predicting AGB with an error of 14% when based on only 5% of the stems, which points to universality in forest structural properties. For the first time in Africa, we identified some dominant species that disproportionally contribute to forest AGB with 1.5% of recorded species accounting for over 50% of the stock of AGB. Consequently, focusing on large trees and dominant species provides precise information on the whole forest stand. This offers new perspectives for understanding the functioning of tropical forests and opens new doors for the development of innovative monitoring strategies. [less ▲]

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See detailAnatomic features underlying wood density, in 110 rainforest tree species from central Congo basin
de Haulleville, Thalès ULg; Rousseau, Mélissa; Morin-Rivat, Julie ULg et al

Poster (2015, May)

Investigate the influence of fiber thickness and vessel diameter on the wood density in 110 rainforest tree species, and the relationships between wood density, wood water content and shrinking ratio.

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See detailTerritoires périurbains : développement, enjeux et perspectives dans les pays du Sud. Une introduction générale
Halleux, Jean-Marie ULg; Courtejoie, Fabienne ULg; Dawance, Sophie ULg et al

in Bogaert, Jan; Halleux, Jean-Marie (Eds.) Territoires périurbains Développement, enjeux et perspectives dans les pays du Sud (2015)

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See detailCosts and Added Value in the Marketing of Charcoal in Bujumbura
Sabuhungu, Emery Gaspard ULg; Ndimanya, Patrice; Bogaert, Jan ULg et al

in Global Journal of Emerging Trends in e-Business, Marketing and Consumer Psychology (2015), 1(2), 328-336

This study analysed the costs, the added value and its components in the marketing of charcoal in Bujumbura to identify areas in which interventions could improve efficiency in the charcoal marketing ... [more ▼]

This study analysed the costs, the added value and its components in the marketing of charcoal in Bujumbura to identify areas in which interventions could improve efficiency in the charcoal marketing system. The study surveyed 100 retailers and 30 wholesale traders of charcoal. The information on their business was collected using a standardized questionnaire. The structure of marketing costs shows that transport and rental to civil servants are the main items in which significant efficiency gains could be achieved. Charcoal marketing is a wealth-creating activity as it generates positive added value. Our results suggest that any improvement in transport infrastructure in rural areas will benefit market efficiency. ___________________________________________________________________________ [less ▲]

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See detailLes vers à soie sauvages à Madagascar : Enjeux écologiques et socio-économiques
Verheggen, François ULg; Haubruge, Eric ULg; Bogaert, Jan ULg

in Entomologie Faunistique = Faunistic Entomology (2015), 68

We here introduce the book « The Malagasy silk moths: ecological and socio-economic challenges » published in 2013 by the Presses agronomiques de Gembloux (Belgium). This book reflects the achievements ... [more ▼]

We here introduce the book « The Malagasy silk moths: ecological and socio-economic challenges » published in 2013 by the Presses agronomiques de Gembloux (Belgium). This book reflects the achievements and scientific activities of the project "Sustainable Management and valorisation of the endemic silkworm Borocera cajani in forest areas in the Antananarivo region" funded by Commission universitaire pour le Développement (CUD - CIUF). [less ▲]

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See detailTermite mound identification through aerial photographic interpretation in Lubumbashi , Democratic Republic of the Congo : methodology evaluation
Vranken, Isabelle ULg; Adam, Marielle; Mujinya Baziraké, Basile et al

in Tropical Conservation Science (2014), 7(4), 733-746

Les termites des régions tropicales sont d’une importance critique pour le fonctionnement et les services écosystémiques dans les régions de forêt claire et de savane. Les termitières peuvent également ... [more ▼]

Les termites des régions tropicales sont d’une importance critique pour le fonctionnement et les services écosystémiques dans les régions de forêt claire et de savane. Les termitières peuvent également être utilisées comme engrais et bio-indicateurs de perturbations anthropiques telles que l’agriculture ou la production de charbon. La télédétection peut contribuer à identifier et caractériser la densité et la distribution des termitières à moindres frais. Afin de tester son efficacité, les termitières ont été identifiées sur le terrain et comparées avec les résultats d’interprétation de photographies aériennes Google Earth en libre accès. Cette comparaison a été appliquée sur 17 sites dans l’hinterland de la ville minière de Lubumbashi, Katanga, République Démocratique du Congo, confrontée à une croissance élevée de population, à l’insécurité alimentaire ainsi que d’intenses fragmentation et dégradation de la couverture originelle de forêt claire (Miombo). Les influences de la hauteur et du diamètre des termitières ainsi que de la période d’acquisition de l’image (année et saison) ont été testées statistiquement. Le nombre de termitières observées sur le terrain est généralement surestimé sur l’image. La hauteur et la saison des pluies en favorisent l’identification correcte, tandis que la distribution spatiale n’est pas significativement influencée par les erreurs d’identification. Un modèle correctif a été défini et sa pertinence statistiquement vérifiée. L’identification des termitières via Google Earth s’avère efficace tant que la position précise de chaque termitière n’est pas requise. Cette approche constitue une réduction considérable des coûts de missions de terrain liées aux études sur les termitières. [less ▲]

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See detailAboveground biomass mapping of African forest mosaics using canopy texture analysis: toward a regional approach.
Bastin, Jean-François ULg; Barbier, Nicolas; Couteron, Pierre et al

in Ecological Applications (2014), 24(8), 1984-2001

In the context of the reduction of greenhouse gas emissions caused by deforestation and forest degradation (the REDD+ program), optical very high resolution (VHR) satellite images provide an opportunity ... [more ▼]

In the context of the reduction of greenhouse gas emissions caused by deforestation and forest degradation (the REDD+ program), optical very high resolution (VHR) satellite images provide an opportunity to characterize forest canopy structure and to quantify aboveground biomass (AGB) at less expense than methods based on airborne remote sensing data. Among the methods for processing these VHR images, Fourier textural ordination (FOTO) presents a good potential to detect forest canopy structural heterogeneity and therefore to predict AGB variations. Notably, the method does not saturate at intermediate AGB values as do pixelwise processing of available space borne optical and radar signals. However, a regional scale application requires to overcome two difficulties: (i) instrumental effects due to variations in sun-scene-sensor geometry or sensor-specific responses that preclude the use of wide arrays of images acquired under heterogeneous conditions and (ii) forest structural diversity including monodominant or open canopy forests, which are of particular importance in Central Africa. In this study, we demonstrate the feasibility of a rigorous regional study of canopy texture by harmonizing FOTO indices of images acquired from two different sensors (Geoeye-1 and QuickBird-2) and different sun-scene-sensor geometries and by calibrating a piecewise biomass inversion model using 26 inventory plots (1 ha) sampled across very heterogeneous forest types. A good agreement was found between observed and predicted AGB (RSE=15%; R²=0.85; p-value<0.001) across a wide range of AGB levels from 26 Mg/ha to 460 Mg/ha, and was confirmed by cross validation. A high-resolution biomass map (100 m pixels) was produced for a 400 km² area, and predictions obtained from both imagery sources were consistent with each other (r=0.86; slope=1.03; intercept=12.01 Mg/ha). These results highlight the horizontal structure of forest canopy as a powerful descriptor of the entire forest stand structure and heterogeneity. In particular, we show that quantitative metrics resulting from such textural analysis offer new opportunities to characterize the spatial and temporal variation of the structure of dense forests and may complement the toolbox used by tropical forest ecologists, managers or REDD+ national monitoring, reporting and verification bodies. [less ▲]

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See detailDeuxième mission de terrain dans la reserve de Yangambi
de Haulleville, Thalès ULg; Bogaert, Jan ULg; Beeckman, Hans

Scientific conference (2014, March 18)

Presentation of Thales de Haulleville's planned fieldwork during his second field mission.

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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 ▲]

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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 ▲]

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