References of "Bogaert, Jan"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailAboveground biomass mapping of African forest mosaics using canopy texture analysis: towards a regional approach.
Bastin, Jean-François ULg; Barbier, Nicolas; Couteron, Pierre et al

in Ecological Applications (in press)

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 ▲]

Detailed reference viewed: 38 (26 ULg)
Full Text
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.

Detailed reference viewed: 9 (0 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 89 (22 ULg)
Full Text
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 ▲]

Detailed reference viewed: 22 (4 ULg)
Full Text
Peer Reviewed
See detailObituary Ivan Impens (1935-2014). Poor is the disciple who does not surpass his master
Bogaert, Jan ULg; Nijs, I; Ceulemans, R

in Tropicultura (2014), 32(1), 110-111

Detailed reference viewed: 8 (1 ULg)
Full Text
Peer Reviewed
See detailAnthropogenic effects in landscapes: Historical context and spatial pattern
Bogaert, Jan ULg; Vranken, Isabelle ULg; Andre, Marie ULg

in Hong, S.-K.; Bogaert, Jan; Min, Q. (Eds.) Biocultural Landscapes: Diversity, Functions and Values (2014)

Detailed reference viewed: 24 (2 ULg)
Full Text
Peer Reviewed
See detailSpatial patterns and morphology of termite ( Macrotermes falciger ) mounds in the Upper Katanga, D.R. Congo
Mujinjya, Baile Baziraké; Adam, Marielle; Mees, Florias et al

in Catena (2014), 114

This study examines the spatial distribution patterns and morphological characteristics of Macrotermes falciger mounds in the peri-urban zone of Lubumbashi, D.R. Congo. Spatial patterns of mounds were ... [more ▼]

This study examines the spatial distribution patterns and morphological characteristics of Macrotermes falciger mounds in the peri-urban zone of Lubumbashi, D.R. Congo. Spatial patterns of mounds were assessed using high-resolution satellite images for 24 plots of variable size (3 to 27 ha). Soil morphological features were described for five termite-mound profiles of 5 to 9 m depth/height. A mean areal number density of 2.9 ± 0.4 mounds ha−1 is estimated for the degraded miombo woodland of the study area. Spatial statistical analyses document that termite mounds are regularly distributed in all studied plots. The overall mean nearest-neighbour distance between termite mounds is 44.6 ± 0.6 m. The high relative number of inactive mounds in the region, with regular distribution patterns, suggests that current termite mound occurrences are largely relict features.There are no clear indications for an impact of the nature of the parent material on the spatial distribution of the mounds. One aspect of differences in morphology between the studied mounds is that the stone layer occurs at greater depth in topographic low areas than at crest and slope positions. This is interpreted as being mainlyconditionedbyerosion.Mn–Fe oxideconcentrationsoccurringinallstudiedtermite moundprofiles reflect a seasonally high perched water table beneath the mound, which is more pronounced at lower landscape positions. In summary, mound positions in the habitat are consistent with intraspecific competition rather than soil and substrate characteristics as controlling factor, whereas variation in morphological characteristics between termite-mound profiles appears to be a function of the parent material [less ▲]

Detailed reference viewed: 44 (7 ULg)
Full Text
See detailLe patron urbain, un facteur influençant l'impact de l'urbanisation sur les écosystèmes: les cas de Kisangani et de Lubumbashi (RDC)
Andre, Marie ULg; Mahy, Grégory ULg; Lejeune, Philippe ULg et al

in PACODEL (Ed.) Colloque international Territoires périurbains: développement, enjeux et perspectives dans les pays du sud (2013, December 19)

Les dynamiques et patrons paysagers de deux villes entre deux années (Kisangani entre 2002 et 2010 ; Lubumbashi entre 2002 et 2008, en République Démocratique du Congo) ont été étudiés afin d’évaluer leur ... [more ▼]

Les dynamiques et patrons paysagers de deux villes entre deux années (Kisangani entre 2002 et 2010 ; Lubumbashi entre 2002 et 2008, en République Démocratique du Congo) ont été étudiés afin d’évaluer leur influence sur l’impact de l’extension et/ou densification de ces villes, et plus particulièrement de leur zone périurbaine, sur leurs écosystèmes internes et périphériques. En effet, le patron paysager occupe une place fondamentale dans l’hypothèse centrale de l’écologie du paysage, appelée pattern-process paradigm puisqu’il influence les processus écologiques et inversement. Sa description et son analyse sont donc particulièrement importantes (Bogaert et al. 2004; Coulson et al. 1999). Les indices de composition, communément utilisés en écologie du paysage, décrivent entre autres le patron en quantifiant la présence et le nombre de taches issues des différentes classes du paysage (Alberti 2008). D’autre part, les villes ne cessant d'augmenter leur emprise sur les paysages dont elles font partie, l'étude des espaces qui les ceinturent, le phénomène de leur extension dans les régions rurales ainsi que les schémas conceptuels de leur morphologie et dynamique interne sont plus que jamais des sujets d'actualité (Bhatta et al., 2010; Borsdorf et al., 2002; De Blij, 1977; Gaston, 2010; Halleux, 2006). Paradoxalement, les scientifiques de différentes disciplines peinent à donner une définition, des caractéristiques et des limites acceptées par tous aux notions se rattachant aux différentes zones présentes dans le gradient urbain-rural. Cette étude se distingue des autres, généralement subjectives, par son approche quantifiée et objective. Pour chacune des deux villes, deux images SPOT 5 ont été classifiées sur base d’une approche orientée-objet (Definiens 2013). Ensuite, des indices de composition paysagère ont été évalués afin 1) d’identifier l’étendue de chaque zone (urbaine, périurbaine, rurale) au sein du gradient urbain-rural en utilisant les définitions de zones proposées par André et al. (sous presse), 2) de décrire ces différentes zones en quantifiant les caractéristiques morphologiques les plus couramment citées avant d’en borner les valeurs (André et al. 2012) et 3) de quantifier la dynamique des différentes zones au cours de la dernière décade. Ensuite, les similarités et différences entre ces villes ainsi que la pertinence et les faiblesses de la méthode ont été identifiées et discutées. Les résultats de cette étude ont pour ambition de contribuer à une meilleure compréhension et prise en compte du rôle du patron paysager dans la résistance potentielle des écosystèmes naturels à l’extension et/ou la densification d’une ville donnée. [less ▲]

Detailed reference viewed: 11 (1 ULg)
Full Text
See detailTous créatifs! Art et Science 2.0: Les scientifiques et l'art
Andre, Marie ULg; Leleux, Violaine ULg; Bogaert, Jan ULg

Conference (2013, October 08)

Detailed reference viewed: 14 (4 ULg)
Full Text
See detailCity pattern as a factor influencing the impact of urbanization on ecosystems - A diachronic analysis of the dynamic of two cities: Kisangani and Lubumbashi (Democratic Republic of Congo)
Andre, Marie ULg; Mahy, Grégory ULg; Lejeune, Philippe ULg et al

Conference (2013, September 06)

The patterns and 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 ... [more ▼]

The patterns and 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 they influence the impact of extension and/or of densification on urban internal and peripheral ecosystems. For each city two SPOT 5 images were classified with a oriented-object supervised approach; then composition landscape metrics (built area proportion index, anthropized surface proportion index, equitability index of area proportion of classes, dominant class index, dominant class proportion index) have been evaluated in order to 1) identify the extend of each area (urban, suburban, rural) within the urban-rural gradient, 2) quantify the most commonly cited morphological characteristics to describe these different areas and 3) quantify the dynamic of the different areas during this decade. Landscape ecology assumes that the landscape pattern description is important because, according to the 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. This study singularizes itself from the subjective ones by its quantified and objective approach. The similarities and differences between these cities, relevance and gaps in the method have then been identified and discussed. The results of this study are aimed to be used by urban planners for the evaluation of the potential resistance of internal and peripheral natural ecosystems to the extension and/or the densification of a given city, taking into account its pattern and dynamic. It might help them in their choice between different planning alternatives. [less ▲]

Detailed reference viewed: 18 (4 ULg)
Full Text
See detailCity pattern as a factor influencing the impact of urbanization on ecosystems - A diachronic analysis of the dynamic of two cities: Kisangani and Lubumbashi (Democratic Republic of Congo)
Andre, Marie ULg; Mahy, Grégory ULg; Lejeune, Philippe ULg et al

in Nunes Silva, Carlos (Ed.) Colonial and postcolonial urban planning in Africa (2013, September 06)

The patterns and 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 ... [more ▼]

The patterns and 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 they influence the impact of extension and/or of densification on urban internal and peripheral ecosystems. For each city two SPOT 5 images were classified with a oriented-object supervised approach; then composition landscape metrics (built area proportion index, anthropized surface proportion index, equitability index of area proportion of classes, dominant class index, dominant class proportion index) have been evaluated in order to 1) identify the extend of each area (urban, suburban, rural) within the urban-rural gradient, 2) quantify the most commonly cited morphological characteristics to describe these different areas and 3) quantify the dynamic of the different areas during this decade. Landscape ecology assumes that the landscape pattern description is important because, according to the 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. This study singularizes itself from the subjective ones by its quantified and objective approach. The similarities and differences between these cities, relevance and gaps in the method have then been identified and discussed. The results of this study are aimed to be used by urban planners for the evaluation of the potential resistance of internal and peripheral natural ecosystems to the extension and/or the densification of a given city, taking into account its pattern and dynamic. It might help them in their choice between different planning alternatives. [less ▲]

Detailed reference viewed: 40 (8 ULg)
Full Text
See detailLes vers à soie malgaches - Enjeux écologiques et socio-économiques
Verheggen, François ULg; Bogaert, Jan ULg; Haubruge, Eric ULg

Book published by Presses agronomiques de Gembloux (2013)

Cet ouvrage reflète les réalisations et activités scientifiques du projet de coopération universitaire « Gestion et valorisation durable du ver à soie endémique Borocera cajani en milieu forestier dans la ... [more ▼]

Cet ouvrage reflète les réalisations et activités scientifiques du projet de coopération universitaire « Gestion et valorisation durable du ver à soie endémique Borocera cajani en milieu forestier dans la région d’Antananarivo » financé par la Commission Universitaire pour le Développement (CUD). Ce projet de recherche est le fruit d’une collaboration étroite entre le Département des Eaux et Forêts de l’école Supérieure des Sciences Agronomiques de l’Université d’Antananarivo, l’Université de Liège et l’Université Libre de Bruxelles. Une première section de l’ouvrage porte sur les aspects biologiques et écologiques des vers à soie endémiques de Madagascar – avec l’accent sur le landibe (Borocera cajani) – notamment sa morphologie, l’estimation de son abondance dans l’aire étudiée, la dynamique de ses populations, ses interactions avec ses plantes hôtes, son comportement d’alimentation et son développement larvaire. La deuxième section étudie les dimensions écologiques et botaniques de l’habitat des vers à soie, à savoir les formations de tapia (Uapaca bojeri), principalement à travers les aspects sylvicoles et botaniques, les causes et indicateurs de dégradation, la discussion autour de sa dénomination, la diversité floristique, la régénération et l’inventaire des ressources sauvages comestibles et leurs caractéristiques chimiques. La troisième section renseigne sur l’état et la valorisation de la filière soie et couvre une diversité d’approches, allant des connaissances et savoir-faire des communautés locales au rôle de la soie dans l’économie rurale. Le contexte socio-institutionnel ainsi que les interactions entre les acteurs concernés par la filière complètent ce volet. L’ouvrage contient 21 contributions scientifiques, rédigées par 34 auteurs, dont certains ont déjà fait l’objet d’une publication dans une revue internationale. Le volume a été composé sous la direction scientifique de François J. Verheggen, Jan Bogaert et éric Haubruge, enseignants à Gembloux Agro-Bio Tech (Université de Liège). Il s’adresse à tous ceux qui s’intéressent à la coopération universitaire et/ou aux recherches écologiques, entomologiques et sociologiques dans un contexte malgache. [less ▲]

Detailed reference viewed: 49 (13 ULg)
Full Text
Peer Reviewed
See detailConventional tree height-diameter relationships significantly overestimate aboveground carbon stocks in the Central Congo Basin
Kearsley, E; de Haulleville, Thalès ULg; Hufkens, K et al

in Nature Communications (2013), 4

Detailed reference viewed: 44 (12 ULg)
Full Text
See detailSynthesis and new definition of the areas included in the urban-rural gradient
Andre, Marie ULg; Mahy, Grégory ULg; Lejeune, Philippe ULg et al

Conference (2013, July 26)

Every scientific studies should begin with the delimitation of the studied system. Ours aims at evaluating and quantifying the resistence of landscape classes and ecosystems to the urbanization process ... [more ▼]

Every scientific studies should begin with the delimitation of the studied system. Ours aims at evaluating and quantifying the resistence of landscape classes and ecosystems to the urbanization process. This is done by studying a dozen cities in sub-Saharan Africa, conducting a diachronic (2000 - 2010) landscape evolution analysis from SPOT satellite imagery. Paradoxaly, when tackling this subject, one must recognize that no consensus exists about the definition and localization of the areas included in the urban-rural gradient. This prevents from comparing the results of different cities. A bibliography analysis has been conducted in order to 1) identify the different areas in the urban-rural gradient, the characteristics and types of characteristics used to define the most cited ones (i.e. urban, suburbs, sprawl, exurban, rurban, periurban and rural) ; 2) Through citation frequency indexes, evaluate the relative importance of characteristics and types of characteristics for every area and then for the whole gradient; 3) Evaluate the principal characteristics according to a series of criteria (the best characteristic is supposed to be quantitative, integrative, marking a consensus, discriminative and easy to apply on the field); 4) On the basis of retained characteristics, propose single and simple definitions to the most cited areas. These new definitions aim at enable areas identification on the field and on satellite images. These new definitions have been applied to the field study of the city of Lubumbashi (D.R.C) and seem to be convenient. Retained characteristics have then been translated into landscape composition indexes for the future study of the following cities on basis of satellite imagery, without field research. Indeed, such indexes are commonly used in landscape ecology because they allow the description of the urban landscape pattern or structure which, according to the central hypothesis of landscape ecology, i.e. “pattern-process paradigm”, influence landscape ecological processes. [less ▲]

Detailed reference viewed: 22 (4 ULg)
Full Text
Peer Reviewed
See detailAbove-ground biomass and structure of 260 african tropical forests
Lewis, Simon L.; Sonké, Bonaventure; Sunderland, Terry et al

in Philosophical Transactions of the Royal Society B (2013), 368

We report above-ground biomass (AGB), basal area, stemdensity and wood mass density estimates from 260 sample plots (mean size: 1.2 ha) in intact closed-canopy tropical forests across 12 African countries ... [more ▼]

We report above-ground biomass (AGB), basal area, stemdensity and wood mass density estimates from 260 sample plots (mean size: 1.2 ha) in intact closed-canopy tropical forests across 12 African countries. Mean AGB is 395.7 Mg dry mass ha21 (95% CI: 14.3), substantially higher than Amazonian values, with the Congo Basin and contiguous forest region attaining AGB values (429 Mg ha21) similar to those of Bornean forests, and significantly greater than East or West African forests. AGB therefore appears generally higher in palaeo- comparedwithneotropical forests.However, mean stem density is low(426+11 stems ha21 greater than or equal to 100 mm diameter) compared with both Amazonian and Bornean forests (cf. approx. 600) and is the signature structural feature of African tropical forests. While spatial autocorrelation complicates analyses, AGB shows a positive relationship with rainfall in the driest nine months of the year, and an opposite association with the wettest three months of the year; a negative relationship with temperature; positive relationship with clay-rich soils; and negative relationshipswith C :Nratio (suggesting a positive soil phosphorus–AGB relationship), and soil fertility computed as the sum of base cations. The results indicate that AGB is mediated by both climate and soils, and suggest that the AGB of African closed-canopy tropical forests may be particularly sensitive to future precipitation and temperature changes. [less ▲]

Detailed reference viewed: 50 (24 ULg)
Full Text
See detailGradient urbain-rural de la ville de Lubumbashi: dynamique entre 2002 et 2009
Andre, Marie ULg; Bogaert, Jan ULg; Mahy, Grégory ULg et al

in Ernoult, Aude (Ed.) Dynamiques écologiques des paysages: de l'agricole à l'urbain (2013, June 12)

Detailed reference viewed: 18 (5 ULg)