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See detailDynamique d’expansion du Pic mar (Dendrocopos medius) en Belgique
Lehaire, François ULg

in Acte du 33 ième Colloque francophone d’ornithologie (2009, December)

Middle Spotted Woodpecker is one of the key species for which understanding the relationship with its habitat can have important implications for improving biodiversity-friendly management of hardwood ... [more ▼]

Middle Spotted Woodpecker is one of the key species for which understanding the relationship with its habitat can have important implications for improving biodiversity-friendly management of hardwood forests. This species is considered as an indicator of a forest ecosystem comprising a high proportion of mature trees and a botanical composition chiefly associated with oaks. For the last two decades, the Middle Spotted Woodpecker distribution range is expanding remarkably in the Walloon Region while, in contrast, other populations are either decreasing in the south-east of Europe or remain stable elsewhere in Europe. The study of this expansion range within the Walloon Region and of the forest habitats used therein is necessary to better assess the ecological requirements of the species. Based on more than 3,000 location data collected in the framework of the Atlas of breeding birds between 2001 and 2007, our study aimed at comparing forest habitats occupied by Middle Spotted Wood peckers between three geographically distinct areas, defined on the basis of the temporal evolution of the species’ distribution in the Walloon Region: the old distribution range, described from 1973-1977 and corresponding to the Ardennes and the Lorraine regions (southern Belgium), the transition range, defined in 1991-1992 and corresponding to the Fagne-Famenne region, and the expansion range, described in 2001-2007 and corresponding to the area colonized further north in the Loess region and Condroz. Overall, 418 woodpecker locations were crossed with 41 forest habitat variables available as part of the Regional Forest Inventory of the Walloon Region (IPRFW). Preliminary results suggest that, in agreement with previously known environmental requirements, forest stands presenting high densities in oak trees have been colonized by the Middle Spotted Woodpecker during its recent range expansion. However, the species is also expanding towards areas with a lower proportion of beech trees compared to the old distribution range, with a marked preference for forest stands presenting high tree diversity. We conclude that the Middle Spotted Woodpecker may exhibit a certain flexibility regarding its habitats requirements in Walloon forests, which led us to suggest several recommendations aimed at promoting the conservation of the species and of the forest biodiversity in general. [less ▲]

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See detailDynamique d’une espèce ligneuse héliophile longévive dans un monde changeant le cas de Pericopsis elata (Harms) Meeuwen (Fabaceae) au sud-est du Cameroun
Bourland, Nils ULg; Doucet, Jean-Louis ULg

Scientific conference (2014, May 13)

Exposé sur l'origine et la dynamique des peuplements formés par Pericopsis elata au Sud-Est du Cameroon.

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See detailDynamique d’une espèce ligneuse héliophile longévive dans un monde changeant : le cas de Pericopsis elata (Harms) Meeuwen (Fabaceae) au sud est du Cameroun
Bourland, Nils ULg

Doctoral thesis (2013)

The Central African forests are characterized by high species richness. While little light generally reaches their litter layer, among the species encountered are major long-lived light-demanding logged ... [more ▼]

The Central African forests are characterized by high species richness. While little light generally reaches their litter layer, among the species encountered are major long-lived light-demanding logged trees. These species may have established in the past because of large disturbances. Indeed, major climate changes have occurred in the past few millennia, in some areas coupled with strong human occupations. Among these light-demanding species we find the assamela / afrormosia (Pericopsis elata (Harms) Meeuwen, Fabaceae), a large high trading value tree of African semi-deciduous moist forests. Nowadays this logged species suffers from significant regeneration problems on its natural range from Ghana to the Democratic Republic of Congo. Therefore, it is included in CITES Appendix II and is recorded as “Endangered A1cd” on the IUCN Red List. No convincing solution can be found in the available scientific literature to overcome the deficiency of its regeneration. In addition, little or no information is available describing ca. its population dynamics, genetics, silviculture or the probable origin of its stands. It is in this context that the present PhD was undertaken. In this study, we have adopted a multidisciplinary approach to understanding the dynamics of this population rich in long-lived light-demanding species logged in the Congo basin. Moreover, we have suggested ways for their management and conservation in a changing world. To do so, we have adopted as a study-model the case of P. elata in southeastern Cameroon. The main results of the study show that, on a local scale, physico-chemical soil parameters have no influence on the presence or absence of this clustered species. However, on the same scale, large quantities of charcoal were found in the soil, mainly inside those clusters. The anthracological analysis has also shown that the vegetation at the time of the burn was similar to that of today. Numerous fragments of pottery were also found in the top soil layers only inside clusters formed by the species. Finally, some 14C datings go back to ca. 200 years BP, which is approximately the average age of concerned clusters. This body of evidence leads us to conclude on an ancient form of shifting cultivation as the most likely origin of the assamela populations currently present in southeastern Cameroon. In addition to its current population structure within the study area, several parameters controlling its population dynamics were estimated. While the annualized natural mortality of the species reaches about 1%, its average diameter growth rate is 0.31 cm.year-1, which is a relatively low value compared to other long-lived light-demanding species. Selective logging seems to have only a light influence on the behavior of the species. On the other hand, the impact of logging on its seed tree populations is only ca. 12%. Each seed tree bears fruit on average only once every five years. The minimum diameter of reproduction and the effective flowering diameter were respectively 32 and 37 cm. The recovery rate, varying greatly from one country to another, is more than 100% in Cameroon, where the conservation status assigned to the species seems excessive. A sufficient regeneration by planting should allow the perpetuation of the assamela populations in the long run, as with other major logged light-demanding trees. [less ▲]

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See detailDynamique d'une expérience spatiale: analyses et vérifications
Defise, Jean-Marc ULg

in Actes du 3ième Congrès national Belge de Mécanique Théorique et Appliquée (1994)

L'expérience EIT est un des nombreux instruments qui font partie de la charge utile du satellite SOHO de l'Agence Spatiale Européenne. A ce titre, un programme complet d'analyse et de vérification a été ... [more ▼]

L'expérience EIT est un des nombreux instruments qui font partie de la charge utile du satellite SOHO de l'Agence Spatiale Européenne. A ce titre, un programme complet d'analyse et de vérification a été mis en oeuvre pour démontrer la bonne tenue dynamique de l'instrument, sur base des spécifications imposées par l'ESA. Par ailleurs, le télescope est composé de plusieurs sous-systèmes réalisés et testés dans des laboratoires différents. Chaque élément est qualifié séparément, avant intégration du modèle de vol. Une approche de type "proto-flight" a été adoptée. Cet article décrit les principaux résultats des analyses et des essais effectués dans le cadre de ce projet. [less ▲]

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See detailDynamique d'une population de martins pêcheurs (Alcedo atthis) en Belgique en liaison avec la gestion des cours d'eau.
Libois, Roland ULg

in Actes du 1er colloque international "gestion et préservation des ressoures en eau" (2004, September)

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See detailDynamique de défense du nid chez Symphodus ocellatus (Forsskål, 1775), poisson labridé méditerranéen. I. Comportements agonistiques entre le mâle territorial nidificateur et cinq autres espèces de labridés
Ylieff, Marc ULg; Michel, Christian ULg; Voss, Jacques

in Cahiers d'Ethologie (1997), 17(1), 49-74

This research in the field consists of a study of interspecific agonistic behaviour of territorial male in Symphodus ocellatus. This behaviour is useful for brood and nest defense. Four questions ... [more ▼]

This research in the field consists of a study of interspecific agonistic behaviour of territorial male in Symphodus ocellatus. This behaviour is useful for brood and nest defense. Four questions involving Symphodus ocellatus towards S. tinca, S. mediterraneus, S. roissali, Thalassoma pavo et Coris julis were investigated. The questions of interest were: (1) aggressors or intruders motivations (predation of the brood (a) and/or territorial conflicts (b)), (2) the recognition of this or that species (recognition studied with selective attacks by territorial male), (3) the organ(s) of perception used for this recognition and (4) the importance of territorial male investment in nest defense; this role could ensure a successful reproduction of the species. Our observations and experimentations (tested labrid fishes presented to T. males) allow us to affirm that in S. ocellatus, nesting territorial males recognize the various tested labrid fishes; that the organ of perception used for social recognition is the visual channel; that spawn protection insured by territorial male, a task guided by his visual system, is necessary towards menace of his congeners, but also the other fishes living in his habitat. Nevertheless, if it’s becoming clear that the Mediterranean labrid fishes have the ability to recognize and preferentially interact with particular individuals, the answer of the question 1, concerning aggressors motivations, is not yet clearly known. [less ▲]

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See detailDynamique de défense du nid chez Symphodus ocellatus (Forsskål, 1775), poisson labridé méditerranéen. II. Comportements agressifs du mâle territorial nidificateur envers des mollusques gastéropodes
Ylieff, Marc ULg; Michel, Christian ULg; Voss, Jacques

in Cahiers d'Ethologie (1998), 18(1), 39-52

This field research examines aggressive behaviour towards gasteropod molluscs in nesting territorial male of Symphodus ocellatus. This behaviour is useful for brood and nest defense. Four questions ... [more ▼]

This field research examines aggressive behaviour towards gasteropod molluscs in nesting territorial male of Symphodus ocellatus. This behaviour is useful for brood and nest defense. Four questions involving Symphodus ocellatus towards gasteropod molluscs were investigated. Questions of interest were: (1) selective cleaning of the nest according to possible predation danger of molluscs on the eggs, (2) visual recognition of natural mollusc from artificially coloured lure, (3) colours discriminating abilities by the visual system and, more generally (4) the importance of territorial male investment in nest defense; this role could ensure a successful reproduction of the species. Our observations and experimentations (coloured dummies) allow us to conclude that in Symphodus ocellatus, nesting territorial males clean every time their nest, any gasteropod mollusc species whatever; that they have sufficient knowledge of their usual biological environment to be able to discriminate a gasteropod mollusc from a dummy; that the organ of perception used for social recognition is the visual channel constituted by a neural system competent to perceive colours finely , a special quality which support the theory about the use of one preferential colour (red for S.ocellatus) for visual communication; that fry protection insured by territorial male, a task guided by his visual system, is necessary considering dangers from some gasteropod molluscs living in his habitat. [less ▲]

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See detailDynamique de l'adaptation au temps et modèle de l'horloge interne
Ferrara, André ULg

Doctoral thesis (1999)

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See detailDynamique de la filière viande de brousse dans la partie continentale du Rio Muni en Guinée équatoriale
Njikam Nsangou, Ibrahim ULg

in Tropicultura (2004), 22(4), 204-210

The aim of this study was to do surveys about bush meat networks around urban centers near the Monte Alen National Park in Equatorial Guinea. During 8 weeks, in the Mundoasi market, one of two principal ... [more ▼]

The aim of this study was to do surveys about bush meat networks around urban centers near the Monte Alen National Park in Equatorial Guinea. During 8 weeks, in the Mundoasi market, one of two principal market of Bata, 4328 wild animal carcases have been indexed, representating 22,600 kg of biomass. A total of 48 animals species have been identified, including 14 which hunting are prohibited. The mammals represent 91.87% of total number with 3 dominants orders, ungulates (37.7%), primates (28.6%) and rodents (18%). The duiker (Cephalophus), the African Brushtailed Porcupine and Guenon are the most important. The district of Niefang, Bata and Evinayong are the principal sources of supply. Hunting with gun becomes very important, follow by snaring, a very wasteful method. Despite that this business squarely growth, signs of wildlife decrease are perceptible, showing evidence of overexploitation. As far as Monte Alen National Park is concerned, this study shows the positive effects of this protected area as wildlife reservoir for peripheral hunting zones. [less ▲]

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See detailDynamique de la haute atmosphère de Vénus
Stiepen, Arnaud ULg

Book published by Editions Universitaires Européennes (2014)

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See detailDynamique de la végétation d'altitude en Afrique centrale atlantique depuis 17 000 ans BP. Analyses préliminaires de la carotte de Bambili (Nord-Ouest du Cameroun).
Assi Kaudjhis, Chimène Cloche M ULg; LEZINE, ANNE - MARIE; Roche, Emile ULg

in Geo-Eco-Trop : Revue Internationale de Géologie, de Géographie et d'Ecologie Tropicales (2008), 32

This article presents the preliminary results of pollen analyses carried out on a 13.5m long core taken from the shore of the crater lake of Bambili, Cameroon (05°56'11.9N; 10°14' 31.6E; 2273m alt.). This ... [more ▼]

This article presents the preliminary results of pollen analyses carried out on a 13.5m long core taken from the shore of the crater lake of Bambili, Cameroon (05°56'11.9N; 10°14' 31.6E; 2273m alt.). This allows us to reconstruct the history of montane forest ecosystems from Atlantic Central Africa since 17 000 years BP. Well diversified microflora, show several changes. At the base of the pollen sequence, the vegetation is dominated by herbaceous plant populations such as Poaceae, associated with “dry” plant types from Amaranthaceae/ Chenopodiaceae families and tree and shrub plant types from savannas and open forest formations types such as Gnidia, Lannea, Combretaceae, Cussonia… The montane forest expansion started from 14 080cal BP with the appearance of the pioneer taxon Myrica. This taxon is followed by Schefflera, Podocarpus, Olea, Syzygium… which widely expanded in the immediate surroundings of the lake from 12 310 to 4 590 cal BP. After this date, the montane forest was strongly reduced. However a short phase of forest regrowth is recorded around 2000 BP during which Schefflera dominated the forest assemblage. [less ▲]

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See detailDynamique de modification de l'habitat physique de reproduction des pondeurs lithophiles sous gravier. Cas de deux frayères à ombre dans l'Aisne
Parkinson, Denis; Petit, François ULg; Houbrechts, Geoffrey ULg et al

in Bulletin de la Société Géographique de Liège (2001), 40

D’octobre 1998 à mars 1999, nous avons étudié dans l’Aisne, petit affluent ardennais de l’Ourthe, la dynamique de modification de deux bancs de gravier utilisés comme frayère par l’ombre commun en mars ... [more ▼]

D’octobre 1998 à mars 1999, nous avons étudié dans l’Aisne, petit affluent ardennais de l’Ourthe, la dynamique de modification de deux bancs de gravier utilisés comme frayère par l’ombre commun en mars-avril 1998. L’étude a été réalisée dans deux stations du cours inférieur de l’Aisne où se sont succédé quatre crues morphogènes. Dans chaque station, nous avons déterminé à intervalle d’environ 1 mois, la profondeur d’érosion et la hauteur de dépôt des sédiments (méthode de la barre d’érosion à chaînes), la granulométrie des matériaux des couches de surface et de subsurface, le dépôt des sédiments fins (placement de pièges à sédiments) et la perméabilité du substrat (méthode du standpipe). En complément, nous avons entrepris dans une station de l’Aisne moyenne, une caractérisation de divers éléments de la dynamique fluviale : identification des débits mobilisateurs (par marquage colorimétrique des sédiments en place), estimation de la vitesse de déplacement de la charge de fond (par étude de la dispersion longitudinale de scories, résidu d’anciennes industries métallurgiques) et estimation des quantités de sédiments charriés par la rivière (à partir des données de dragage). [less ▲]

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See detailDynamique de population de la Pie-grièche écorcheur (Lanius collurio) dans le sud-est de la Belgique : modélisation de l’influence du climat.
Metzmacher, Maxime ULg; van Nieuwenhuyse, Dries

in Revue d'Ecologie (La Terre et la Vie) (2012), 67(4), 353-374

In some areas of Western Europe, red-backed shrike populations, following a strong decline in the third quarter of the 20th century, were re-established in recent decades. Variations in climate seem to ... [more ▼]

In some areas of Western Europe, red-backed shrike populations, following a strong decline in the third quarter of the 20th century, were re-established in recent decades. Variations in climate seem to have played a crucial part in this striking evolution by modulating the species breeding success. In order to test this hypothesis, the annual fluctuations of several of these populations in south-eastern Belgium were compared with the variations in a series of climatic factors. This study derives from a number of censuses, completed during the breeding period between 1979 and 2008, and the data from the weather stations closest to the populations studied. The modelling of climate influence on annual population fluctuations is based on a Partial Least Squares regression (PLS), following the classification of variables using a latent variable approach. From 1980 to 2008, for the April-August period, the mean minimum temperature tended to rise. During these five months, rainfall intensity reached a minimum in the 1990’s and increased significantly thereafter. During the three last decades, rainfall intensity for June tended to decrease whereas that for August increased. The annual variations of these monthly averages were very high. As for breeding population fluctuations, our results highlighted the significant role of various parameters related to minimum temperature and pluviometry during the breeding period. Spring and cold wet summer periods seem to have a significant negative impact on the rate of breeder recruitment. These results suggest that the breeding success of red-backed shrike can benefit from global climate change due to the higher success rate of broods. This however applies provided that its habitat is preserved – in terms of quality and surface area – and that this warming does not generate overly high rainfall during a critical period of its breeding cycle. The importance of climatic factors in population fluctuations for this shrike provides opportunities for further investigation, particularly in studying the mechanisms that underlie these variations. [less ▲]

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See detailDynamique des constructions maritimes et offshores
Marchal, Jean ULg

Learning material (1979)

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