References of "Doucet, Jean-Louis"
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See detailDéfinition du profil écologique de l'azobé, Lophira alata, une espèce ligneuse africaine de grande importance : synthèse bibliographique et perspectives pour des recherches futures
Biwole, Achille ULg; Bourland, Nils ULg; Daïnou, Kasso ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(2), 217-228

Over two decades, labors made in order to promote sustainable management of African tropical forests are tackled to the lack of knowledge about this complex ecosystem. Ecological parameters of timber ... [more ▼]

Over two decades, labors made in order to promote sustainable management of African tropical forests are tackled to the lack of knowledge about this complex ecosystem. Ecological parameters of timber species are no more studied, this complicates long-term sustainable forest management. This literature review related to the ecology and silviculture of ekki, Lophira alata Banks ex C.F.Gaertn. (Ochnaceae), a main African timber species recorded as “vulnerable” in the IUCN Red List, will serve as a study’s case. The planned literature review reveals the doubt about its taxonomy, as well as the lack of understanding concerning its reproductive biology, growth conditions, population dynamics parameters, and the spatial distribution of its genetic diversity. The deficiency of knowledge about its ecological needs and the factors which have historically influenced its population dynamics explain why most silvicultural trails provide hazardous and uncertain results. Remedying these gaps in order to improve its ecological characterization and innovative silvicultural trails, would be a significant contribution to the sustainable management of its populations. [less ▲]

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See detailDynamique forestière et enrichissements forestiers. Site de Mbang. Rapport n° 8.
Doucet, Jean-Louis ULg; Amandé, Jean; Bracke, Charles et al

Report (2012)

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See detailRecent disturbances in the Congo Basin : an anthracological contribution to vegetation reconstructions
Morin-Rivat, Julie ULg; Hubau, Wannes; Gillet, Jean-François ULg et al

Poster (2012, March 01)

In contrast to the well-known vegetation history of the northern hemisphere, few is known about past vegetation change in Central Africa. However, recent palaeoecological and biogeographical studies ... [more ▼]

In contrast to the well-known vegetation history of the northern hemisphere, few is known about past vegetation change in Central Africa. However, recent palaeoecological and biogeographical studies suggest that early human disturbances had a substantial influence on Central Africa vegetation patterns, particularly allowing the expansion of light-demanding species. This interesting hypothesis is the basis of one of the main research questions of the ERA-net BIODIVERSA CoForChange project: what was and is the relationship between (increasing) human activity and vegetation change? A recently developed protocol for the identification of ancient Central African charcoal fragments opened the door for vegetation reconstructions with a high spatial and taxonomical resolution. Therefore, we chose to study macro-charcoals from pedoanthracological profiles situated in N Congo and SE Camero0n. In total, 48 taxa were found in nine radiocarbon dated profiles. At the moment, three taxa have been identified down to species level. First, we found numerous fragments of Gilbertiodendron dewevrei under a current monodominant forest of G. dewevrei (40 cm depth, 1421-1327 cal. BP). This seems to confirm the presumption that monodominant forests of G. dewevrei, shade-bearer species, are relatively stable. Second, we evidenced the lack of Triplochiton scleroxylon charcoals under a T. scleroxylon stand, which could confirm the hypothesis of the recent nature of those stands. Finally, our results suggest that taxonomic diversity of charcoal findings in open canopy Marantaceae forests is greater than in dense forests. Pterocarpus soyauxii and Millettia drastica have been found under an open Marantaceae forest at 40 cm depth (1184-1055 cal. BP). The abundance of the light-demanding species P. soyauxii appears to be decreasing over time (levels 20 to 40 cm depth) to the benefit of giant herbs. Anthracology in Central Africa is on the rise and the first results of the CoForChange project are promising. More identifications will follow, resulting in a better understanding of the evolution of Central African forests. [less ▲]

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See detailHow pristine is the Congo Basin forest ? Some answers from Erythrophleum spp. (Caesalpiniaceae) and Pericopsis elata (Fabaceae) natural stands in southeastern Cameroon
Bourland, Nils ULg; Livingstone Smith, Alexandre; Guion, Hélène ULg et al

Poster (2012, March 01)

Erythrophleum spp. and Pericopsis elata are two important African timber taxa suffering from regeneration problems. Those light demanding trees could have established in openings made by past human ... [more ▼]

Erythrophleum spp. and Pericopsis elata are two important African timber taxa suffering from regeneration problems. Those light demanding trees could have established in openings made by past human activities (mainly slash-and-burn cultivation). Our study aimed at verifying this assumption in a 340,000 ha forest concession in southeastern Cameroon. Anthracological excavations were made alongside transects opened in patches where those taxa occur as well as the surrounding environment. Numerous charcoal elements and some pottery fragments were found in excavated soils in all studied sites. Charcoals and pieces of pottery were found within the first 100 and 50 cm of soil, respectively. According to radiocarbon dating conducted on charcoals and burnt seeds, fires occurred between 2,150 to 195 years BP. This finding was consistent with the analysis of archaeological materials decoration techniques. Our results revealed intense past anthropological activities in this area, seriously questioning the assumption of a pristine Congo Basin [less ▲]

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See detailCould current Pericopsis elata (Fabaceae) patches in southeastern Cameroon be reasonably linked to past anthropogenic activities ?
Bourland, Nils ULg; Cerisier, François ULg; Livingstone Smith, Alexandre et al

Poster (2012, March 01)

Pericopsis elata is one of the most valuable African timber species. This IUCN Red Listed tree suffers from a lack of regeneration, thus its current presence provokes questioning. Our work aimed at ... [more ▼]

Pericopsis elata is one of the most valuable African timber species. This IUCN Red Listed tree suffers from a lack of regeneration, thus its current presence provokes questioning. Our work aimed at understanding its origins so as to help securing its future. This study, lead away from engineering works, was conducted in four different sites located within the natural distribution area of the species and took into account the different growing conditions were the species occurs. Our observations were based on an analysis of charcoal elements and pottery fragments discovered in subsurface layers of soils as well as on current botanical and pedological surveys. Discovered evidence of past human activities led to the assumption that this part of the Congo Basin was much more inhabited than previously thought. Some of the results obtained for P. elata could apply for other long lived light demanding species growing in the same environment. [less ▲]

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See detailRole of western lowland gorilla (Gorilla gorilla gorilla Savage & Wyman, 1847) on the dynamics of tropical logged forest ecosystems
Haurez, Barbara ULg; Petre, Charles-Albert ULg; Doucet, Jean-Louis ULg

Poster (2012, February 08)

The western lowland gorilla (Gorilla gorilla gorilla Savage & Wyman) (WLG) which is considered as a critically endangered species by IUCN, could play a fundamental function in seeds dispersal of several ... [more ▼]

The western lowland gorilla (Gorilla gorilla gorilla Savage & Wyman) (WLG) which is considered as a critically endangered species by IUCN, could play a fundamental function in seeds dispersal of several plant species. This could be related to its frugivorous diet, its stomach capacity and the long gut retention time of the ingested food, its extensive daily path length, and its ability to swallow seeds of variable sizes. In addition, this animal tends to deposit most of ingested seeds in suitable habitats (especially logging gaps and old logging roads) for light-demanding plant development. This research will be conducted within the moist evergreen forest of Central Gabon in a logging concession granted to the company CEB Precious Woods. A preliminary study was undertaken as a Master thesis. It was aiming at obtaining a first insight of interactions between WLG and timber exploitation in Central Gabon and at assessing the extent to which they may benefit of each other. WLG abundances were estimated in unlogged and logged sites in the concession, and nesting behavior described. Seeds dispersed during the study period (February-May) by WLG were identified through fecal analysis. Relatively high WLG abundances were observed in the concession. WLG were found to nest preferentially in open areas and to frequently use old logging road network for nesting and feeding. Sixteen species were observed to be dispersed by WLG. Seeds of the most abundant species, Santiria trimera, were subjected to four treatments: (1) passed seeds, (2) passed seeds in fecal matrix, (3) seeds surrounded by fresh pulp and (3) seeds extracted from fresh fruits. The germination successes of S. trimera were significantly higher after gut passage partly thanks to fruit pulp removal. Our PhD study aims to characterize the functional ecology of WLG in tropical forests dynamics, especially regarding logging biotopes. Our research will be organized in three parts: (1) the survey of gorilla populations in the study area coupled with the characterization of their nests and habitats, (2) the study of dispersed species and of the effect of passage through gorilla gut on seed germination, (3) the estimate of dispersal distances for the species Santiria trimera (Burseraceae) by using molecular markers. Data for the second and third parts will be collected in one site selected thanks to the results of the survey for its high gorilla density, to assess the following assumptions: (1) gorillas favor the regeneration of many plant species, including timber trees; (2) they improve the genetic diversity and limit the genetic structure by widening the genetic pool and dispersing diasporas on large distances. If these hypotheses are accepted, sylvicultural practices may be adapted so as to take advantage from the presence of gorilla population. [less ▲]

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See detailDéfinition du profil écologique de l'azobé (Lophira alata Banks ex Gaertn F., Ochnaceae) dans les forêts sempervirentes du Cameroun
Biwole, Achille ULg; Bourland, Nils ULg; Doucet, Jean-Louis ULg

Poster (2012, February 08)

Ekki or L. alata is a commercial timber species in Guinea-Congolian region considered vulnerable (IUCN, 2011). Indeed, its population structure shows a severe lack of regeneration in some rainforests ... [more ▼]

Ekki or L. alata is a commercial timber species in Guinea-Congolian region considered vulnerable (IUCN, 2011). Indeed, its population structure shows a severe lack of regeneration in some rainforests (Palla et al., 2002). Moreover, in logging areas, insufficient knowledge about its ecological profile limits any reliable modeling of population dynamics on a long term. Consequently, original research, to improve its ecological characterization to ensure its sustainable management is conducted in moist evergreen forest in southern Cameroon. First results on population dynamics of this species show, in plots study of recruitment, a population without major deficit regeneration. On its silvicultural ability, although that estimated on plantations on parks under 2 years old, the trends of growth (ca 30 and 0.5 cm / year respectively in height and diameter) and mortality (3, 3% / year) suggest a positive perspective. Current work in relation to other topics of research should provide further insights into its ecological profile in the evergreen forests of Cameroon. [less ▲]

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See detailExtent of paleofires and past human settlements in the current rainforest patchwork of the Northern Republic of Congo
Gillet, Jean-François ULg; Doucet, Jean-Louis ULg

Poster (2012, January 04)

Objectives The origins of the patchwork of lowland semi-deciduous forests in the Northern Republic of Congo were apprehended. The aim of this study was to show that dense forests suffered fewer ... [more ▼]

Objectives The origins of the patchwork of lowland semi-deciduous forests in the Northern Republic of Congo were apprehended. The aim of this study was to show that dense forests suffered fewer disturbances than the open canopy forest types. Old disturbances associated with fires and human settlements seem to have had and still have today a substantial impact on the physiognomy and the composition of the forest types. Understanding past forest dynamics is a major component to predict the effects of both present climate change and human activities. Method Fifteen locations were studied along a 400-km-long SW-NE gradient in the NW of the Congo Basin through the ERA-net BiodivERsA CoForChange project. An anthraco-archaeological study was carried out in association with floristic inventories of three strata. Two main geology substrates were considered: the Mesozoic sandstones and Quaternary alluvial deposits. The abundance of charcoal fragments and human artifacts were evaluated by a network of 1-m-deep boring augers (n =208) and a 1.5-m-deep reference soil pit (n =15) in each site. A rating system was used to quantify the abundance of charcoal, charred Elaeis guineensis seeds and other artifacts (ceramic and metallurgic slag). Estimations were based on 20-cm-depth intervals (augers) or on pedological layers (pits). Twelve radiocarbon dating were performed in the major disturbed layers of each vegetation type studied. Results Two main groups of vegetation were highlighted according to the relative openness of the woody stand, the importance of the woody regeneration, and the development of the herbaceous cover. The two dense forests sampled were preferentially found in the northern part: the dense forest with Manilkara mabokeensis and Haumania dankelmaniana, and the Gilbertiodendron dewevrei forest on dry land. Most parts of the understorey exhibited the woody regeneration. The southern part presented more openness including the largest areas of open canopy vegetation types. Three forest types were identified: the Macaranga barteri pioneer forest, the open canopy vegetation type with Aframomum and Marantaceae, and the sparse forest with Megaphrinium macrostchyum and/or Haumania liebrestisiana. The understorey was a dense thicket of giant herbs belonging to the families Marantaceae and Zingiberaceae, causing a very scarce woody regeneration. Regardless the auger depth, charcoals were more profuse in the soils of the southern open canopy vegetation types (2-Way ANOVA, F=5.46, p=0.02). As in pit layers, charred oil palm nuts were more plentiful in the soils of these vegetation types (Mann-Whitney test, p<0.05). Of the five sites containing artifacts, only one recent potsherd dated 466-302 BP was located in dense forest but near a main river. The oldest signs of ceramic and metallurgical activities dated 2160-1407 BP were found in the current open canopy vegetation types. Within the latter, two expansion phases of the oil palm tree E. guineensis were observed: between 2146-1055 BP and 558-347 BP. Conversely, the oldest palaeofire was discovered in the M. mabokeensis dense forest and dated at 5467-5285 BP. Conclusions The dense forests contained less evidence of ancient fires and human settlements. They currently include evergreen and shade-tolerant tree species such as G. dewevrei and M. mabokeensis. The more sustained and repeated fires in the open canopy vegetation types were often associated with ancient human occupation. Today, the light-demanding giant herbaceous species such as Aframomum sp. and M. macrostchyum proliferate in the understorey below a simplified woody component of pioneer species such as M. barteri. The largest expansion phases of the oil palm tree E. guineensis in the southern part would be linked to ancient human occupation associated with larger canopy openings and fire events. The water availability, more evenly distributed near the heavily-irrigated Congo Basin, would also be a discriminating factor. [less ▲]

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See detailNature+ asbl - Rapport d'activités 2011
Federspiel, Michèle; Bourland, Nils ULg; Daïnou, Kasso ULg et al

Report (2012)

En 2011, Nature+ a rencontré ses missions, notamment : en mettant en oeuvre deux projets de foresterie communautaire financés par des bailleurs internationaux ; en participant à la gestion durable de près ... [more ▼]

En 2011, Nature+ a rencontré ses missions, notamment : en mettant en oeuvre deux projets de foresterie communautaire financés par des bailleurs internationaux ; en participant à la gestion durable de près de 2 millions d’hectares de forêts denses humides tropicales grâce à nos collaborations avec des sociétés forestières engagées dans les processus de certification FSC ; en accueillant dans nos divers projets 12 étudiants en fin de cursus universitaire ainsi que 8 doctorants. 7 universités différentes ont ainsi reçu un appui administratif, technique et scientifique de Nature+. [less ▲]

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See detailScaphandre La science rencontre l'art: L'art
Haubruge, Eric ULg; Bay, Daniel ULg; Semal, Jean et al

in Haubruge, Eric; Bay, Daniel; Semal, Jean (Eds.) Scaphandre La science rencontre l'art (2012)

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See detailLes 5 arbres protégés du Gabon
Moumbogou, Carl; Meunier, Quentin; Ogoula Ikinda, L. B. et al

Learning material (2012)

Ces cinq essences forestières sont réputées pour la qualité de leur bois et ont fait l’objet d’exploitation dans le pays. Elles font également partie intégrante de la vie des communautés rurales du Gabon ... [more ▼]

Ces cinq essences forestières sont réputées pour la qualité de leur bois et ont fait l’objet d’exploitation dans le pays. Elles font également partie intégrante de la vie des communautés rurales du Gabon, tant pour leurs vertus alimentaires et médicinales que pour leur importance dans les rites initiatiques traditionnels. [less ▲]

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See detailEcology and management of Pericopsis elata (Harms) Meeuwen (Fabaceae) populations: a review
Bourland, Nils ULg; Kouadio, Yao Lambert; Fétéké, Fousséni et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(4), 486-498

Pericopsis elata (Fabaceae) is a valuable timber species occurring in moist semi-deciduous African forests. While it is at present substantially reduced, the tree’s natural distribution previously covered ... [more ▼]

Pericopsis elata (Fabaceae) is a valuable timber species occurring in moist semi-deciduous African forests. While it is at present substantially reduced, the tree’s natural distribution previously covered several distinct areas from Côte d’Ivoire to the Democratic Republic of Congo. This species has been logged since the second half of the 20th century. Because it suffers from a lack of regeneration, P. elata is now included in CITES Appendix II and is recorded as “Endangered A1cd” on the IUCN Red List. As with other long-lived light-demanding species, the survival of P. elata may have been favored by important disturbances that occurred in the Congo Basin during the last millennia. While both international trade and industrial uses of the wood of P. elata are well documented, information about its ecology are very sparse or contradictory, and even absent in some cases (e.g., regarding its effective flowering diameter). Furthermore, data describing the management of P. elata are scarce, including potential solutions to compensate for the deficit of natural regeneration. Along the same lines, genetic studies still remain at an early stage and only vague hypotheses have been offered to explain the origins of the tree’s populations. We emphasize the need for new research on those topics. Further studies would be useful in deciding whether P. elata populations can continue to be logged without the species being threatened with extinction. Finally, such research needs to target effective and inexpensive management procedures that could secure the future of the species in a logging context. [less ▲]

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See detailPhenological patterns in a natural population of a tropical timber tree species, Milicia excelsa (Moraceae): evidence of Isolation By Time and its interaction with feeding strategies of dispersers
Daïnou, Kasso ULg; Laurenty, Eric; Mahy, Grégory ULg et al

in American Journal of Botany (2012), 99(9), 1-11

Population genetic structuring over limited timescales is commonly viewed as a consequence of spatial constraints. Indirect approaches have recently revealed existence of reproductive isolation due to ... [more ▼]

Population genetic structuring over limited timescales is commonly viewed as a consequence of spatial constraints. Indirect approaches have recently revealed existence of reproductive isolation due to flowering time (the so-called isolation by time, IBT). Since phenological processes can be subject to selection, the persistence of flowering asynchrony may be due to opposing selective pressures during mating, dispersal and regeneration phases. Our study aimed to investigate phenology, fruit-handling by animals and their interaction, in a timber tree species, Milicia excelsa. We analyzed phenological data collected over a 6-year period on 69 genotyped trees in a Cameroonian natural rainforest complemented by data from germination trials and field observations of dispersers. Initiation of flowering correlated with variation in temperature and relative humidity, but was also affected by genetic factors: pairwise differences in flowering time between nearby individuals correlated with kinship coefficient, and earliness of flowering remained stable over time. A decrease in mean seed production per fruit with increasing flowering time suggests selection against late bloomers. However, germination rate was not affected by seed collection date, and the main seed disperser, the bat Eidolon helvum, seemed to increase in abundance at the end of the reproductive season, and preferred trees in open habitats where early and late bloomers are expected. The pairwise approach performs well to detecting IBT. The persistence of different mating pools in such a case may result from a trade-off between selective forces during the mating and seed dispersal processes. [less ▲]

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See detailA commented checklist of woody plants in the Northern Republic of Congo
Gillet, Jean-François ULg; Doucet, Jean-Louis ULg

in Plant Ecology and Evolution (2012), 145(2), 258-271

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See detailIdentité et écologie des espèces forestières commerciales d'Afrique Centrale: le cas de Milicia spp.
Daïnou, Kasso ULg; Doucet, Jean-Louis ULg; Sinsin, Brice et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16

Le terme iroko regroupe les deux espèces du genre africain Milicia et désigne le bois qui en est dérivé. Malgré une importance économique reconnue depuis plus de deux siècles et une diminution sensible ... [more ▼]

Le terme iroko regroupe les deux espèces du genre africain Milicia et désigne le bois qui en est dérivé. Malgré une importance économique reconnue depuis plus de deux siècles et une diminution sensible des densités de population du fait de l'exploitation, les connaissances scientifiques utiles à la gestion durable de l'iroko font défaut, particulièrement en Afrique Centrale. L'existence même d'une spéciation au sein du genre Milicia mérite d'être revérifiée: les caractères utilisés pour séparer les deux taxons M. excelsa (Welw.) C.C. Berg et M. regia (A. Chev.) C.C. Berg sont peu consistants et une révision de ces traits distinctifs permettrait de réétudier le niveau de vulnérabilité des populations de Milicia spp., et donc de revoir les stratégies de gestion de ce groupe taxonomique. M. regia n'a fait l'objet que de rares études écologiques tandis que M. excelsa, plus largement distribuée, a retenu l'attention scientifique en Afrique de l'Ouest, dans une certaine mesure. Dans tous les cas, les traits d'histoire de vie conditionnant la diversité génétique et le taux de régénération naturelle méritent d'être identifiés ou mieux décrits. En particulier, les connaissances existantes sur les populations reproductrices, les facteurs régulant la floraison, les patrons de fructification et de dispersion des diaspores, ainsi que d'autres caractères qui amènent à décrire l'iroko comme un arbre pionnier (besoins en lumière, dormance des graines) devraient être mieux documentés. Enfin, la dynamique même des populations naturelles de juvéniles devra également être mieux caractérisée. En l'absence de données fines en écologie, la durabilité de nombreuses ressources ligneuses commerciales est tributaire d'actions sylvicoles, lesquelles peuvent être coûteuses et ne pas être garanties sur le long terme. [less ▲]

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