References of "Doucet, Jean-Louis"
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See detailRapport final du projet FRFC n° 2.4577.10. Dynamique des populations d’arbres et d’herbacées héliophiles en relation avec les anciennes perturbations anthropiques et climatiques
Doucet, Jean-Louis ULg; Hardy, Olivier

Report (2014)

L’objectif principal de ce projet était d’étudier dans quelle mesure l’organisation de la biodiversité végétale des forêts d’Afrique centrale a été influencée par les activités anthropiques et les ... [more ▼]

L’objectif principal de ce projet était d’étudier dans quelle mesure l’organisation de la biodiversité végétale des forêts d’Afrique centrale a été influencée par les activités anthropiques et les changements climatiques qui se sont déroulés au cours des quelques derniers millénaires. A cette fin, cinq disciplines ont été utilisées : (1) l'archéologie afin de dater et de quantifier l’intensité de l’occupation humaine ; (2) l'anthracologie pour reconstituer la végétation présente lors du passage des feux ; (3) la dendrochronologie en vue d’établir des corrélations entre les événements passés et l'âge des arbres ; (4) l'écologie des communautés pour permettre de tester l’existence d’une corrélation entre l’abondance d’espèces héliophiles et les indices d’occupation humaine ; (5) la génétique des populations afin d'identifier des signatures génétiques d’anciens évènements de fragmentation et de changement démographique. [less ▲]

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See detailThe end of roaming in the forest causes a loss of timber resources: the paradox of slash-and-burn agriculture
Morin-Rivat, Julie ULg; Fayolle, Adeline ULg; Favier, Charly et al

Conference (2014, February 27)

Tropical forests are not believed as pristine anymore. Their structure and specific composition are induced by past climatic and human disturbances over years. In the African moist forests, the emergent ... [more ▼]

Tropical forests are not believed as pristine anymore. Their structure and specific composition are induced by past climatic and human disturbances over years. In the African moist forests, the emergent trees are mainly light-demanding. These trees are considered to derive from the recent disturbances of the last centuries. Most of them are exploited for their timber. However, several of these tree species are currently suffering from a lack of regeneration that threatens the specific diversity of the forests and the sustainability of timber exploitation. Through dendrometric and radiocarbon analyses we found that the majority of the trees of the Congo Basin are not older than 160 years. This corresponds to about the year 1850 when the Europeans colonized the inner regions of Central Africa. By reassembling people along the road axes, the colonial administration reduced the forest roaming. Former activities such as slash and burn agriculture created large openings in the canopy that allowed light-demanding tree species to establish. Currently we observed that timber logging does not provide openings large enough for the recruitment of these species. We thus anticipate that adjustments in forest management strategies shall be made to preserve the forest resources, for instance by recreating the conditions of slash and burn agriculture. [less ▲]

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See detailSpeciation slowing down in widespread and long-living tree taxa : insights from the tropical timber tree genus Milicia (Moraceae)
Daïnou, Kasso ULg; Mahy, Grégory ULg; Duminil, Jérôme et al

in Heredity (2014)

The long generation time and large effective size of widespread forest tree species can result in slow evolutionary rate and incomplete lineage sorting, complicating species delimitation. We addressed ... [more ▼]

The long generation time and large effective size of widespread forest tree species can result in slow evolutionary rate and incomplete lineage sorting, complicating species delimitation. We addressed this issue with the African timber tree genus Milicia that comprises two morphologically similar and often confounded species: M. excelsa, widespread from West to East Africa, and M. regia, endemic to West Africa. We combined information from nuclear microsatellites (nSSRs), nuclear and plastid DNA sequences, and morphological systematics to identify significant evolutionary units and infer their evolutionary and biogeographical history. We detected five geographically coherent genetic clusters using nSSRs and three levels of genetic differentiation. First, one West African cluster matched perfectly with the morphospecies M. regia that formed a monophyletic clade at both DNA sequences. Second, a West African M. excelsa cluster formed a monophyletic group at plastid DNA and was more related to M. regia than to Central African M. excelsa, but shared many haplotypes with the latter at nuclear DNA. Third, three Central African clusters appeared little differentiated and shared most of their haplotypes. Although gene tree paraphyly could suggest a single species in Milicia following the phylogenetic species concept, the existence of mutual haplotypic exclusivity and nonadmixed genetic clusters in the contact area of the two taxa indicate strong reproductive isolation and, thus, two species following the biological species concept. Molecular dating of the first divergence events showed that speciation in Milicia is ancient (Tertiary), indicating that long-living tree taxa exhibiting genetic speciation may remain similar morphologically. [less ▲]

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See detailWood charcoal analysis: a relatively new tool for palaeoecology in tropical Africa
Morin-Rivat, Julie ULg; Biwole, Achille ULg; Bourland, Nils ULg et al

Scientific conference (2014, February 14)

This is an introduction about wood charcoal properties, collection and taxonomical identification in the framework of palaeoecological studies in Central Africa through examples of possible applications.

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See detailA short insight into the ecology of Pericopsis elata (Harms) Meeuwen (Fabaceae) in southeastern Cameroon
Bourland, Nils ULg; Doucet, Jean-Louis ULg

Scientific conference (2014, February 14)

Some key points of the autecology of Pericopsis elata in Southeastern Cameroon. Implications are given for the sustainable forest management of the species in the context of selective logging.

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See detailFrom wood charcoals to trees: pitfalls and successes of the taxonomic identification in tropical contexts
Morin-Rivat, Julie ULg; De Weerdt, Joëlle; Hubau, Wannes et al

Poster (2014, February 07)

So as to document the past history of tropical forests, several palaeoenvironmental proxies have been used. For instance, charcoals from soil deposits provide a local signal of the evolution of the ... [more ▼]

So as to document the past history of tropical forests, several palaeoenvironmental proxies have been used. For instance, charcoals from soil deposits provide a local signal of the evolution of the vegetation together with snapshots of human interactions with the environment. As charcoal analyses are rare in tropical contexts, here we aim at presenting the different aspects of charcoal studies through their pitfalls and successes as well as the needs for further research. Charcoal analysis (anthracology) is a discipline initially from archaeobotany that consists in the analysis of pieces of charred wood primarily found in archaeological contexts but also in natural soil layers. Its goal is to identified the species that burnt during the past through the observation of the charred wood structure. Indeed carbonization, as the incomplete combustion of the ligneous material, preserves the wood structure. The identifications obtained through microscopic observations allow assessing past uses of wood and human impacts on the forest landscape. However, issues typically tropical exist: difficulties related to fieldwork accessibility, to sampling, to soil processing so as to collect the charcoals, difficulties related to the taxonomic identification because of the huge number of species and of the limited number of anatomical descriptions. New developments are nonetheless emerging for Central Africa with original anatomical descriptions, identification protocols and visual keys. [less ▲]

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See detailIdentification des zones d'intérêt écologique dans les concessions d'exploitation forestière. Concilier les objectifs de production de bois d'oeuvre avec la conservation de la biodiversité.
Sépulchre, Frédéric; Federspiel, Michèle; Doucet, Jean-Louis ULg

in Bühler, Arthur; Demenois, Julien; Doucet, Jean-Louis (Eds.) et al Etudes sur le plan pratique de l'aménagement des forêts naturelles de production tropicales africaines. Volet 4: Gestion durable et préconisations en vue de la certification. (2014)

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See detailSuivi et gestion des populations d'essences commerciales. Protection des espèces sensibles et viabilité écologique de l'exploitation.
Sépulchre, Frédéric; Federspiel, Michèle; Doucet, Jean-Louis ULg

in Bühler, Arthur; Demenois, Julien; Doucet, Jean-Louis (Eds.) et al Etudes sur le plan pratique de l'aménagement des forêts naturelles de production tropicales africaines. Volet 4: Gestion durable et préconisations en vue de la certification. (2014)

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See detailSoil Seed Bank : a poorly know component of forest regeneration
Douh, Chauvelin ULg; Daïnou, Kasso ULg; Fernandez Pierna, Juan-Antonio et al

Poster (2014, February)

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See detailFunctional traits and speciation of tropical African species: the case of genus Guibourtia Benn
Tosso, Dji-ndé Félicien ULg; Daïnou, Kasso ULg; Hardy, J. Olivier et al

Poster (2014, January 07)

Nowadays, comparative ecology approach is widely used to understand mechanisms of speciation. In evolutionary biology, few studies take into account the importance of physiological traits as criteria for ... [more ▼]

Nowadays, comparative ecology approach is widely used to understand mechanisms of speciation. In evolutionary biology, few studies take into account the importance of physiological traits as criteria for interspecific differentiation, although such an approach is particularly suited to infer the adaptive capacities of taxa. The genus Guibourtia Benn (Fabaceae / Caesalpinioideae), composed of 13 species in Africa, seems an ideal candidate for this study. As a matter of fact, this model includes not only species of different vegetation ecosystems (forest and savanna) but also morphologically very similar species found in various areas with different climates and soils (sandy, clayloam, limestone, hydromorph). Addressing speciation issues, our study seeks to test the hypothesis that populations of closely related species should be studied in terms of both functional traits and phylogeny. In this research, two questions are asked: (i) what are the phylogenetic differences within the genus Guibourtia? (ii) To what extent phylogeny, functional traits and bioclimatic envelope are linked? The results of the study will help to realize the distribution modeling of different evolutionary units of Guibourtia using a dynamic vegetation model (CARAIB) in order to propose strategies for conservation and sustainable management in the context of Central African forests. [less ▲]

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See detailNew Evidence of Human Activities during the Holocene in the Lowland Forests of the Northern Congo Basin
Morin-Rivat, Julie ULg; Fayolle, Adeline ULg; Gillet, Jean-François ULg et al

in Radiocarbon (2014), 56(1), 209-220

In the last decade, the myth of the pristine tropical forest has been seriously challenged. In central Africa, there is a growing body of evidence for past human settlements along the Atlantic forests ... [more ▼]

In the last decade, the myth of the pristine tropical forest has been seriously challenged. In central Africa, there is a growing body of evidence for past human settlements along the Atlantic forests, but very little information is available about human activities further inland. In this study, we aimed at determining the temporal and spatial patterns of human activities in an archaeologically unexplored area of 110,000 km² located in the northern Congo Basin and currently covered by dense forest. Fieldwork involving archaeology as well as archaeobotany was undertaken in 36 sites located in southeastern Cameroon and in the northern Republic of Congo. Evidence of past human activities through either artifacts or charred botanical remains was observed in all excavated test pits across the study area. The set of 43 radiocarbon dates extending from 15,000 BP to the present time showed a bimodal distribution in the Late Holocene which was interpreted as two phases of human expansion with an intermediate phase of depopulation. The 2300–1300 BP phase is correlated with the migrations of supposed farming populations from northwestern Cameroon. Between 1300 and 670 BP, less material could be dated. This is in agreement with the population collapse already reported for central Africa. Following this, the 670–20 BP phase corresponds to a new period of human expansion known as the Late Iron Age. These results bring new and extensive evidence of human activities in the northern Congo Basin and support the established chronology for human history in central Africa. [less ▲]

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See detailImprove the characterization of tropical forests to improve management: policy brief
Gourlet-Fleury, Sylvie; Aleman, Julie; Bayol, Nicolas et al

Report (2014)

CoForChange has shown that management plans based on timber stock recovery are not enough to ensure the sustainability of these production forests. The variability of forest characteristics and their ... [more ▼]

CoForChange has shown that management plans based on timber stock recovery are not enough to ensure the sustainability of these production forests. The variability of forest characteristics and their different responses to disturbance should be considered in management decisions. [less ▲]

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See detailExplorer la banque de graines du sol pour mieux comprendre la dynamique de régénération des forêts tropicales africaines (synthèse bibliographique)
Douh, Chauvelin ULg; Daïnou, Kasso ULg; Loumeto, Jean Joël et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2014), 18(4), 558-565

La banque de graines du sol des forêts denses humides africaines a été très peu étudiée, alors qu’elle pourrait jouer un rôle déterminant dans les cycles sylvigénétiques naturels. Elle pourrait également ... [more ▼]

La banque de graines du sol des forêts denses humides africaines a été très peu étudiée, alors qu’elle pourrait jouer un rôle déterminant dans les cycles sylvigénétiques naturels. Elle pourrait également être avantageusement utilisée dans les programmes de restauration, à l’instar de ce qui se fait sur d’autres continents. La présente synthèse bibliographique fait le point sur les connaissances actuelles relatives à la banque de graines du sol, en mettant l’accent sur le continent africain. Elle montre qu’une meilleure caractérisation de la banque de graines du sol des différentes communautés végétales constituerait une contribution notable pour la gestion durable des forêts tropicales d’Afrique. [less ▲]

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See detailReproductive ecology of Coula edulis Baill., source of a valuable non-timber forest product
Moupela, Christian ULg; Doucet, Jean-Louis ULg; Daïnou, Kasso ULg et al

in Tropical Ecology (2014), 55(3), 327-338

The reproductive ecology of Coula edulis (Olacaceae), source of a highly valuable non-timber product for African populations, has been investigated on a large tree sample size in a Gabonese forest for a 3 ... [more ▼]

The reproductive ecology of Coula edulis (Olacaceae), source of a highly valuable non-timber product for African populations, has been investigated on a large tree sample size in a Gabonese forest for a 3-year period, in order to propose options for its domestication. Reproduction is annual and the minimum tree diameter for flowering was 10.6 cm while the diameter for regular fructification was 23 cm. The annual diameter increment (ADI; mean = 0.22 cm year-1) was affected by crown exposure, but not by initial tree diameter or fruit production. Tree diameter influenced fruiting frequency and fruit production. There was a strong correlation between fruit production of 2011 and 2012 (Pearson's r = 0.85; P < 0.001), suggesting a high heritability of that trait. Phenotypical selection should be performed prior to any propagation activity. Moreover, as most of C. edulis fruits were sterile (64 %), we propose that sylvicultural strategies should be based on vegetative propagation. [less ▲]

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See detailEnrichissement des trouées d'abattage en forêt de production
Doucet, Jean-Louis ULg; Daïnou, Kasso ULg

in de Wasseige, Carlos; Flynn, J.; Louppe, Dominique (Eds.) et al Les forêts du Bassin du Congo - Etat des forêts 2013 (2014)

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See detailPatterns of tree species composition across tropical African forests
Fayolle, Adeline ULg; Swaine, Michael D.; Bastin, Jean-François ULg et al

in Journal of Biogeography (2014), online

Aim : In this study we identified large-scale variation in tree species composition across tropical African forests and determined the underlying environmental and historical factors. Location : Tropical ... [more ▼]

Aim : In this study we identified large-scale variation in tree species composition across tropical African forests and determined the underlying environmental and historical factors. Location : Tropical forests from Senegal to Mozambique. Methods : Distribution data were gathered for 1175 tree species in 455 sample sites scattered across tropical Africa, including all types of tropical forests (wet, moist, dry, and lowland to moderate elevation montane forests). The value of elevation and 19 climatic variables extracted from the BIOCLIM data set were assigned to each sample site. We determined the variation in species composition using correspondence analysis and identified the environmental correlates. We defined floristic clusters according to species composition and identified the characteristic species using indicator analysis. Results : We identified a major floristic discontinuity located at the Albertine rift that separated the dry, moist and wet forests of West and Central Africa (the entire Guineo-Congolian Region) from the upland and coastal forests of East Africa. Except for the Albertine Rift, we found no evidence to support the other proposed floristic discontinuities (Dahomey Gap etc.). We detected two main environmental gradients across tropical African forests. The rainfall gradient was strongly correlated with the variation in tree species composition in West and Central Africa. The elevation/temperature gradient highlighted the major floristic differences within East Africa and between East Africa and the Guineo-Congolian Region, the latter being most probably due to the geological disruption and associated climatic history of the East African uplift. Main conclusions : We found floristic evidence for three main biogeographical regions across the tropical African forests, and described six floristic clusters with particular environmental conditions within these regions: Coastal and Upland for East Africa, Dry and Wet-Moist for West Africa, and Moist and Wet for Central Africa. [less ▲]

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See detailLes plantations forestières en Afrique centrale : des sylvicultures nouvelles pour répondre aux nouveaux besoins des sociétés
Marien, Jean-Noël; Gourlet-Fleury, Sylvie; Peltier, Régis et al

in de Wasseige, Carlos; Flynn, J.; Louppe, Dominique (Eds.) et al Les forêts du Bassin du Congo - Etat des forêts 2013 (2014)

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See detailEnrichissement des pistes de débardage en forêts clairsemées à Marantacées
Doucet, Jean-Louis ULg; Gillet, Jean-François ULg

in de Wasseige, Carlos; Flynn, J.; Louppe, Dominique (Eds.) et al Les forêts du Bassin du Congo - Etat des forêts 2013 (2014)

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