References of "Doucet, Jean-Louis"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailAnalyzing soil charcoals to assess the naturalness of tropical forest
Morin-Rivat, Julie ULg; Gorel, Anaïs-Pasiphaé; Daïnou, Kasso ULg et al

Conference (2013, June 26)

For conservation biology and sustainable management, the natural character of tropical forest is a crucial issue. Its assessment is usually based on ecological proxies such as forest composition and ... [more ▼]

For conservation biology and sustainable management, the natural character of tropical forest is a crucial issue. Its assessment is usually based on ecological proxies such as forest composition and structure. However the estimation made on this basis only considers short term processes at a local scale. In contrast the long term processes are appraised by palaeoecological proxies (such as pollen) at a regional scale. So as to assess the degree of naturalness of tropical ecosystems in a conservation perspective it is important to combine a long temporal scale as well as a fine resolution spatial scale. Such approaches using palaeoecological proxies have been recently tested in temperate Europe but little in tropical ecosystems. Nonetheless the long term preservation of the palaeoecological material and its broad presence in the environment are necessary conditions to fulfill. In this perspective soil charcoal appears to meet these requirements. In this paper we aimed at assessing the naturalness of tropical forest using soil charcoal from southeastern Cameroon. Fieldwork involving as well archaeology as botany was undertaken at 53 sites. We quantified charcoal in soil samples by layers of 10 cm taken from pits located in the center of plots of botanical inventory. Spatial projections were performed using statistics together with multivariate analyses. Radiocarbon dating allowed interpreting the temporal framework. Results showed the ubiquitous presence of charcoal at each site. Main charcoal peaks were interpreted as fields (slash-and-burn agriculture) in the vicinity of ancient villages. These practices shaped the forest over time which cannot be considered as natural anymore. This underlines the potential input of the use of palaeoecological material in conservation biology and sustainable management issues. Charcoal fragments are under taxonomical identification and may provide new insights on the long term history of forest composition. [less ▲]

Detailed reference viewed: 182 (38 ULg)
Full Text
Peer Reviewed
See detailImpacts of past Human disturbances on present day tree species assembly in the tropical forests of South-East Cameroon
Vleminckx, Jason; Doucet, Jean-Louis ULg; Daïnou, Kasso ULg et al

Poster (2013, June 25)

Non-random spatial distribution of trees is the result of both neutral and deterministic factors. Neutral models suggest that species within a community are equally competitive, with spatial structures ... [more ▼]

Non-random spatial distribution of trees is the result of both neutral and deterministic factors. Neutral models suggest that species within a community are equally competitive, with spatial structures mainly due to dispersal limitation. Deterministic (or non-neutral) models consider species assemblages as the result of what we name “induced spatial dependence”, where forcing (explanatory) variables shape diversity organization. However, deterministic models have often included habitat variables only, without considering human disturbance which we know enhances the competitive advantage of heliophytic (light-demanding) species and therefore the floristic composition of phytocenoses. Based on charcoal abundance in the soil (used as an indicator of anthropogenic perturbation), species abundance, and environmental data from a forest of south-east Cameroon, we applied modern variation partitioning methods to assess the relative impact of human disturbance on floristic patterns, controlling for purely spatial and habitat effects. Significant signals of human influence have been found so far, and a new collection of data should establish with a better precision the importance of the anthropogenic impact on tree species assemblages. [less ▲]

Detailed reference viewed: 87 (21 ULg)
Full Text
Peer Reviewed
See detailLife history traits related to hydraulic functioning in 211 African tropical woody species
Morin-Rivat, Julie ULg; Fayolle, Adeline ULg; Doucet, Jean-Louis ULg et al

Poster (2013, June 06)

In the context of global change understanding the interactions between plant ecology and plant physiology remains a crucial issue. In this study we aimed at analyzing the vascular characteristics involved ... [more ▼]

In the context of global change understanding the interactions between plant ecology and plant physiology remains a crucial issue. In this study we aimed at analyzing the vascular characteristics involved in the ecological traits of woody species from the northern Congo Basin. We crosschecked three databases: the botanical inventories (857 spp.) and the database of life history traits (464 spp.) produced during the CoForChange project, and the anatomical database Inside Wood (761 spp. and genera for tropical Africa). A total of 211 shared species was obtained. We performed correspondence analyses between the tangential diameter of the vessel lumina (40-43), the number of vessels per mm² (46-50) and five life history traits: leaf phenology, light requirement, seed dispersal, tree size and wood density. Species were distributed along a gradient from species with numerous small vessels to species with few large vessels. This distribution was correlated to a gradient in leaf phenology and light requirement: from evergreen shade-tolerant species to deciduous non-pioneer and pioneer light-demanding species. Dispersal followed this distribution in a lesser extent: from zoochoria to autochoria via anemochoria. Finally, a gradient in size was observed, from small shrubs to tall trees, as well as a gradient in wood density, from dense to light woods. We conclude that the ecological traits of the African tropical woody species are closely related to their hydraulic functioning. The strategies adopted by plants regarding light and water availability can thus be deduced from their vascular characteristics. On this basis we anticipate that climate change will foster light-demanding tree species as better competitors than shade-tolerant species, especially as drought stress is concerned. Further research is needed to increase the input of wood anatomy in explaining the life history traits in African tropical species. [less ▲]

Detailed reference viewed: 145 (25 ULg)
Full Text
Peer Reviewed
See detailImpacts of logging and hunting on western lowland gorilla (Gorilla gorilla gorilla) populations and consequences for forest regeneration. A review
Haurez, Barbara ULg; Petre, Charles-Albert ULg; Doucet, Jean-Louis ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2013), 17(2), 364-372

Timber exploitation is rapidly expanding throughout the Congo Basin. Forest areas assigned to timber harvesting have sharply expanded over the decades and logging concessions now largely overlap with the ... [more ▼]

Timber exploitation is rapidly expanding throughout the Congo Basin. Forest areas assigned to timber harvesting have sharply expanded over the decades and logging concessions now largely overlap with the range of western lowland gorilla (Gorilla gorilla gorilla Savage & Wyman, 1847). However this species, which is considered as critically endangered by IUCN, could play an essential role in maintaining the structure and composition of tropical rainforest notably through seed dispersal services. This is likely due to its frugivorous diet, high stomach capacity and ability to swallow seeds of variable sizes. Moreover gorillas have a long gut retention time of ingested food, travel long daily distances and deposit most ingested seeds in suitable habitats for plant development (such as logging gaps). Consequently, the preservation of the role of gorilla in forest regeneration is essential in the context of logged forest ecosystems. Timber harvesting has two major opposing impacts on gorilla populations: on the one hand, gorillas benefit from growth of herbaceous vegetation (e.g. Marantaceae and Zingiberaceae) following forest canopy opening, as such herbs provide both staple food and nest-building materials; on the other hand, gorilla populations suffer with the rise in hunting associated with logging activity, especially with road network installation. Considering the potential negative knock-on effects of logging concessions on the ecological function of western lowland gorilla, the implementation of timber harvesting methods that preserve gorilla populations is a considerable challenge for forest sustainability, as well as for gorilla’s conservation. [less ▲]

Detailed reference viewed: 46 (22 ULg)
Full Text
Peer Reviewed
See detailSpecies delimitation and diversification in the widespread tree genus Milicia (Moraceae)
Daïnou, Kasso ULg; Mahy, Grégory ULg; Duminil, Jérôme et al

Conference (2013, June)

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, which 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 non-admixed 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 ▲]

Detailed reference viewed: 59 (17 ULg)
Full Text
See detailEcological wood anatomy of 155 African tropical hardwoods
Beeckman, Hans; Fayolle, Adeline ULg; Doucet, Jean-Louis ULg et al

Conference (2013, April 19)

In this study we aimed at identifying the anatomical characters expressing life history traits of woody species from the northern Congo Basin. We crosschecked three databases: the botanical inventories ... [more ▼]

In this study we aimed at identifying the anatomical characters expressing life history traits of woody species from the northern Congo Basin. We crosschecked three databases: the botanical inventories produced during the CoForChange project (857 spp.), the database of life history traits established by the CIRAD (France) and GxABT (Belgium) (464 spp.), and the anatomical database Inside Wood (761 spp. and genera for tropical Africa). A total of 155 shared species was obtained. We performed correspondence analyses between the anatomical characters and two main groups of traits: leaf phenology and light-requirement. Results showed: (i) that wood anatomy is involved in leaf phenology and light-requirement in a significant way (7.56% of the variance on axe1), (ii) that evergreenness was correlated to IAWA characters 14 to 18 (scalariform perforation plates, e.g. Olacaceae) and deciduousness to characters 118 to 122 (storied structures, e.g. Malvaceae and Meliaceae), (iii) that pioneer (P) and non-pioneer light-demanding (NPLD) species showed similar traits but were different from shade-tolerant (ST) species, (iv) that deciduous and evergreen species showed separate distributions, and (v) that wood anatomy validated the well documented strong correlation between evergreen species and ST species, with an inversion of the tendency for deciduous species correlated to P and NPLD species. We conclude that anatomical characters can be used as indicators of life history traits in species-rich biomes. Further investigations are needed to increase the input of wood anatomy in explaining the life history traits in African tropical species. [less ▲]

Detailed reference viewed: 162 (19 ULg)
Full Text
See detailWestern lowland gorilla populations and logging concessions: is the coexistence possible?
Haurez, Barbara ULg; Petre, Charles-Albert ULg; Doucet, Jean-Louis ULg

Conference (2013, April)

Timber exploitation is rapidly expanding throughout the Congo Basin. Around 26 % of the moist forests are devoted to logging activities. Logging concessions largely overlap with the range of western ... [more ▼]

Timber exploitation is rapidly expanding throughout the Congo Basin. Around 26 % of the moist forests are devoted to logging activities. Logging concessions largely overlap with the range of western lowland gorilla (WLG) considered as critically endangered by IUCN. However, this species could play an essential role in maintaining vegetal diversity notably through seed dispersal services. Particularly some tree species harvested for their timber may be dispersed by WLG. In this communication interactions between WLG and a timber exploitation are studied in Central Gabon. WLG density is estimated in an Annual Allowable Cut (AAC), and nesting behavior is described. Seeds dispersed by WLG are identified through fecal analysis and germination trials are conducted to assess seed viability after gut passage. Four treatments are realized for the most abundant species: passed seeds, passed seeds in fecal matrix, seeds surrounded by fresh pulp and seeds extracted from fresh fruits. A relatively high WLG density is observed in the AAC (2.0 weaned gorillas/km²). WLG nest preferentially in open terra firme forest and frequently use old logging road covered with herbaceous vegetation for nesting and feeding. They avoid nesting in closed terra firme forest. Seed dispersal and impacts of the passage in gorilla’s gut on seed germination are currently described. Germination success after gut passage depends on the seed species and varies from 0.0 to 100% in the course of monitoring time. The first results of this study suggest that timber exploitation and WLG conservation are not mutually exclusive. WLG are important agents of forest regeneration by dispersing seeds in logged areas. Nest sites in logging gaps could be particularly favorable for seedlings development. This consideration must encourage forest managers to strengthen WLG-conservative practices in their concessions. [less ▲]

Detailed reference viewed: 43 (7 ULg)
Full Text
See detailLes forêts communautaires, c'est aussi une histoire de femmes
Meunier, Quentin; Boldrini, Sylvie ULg; Morin, Amélie et al

Learning material (2013)

Detailed reference viewed: 37 (7 ULg)
Full Text
See detailLes équations allométriques pan-tropicales plurispécifiques sont-elles valables en Afrique centrale ?
Fayolle, Adeline ULg; Doucet, Jean-Louis ULg; Gillet, Jean-François ULg et al

in Picard, Nicolas; Henry, Mathieu (Eds.) Compte-rendu de l'Atelier scientifique régional sur les équations allométriques en Afrique Centrale : PREREDD, Yaoundé 2-5 avril 2013 (2013, April)

Detailed reference viewed: 63 (25 ULg)
Full Text
See detailRelation entre composition floristique et accumulation de biomasse dans deux types de forêts de la Réserve de Biosphère du Dja (Cameroun)
Djuikouo, Marie Noel K.; Doucet, Jean-Louis ULg; Nguembou, Charlemagne K. et al

Poster (2013, April)

Detailed reference viewed: 30 (5 ULg)
Full Text
See detailLes forêts vierges du Bassin du Congo - mythe ou réalité ?
Morin-Rivat, Julie ULg; Bourland, Nils ULg; Gillet, Jean-François ULg et al

Scientific conference (2013, March 21)

Les forêts du bassin du Congo ont longtemps été considérées comme des massifs historiquement épargnés par l'action de l'homme. Des résultats plus ou moins récents de recherches scientifiques remettent en ... [more ▼]

Les forêts du bassin du Congo ont longtemps été considérées comme des massifs historiquement épargnés par l'action de l'homme. Des résultats plus ou moins récents de recherches scientifiques remettent en question cette vision des forêt denses humides africaines. [less ▲]

Detailed reference viewed: 213 (23 ULg)
Full Text
See detailLettre d’information trimestrielle du projet Développement d’Alternatives Communautaires à l’Exploitation Forestière Illégale
Boldrini, Sylvie; Moumbogou; Meunier, Quentin et al

E-print/Working paper (2013)

Detailed reference viewed: 48 (9 ULg)
Full Text
See detailLes formations végétales du Sénégal : description et menaces
Doucet, Jean-Louis ULg

Conference given outside the academic context (2013)

Detailed reference viewed: 4 (1 ULg)
Full Text
See detailNature+ asbl - Rapport d'activités 2012
Federspiel, Michèle; Doucet, Jean-Louis ULg; Daïnou, Kasso ULg et al

Report (2013)

En 2012, Nature+ a rencontré ses missions, notamment : en mettant en oeuvre trois projets de foresterie communautaire financés par des bailleurs internationaux ; en participant à la gestion durable de ... [more ▼]

En 2012, Nature+ a rencontré ses missions, notamment : en mettant en oeuvre trois projets de foresterie communautaire financés par des bailleurs internationaux ; en participant à la gestion durable de près de 2,7 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 10 étudiants en fin de cursus universitaire ainsi que 11 doctorants. Huit universités différentes ont ainsi reçu un appui administratif, technique et scientifique de Nature+ ; en attribuant sa 2eme bourse de formation à un chercheur congolais. [less ▲]

Detailed reference viewed: 3 (1 ULg)
Full Text
Peer Reviewed
See detailEssais de propagation par semis et marcottage aérien de Coula edulis Baill. et perspectives pour sa domestication
Moupela, Christian; Doucet, Jean-Louis ULg; Daïnou, Kasso ULg et al

in Bois et Forêts des Tropiques (2013), 318(4), 3-13

Le noisetier d’Afrique, Coula edulis Baill. Olacaceae, est un arbre des forêts denses humides africaines. Il produit des graines d’une grande valeur nutritive qui sont régulièrement récoltées et ... [more ▼]

Le noisetier d’Afrique, Coula edulis Baill. Olacaceae, est un arbre des forêts denses humides africaines. Il produit des graines d’une grande valeur nutritive qui sont régulièrement récoltées et commercialisées par les populations d’Afrique centrale et de l’Ouest. Cependant, le manque d’informations relatives aux techniques de multiplication de l’espèce est la principale contrainte à sa domestication et à son intégration dans les systèmes agroforestiers locaux. L’étude, conduite parallèlement en pépinière et en milieu naturel, vise à mieux caractériser la germination de C. edulis et à déterminer ses aptitudes au marcottage aérien. Les résultats obtenus indiquent que la germination de C. edulis est très lente et échelonnée avec des taux de levée très faibles, voire nuls. De plus, les prétraitements appliqués aux graines se sont révélés inefficaces pour améliorer la vitesse et le taux de levée des semences. En revanche, le marcottage aérien permet de produire des plants de C. edulis d’une vigueur bien supérieure et dans un délai plus court que les semis en pépinière. Les résultats préliminaires du marcottage aérien sont prometteurs et ouvrent des perspectives intéressantes pour la multiplication et la domestication de l’espèce. L’intégration de Coula edulis dans les systèmes agroforestiers des plants issus du marcottage aérien est donc envisageable. [less ▲]

Detailed reference viewed: 13 (3 ULg)