References of "Doucet, Jean-Louis"
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See detailPerceptions of ecosystem services provided by tropical forests to local populations in Cameroon
Lhoest, Simon ULiege; Dufrêne, Marc ULiege; Vermeulen, Cédric ULiege et al

in Ecosystem Services (2019), 38

In Central Africa, local populations are deeply dependent on tropical forests, which provide numerous ecosystem services (ES). For the first time in Central Africa, we assessed the perceptions of ES ... [more ▼]

In Central Africa, local populations are deeply dependent on tropical forests, which provide numerous ecosystem services (ES). For the first time in Central Africa, we assessed the perceptions of ES provided by tropical forests to local populations, considering three land allocation types: a protected area, a Forest Stewardship Council (FSC)-certified logging concession, and three community forests. We conducted a questionnaire survey with 225 forest stakeholders in southeastern Cameroon, combining an open-ended question and 16 directed questions to evaluate the perceptions of ES significance and abundance, respectively. The ES most frequently reported as significant were provisioning (93% of respondents) and cultural & amenity services (68%), whereas regulating services were less mentioned (16%). Bushmeat provision was the only ES perceived as highly significant but not very abundant. There were slight variations of perceptions among forest land allocation types and respondents, suggesting a relative homogeneity in ES abundance. For further integrative ES assessment, we suggest quantifying ES with complementary ecological and economic approaches, such as meat provision, recreation, tourism, timber provision, spiritual experience, firewood provision, water quality regulation, and inspiration for culture. We also give three concrete recommendations for forest management, the most urgent being to provide sources of protein alternative to bushmeat. [less ▲]

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See detailSeed and pollen dispersal distances in two African legume timber trees and their reproductive potential under selective logging
Hardy, Olivier J.; Delaide, Boris; Hainaut, Hélène et al

in Molecular Ecology (2019)

The natural regeneration of tree species depends on seed and pollen dispersal. To assess whether limited dispersal could be critical for the sustainability of selective logging practices, we performed ... [more ▼]

The natural regeneration of tree species depends on seed and pollen dispersal. To assess whether limited dispersal could be critical for the sustainability of selective logging practices, we performed parentage analyses in two Central African legume canopy species displaying contrasted floral and fruit traits: Distemonanthus benthamianus and Erythrophleum suaveolens. We also developed new tools linking forward dispersal kernels with backward migration rates to better characterize long‐distance dispersal. Much longer pollen dispersal in D. benthamianus (mean distance dp = 700 m, mp = 52% immigration rate in 6 km2 plot, s = 7% selfing rate) than in E. suaveolens (dp = 294 m, mp = 22% in 2 km2 plot, s = 20%) might reflect different insect pollinators. At a local scale, secondary seed dispersal by vertebrates led to larger seed dispersal distances in the barochorous E. suaveolens (ds = 175 m) than in the wind‐dispersed D. benthamianus (ds = 71 m). Yet, seed dispersal appeared much more fat‐tailed in the latter species (15%–25% seeds dispersing >500 m), putatively due to storm winds (papery pods). The reproductive success was correlated to trunk diameter in E. suaveolens and crown dominance in D. benthamianus. Contrary to D. benthamianus, E. suaveolens underwent significant assortative mating, increasing further the already high inbreeding of its juveniles due to selfing, which seems offset by strong inbreeding depression. To achieve sustainable exploitation, seed and pollen dispersal distances did not appear limiting, but the natural regeneration of E. suaveolens might become insufficient if all trees above the minimum legal cutting diameter were exploited. This highlights the importance of assessing the diameter structure of reproductive trees for logged species. [less ▲]

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See detailQuelles forêts laisserons-nous à nos petits-enfants ?
Doucet, Jean-Louis ULiege; Lejeune, Philippe ULiege

Conference given outside the academic context (2019)

•Les forêts et la déforestation •Les forêts d’Afrique centrale •La forêt wallonne •Les forêts et le changement climatique

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See detailDo topography and fruit presence influence occurrence and intensity of crop-raiding by forest elephants (Loxodonta africana cyclotis)?
Ngama, Steeve ULiege; Bindelle, Jérôme ULiege; Poulsen, John R. et al

in PLoS ONE (2019), 14(3), 16

Crop damage by forest elephants (Loxodonta africana cyclotis) and the resulting human-elephant conflict are issues of great concern for both the conservation of the species and the protection of rural ... [more ▼]

Crop damage by forest elephants (Loxodonta africana cyclotis) and the resulting human-elephant conflict are issues of great concern for both the conservation of the species and the protection of rural livelihoods in Central Africa. Addressing these problems requires identifying the factors that facilitate or impede crop-raiding by forest elephants. Yet to date, the environmental or anthropogenic factors that influence the occurrence and intensity of cropraiding by forest elephants are largely unknown. We used a multivariate approach to investigate conditions under which forest elephants raid some fields and not others in the buffer zone of Monts de Cristal National Park (MCNP), Gabon. We first interviewed 121 farmers from 11 villages situated within 10 km of MCNP regarding the occurrence of elephant cropraiding of their fields. We then collected data on 39 explanatory variables to characterize the agricultural fields. Of these, the most important predictors of elephant raid occurrence of crop damage were presence of fruit trees, elephant deterrents (scarecrows, fire, wire string fences and empty barrels), and field topography. We secondly assessed the effect of stage of crop growth, presence of fruit trees, field topography and presence of elephant deterrents on crop-raiding occurrence and intensity by counting raids and measuring areas of crop damage every week in 17 plantations over 19 weeks in the most elephant-impacted zone of the study area. We found that fruit presence and stage of crop growth led to more intense damage to crops, whereas local deterrents did not inhibit raiding events and crop damage by elephants. We report a tradeoff between non-timber forest products (NTFP) services and crop-raiding by elephants. We show for the first time that steep topography impedes elephant damage to crops with no raids recorded in fields with surrounding slopes greater than 25%. We discuss whether farming on steep fields could be used as a strategy for mitigating crop-raiding to favor human-elephant coexistence and enhance elephant conservation. [less ▲]

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See detailÉtat des connaissances sur les céphalophes (genres Cephalophus et Philantomba) des forêts denses humides d’Afrique centrale (synthèse bibliographique)
Houngbegnon, Fructueux ULiege; Sonké, Bonaventure; Vermeulen, Cédric ULiege et al

in Biotechnologie, Agronomie, Société et Environnement (2019)

Introduction. This article provides a synthesis of current knowledge on classification, ecology and biology of duikers living in central African rainforests (genera Cephalophus and Philantomba). It also ... [more ▼]

Introduction. This article provides a synthesis of current knowledge on classification, ecology and biology of duikers living in central African rainforests (genera Cephalophus and Philantomba). It also provides an update on the anthropogenic pressures on these terrestrial mammals. Literature. Many publications on central African duikers are focused on subsistence or commercial hunting, and poaching. As the taxonomic classification of duikers has recently been revised, new species have been described with very little information available on their ecology. This synthesis highlights the gaps in the scientific knowledge and proposes priority themes for future research. Conclusions. Although many aspects remain to be explored for some species (i.e., habitat use, home range), it is suggested to investigate in priority: the inventory methods, the role of duikers in forest dynamics, and the impact of logging on their populations. [less ▲]

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See detailEcosystem services assessment in Southeast Cameroon tropical forests
Lhoest, Simon ULiege; Dufrêne, Marc ULiege; Jamar, Pierre et al

Scientific conference (2019, March 11)

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See detailEcological niche divergence associated with species and populations differentiation in Erythrophleum (Fabaceae, Caesalpinioideae)
Gorel, Anaïs ULiege; Duminil, Jérôme; Doucet, Jean-Louis ULiege et al

in Plant Ecology and Evolution (2019)

Background and aims – The isolation of populations inside forest refugia during past climate changes has widely been hypothesized as a major driver of tropical plant diversity. Environmental conditions ... [more ▼]

Background and aims – The isolation of populations inside forest refugia during past climate changes has widely been hypothesized as a major driver of tropical plant diversity. Environmental conditions can also influence patterns of diversity by driving divergent selection leading to local adaptation and, potentially, ecological speciation. Genetic and phylogenetic approaches are frequently used to study the diversification of African tree clades. However, the environmental space occupied by closely related species or intra-specific gene pools is barely quantified, though needed to properly test hypotheses on diversification processes. Methods – Using species distribution models, we determined the bioclimatic constraints on the distribution of closely related species and intra-specific gene pools. Our study model, Erythrophleum (Fabaceae - Caesalpinioideae), is a tropical tree genus widespread across Africa, and vastly investigated for genetics. Here, we combined the available phylogenetic data with information on niche divergence to explore the role of ecology into diversification at the species and gene pool levels. Key results – Ecological speciation through climate has probably played a key role in the evolution of the Erythrophleum species. The differential climatic niche of the species indicated adaptive divergence along rainfall gradients, that have probably been boosted by past climate fluctuations. At the gene pool level, past climate changes during the Pleistocene have shaped genetic diversity, though within Erythrophleum suaveolens, adaptive divergence also occurred. Conclusions – We believe that ecological speciation is a key mechanism of diversification for tropical African tree species, since such climatic niche partition exist among many other genera. Modeling the environmental niche of closely related taxa, and testing for niche differentiation, combined with divergence dates offered new insights on the process of diversification. [less ▲]

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See detailConservation value of protected and logged tropical forests in Cameroon
Lhoest, Simon ULiege; Fonteyn, Davy ULiege; Daïnou, Kasso ULiege et al

Scientific conference (2019, January 25)

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See detailDe la forêt aux molécules : repenser l’exploitation forestière ?
Doucet, Jean-Louis ULiege

Conference given outside the academic context (2019)

Les ressources en bois tropicaux s’épuisent malgré l’existence de plans d’aménagement. Que faire ? 1. Rediriger l’exploitation vers des essences dont la capacité de production est garantie sur le long ... [more ▼]

Les ressources en bois tropicaux s’épuisent malgré l’existence de plans d’aménagement. Que faire ? 1. Rediriger l’exploitation vers des essences dont la capacité de production est garantie sur le long terme 2. Valoriser mieux et plus de produits issus des forêts [less ▲]

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See detailTesting the divergent adaptation of two congeneric tree species on a rainfall gradient using eco-physio-morphological traits
Gorel, Anaïs ULiege; Steppe, Kathy; Beeckman, Hans et al

in Biotropica (2019)

In tropical Africa, evidence of widely distributed genera transcending biomes or habitat boundaries has been reported. The evolutionary processes that allowed these lineages to disperse and adapt into new ... [more ▼]

In tropical Africa, evidence of widely distributed genera transcending biomes or habitat boundaries has been reported. The evolutionary processes that allowed these lineages to disperse and adapt into new environments are far from being resolved. To better understand these processes, we propose an integrated approach, based on the eco-physio-morphological traits of two sister species with adjacent distributions along a rainfall gradient. We used wood anatomical traits, plant hydraulics (vulnerability to cavitation, wood volumetric water content and hydraulic capacitance) and growth data from the natural habitat, in a common garden, to compare species with known phylogeny, very similar morphologically, but occupying contrasting habitats: Erythrophleum ivorense (wet forest) and Erythrophleum suaveolens (moist forest and forest gallery). We identified some slight differences in wood anatomical traits between the two species associated with strong differences in hydraulics, growth, and overall species distribution. The moist forest species, E. suaveolens had narrower vessels and intervessel pits, and higher vessel cell-wall reinforcement than E. ivorense. These traits allow a high resistance to cavitation and a continuous internal water supply of the xylem during water shortage, allowing a higher fitness during drought periods, but limiting growth. Our results confirm a trade-off between drought tolerance and growth, controlled by subtle adaptations in wood traits, as a key mechanism leading to the niche partitioning between the two Erythrophleum species. The generality of this trade-off and its importance in the diversification of the African tree flora remains to be tested. Our integrated eco-physio-morpho approach could be the way forward. [less ▲]

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See detailThe persistence of carbon in the African forest understory
Hubau, Wannes; De Mil, Tom; Van den Bulcke, Jan et al

in Nature Plants (2019)

Quantifying carbon dynamics in forests is critical for understanding their role in long-term climate regulation1–4. Yet little is known about tree longevity in tropical forests3,5–8, a factor that is ... [more ▼]

Quantifying carbon dynamics in forests is critical for understanding their role in long-term climate regulation1–4. Yet little is known about tree longevity in tropical forests3,5–8, a factor that is vital for estimating carbon persistence3,4. Here we calculate mean carbon age (the period that carbon is fixed in trees7) in different strata of African tropical forests using (1) growthring records with a unique timestamp accurately demarcating 66 years of growth in one site and (2) measurements of diameter increments from the African Tropical Rainforest Observation Network (23 sites). We find that in spite of their much smaller size, in understory trees mean carbon age (74 years) is greater than in sub-canopy (54 years) and canopy (57 years) trees and similar to carbon age in emergent trees (66 years). The remarkable carbon longevity in the understory results from slow and aperiodic growth as an adaptation to limited resource availability9–11. Our analysis also reveals that while the understory represents a small share (11%) of the carbon stock12,13, it contributes disproportionally to the forest carbon sink (20%). We conclude that accounting for the diversity of carbon age and carbon sequestration among different forest strata is critical for effective conservation management14–16 and for accurate modelling of carbon cycling4. [less ▲]

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See detailGrowth determinants of timber species Triplochiton scleroxylon and implications for forest management in central Africa
Ligot, Gauthier ULiege; Fayolle, Adeline ULiege; Gourlet-Fleury, Sylvie et al

in Forest Ecology and Management (2019), 437

The sustainability of the polycyclic logging system in tropical forests has been increasingly questioned for a variety of reasons, and particularly in central Africa as commercial species, mostly light ... [more ▼]

The sustainability of the polycyclic logging system in tropical forests has been increasingly questioned for a variety of reasons, and particularly in central Africa as commercial species, mostly light-demanding long-lived pioneer species, usually fail to recover a stable number of large trees after exploitation. Several factors are known to affect tropical tree demographic processes, like tree growth, survival and recruitment. Tree growth has particularly been showed to depend on ecological conditions, tree genetics, and competition with surrounding vegetation, as well as tree size or ontogeny. Yet, due to the paucity of available data, the importance of such factors is unclear and usually ignored when estimating future timber yields. To fill this gap, we chose to evaluate the variability in growth of one African long-lived pioneer and commercially very important species: Triplochiton scleroxylon K. Schum, gathering a broad dataset composed of tree ring data recorded in one site in Cameroon and periodic field inventory data recorded in seven sites across central Africa. In total, we analyzed 13,225 records of annual tree diameter increments recorded over 920 trees from seven sites in Cameroon, Republic of the Congo and Central African Republic. We evaluated (i) to what extent the average growth of trees that reach harvestable dimensions differs from population average and (ii) to what extent past perturbations influence the growth of remaining trees. We found the diameter growth of T. scleroxylon to be remarkably variable and this study provided an unprecedented quantification of the magnitude of some key growth determinants. In unlogged forests, the diameter increment of T. scleroxylon ranged between 0.40 cm year-1 in Southern Cameroon and 0.83 cm year-1 in South-Eastern Cameroon. The diameter increment was weakly related to tree size but increased twofold from unlogged to logged forests. Perturbation caused by logging stimulates growth of T. scleroxylon for at least 10-15 years. Finally, harvestable timber stock of large-sized T. scleroxylon was found to be constituted by trees that grew in average twice faster than trees of the entire extant population. As more and more inventory data become available, quantifying these effects could be replicated for other timber species and in other sites, to improve the accuracy of future timber resource estimates and improve forest management guidelines. [less ▲]

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See detailBanque de graines du sol et déterminants de la germination du tali, Erythrophleum suaveolens (Guill. & Perr.) Brenan
Douh, Chauvelin ULiege; Gorel, Anaïs ULiege; Daïnou, Kasso ULiege et al

in Bois et Forêts des Tropiques (2018), 338

Cette étude évalue l’abondance des graines d’Erythrophleum suaveolens dans la banque du sol des forêts denses humides d’Afrique centrale. Les travaux ont été menés au Nord-Congo dans deux types forestiers ... [more ▼]

Cette étude évalue l’abondance des graines d’Erythrophleum suaveolens dans la banque du sol des forêts denses humides d’Afrique centrale. Les travaux ont été menés au Nord-Congo dans deux types forestiers : la forêt à Celtis sur des sols argilo-sableux à sablo-argileux et la forêt à Manilkara sur des sols sableux. Les tiges d’E. suaveolens (dhp ≥ 10 cm) ont été inventoriées dans deux parcelles de 400 ha, et les structures diamétriques de leurs populations ont été comparées. En outre, 80 fosses (2 x 40 fosses par type de forêt) ont été creusées aux pieds de 20 arbres (10 par forêt), sur trois couches contiguës de 10 cm chacune, soit à une profondeur totale de 30 cm, et l’abondance des graines dans la banque du sol a été évaluée. La dormance des graines récoltées a été testée par des essais de germination après traitement au H2SO4 et cinq graines prélevées jusqu’à une profondeur de 20 cm dans la forêt à Celtis ont été utilisées pour estimer leur âge par Spectroscopie de Masse par Accélérateur (SMA). La comparaison des structures diamétriques indique une plus grande proportion de tiges de faible diamètre dans la forêt à Celtis. Alors que les densités de tiges (dhp ≥ 10 cm) sont proches, avec 0,85 et 1,05 tige/ha respectivement, dans la forêt à Celtis et la forêt à Manilkara, les densités de graines sont significativement plus élevées dans la forêt à Celtis (8,55 graines/m2) que dans la forêt à Manilkara (0,15 graine/m2). Le pourcentage maximum de germination obtenu était de 19,1 % pour des graines n’ayant subi aucun traitement. Les lots traités à l’acide ont présenté de moindres taux de germination. Ces graines pourraient se conserver une dizaine d’années dans la banque du sol. Les facteurs pouvant influencer les variations de densité des graines sont discutés et des recommandations sylvicoles sont formulées. [less ▲]

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See detailRéviser les tarifs de cubage pour prendre en compte l'évolution de la ressource au Cameroun
Ligot, Gauthier ULiege; Dubart, Nicolas; Tchowo Hapi, Mauriad et al

in Bois et Forêts des Tropiques (2018), 338

La connaissance du volume exploitable est une information essentielle tant pour la gestion que pour le contrôle de l’exploitation forestière. En Afrique centrale, l’estimation des volumes repose ... [more ▼]

La connaissance du volume exploitable est une information essentielle tant pour la gestion que pour le contrôle de l’exploitation forestière. En Afrique centrale, l’estimation des volumes repose essentiellement sur l’utilisation de tarifs de cubage à une entrée, spécifique à chaque essence, et prédisant le volume exploitable à partir du diamètre de l’arbre. Or, récemment, de nombreux acteurs de la gestion forestière au Cameroun reportent une inadéquation entre les volumes commerciaux estimés avec les tarifs de cubage imposés par l’administration et les volumes estimés à partir des mesures de la longueur et du diamètre des billes exploitées. Afin de vérifier la justesse des tarifs de cubage imposés par l’administration camerounaise, nous avons réalisé un échantillonnage destructif pour 12 essences jouant un rôle crucial dans le commerce du bois au Cameroun, et développé de nouveaux tarifs de cubage, qui ont été comparés avec les tarifs imposés par l’administration camerounaise et 52 autres tarifs de cubage disponibles dans la littérature. Dans quatre concessions forestières du Cameroun, représentatives des différentes conditions écologiques prévalant dans ce pays, 732 arbres ont été abattus et leur volume a été mesuré par la méthode des billons successifs. Des tarifs de cubage à une entrée, fonction uniquement du diamètre de référence, ont ensuite été ajustés par la méthode des moindres carrés généralisés. Notre étude confirme l’existence de biais entre les volumes mesurés et les volumes estimés en utilisant les tarifs de cubage imposés par l’administration camerounaise. En conséquence, de nouveaux tarifs de cubage et un abaque de correction sont proposés. Enfin, la majorité des tarifs de cubages testés présentaient un biais similaire qui résulte vraisemblablement d’une évolution de la ressource et des pratiques d’exploitation. [less ▲]

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See detailTowards a tragic end of the sustainable forest management in Central Africa ?
Doucet, Jean-Louis ULiege

Conference given outside the academic context (2018)

• The land use in Central Africa • The sustainable forest management • The recent decrease of the certified area • Consequences • Solutions

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See detailAssessment of mammal biodiversity and bushmeat offtake in the tropical forests of southeastern Cameroon
Lhoest, Simon ULiege; Fonteyn, Davy ULiege; Hette, Samuel et al

Poster (2018, November 27)

Tropical forests of central Africa host an important part of the world’s terrestrial biodiversity and provide numerous provisioning, regulating, and cultural ecosystem services to human populations. Major ... [more ▼]

Tropical forests of central Africa host an important part of the world’s terrestrial biodiversity and provide numerous provisioning, regulating, and cultural ecosystem services to human populations. Major threats hang over those diverse ecosystems, namely land use changes and consumption of bushmeat. Our study aimed to assess mammal diversity and bushmeat consumption in three contrasted and largely represented forest land allocation types in southeastern Cameroon: (i) a protected area, (ii) a FSC-certified logging concession, and (iii) three community forests. Mammal inventories were conducted with 44 camera traps installed for 3 months. Bushmeat consumption was quantified using both tracking of volunteer hunters over 651 kilometers and the daily monitoring of the food bowl of 55 households for 3 months. Though a great part of the mammal diversity is retained inside the logging concession, the protected area holds the richest and most abundant mammal communities, whereas community forests were found to be defaunated and structurally disturbed. The size of the hunting territories is influenced by many factors such as human population density or the presence of alternative protein sources. Although poaching controls in the protected area and, to a lesser extent, in the certified logging concession appear to play a deterrent role, evidence of hunting activities were found in all land allocation types. Bushmeat represents on average 56% of the animal protein consumed by households, the remaining part being mainly fish. Our results demonstrated the ability of the certified logging concession and the protected area in the conservation of wildlife species and the provision of bushmeat for local populations. It remains essential to maintain and develop anti-poaching patrols in those areas, strategically based on geographic data of hunting pressure. Current levels of hunting activities also confirm the need for the development of alternatives to bushmeat. [less ▲]

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See detailThe African timber tree Entandrophragma congoense (Pierre ex De Wild.) A.Chev. is morphologically and genetically distinct from Entandrophragma angolense (Welw.) C.DC
Monthe, Franck K.; Duminil, Jérôme; Kasongo Yakusu, Emmanuel et al

in Tree Genetics and Genomes (2018), 14

Interpreting morphological variability in terms of species delimitation can be challenging. However, correcting species delineation can have strong implications for the sustainable management of exploited ... [more ▼]

Interpreting morphological variability in terms of species delimitation can be challenging. However, correcting species delineation can have strong implications for the sustainable management of exploited species. Up to now, species delimitation between two putative timber species from African forests, Entandrophragma congoense and E. angolense, remained unclear. To investigate their differences, we applied an integrated approach which combines morphological traits and genetic markers.We defined 13 morphological characters from 81 herbarium specimens and developed 15 new polymorphic microsatellite markers to genotype 305 samples (herbarium samples and specimens collected in the field across the species distribution ranges). Principal component analysis (PCA) of morphological data and the Bayesian clustering analyses of genetic data were used to assess differentiation between putative species. These analyses support two well-differentiated groups (FST = 0.30) occurring locally in sympatry. Moreover, these two groups present distinct morphological characters at the level of the trunk, leaflets, and seeds. Our genetic markers identified few individuals (4%) that seem to be hybrids, though there is no evidence of genetic introgression from geographic patterns of genetic variation. Hence, our results provide clear support to recognize E. congoense as a species distinct from E. angolense, with a much lower genetic diversity than the latter, and that should be managed accordingly. This work highlights the power of microsatellite markers in resolving species boundaries. [less ▲]

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See detailWhat controls local-scale aboveground biomass variation in central Africa? Testing structural, composition and architectural attributes
Loubota Panzou, Grâce Jopaul ULiege; Fayolle, Adeline ULiege; Feldpausch, Ted R. et al

in Forest Ecology and Management (2018), 429

Tropical forests play a key role in regulating the terrestrial carbon cycle and climate change by storing a large amount of carbon. Yet, there is considerable uncertainty about the amount and spatial ... [more ▼]

Tropical forests play a key role in regulating the terrestrial carbon cycle and climate change by storing a large amount of carbon. Yet, there is considerable uncertainty about the amount and spatial variation of aboveground biomass (AGB), especially in the relatively less studied African tropical forests. In this study, we explore the local-scale variation and determinants of plot-level AGB, between and within two types of forests, the Celtis and Manilkara forests, growing under the same climate but on different geological substrates in the northern Republic of Congo. In each forest site, all trees ≥10 cm diameter were censured in 36 × 1-ha plots and we measured tree height and crown size using a subsample of 18 × 1-ha of these plots. We developed height-diameter and crown-diameter allometric relationships and tested whether they differed between the two sites. For each 1-ha plot, we further estimated the AGB and calculated structural attributes (stem density and basal area), composition attributes (wood density) and architectural attributes (tree height and crown size), the latter being derived from site-specific allometric relationships. We found strong between-site differences in height-diameter and crown-diameter allometries. For a given diameter, trees were taller in the Celtis forest while they had larger crown in the Manilkara forest. Similar trends were found for the sixteen species present in both forest sites, suggesting an environmental control of tree allometry. Although there were some between-site differences in forest structure, composition and architecture, we did not detect any significant difference in mean AGB between the Celtis and the Manilkara forests. The AGB variation was related to the heterogeneous distribution of large trees, and influenced by basal area, height and crown dimensions, and to a lesser extent wood density. These forest attributes have strong practical implications on emerging remote-sensing technologies for carbon monitoring in tropical forests. [less ▲]

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See detailEnrichissement des concessions forestières en essences à haute valeur commerciale
Doucet, Jean-Louis ULiege

Conference given outside the academic context (2018)

Les ressources en bois tropicaux s’épuisent malgré l’existence de plans d’aménagement. Certains Etats prennent des mesures, mais... • Manque de connaissance sur l’écologie des essences commerciales • ... [more ▼]

Les ressources en bois tropicaux s’épuisent malgré l’existence de plans d’aménagement. Certains Etats prennent des mesures, mais... • Manque de connaissance sur l’écologie des essences commerciales • Manque d’itinéraires techniques pragmatiques Objectifs : Proposer des techniques pragmatiques d’enrichissement forestier visant à maintenir sur le long terme des populations viables d’essences commerciales [less ▲]

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