Institute Of Recherche En Ecologie Tropicale Iret

Libreville, Gabon

Institute Of Recherche En Ecologie Tropicale Iret

Libreville, Gabon
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Medjibe V.P.,University of Florida | Putz F.E.,University of Florida | Starkey M.P.,Wildlife Conservation Society | Ndouna A.A.,Projet EFI Gabon | And 2 more authors.
Forest Ecology and Management | Year: 2011

Selective logging is an important socio-economic activity in the Congo Basin but one with associated environmental costs, some of which are avoidable through the use of reduced-impact logging (RIL) practices. With increased global concerns about biodiversity losses and emissions of carbon from forest in the region, more information is needed about the effects of logging on forest structure, composition, and carbon balance. We assessed the consequences of low-intensity RIL on above-ground biomass and tree species richness in a 50. ha area in northwestern Gabon. We assessed logging impacts principally in 10 randomly located 1-ha plots in which all trees ≥10. cm dbh were measured, identified to species, marked, and tagged prior to harvesting. After logging, damage to these trees was recorded as being due to felling or skidding (i.e., log yarding) and skid trails were mapped in the entire 50-ha study area. Allometric equations based on tree diameter and wood density were used to transform tree diameter into biomass.Logging was light with only 0.82trees (8.11m3) per hectare extracted. For each tree felled, an average of 11 trees ≥10cm dbh suffered crown, bole, or root damage. Skid trails covered 2.8% of the soil surface and skidding logs to the roadside caused damage to an average of 15.6 trees ≥10cm dbh per hectare. No effect of logging was observed on tree species richness and pre-logging above-ground forest biomass (420.4Mgha-1) declined by only 8.1% (34.2Mgha-1). We conclude from these data that with harvest planning, worker training in RIL techniques, and low logging intensities, substantial carbon stocks and tree species richness were retained in this selectively logged forest in Gabon. © 2011 Elsevier B.V.

Iponga D.M.,Stellenbosch University | Iponga D.M.,Institute Of Recherche En Ecologie Tropicale Iret
Journal of Arid Environments | Year: 2010

This study investigates the extent to which seed production in Schinus molle is dependent upon pollinators and outcrossing with the objective of understanding whether pollination and seed set could be a barrier to the spread of S. molle in arid savannas of South Africa. Pollination experiments demonstrated that seed set was greater in female flowers exposed to natural pollinators than in those from which pollinators were excluded. However, the fact that a few seeds were also found in treatments protected from pollinators and not treated with pollen may indicate that some S. molle flowers might be bisexual and capable of self-pollination. The results suggest that S. molle fruit set is mainly affected by insect pollination, but there is also the possibility of self-pollination and apomixis. © 2009 Elsevier Ltd. All rights reserved.

Yombiyeni P.,Institute Of Recherche En Ecologie Tropicale Iret | Decock C.,Catholic University of Louvain
Plant Ecology and Evolution | Year: 2017

Background and aims – This study is a part of an ongoing survey of Hymenochetaceae (Basidiomycota, Hymenochaetales) in the Guineo-Congolian phytogeographic region and presents a new species of Phylloporia from the lower Guinean sub-region in Southwestern Gabon. Methods – The species is described using morphological methods. DNA-based, phylogenetic analysis also are used to search for affinities. Key results – Phylloporia littoralis sp. nov. is described, based on specimens found growing from living shrubs of a Nichallea species (Rubiaceae) in a coastal, sclerophylous vegetation in Southwestern Gabon. Phylogenetic inferences using DNA sequence data from partial nuc 28S (region including the D1/D2/D3 domains) resolved this species as a distinct clade within the Phylloporia lineage, affine to Phylloporia flacourtiae, a taxon known from subtropical, eastern Asia, in China. Conclusion – Phylloporia littoralis is the sixth species of the genus described and so far only known from the lower Guinean phytogeographic sub-region in Gabon since 2015. Previously, none Phylloporia species was reported from Gabon. An identification key to the species occurring in Gabon or reported from the Guineo-Congolian phytochorion is provided. © 2017 Botanic Garden Meise and Royal Botanical Society of Belgium. All rights reserved.

Yombiyeni P.,Institute Of Recherche En Ecologie Tropicale Iret | Douanla-Meli C.,University of Kassel | Amalfi M.,Catholic University of Louvain | Decock C.,Catholic University of Louvain
Mycological Progress | Year: 2011

Phellinus gabonensis sp. nov. is described and illustrated on the basis of several collections made in three protected areas of primary rain forest in the western edge of the Guineo-Congolian center of endemism, in Gabon. The species is characterized by resupinate, perennial basidiomes, numerous, straight to commonly apically hooked hymenial setae, and ellipsoid to broadly ellipsoid, thin- to thick-walled, hyaline to yellowish basidiospores. Both the morphology and the phylogenetic inferences based on partial nuc-LSU relate this species to Ph. caribaeo-quercicolus. © 2010 German Mycological Society and Springer.

PubMed | Nihon University, Institute Of Recherche En Ecologie Tropicale Iret, Tokyo University of Agriculture and Technology, Yamaguchi University and 2 more.
Type: Journal Article | Journal: Virus genes | Year: 2016

Adenoviruses are widespread in human population as well as in great apes, although the data about the naturally occurring adenovirus infections remain rare. We conducted the surveillance of adenovirus infection in wild western lowland gorillas in Moukalaba-Doudou National Park (Gabon), in order to investigate naturally occurring adenovirus in target gorillas and tested specifically a possible zoonotic transmission with local people inhabiting the vicinity of the park. Fecal samples were collected from western lowland gorillas and humans, and analyzed by PCR. We detected adenoviral genes in samples from both gorillas and the local people living around the national park, respectively: the overall prevalence rates of adenovirus were 24.1 and 35.0% in gorillas and humans, respectively. Sequencing revealed that the adenoviruses detected in the gorillas were members of Human mastadenovirus B (HAdV-B), HAdV-C, or HAdV-E, and those in the humans belonged to HAdV-C or HAdV-D. Although HAdV-C members were detected in both gorillas and humans, phylogenetic analysis revealed that the virus detected in gorillas are genetically distinct from those detected in humans. The HAdV-C constitutes a single host lineage which is compatible with the host-pathogen divergence. However, HAdV-B and HAdV-E are constituted by multiple host lineages. Moreover, there is no evidence of zoonotic transmission thus far. Since the gorilla-to-human transmission of adenovirus has been shown before, the current monitoring should be continued in a broader scale for getting more insights in the natural history of naturally occurring adenoviruses and for the safe management of gorillas populations.

Mikissa J.B.,University of Paris 13 | Mikissa J.B.,Agro ParisTech | Mikissa J.B.,Institute Of Recherche En Ecologie Tropicale Iret | Jeffery K.,Institute Of Recherche En Ecologie Tropicale Iret | And 2 more authors.
Ecological Entomology | Year: 2013

In tropical West Africa, the ant Tetraponera aethiops obligately inhabits the domatia of Barteria fistulosa trees, aggressively defending the trees from herbivory and pruning off lianas. We compared the occurrence of ants and lianas on B. fistulosa trees in areas of Gabon, where the invasive little fire ant, Wasmannia auropunctata, was absent (uninfested area) and present (infested area). We found that T. aethiops occurred significantly more often in larger B. fistulosa trees, and that occurrence rates were much higher in the uninfested area versus the infested area: on < 1 m trees: 17% vs. 0%; 1-5 m trees: 58% vs. 3%; > 5 m trees: 90% vs. 10%). In contrast, lianas occurred significantly less often in the uninfested area versus the infested area: on < 1 m trees: 0% vs. 100%; 1-5 m trees: 0% vs. 77%; > 5 m trees: 10% vs. 63%). In the infested area, W. auropunctata occurred significantly less often in larger B. fistulosa trees (on < 1 m trees: 100%; 1-5 m trees: 97%; > 5 m trees: 90%). Here T. aethiops and W. auropunctata coexisted on few trees (on < 1 m trees: 0%; 1-5 m trees: 1%; > 5 m trees: 4%). The negative consequences for the trees are already evident, and the situation for native ants is likely to decline further in future because they will not be able to generate the large (relatively resistant) colonies found on large trees. © 2013 The Royal Entomological Society.

Decock C.,Catholic University of Louvain | Mossebo D.C.,University of Yaounde I | Yombiyeni P.,Institute Of Recherche En Ecologie Tropicale Iret
Plant Ecology and Evolution | Year: 2011

Background and aims - The Polypores of central Africa (or in biogeographical terms, the Guineo-Congolian phytogeographic region) are still poorly investigated. As part of an ongoing survey of the Polypores in this region, an undescribed species of Perenniporia was collected in the Dja Biosphere Reserve, in south-eastern Cameroon. Methods - Species are described using morphology-based methods. Key results - Perenniporia alboferruginea sp. nov. is proposed, described and illustrated. Several new collections of poorly known species are reported, and an identification key for the Perenniporia species occurring in the Dja Biosphere Reserve and neighbouring areas is presented. Conclusion - About ten years ago, two Perenniporia species were recorded from the Dja Biosphere Reserve. Nowadays, seven species are known from the area, of which four were described based on material originating from this locality. © 2011 National Botanic Garden of Belgium and Royal Botanical Society of Belgium.

PubMed | Smithsonian Institution, Smithsonian Conservation Biology Institute, Utah State University and Institute Of Recherche En Ecologie Tropicale Iret
Type: Journal Article | Journal: PloS one | Year: 2016

Tropical forests have long been recognized for their biodiversity and ecosystem services. Despite their importance, tropical forests, and particularly those of central Africa, remain understudied. Until recently, most forest inventories in Central Africa have focused on trees 10 cm in diameter, even though several studies have shown that small-diameter tree population may be important to demographic rates and nutrient cycling. To determine the ecological importance of small-diameter trees in central African forests, we used data from a 25-ha permanent plot that we established in the rainforest of Gabon to study the diversity and dynamics of these forests. Within the plot, we censused 175,830 trees 1 cm dbh from 54 families, 192 genera, and 345 species. Average tree density was 7,026 trees/ha, basal area 31.64 m2/ha, and above-ground biomass 369.40 Mg/ha. Fabaceae, Ebenaceae and Euphorbiaceae were the most important families by basal area, density and above-ground biomass. Small-diameter trees (1 cm dbh <10 cm) comprised 93.7% of the total tree population, 16.5% of basal area, and 4.8% of the above-ground biomass. They also had diversity 18% higher at family level, 34% higher at genus level, and 42% higher at species level than trees 10 cm dbh. Although the relative contribution of small-diameter trees to biomass was comparable to other forests globally, their contribution to forest density, and diversity was disproportionately higher. The high levels of diversity within small-diameter classes may give these forests high levels of structural resilience to anthropogenic/natural disturbance and a changing climate.

Yombiyeni P.,Institute Of Recherche En Ecologie Tropicale Iret | Balezi A.,University Officielle Of Bukavu | Amalfi M.,Catholic University of Louvain | Decock C.,Catholic University of Louvain
Mycologia | Year: 2015

Four species are added to Phylloporia. Three species, originating from the western edge of the Guineo-Congolian rainforest in Gabon (central Africa), are described as new. Phylloporia afrospathulata sp. nov. forms seasonal, stipitate, solitary basidiomata emerging from soil, more likely connected to buried roots, and has broadly ellipsoid basidiospores. Phylloporia inonotoides sp. nov. forms seasonal sessile, soft basidiomata, solitary at the base of small-stemmed trees including Crotonogyne manniana (Euphorbiaceae) and Garcinia cf. smeathmannii (Clusiaceae). It has a homogeneous context, large pores (2-3 mm), and oblong-ellipsoid to suballantoid basidiospores. Phylloporia fulva sp. nov. forms sessile, conchate, mostly pendant, gregarious basidiomata emerging from the trunk of an unidentified small-stemmed tree and has small, subglobose basidiospores. This species is compared to Polyporus pullus and Phylloporia pulla comb. nov. and proposed based on the study of the type specimen. Phylogenetic inferences using partial nuc 28S DNA sequence data (region including the D1/D2/D3 domains) and the most exhaustive dataset available to date resolved these new morphospecies as three distinct terminal lineages. No sequence data of P. pulla currently is available. The 28S-based phylogenic inferences poorly resolved the interspecific relationships within the Phylloporia clade. © 2015 by The Mycological Society of America, Lawrence, KS 66044-8897.

Amalfi M.,Catholic University of Leuven | Yombiyeni P.,Institute Of Recherche En Ecologie Tropicale Iret | Decock C.,Catholic University of Leuven
Mycologia | Year: 2010

Fomitiporia nobilissima sp. nov., F. gabonensis sp. nov. and F. ivindoensis sp. nov., three species from the rainforest of the Guineo-Congolian phytogeographic region in Gabon, are described and illustrated. These species share a pileate basidiome, small basidiospores and an absence of setae. The critical morphological features that differentiate them are the pileus habit or shape, pore surface color, pore diameter and possibly ecology. Each new species forms distinct but closely related clades in phylogenetic analysis of DNA sequences from nuclear ribosomal LSU, ITS and translation elongation factor 1-α. Other species in sub-Saharan Africa are discussed briefly. A key to six species of Fomitiporia from sub-Saharan Africa is provided. The new combination Fomitiporia apiahyna is proposed. © 2010 by The Mycological Society of America.

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