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Background and Aims The botanic gardens of the world are now unmatched ex situ collections of plant biodiversity. They mirror two biogeographical patterns (positive diversity-area and diversity-age relationships) but differ from nature with a positive latitudinal gradient in their richness. Whether these relationships can be explained by socio-economic factors is unknown. Methods Species and taxa richness of a comprehensive sample of botanic gardens were analysed as a function of key ecological and socio-economic factors using (a) multivariate models controlling for spatial autocorrelation and (b) structural equation modelling. Key Results The number of plant species in botanic gardens increases with town human population size and country Gross Domestic Product (GDP) per person. The country flora richness is not related to the species richness of botanic gardens. Botanic gardens in more populous towns tend to have a larger area and can thus host richer living collections. Botanic gardens in richer countries have more species, and this explains the positive latitudinal gradient in botanic gardens' species richness. Conclusions Socio-economic factors contribute to shaping patterns in the species richness of the living collections of the world's botanic gardens

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Background and aims - Eighty per cent of Gabon's territory is covered by forest with most species inventory work focused on these areas. However, herbaceous open vegetation types are abundant in this country and can be found in savannas on the coast, in the centre and in the south, and on inselbergs. The species diversity patterns of these habitats remain largely unexplored yet are targeted for both conservation and development. Here, we evaluate the floristic diversity of savannas in Gabon, their affinities with the inselberg open vegetation, and their contribution to the national park system in Gabon, which is currently undergoing a gap analysis. We then use a case study from the Batéké Plateaux to demonstrate species rarity in a single savanna. Materials and methods - Species presence in the grassy formations of the savannas in Loango, Lopé, Pongara, and Plateaux Batéké national parks and in Kum inselberg is compared using ordination and clustering based on a similarity matrix (Sorensen index). For the Batéké Plateaux savannas, the species rarity and distributions are assessed using Star ratings. Key results - The species in the open herbaceous vegetation in Gabon account for at least 11% of the total flora of the country (508 species out of 4, 710). Except for the coastal savannas, all sites are highly dissimilar in floristic composition (Sorensen index 0.065-0.26) and no dominant savanna type occurs within the dataset. The inselberg site is the most dissimilar and constitutes a separate vegetation unit. Most savanna species of the Batéké Plateaux area are widely distributed, but not weedy. A few are extremely rare and are linked with moist habitats, substrate, and fire occurrence. Our results show the diversity and the conservation value of open, herbaceous habitats. Currently, the Gabonese National Park network is partly protecting the savanna and inselberg vegetation. However, several areas remain un-assessed and merit further exploration. ©2013 National Bota, SCOPUS: ar.k, info:eu-repo/semantics/published

DNA barcoding of rain forest trees could potentially help biologists identify species and discover new ones. However, DNA barcodes cannot always distinguish between closely related species, and the size and completeness of barcode databases are key parameters for their successful application. We test the ability of rbcL, matK and trnH-psbA plastid DNA markers to identify rain forest trees at two sites in Atlantic central Africa under the assumption that a database is exhaustive in terms of species content, but not necessarily in terms of haplotype diversity within species., Journal Article, Research Support, Non-U.S. Gov't, SCOPUS: ar.j, info:eu-repo/semantics/published

The seeds of Pentadesma butyracea (butter tree) are exploited by rural populations in West Africa to produce butter used for consumption and as an ingredient in cosmetics and medicinal preparations. To improve our knowledge of this under-studied species, the morphological variation of the trees, fruits and seeds in 12 natural populations of Benin distributed over a gradient of climate aridity is described with 14 quantitative and 13 qualitative descriptors. Most traits, except seed shape categories, show significant differences among populations. Multivariate analyses distinguish two eco-geographical groups: trees located in the more humid southern part of the species distribution are taller and have larger fruits and seeds than trees located in the north. To disentangle the relative roles of genetic variation and phenotypic plasticity in shaping, further phenotypic studies should be performed in common garden experiments. © 2012 Springer Science+Business Media B.V., SCOPUS: ar.j, info:eu-repo/semantics/published

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Plant communities of soils naturally enriched in copper and cobalt in Katanga (D. R. Congo) are critically threatened in the short term due to mining activities. For biodiversity conservation and ecosystem restoration purposes, there is an urgent need to acquire more knowledge on those plant communities including their diversity and their relationships to environmental factors. The classification of 62 vegetation plots located in 6 metal-rich rocky hills in the Tenke Fungurume mining area resulted in 3 well-defined steppic and steppic savanna communities. Canonical analysis showed that the community comprising the largest proportion of strictly endemic metallophytes (i.e. species that only occur on metal-rich soils) developed in the soils with the most elevated concentrations of Cu and Co. However, contrasting species assemblages in the two other plant communities were explained by soil nutrients and percentage rocks in addition to heavy metal concentrations. The results of this study will assist with restoration efforts because they (1) provide a rigorous assessment of communities before a disturbance and (2) define essential edaphic conditions needed for the reestablishment of critical communities., FLWIN, info:eu-repo/semantics/published

Cuprophytes are plants that mostly occur on Cu-rich soil. In South Central Africa, these species are threatened by intensive mining exploitation destroying their habitats. Crepidorhopalon tenuis (Scrophulariaceae) is a tiny annual cuprophyte endemic to the Zambesian center of endemism and is particularly abundant in the Lubumbashi area. We investigate here the ecological niche of C. tenuis through the analyses of its abundance and distribution in relation to soil factors, plant community composition, and anthropogenic perturbations. Soil and vegetation data were collected in seven sites (five metalliferous and two nonmetalliferous). The current study shows that C. tenuis has its ecological optimum on copper-rich soil and can be referred to as an elective pseudometallophyte. This species is rare in primary steppic savanna on natural metalliferous soil. Its frequency and abundance peak in pioneer communities on bare soil. In particular, the species showed a surprising ecological plasticity as it was able to benefit from anthropogenic disturbance and to colonize the large areas of bare, contaminated soil left over by mining activities. Our results strongly suggest that C. tenuis was a very rare species in natural metalliferous communities, restricted to patchy areas of open soil in steppic savanna. Recent anthropogenic habitats may have conservation value for some rare metallophytes with colonizing traits and low competitive ability. © 2009 Society for Ecological Restoration International., SCOPUS: ar.j, FLWIN, info:eu-repo/semantics/published

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Programme & Abstracts. Scripta Botanica Belgica 48, info:eu-repo/semantics/published

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SCOPUS: ar.j, FLWIN, info:eu-repo/semantics/published

This study describes xeric saxicolous plant communities of inselbergs embedded in a savannah matrix (in West Africa) and of inselbergs embedded in rainforest (in Atlantic central Africa). We looked at how the species' socio-ecology and distribution differ according to the different matrix vegetation. TWINSPAN-classification of 188 phytosociological relevés defined three plant communities all dominated by the polkilohydric mat-forming sedge Afrotrilepis pilosa. Besides this Cyperaceae, the communities in West Africa and Atlantic central Africa share only one species. Two new associations are described: Cyanotido lanatae-Afrotrilepidetum pilosae on West African inselbergs and Oreonesiono testui-Afrotrilepidetum pilosae on inselbergs from Atlantic central Africa. Each of them typifies a new alliance included in a new order. This new order typifies a new class: Afrotrilepidetum pilosae. Therophytes occurs with many species in Cyanotido lanatae-Afrotrilepidetum pilosac while chamacphytes are most abundant in Oreonesiono testui-Afrotrilepidetum pilosae. The flora of inselbergs surrounded by savannah is characterized by species largely distributed in tropical Africa (60%). Most species occur also in the matrix surrounding the inselbergs, only one being strictly confined to the inselberg habitat. On inselbergs embedded in rainforest 40% of the species originate from the Lower Guinea sub-center of endemism. Nine species are only known to grow in the inselberg habitat. Mantel tests of correlation between floristic, climatic and spatial distances were computed in the two contrasted situations (savannah and rainforest matrix). For rainforest inselbergs the floristic dissimilarity is positively correlated to the spatial and climatic distances, while there was no significant correlation for savannah inselbergs. In our data set, the flora of inselbergs embedded in a savannah matrix was thus more uniform than that of inselbergs surrounded by rainforest. © 2006 Gebrüder Borntraeger., SCOPUS: ar.j, info:eu-repo/semantics/published

Inselbergs are rock outcrops forming "xeric islands" in the rain forest. Plants on inselbergs endure very harsh edaphic and microclimatic conditions. Monocotyledonous mats develop on the rock surface, and grasslands are present on the shallow soils. The inselberg-rain forest ecocline is characterized by the spatial transition from an herbaceous fringe to a shrubby fringe, a forest fringe and a saxicolous forest. We describe here the plant communities of the inselberg grasslands and herbaceous fringes of 24 sites in Southern Cameroon, Equatorial Guinea and Gabon. The plant communities defined from the classification of 177 phytosociological relevés are compared to the existing phytosociological literature and the correlation between the floristic data and the environmental and spatial variables is analyzed. We define a new phytosociological order: the Sclerio melanotrichae-Habenarietalia procerae, two new alliances and four new associations. Herbaceous fringes and grasslands differ both in their flora and in their life form spectra, but the main differentiating factor in the floristic data set is the geographical location of the relevés rather than the plant formation. Three ecogeographical groups of inselbergs are identified. Weeds are an important component of the inselberg flora. They are well adapted to the harsh inselberg habitat by their ability to cope with unpredictable environmental fluctuations (e. g. drought). Grazing and trampling by wild herds of buffaloes contribute to create suitable habitats for these species. Epiphytes are present in the herbaceous fringes. This is explained by the similarity of the environmental conditions on the rock and on the inselberg rain forest ecocline with the environmental conditions encountered by epiphytes in the upper part of the forest canopy. The inselberg grasslands and herbaceous fringes contribute to the regional biodiversity in three ways: a) fourteen species are restricted to the inselberg habitat and to the Guine, SCOPUS: ar.j, info:eu-repo/semantics/published

The ecology and distribution of Poaceae species found on 12 inselbergs embedded in savannah and woodland (Benin) and on 25 inselbergs enclosed in rain forest (CEG: Cameroon, Equatorial Guinea and Gabon) are described. A total of 77 species were observed, 46 in Benin and 36 in CEG. Five species were strictly saxicolous in Benin and three in CEG, but most species (83%) were also present in the vegetation surrounding the inselbergs (the matrix). In Benin, 46% of the species were present on half of the inselbergs, while only one species did so in CEG. This unequal distribution of the species amongst sites in CEG could originate from dispersal limitation due to the strong ecological contrast between the inselberg biotope and the rain forest. Ecological conditions on the inselbergs are more similar to that of a savannah and woodland matrix, which could explain the homogeneity of inselberg vegetation in Benin. In CEG, four species were mainly distributed outside the lowland rain forest region: two in savannah and woodland, and two in mountainous vegetation. The discontinuous distribution of these species with inselberg satellite populations in the lowland rainforest is probably related to Quaternary vegetation changes. Inselberg in both study area contribute significantly to the regional species diversity by the presence of strictly saxicolous species or of species from other phytochoria. The inselberg habitat should therefore be considered in conservation policies. © 2006 Royal Botanical Society of Belgium., SCOPUS: ar.j, info:eu-repo/semantics/published

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Doctorat en Sciences, info:eu-repo/semantics/nonPublished

The study of the vegetation of inselbergs and forest types in these two afrotropical countries lead to the description of three new taxa. Justicia amanda subsp. saxatilis, growing on inselbergs in Equatorial Guinea is a vicariant taxon of the typical subspecies which is only known from the mountains of Eastern Congo-Kinshasa, Rwanda and Burundi. Dischistocalyx lithicola, also growing on inselbergs, differs from the other species by its complete glabrescence, its strongly two-coloured, narrow, coriaceous although thin leaves, and from D. strobilinus, the closest species, by its larger corolla. Dischistocalyx alternifolius, growing in rainforest, differs from all other species of the genus by its complete anisophylly, with the complete reduction of one leaf in each pair., SCOPUS: ar.j, info:eu-repo/semantics/published

A new species of Polystachya Hook.f. sect. Polychaete Cribb (Orchidaceae) is described from São Tomé, Gabon and Rio Muni (Equatorial Guinea): Polystachya moniquetiana Stévart & Geerinck. It is related to Polystachya polychaete Kraenzl. from which it differs in the lip and plant size., SCOPUS: ar.j, info:eu-repo/semantics/published

We investigated the vegetation composition of three inselbergs from continental Equatorial Guinea in relation to six environmental variables. The most influent factors on vegetation appeared to be soil depth, pH and the position relative to the upper or lower forest fringe. There was no effect of slope or aspect. Although the three inselbergs are very close to each other (100 to 500 m), they significantly differ in their vegetation (site effect). This effect could partly be explained by the insular property of inselberg vegetation surrounded by rainforest. The position of Afrotrilepis pilosa (W.C.Boeck) J.Raynal, the most characteristic species of West African inselberg grasslands, along the main ecological gradient is discussed., SCOPUS: ar.j, info:eu-repo/semantics/published

A phytosociological investigation was carried out on fourteen inselbergs from continental Equatorial Guinea. Results are (i) eight vegetation units, (ii) the unequal distribution of those eight units on the different inselbergs, (iii) the high species diversity, (iv) the presence of rare species and plant formations, of species with a disjunct distribution and of mountain species at a low altitude (600-750 m). Twelve differentiating factors that may partially explain the existing differences between the fourteen sites have been recognized., SCOPUS: cp.j, info:eu-repo/semantics/published