Are the living collections of the world's botanical gardens following species-richness patterns observed in natural ecosystems?

Pautasso M. and Parmentier I. 2007. Are the living collections of the world's botanical gardens following species-richness patterns observed in natural ecosystems? Bot. Helv. 117: 15 - 28. Botanical gardens aim to promote the awareness, study and conservation of plant species diversity, but little is known about the species diversity of botanical gardens themselves. We therefore investigated whether the species richness of the world's botanical gardens is related to their size, age and geographical location by compiling data from gardens in 124 different countries. The data show that even in these highly managed ecosystems, species richness can be described in terms of a relatively small number of large-scale patterns. As with most natural ecosystems, there were positive species-area and species-age relationships. There was also a positive latitudinal gradient in species richness, which contrasts with the trend observed in natural ecosystems. This discrepancy may be due to the use of heated greenhouses at high latitudes, the rarity of old botanical gardens in the tropics, and the problem of poverty in developing countries, where most hotspots of plant biodiversity are located. There is thus a need to allocate more funds to botanical gardens in species-rich regions. This study also calls for an increase in the coordination of data management between botanical garden

Catálogo de Melastomataceae de Guinea Ecuatorial

A chec klist of the Melastomataceae of Equatorial Guinea is presented with 57 taxa. Three species were accepted based only on literature records, their distribution área strongly suggests their presence in Equatorial Guinea. Six species are known from Annobón, 23 from Bioko and 49 from Río Muni. Best-represented genera are Memecylon (10), Calvoa (10) and Tristemma (7). Twenty-six taxa are newly recorded for the country. Heterotis obamae Lejoly & Lisowski is set in synonymy with the previously described Heterotis arenaria Jacq.-Fél.Se presenta el catálogo florístico de la familia Melastomataceae en Guinea Ecuatorial. Se recogen un total de 57 táxones. Tres especies fueron aceptadas teniendo en cuenta solamente la literatura. Su distribución sugiere que su presencia en Guinea Ecuatorial es muy probable. En Annobón están presentes 6 especies, 23 en Bioko y 49 en Río Muni. Los géneros mejor representados son Memecylon (10 especies), Calvoa (10) y Tristemma (7).Veintiséis táxones son citados por primera vez en Guinea Ecuatorial. Se propone Heterotis obamae Lejoly & Lisowski como sinónimo de Heterotis arenaria Jacq.-Fél

Species-richness patterns of the living collections of the world's botanic gardens: a matter of socio-economics?

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 garden

How Effective Are DNA Barcodes in the Identification of African Rainforest Trees?

Background: 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. Methodology/Principal Findings: We assess the accuracy of identification to species or genus using a genetic distance matrix between samples either based on a global multiple sequence alignment (GD) or on a basic local alignment search tool (BLAST). Where a local database is available (within a 50 ha plot), barcoding was generally reliable for genus identification (95-100% success), but less for species identification (71-88%). Using a single marker, best results for species identification were obtained with trnH-psbA. There was a significant decrease of barcoding success in species-rich clades. When the local database was used to identify the genus of trees from another region and did include all genera from the query individuals but not all species, genus identification success decreased to 84-90%. The GD method performed best but a global multiple sequence alignment is not applicable on trnH-psbA. Conclusions/Significance: Barcoding is a useful tool to assign unidentified African rain forest trees to a genus, but identification to a species is less reliable, especially in species-rich clades, even using an exhaustive local database. Combining two markers improves the accuracy of species identification but it would only marginally improve genus identification. Finally, we highlight some limitations of the BLAST algorithm as currently implemented and suggest possible improvements for barcoding applications

Etude de la végétation des inselbergs de la forêt dense d'Afrique centrale atlantique

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Study of the vegetation composition in three inselbergs from continental Equatorial Guinea (Western Central Africa): Effects of site, soil factors and position relative to forest fringe

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.jinfo:eu-repo/semantics/publishe

Ecology and distribution of Melastomataceae in African rain forest inselbergs

The ecology and distribution of thirty-seven Melastomataceae species found on 29 inselbergs in the rain forest of Equatorial Guinea, Gabon, and Cameroon are described. The relative contributions of climatic determinism, and stochastic and historical processes to the present distribution of the species amongst the study sites are investigated. Inselbergs are rock outcrops enduring very harsh edaphic and microclimatic conditions, forming "xeric islands" in the rain forest, where natural grasslands develop. For each Melastomataceae species, the habitats where they were collected on the inselbergs and in other biotopes were listed, and their phytogeographical distribution was established. Three species are restricted to rock outcrops. Most species are distributed inside the Guineo-Congolian Region. Three species have disjunct distributions on rain forest inselbergs and have their main distribution area outside the forested zone. The distribution of the species amongst the inselbergs is correlated to the altitude and the annual rainfall of the sites, and to inselberg geographical location. This correlation of the species distribution with the geographical location of the inselberg is attributed to the spatial autocorrelation of environmental variables and to the combined effects of the history of past vegetation changes due to climatic fluctuations and dispersal limitation.SCOPUS: ar.jFLWINinfo:eu-repo/semantics/publishe

Étude de la végétation des inselbergs de la forêt dense d'Afrique centrale atlantique

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Premières études sur la diversité végétale des inselbergs de Guinée Equatoriale continentale

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.jinfo:eu-repo/semantics/publishe

Species-richness of the living collections of the world's botanical gardens - patterns within continents

Summary: The broad aims of most botanic gardens are to promote the knowledge, conservation and use of plant biodiversity. The living collections of all but the most recently founded botanical gardens are the outcome of the work of generations of botanists. However, there has been little historical co-ordination between different gardens in assembling these collections. It is thus fascinating that these mostly artificial ecosystems follow two of the major biogeographical patterns observed in nature (a significant positive species-area and species-age relationship) when pooling data from all over the world. An open question is whether such patterns are confirmed when analysing the available data for the various landmasses. We found that the positive species-area and species-age relationships of the living collections of botanic gardens are confirmed when analysing data for (1) the Americas, (2) Africa and Europe, and (3) Asia and Australia. When controlling for spatial autocorrelation these groups of botanic gardens differ from the worldwide analysis in showing no significant positive latitudinal gradient in species richness. This result is still a discrepancy from the negative latitudinal gradient commonly observed in nature and confirms the necessity to better sustain botanic gardens in the tropics. Also when subdividing the analysis within continents, it is possible to describe a substantial amount of variation in the living collections of the world's botanic gardens with a relatively small number of broad-scale patterns. This study supports the view that there is a need for an increased co-ordination in the conservation activities of the various botanical gardens. © 2011 The Board of Trustees of the Royal Botanic Gardens, Kew.SCOPUS: ar.jinfo:eu-repo/semantics/publishe