Guineo-Congolian Rainforest Research Articles

Documenting biogeographical patterns of African timber species using herbarium records: a conservation perspective based on native trees from Angola.

In many tropical regions the development of informed conservation strategies is hindered by a dearth of biodiversity information. Biological collections can help to overcome this problem, by providing baseline information to guide research and conservation efforts. This study focuses on the timber trees of Angola, combining herbarium (2670 records) and bibliographic data to identify the main timber species, document biogeographic patterns and identify conservation priorities. The study recognized 18 key species, most of which are threatened or near-threatened globally, or lack formal conservation assessments. Biogeographical analysis reveals three groups of species associated with the enclave of Cabinda and northwest Angola, which occur primarily in Guineo-Congolian rainforests, and evergreen forests and woodlands. The fourth group is widespread across the country, and is mostly associated with dry forests. There is little correspondence between the spatial pattern of species groups and the ecoregions adopted by WWF, suggesting that these may not provide an adequate basis for conservation planning for Angolan timber trees. Eight of the species evaluated should be given high conservation priority since they are of global conservation concern, they have very restricted distributions in Angola, their historical collection localities are largely outside protected areas and they may be under increasing logging pressure. High conservation priority was also attributed to another three species that have a large proportion of their global range concentrated in Angola and that occur in dry forests where deforestation rates are high. Our results suggest that timber tree species in Angola may be under increasing risk, thus calling for efforts to promote their conservation and sustainable exploitation. The study also highlights the importance of studying historic herbarium collections in poorly explored regions of the tropics, though new field surveys remain a priority to update historical information.

Testing a short nuclear marker for inferring staphylinid beetle diversity in an African tropical rain forest.

BackgroundThe use of DNA based methods for assessing biodiversity has become increasingly common during the last years. Especially in speciose biomes as tropical rain forests and/or in hyperdiverse or understudied taxa they may efficiently complement morphological approaches. The most successful molecular approach in this field is DNA barcoding based on cytochrome c oxidase I (COI) marker, but other markers are used as well. Whereas most studies aim at identifying or describing species, there are only few attempts to use DNA markers for inventorying all animal species found in environmental samples to describe variations of biodiversity patterns.Methodology/Principal FindingsIn this study, an analysis of the nuclear D3 region of the 28S rRNA gene to delimit species-like units is compared to results based on distinction of morphospecies. Data derived from both approaches are used to assess diversity and composition of staphylinid beetle communities of a Guineo-Congolian rain forest in Kenya. Beetles were collected with a standardized sampling design across six transects in primary and secondary forests using pitfall traps. Sequences could be obtained of 99% of all individuals. In total, 76 molecular operational taxonomic units (MOTUs) were found in contrast to 70 discernible morphospecies. Despite this difference both approaches revealed highly similar biodiversity patterns, with species richness being equal in primary and secondary forests, but with divergent species communities in different habitats. The D3-MOTU approach proved to be an efficient tool for biodiversity analyses.Conclusions/SignificanceOur data illustrate that the use of MOTUs as a proxy for species can provide an alternative to morphospecies identification for the analysis of changes in community structure of hyperdiverse insect taxa. The efficient amplification of the D3-marker and the ability of the D3-MOTUs to reveal similar biodiversity patterns as analyses of morphospecies recommend its use in future molecular studies on biodiversity.

Fomitiporia in sub-Saharan Africa: morphology and multigene phylogenetic analysis support three new species from the Guineo-Congolian rainforest

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.

Poroid Hymenochaetaceae from Guineo–Congolian rainforest: Phellinus gabonensis sp. nov. from Gabon – taxonomy and phylogenetic relationships

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.

Molecular phylogenetics reveal multiple tertiary vicariance origins of the African rain forest trees

BackgroundTropical rain forests are the most diverse terrestrial ecosystems on the planet. How this diversity evolved remains largely unexplained. In Africa, rain forests are situated in two geographically isolated regions: the West-Central Guineo-Congolian region and the coastal and montane regions of East Africa. These regions have strong floristic affinities with each other, suggesting a former connection via an Eocene pan-African rain forest. High levels of endemism observed in both regions have been hypothesized to be the result of either 1) a single break-up followed by a long isolation or 2) multiple fragmentation and reconnection since the Oligocene. To test these hypotheses the evolutionary history of endemic taxa within a rain forest restricted African lineage of the plant family Annonaceae was studied. Molecular phylogenies and divergence dates were estimated using a Bayesian relaxed uncorrelated molecular clock assumption accounting for both calibration and phylogenetic uncertainties.ResultsOur results provide strong evidence that East African endemic lineages of Annonaceae have multiple origins dated to significantly different times spanning the Oligocene and Miocene epochs. Moreover, these successive origins (c. 33, 16 and 8 million years – Myr) coincide with known periods of aridification and geological activity in Africa that would have recurrently isolated the Guineo-Congolian rain forest from the East African one. All East African taxa were found to have diversified prior to Pleistocene times.ConclusionMolecular phylogenetic dating analyses of this large pan-African clade of Annonaceae unravels an interesting pattern of diversification for rain forest restricted trees co-occurring in West/Central and East African rain forests. Our results suggest that repeated reconnections between the West/Central and East African rain forest blocks allowed for biotic exchange while the break-ups induced speciation via vicariance, enhancing the levels of endemicity. These results provide an explanation for present day distribution patterns and origins of endemicity for African rain forest trees. Moreover, given the pre-Pleistocene origins of all the studied endemic East African genera and species, these results also offer important insights for setting conservation priorities in these highly diversified but threatened ecosystems.

Mechanisms and tempo of evolution in the African Guineo–Congolian rainforest

This paper reviews how and when African rainforest diversity arose, presenting evidence from both plant and animal studies. Preliminary investigations show that these African forests are an assemblage of species of varying age. Phylogenetic evidence, from both African rainforest angiosperms and vertebrates, suggest a Tertiary origin for the major lineages in some of these groups. In groups where savannah species are well represented and rainforest species are a minority, the latter appear to be relics of a Mid-Tertiary rainforest. By contrast, species that are primarily adapted to rainforest have arisen in the past 10 Myr with the main morphological innovations dating from the Late Miocene, and Quaternary speciation dominating in large, morphologically homogeneous groups. The small number of species-level phylogenies for African rainforest plants hinders a more incisive and detailed study into the historical assembly of these continental forests.

Islands in the Desert—Forest Vegetation of Kenya'S Smaller Mountains and Highland Areas (Nyiru, Ndoto, Kulal, Marsabit, Loroghi, Ndare, Mukogodo, Porror, Mathews, Gakoe, Imenti, Ngaia, Nyambeni, Loita, Nguruman, Nairobi)

A syntaxonomic survey of Kenyan montane forests was performed in a field study from 1992–1996. Most forests encountered belong to the Juniperetea procerae floral community (cedar forests), of which the Juniperion procerae Faureo salignae-Ilicetum mitis on the wet mountaintops and the Myrsino africanae-Juniperetum procerae in drier areas, were most commonly encountered. On Mt Marsabit the Coffeo arabicae-Rinoreetum convallarioidis was found as a new association of the Cassipourion malosanae. The top of Mt Nyiru is covered with large stands of the Hagenietea abyssinicae and extensive bamboo forests (Sinarundinarietea alpinae). Mathews Range harbours the largest forest tracts remaining in the dry norm of Kenya. On the lower slopes of mis mountain, a new alliance, assessed as Crotonion megalocarpi is described. Camphor forests (Ocotetea usambarensis) cover altitudes from 1,600–2,400 m in the southern Aberdare Range. In the submontane Imenti and Ngaia forests, and the Nyambeni Hills, between 1,200–1,600 m altitude, a variety of forest types related to the Guineo Congolian rainforest were encountered. These forests are assessed as Lovoion swynnertonii. In the montane zone of Nyambeni dense bamboo forests cover the wetter areas, whereas drier parts are covered by cedar forests.On the drier hill slopes of southern Kenya the Juniperion procerae is the prevalent forest type. On the often mist-covered and cloudy hilltops, associations of the Cassipourion malosanae are growing. The forests around Nairobi clearly belong to the Brachylaenion huillensis. Although some syntaxa had to be newly described, the forests of the study areas clearly fit into the classification system of Bussmann & Beck (1995).

Biogeography, Diversity and Seasonality of Syrphidae (Diptera) in a Guineo-Congolian Rain Forest in Kenya

Syrphidae (Diptera) were collected from different sites in Kakamega Forest, the only dry guineo-congolian rain forest relict in Kenya. In addition, literature records were compiled and old collections specimens were re-identified. In total, 74 species or 43 % of the known syrphid fauna in Kenya, were identified. The fauna indicates a biogeographical affinity with the main central and western African rain forest belt, with 12 out of the 74 species being indicator species for such a link. The alpha and beta diversity were compared at four sites, representing the main ecological habitats within the forest complex. Mostly undisturbed forest habitat shows the highest diversity. It also harbours a large proportion of the indicator species (seven out of 12). Natural glades in the forest show a low similarity with the other habitats, indicating the more exceptional fauna of the natural grasslands. The seasonal fluctuations for the more abundant species are briefly discussed. Most species reach highest abundance during the dry season.