Mixed-forest species establishment in a monodominant forest in Central Africa: Implications for tropical forest invasibility

Background: Traits of non-dominant mixed-forest tree species and their synergies for successful co-occurrence in monodominant Gilbertiodendron dewevrei forest have not yet been investigated. Here we compared the tree species diversity of the monodominant forest with its adjacent mixed forest and then determined which fitness proxies and life history traits of the mixed-forest tree species were most associated with successful co-existence in the monodominant forest. Methodology/Principal Findings: We sampled all trees (diameter in breast height [dbh]≥10 cm) within 6x1 ha topographically homogenous areas of intact central African forest in SE Cameroon, three independent patches of G. dewevrei-dominated forest and three adjacent areas (450-800 m apart). Monodominant G. dewevrei forest had lower sample-controlled species richness, species density and population density than its adjacent mixed forest in terms of stems with dbh≥10 cm. Analysis of a suite of population-level characteristics, such as relative abundance and geographical distribution, and traits such as wood density, height, diameter at breast height, fruit/seed dispersal mechanism and light requirement-revealed after controlling for phylogeny, species that co-occur with G. dewevrei tend to have higher abundance in adjacent mixed forest, higher wood density and a lower light requirement. Conclusions/Significance: Our results suggest that certain traits (wood density and light requirement) and population-level characteristics (relative abundance) may increase the invasibility of a tree species into a tropical closed-canopy system. Such knowledge may assist in the pre-emptive identification of invasive tree species. © 2014 Peh et al

Un Bertiera (Rubiaceae) nouveau et hétérophylle du Cameroun et du Gabon

A new species of Bertiera (Rubiaceae) from Cameroon and Gabon, Bertiera heterophylla Nguembou & Sonké, is described and illustrated. This new species belongs to the subgenus Bertiera and appears to be closely related to Bertiera bicarpellata. Bertiera heterophylla differs from B. bicarpellata in having lateral branches with terminal inflorescences while on the main stem, the inflorescences are axillary. © 2006 National Botanic Garden of Belgium.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Une espèce nouvelle de Bertiera (sous-genre Bertierella, Rubiaceae) d'Afrique centrale atlantique

A new species belonging to the genus Bertiera (subgenus Bertierella, Rubiaceae) from West Central Africa (Cameroon, Equatorial Guinea and Gabon) is described. Its diagnostic characters are elucidated, its taxonomic affinities are discussed and notes on its conservation status are provided. © Publications Scientifiques du Muséum national d'Histoire naturelle, Paris.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Synopsis of the genus Chamaeangis (Orchidaceae), including two new taxa

A synopsis of Chamaeangis (Orchidaceae) with a taxonomic key to the genus is provided. Twelve taxa are recognized. Detailed examination of the specimens revealed two novelties: Chamaeangis spiralis from Nigeria and Cameroon, and Chamaeangis lecomtei var. tenuicalcar, a new variety from Ivory Coast, Ghana, and Gabon. Chamaeangis pauciflora is shown to be synonymous with Chamaeangis letouzeyi, which is here redescribed in detail. Chamaeangis thomensis is neotypified, and Chamaeangis lecomtei var. lecomtei is lectotypified. Chamaeangis gracilis is treated as an excluded species. Several new country records of Chamaeangis are provided. © Copyright 2009 by the American Society of Plant Taxonomists.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Stand structure and species co-occurrence in mixed and monodominant Central African tropical forests

We compare forests dominated by Gilbertiodendron dewevrei at the Dja Biosphere Reserve (Cameroon) with adjacent high-diversity mixed forests in terms of tree-species composition and stand structure, in order to understand the co-occurrence of mixed forest tree species in the monodominant forest. A total of 18 1-ha permanent plots were established in the two forest types. In each plot, all trees with dbh ?10 cm were identified as were those <10 cm dbh within a subsample of 300 m2. Species richness was significantly different between the two forest types. Mixed forest had an average of 109 species ha?1 for trees ?10 cm dbh and 137 species for trees <10 cm dbh. By contrast, G. dewevrei-dominated forest had an average of 47 species ha?1 (?10 cm dbh) and 92 species (<10 cm dbh). There was no significant difference in terms of stem density of the trees with dbh <10 cm between the two forests (mixed: 3.7 stems m?2; monodominant: 3.1 stems m?2). As G. dewevrei is a shade-tolerant species that can regenerate under its own shade, its higher stem density and basal area can reduce species richness of an area

Mine versus Wild : a plant conservation checklist of the rich Iron-Ore Ngovayang Massif Area (South Cameroon)

International audienceBackground and aims – The rapid expansion of human activities in South Cameroon, particularly mining in mountainous areas, threatens this region’s exceptional biodiversity. To comprehend the effects of land-use change on plant diversity and identify conservation priorities, we aim at providing a first comprehensive plant checklist of the Ngovayang Massif, focusing on the two richest plant families, Orchidaceae and Rubiaceae.Location – The Ngovayang Massif Area (NMA) is located in the South Region of Cameroon. It is covered by lowland and submontane rainforest (100 to 1110 m elevation).Methods – We compiled a dataset of 6116 georeferenced herbarium specimens, of which 2787 belong to Rubiaceae and Orchidaceae. We used rarefaction methods to explore sampling and diversity patterns, and investigated the altitudinal distribution of rare and/or threatened taxa.Key results – The NMA, which houses about 1500 vascular plant taxa, is the richest documented area for Rubiaceae in Atlantic Central Africa (ACA) and the fifth for Orchidaceae, with respectively 281 and 111 taxa. Among these taxa, 178 (45%) are endemic to ACA and 67 (17%) are considered globally threatened according to IUCN categories and criteria. We show that higher elevation areas (> 750 m), which are also the main areas targeted for mining, are the richest in endangered and/or rare species. Three new records for Cameroon are reported here.Conclusion – The NMA represents an Important Plant Area of Cameroon as confirmed by its exceptional plant diversity (> 20% of the total Flora of Cameroon), by the concentration of many threatened and/or restricted range species (10 taxa are strict endemics of the massif) as well as by the threat on rare habitats (i.e. the submontane vegetation above ~750 m elevation). A management plan involving in situ and ex situ conservation actions is urgently needed to reduce the potential threats of future mining activities

The association of wood density categories and successful mixed-forest species in the monodominant <i>Gilbertiodendron</i> forest.

<p>The white bars represent the species absent in the monodominant forest and the grey bars represent those present in the monodominant forest.</p

Sample-based rarefaction curves of the tree communities found in monodominant <i>Gilbertiodendron</i> forests (red dots and line) and mixed forests (blue dots and line) comparing number of species (A), species density (B) and population density (C).

<p>Error bars represent 95% confidence interval.</p

Binary regression models for successful non-dominant tree species co-occurrence in monodominant <i>Gilbertiodendron</i> forest at Dja Faunal Reserve with corresponding log-likelihood, number of parameter (<i>K</i>), Akaike’s information Criterion (AIC_c) score and Akaike parameter weight (<i>w</i>_p).

<p>ΔAIC_c indicates the difference between each model and the best model (lowest ΔAICc; rank 1). Data include 145 tree species sampled in all monodominant and mixed forest plots. Abundance, density and shade refer to fitness proxy and life-history variables: abundance, number of individuals found in the mixed forest plots; density, wood density; and shade, light requirement for seedling establishment. Models are ranked by ΔAIC_c and <i>w</i>_p. The best model that has ΔAIC_c<1 is bolded.</p