Three new species of Tricalysia (Rubiaceae) from Atlantic Central Africa

Background and aims – The genus Tricalysia A.Rich. (Rubiaceae), regarded here in the strict sense (i.e., excluding Empogona Hook.f.), includes 77 species in tropical Africa, Madagascar and the Comoros. In the current paper, three new species from Atlantic Central Africa are described and illustrated; their conservation status is also assessed.Material and methods – This paper is based on a study of herbarium collections from BR, BRLU, K, LBV, P, WAG and YA. Normal practices of herbarium taxonomy have been applied. The conservation status assessments follow the IUCN Red List criteria.Results – Tricalysia lophocarpa O.Lachenaud & Sonké is endemic to Gabon and is best recognised by its fruits with 8–10 narrow longitudinal ribs. Tricalysia obovata O.Lachenaud & Sonké is endemic to Equatorial Guinea (Rio Muni) and may be recognised by its obovate leaves with rounded base, glabrous stems, and sessile flowers with included style and half-exserted anthers. Tricalysia wilksii O.Lachenaud & Sonké occurs in Gabon and southwestern Republic of Congo, and may be recognised by its glabrous stems and leaves, the latter with crypt domatia, its linear calyx teeth equalling or exceeding the tube in length, and its shortly pedicellate fruits. The three species are assessed respectively as Near-threatened (T. lophocarpa), Critically Endangered (T. obovata) and Vulnerable (T. wilksii)

A checklist of rheophytes of Cameroon

Rivers in Cameroon were surveyed to collect and document rheophytic plants. Rheophytes are the dominant aquatic macrophytes in tropical river systems, where they are adapted to extreme environments of rushing water (e.g., river rapids, waterfalls and flash floods). Rheophytic plants are useful indicators of river health. However, their habitats are threatened by human activities such as agriculture, plantation development, alluvial mining and dam construction, particularly in tropical countries. In this survey we documented 66 rheophytic species in 29 genera and 16 families. Two ferns, 8 monocotyledons and 56 dicotyledons were listed. Apart from the Podostemaceae family in which all species are rheophytic, the other 15 families have few species which are rheophytic. Five of these families have up to four species and the remaining 10 have only one member as a rheophytic species. The conservation status of each species is assessed and discussed. This work urges botanists, conservationists, and policy makers to do more to protect the habitats of rheophytes and put in place strategies and action plans for the conservation of this important biological group

Kupeantha (Coffeeae, Rubiaceae), a new genus from Cameroon and Equatorial Guinea

Two new coffee relatives (tribe Coffeeae, Rubiaceae), discovered during botanical expeditions to Cameroon, are examined for generic placement, and the placement of three previously known species (Argocoffeopsis fosimondi, A. spathulata and Calycosiphonia pentamera) is reinvestigated using plastid sequence (accD-psa1, rpl16, trnL-F) and morphological data. Seed biochemistry of the new species and pollen micromorphology (only one of the two species) are also studied. Based on the plastid sequence data, the new taxa are nested in a wellsupported monophyletic group that includes Argocoffeopsis and Calycosiphonia. Within this clade, three well-supported subclades are recovered that are morphologically easy to diagnose: (1) Calycosiphonia (excluding C. pentamera), (2) Argocoffeopsis (excluding A. fosimondi and A. spathulata), and (3) a clade including the above excluded species, in addition to the new species. Based on the results, Kupeantha, a new genus of five species, is described, including two new Critically Endangered taxa from the Highlands of Cameroon: Kupeantha ebo and K. kupensis. Phytochemical analysis of Kupeantha seeds reveals compounds assigned as hydroxycinnamic acid derivatives, amino acids and ent-kaurane diterpenoids; caffeine was not detected. Kupeantha is the first new genus described in tribe Coffeeae in 40 years

Two new species of Raphia (Palmae/Arecaceae) from Cameroon and Gabon

Raphia (Arecaceae, Calamoideae) is the most diverse genus of African palms with around 20 species. Two new species from Cameroon and Gabon, Raphia gabonica Mogue, Sonké & Couvreur, sp. nov. and Raphia zamiana Mogue, Sonké & Couvreur, sp. nov. are described and illustrated. Their affinities are discussed and the conservation status of each species is assessed. For both species, distribution maps are provided. Raphia gabonica is restricted to two small populations from central Gabon, where it occurs on hillsides on tierra firme soil, and close to small streams. Its preliminary IUCN status is Endangered, being amongst the five most threatened palm species in Africa. Raphia gabonica potentially belongs to the moniliform section. Raphia zamiana is largely distributed from south Cameroon to south Gabon and is very common. It is also a multi-used palm, from which wine, grubs and construction material are extracted and sold. It generally occurs in large stands in a wide range of ecosystems such as swamps, coastal forests on partially inundated sandy soils and inundated savannahs. Its large stature, hard to access habitat (swamps) and abundant presence might have discouraged botanists to collect it until now. Raphia zamiana belongs to the taxonomically complex raphiate section

A matter of warts: a taxonomic treatment for Drypetes verrucosa (Putranjivaceae, Malpighiales) and a new cauliflorous species from Cameroon and Nigeria, D. stevartii

Background and aims – Specimens of a new tree species in the genus Drypetes (Putranjivaceae) distributed in Cameroon and eastern Nigeria, D. stevartii, were associated with D. verrucosa, another tree species endemic to Gabon, due to its warty fruits and to the overall morphological resemblances of both species. Material and methods – The present study is based on the study of 20 gatherings of D. verrucosa and 26 gatherings of D. stevartii. Morphological observations on herbarium specimens belonging to the new species and D. verrucosa were carried out in order to describe them. Key results – This treatment includes the detailed descriptions of these two species, the typification of their names, a comparative table summarizing their main morphological differences, an identification key, photographs of both, as well as information about their distribution, habitat, and phenology. Preliminary IUCN Red List assessments show that both D. verrucosa and D. stevartii are ‘Near Threatened’ species

Sentiers de suivi de la croissance, de la mortalité et de la phénologie des arbres tropicaux. Guide méthodologique

The sustainability of natural forest management in Central Africa depends on a thorough understanding of the population dynamics of commercial tree populations. These dynamics are studied in systems designed to be monitored over the long term, known as plots and trails. While the methodological approach for setting up and monitoring plots is fairly well documented, the approach for trails is less well documented. This book fills this gap by capitalizing on the experience accumulated over more than 20 years by the members of the DYNAFAC collective, a group created on the initiative of ATIBT, CIRAD, Nature+ and Gembloux Agro-Bio Tech. It is a practical and illustrated guide explaining the process necessary for the installation and monitoring of these trails. In addition to the technical procedures, the guide also assesses the costs, taking into account the economic specificities of different countries in the sub-region. By addressing all stakeholders in the development and management of Africa's forests, the book aims to promote the implementation of robust and efficient systems within everyone's reach. / La durabilité de l'aménagement des forêts naturelles d'Afrique centrale est tributaire d'une connaissance approfondie de la dynamique démographique des populations d'arbres commerciaux. Cette dynamique est étudiée dans des dispositifs destinés à être suivis sur le long terme, dénommés parcelles et sentiers. Si la démarche méthodologique d'installation et de suivi des parcelles est assez bien documentée, celle des sentiers l'est moins. Le présent ouvrage vient combler ce vide en capitalisant l'expérience accumulée depuis plus de 20 ans par les membres du collectif DYNAFAC, un collectif créé à l'initiative de l'ATIBT, du CIRAD, de Nature+ et de Gembloux Agro-Bio Tech. Il s'agit d'un guide pratique et illustré explicitant la démarche nécessaire à l'installation et au suivi de ces sentiers. Outre les procédures techniques, le guide évalue également les coûts en tenant compte des spécificités économiques de différents pays de la sous-région. En s'adressant à l'ensemble des parties prenantes de l'aménagement et de la gestion des forêts d'Afrique, l'ouvrage a pour ambition de promouvoir la mise en oeuvre de dispositifs robustes et efficients à la portée de tous

MODIS Vegetation Continuous Fields tree cover needs calibrating in tropical savannas

The Moderate Resolution Imaging Spectroradiometer Vegetation Continuous Fields (MODIS VCF) Earth observation product is widely used to estimate forest cover changes and to parameterize vegetation and Earth system models and as a reference for validation or calibration where field data are limited. However, although limited independent validations of MODIS VCF have shown that MODIS VCF's accuracy decreases when estimating tree cover in sparsely vegetated areas such as tropical savannas, no study has yet assessed the impact this may have on the VCF-based tree cover data used by many in their research. Using tropical forest and savanna inventory data collected by the Tropical Biomes in Transition (TROBIT) project, we produce a series of calibration scenarios that take into account (i) the spatial disparity between the in situ plot size and the MODIS VCF pixel and (ii) the trees' spatial distribution within in situ plots. To identify if a disparity also exists in products trained using VCF, we used a similar approach to evaluate the finer-scale Landsat Tree Canopy Cover (TCC) product. For MODIS VCF, we then applied our calibrations to areas identified as forest or savanna in the International Geosphere-Biosphere Programme (IGBP) land cover mapping product. All IGBP classes identified as “savanna” show substantial increases in cover after calibration, indicating that the most recent version of MODIS VCF consistently underestimates woody cover in tropical savannas. We also found that these biases are propagated in the finer-scale Landsat TCC. Our scenarios suggest that MODIS VCF accuracy can vary substantially, with tree cover underestimation ranging from 0 % to 29 %. Models that use MODIS VCF as their benchmark could therefore be underestimating the carbon uptake in forest–savanna areas and misrepresenting forest–savanna dynamics. Because of the limited in situ plot number, our results are designed to be used as an indicator of where the product is potentially more or less reliable. Until more in situ data are available to produce more accurate calibrations, we recommend caution when using uncalibrated MODIS VCF data in tropical savannas

Using Model Analysis to Unveil Hidden Patterns in Tropical Forest Structures

peer reviewedWhen ordinating plots of tropical rain forests using stand-level structural attributes such as biomass, basal area and the number of trees in different size classes, two patterns often emerge: a gradient from poorly to highly stocked plots and high positive correlations between biomass, basal area and the number of large trees. These patterns are inherited from the demographics (growth, mortality and recruitment) and size allometry of trees and tend to obscure other patterns, such as site differences among plots, that would be more informative for inferring ecological processes. Using data from 133 rain forest plots at nine sites for which site differences are known, we aimed to filter out these patterns in forest structural attributes to unveil a hidden pattern. Using a null model framework, we generated the anticipated pattern inherited from individual allometric patterns. We then evaluated deviations between the data (observations) and predictions of the null model. Ordination of the deviations revealed site differences that were not evident in the ordination of observations. These sites differences could be related to different histories of large-scale forest disturbance. By filtering out patterns inherited from individuals, our model analysis provides more information on ecological processes