The earliest iron-producing communities in the Lower Congo region of Central Africa : new insights from the Bu, Kindu and Mantsetsi sites

In 2015 the KongoKing research project team excavated the Bu, Kindu and Mantsetsi sites situated in the Kongo-Central Province of the Democratic Republic of Congo (DRC). All are part of the Kay Ladio Group. This is the first detailed publication on this cultural group, to which no contemporary ones can currently be linked, either from the Atlantic coast of Congo-Brazzaville or from along the Congo River and its tributaries upstream of Kinshasa. Dated to between cal. AD 30 and 475, these settlements mark the presence of what are so far the oldest known iron-producing communities south of the Central African equatorial forest. Evidence for metallurgy is associated with remants of polished stone axes, which were perhaps being used for ritual purposes by this point in time. The charcoal remains found at the sites indicate a savanna environment that was more wooded in Kindu and Mantsetsi than in Bu

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees.Publisher PDFPeer reviewe

Co-limitation towards lower latitudes shapes global forest diversity gradients

The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers

Effets des extraits aqueux de ricin (Ricinus communis) et de neem (Azadiracta indica) sur la pression des bio-agresseurs de Niébé (Vigna unguiculata) à Mbujimayi

With the aim of valorizing plant species with insecticidal properties and seeking alternative methods to the use of chemical insecticides, it is imperative to develop bio-pesticides that are effective, less costly, accessible, easy for farmers to handle and respectful of human health and the environment. For this purpose, this study set out to determine the efficiency of aqueous extracts of castor bean (Ricinus communis L.) and Neem seeds (Azadiracta indica L.) on cowpea crop pests under the ecological conditions of Mbujimayi (DRC). A completely randomized experimental design was adopted, with a total area of 180 m², consisting of three blocks and four treatments, namely, T0 (control), T1 (Deltamethrin (1.11 liter/m²), T2 (Neem seed extract (1.11 liter/m²) and T3 (Ricin seed extract (1.11 liter/m²). After application of Deltamethrin, aqueous Neem extracts and castor oil, we noted that the number insects of Ootheca mutabilis, Maruca vitrata, Aneplocnemis curvipes and Riptortus dentipes varied, and the analysis of variance showed significant differences between treatments compared with the insects counts before application of the phytosanitary products. Keywords: Biopesticide, castor oil, neem, cowpea, Mbujimayi, DRCDans le but de valoriser les espèces végétales à propriétés insecticides et la recherche des méthodes alternatives à l'utilisation des insecticides chimiques, il est impérieux de mettre en place de bio-pesticides, qui soient efficaces, moins coûteux, accessibles, faciles à manipuler par les paysans et respectueux de la santé humaine et de l’environnement. Pour ce faire, cette étude s’est fixée comme objectif de déterminer l’efficacité des extraits aqueux des graines de ricin (Ricinus communis L.) et de Neem (Azadiracta indica L.) sur les ravageurs de la culture de niébé dans les conditions écologiques de Mbujimayi (RDC). Un dispositif expérimental complètement randomisé a été installé, sur une superficie totale de 180 m², constitué de trois blocs et quatre traitements, à savoir, T0 (témoin), T1 (Deltamethrine (1,11 litre/m²), T2 (Extraits des graines de neem (1,11 litre/m²) et T3 (Extraits des graines de ricin (1,11 litre/m²). Après application des traitements, il a été noté que le nombre d’insectes d’Ootheca mutabilis, de Maruca vitrata, d’Aneplocnemis curvipes, de Riptortus dentipes, a varié et l’analyse de variance a dégagé une différence significative entre les traitements comparativement aux nombres d’insectes dénombrés avant application des produits phytosanitaires. Mot clés: Biopesticide, ricin, neem, niébé, Mbujimay