African Rainforest Research Articles

High Inter-Specific Diversity and Seasonality of Trunk Radial Growth in Trees Along an Afrotropical Elevational Gradient.

Understanding mechanisms driving tropical tree growth is essential for comprehending carbon sequestration and predicting the future of tropical forests amid rapid deforestation. We conducted a natural experiment in Mount Cameroon to identify climatic factors limiting diurnal and seasonal growth in dominant tree species across a 2200-m elevation gradient, from lowland rainforests to montane mist forests with distinct wet and dry seasons. Using high-precision automatic dendrometers, we recorded radial growth rates of 28 tropical tree species from 2015 to 2018, correlating them with rainfall (11 100-2500 mm) and temperatures (23-14°C) across elevations. Significant growth limitations were suggested at both extremes of water availability. Tree growth peaked during the dry and prewet seasons at humid lower elevations and during wet seasons at drier higher elevations. Growth rates increased with soil moisture at higher elevations and peaked at medium soil moisture at lower elevations. Trees grew fastest at lower temperatures relative to their elevation-specific means, with growth limited by high daytime temperatures and promoted by nighttime temperatures. Our results revealed significant interspecific diurnal and seasonal growth variations hindered by both water scarcity and excess in West African rainforests, essential for forecasting and modelling carbon sinks.

Light-demanding canopy tree species do not indicate past human disturbance in the Yangambi rainforest (Democratic Republic of the Congo)

Key messageIn a former paper, we investigated whether the presence of light-demanding tree species in the forest canopy of the Yangambi Biosphere Reserve (central Congo basin) might be a result of past human disturbances (Luambua et al., Ecol Evol 11:18691–18707, 2021). We focussed on the spatial distribution of the most abundant light demanders, but this approach did not yield conclusive results. In the present study, we focus on all species in the forest and conclude that light demanders are not a transient feature of successional tropical forests but an intrinsic component of old-growth forests in Yangambi.ContextCentral African rainforests are characterised by an abundance of light-demanding tree species, which are aggregated in the canopy but underrepresented in the understorey. A popular explanation is that these forests are recovering from slash-and-burn farming activities preceding the relocation of settlements during the colonial era. In a former paper, we showed that the abundance of light-demanding tree species in the Yangambi Biosphere Reserve (central Congo basin) cannot be unambiguously attributed to past human disturbances, using an approach that focused on the spatial distribution of the most abundant light demanders (Luambua et al., Ecol Evol 11:18691–18707, 2021).AimsAs the former study was inconclusive, the present study aims to further test the assumptions behind the ‘recovery from human disturbance hypothesis’, by considering all species in the forest of Yangambi. We addressed four specific research questions: (i) do light demanders occur in large ‘pockets’ occupying large areas of forest? (ii) Are light demanders abundant? (iii) Do they exhibit a regeneration deficit? (iv) Is species composition in pockets of light demanders different from the surrounding forests?MethodsWe identified the location and size of pockets of light demanders in several transects cumulating to 50 km. We installed permanent inventory plots within and outside these pockets and calculated the diameter and age distributions of light demanders within each pocket. We assessed whether pockets of light demanders are different from surrounding forests, using plot clustering analysis.ResultsOur results showed that light demanders were aggregated, but the pockets were small, scarce, and represent a minor fraction of the total forest area. Furthermore, light demanders were not abundant, even in pockets where they were aggregated. Their age distributions did not show a regeneration deficit. Finally, species composition in pockets of light demanders did not differ substantially from surrounding forests where they were scarce or absent.ConclusionsWe conclude that light-demanding canopy species do not indicate past human disturbance in Yangambi and that they are an intrinsic component of old-growth forests rather than a transient feature of successional forests. Our insights show that the large carbon sink observed in mature forests in this region is not driven by successional forest dynamics.

Anthropogenic extinctions explain most size and trophic mismatches between large mammalian primary consumers from Amazonian and African rainforests

Anthropogenic extinctions explain most size and trophic mismatches between large mammalian primary consumers from Amazonian and African rainforests

Taxonomic review of the grasshopper genus Pteropera Karsch, 1891 (Orthoptera, Acrididea, Catantopinae) with description of three new species and a preliminary phylogeny of the Cameroonian species.

The Afrotropical grasshopper genus Pteropera Karsch, 1891, is reviewed. Some species present in Cameroon are described, Pteroperaaugustini Donskoff, 1981, is recorded for the first time in the country, and three new species are described from Cameroon, Pteroperakennei Yetchom & Husemann, sp. nov., Pteroperamatzkei Yetchom & Husemann, sp. nov. and Pteroperamissoupi Yetchom & Husemann, sp. nov., increasing the number of Pteropera species in Cameroon from eight to 12, and overall to 30 species in Central Africa. An updated key of Pteropera is provided. Photographs with data on the distributions of all known species are given. In addition, a phylogenetic tree was constructed using maximum likelihood and Bayesian inference on the basis of a concatenated dataset of COI, 16S, and 12S markers of available Cameroonian species. The maximum likelihood and Bayesian inference analyses of the concatenated datasets resulted in a well-resolved phylogeny of the group and species of Pteropera were recovered as monophyletic, largely with high support. In all cases, the discrimination of all studied species based on barcode information was congruent with the species limits determined by traditional taxonomy. Our findings show the potential of integrative taxonomy to resolve the relationships among grasshoppers below the family level. Further analyses, including more comprehensive taxon sampling and additional nuclear markers, are needed, and the occurrence of several taxa still needs to be confirmed in African rainforests.

Genetic differentiation in Khaya Ivorensis A. Chev., a threaten tree of evergreen African rainforests

Genetic differentiation in Khaya Ivorensis A. Chev., a threaten tree of evergreen African rainforests

BaTwa populations from Zambia retain ancestry of past hunter-gatherer groups

Sub-equatorial Africa is today inhabited predominantly by Bantu-speaking groups of Western African descent who brought agriculture to the Luangwa valley in eastern Zambia ~2000 years ago. Before their arrival the area was inhabited by hunter-gatherers, who in many cases were subsequently replaced, displaced or assimilated. In Zambia, we know little about the genetic affinities of these hunter-gatherers. We examine ancestry of two isolated communities in Zambia, known as BaTwa and possible descendants of recent hunter-gatherers. We genotype over two million genome-wide SNPs from two BaTwa populations (total of 80 individuals) and from three comparative farming populations to: (i) determine if the BaTwa carry genetic links to past hunter-gatherer-groups, and (ii) characterise the genetic affinities of past Zambian hunter-gatherer-groups. The BaTwa populations do harbour a hunter-gatherer-like genetic ancestry and Western African ancestry. The hunter-gatherer component is a unique local signature, intermediate between current-day Khoe-San ancestry from southern Africa and central African rainforest hunter-gatherer ancestry.

Integration of large and diverse angiosperm DNA fragments into Asian Gnetum mitogenomes

BackgroundHorizontal gene transfer (HGT) events have rarely been reported in gymnosperms. Gnetum is a gymnosperm genus comprising 25‒35 species sympatric with angiosperms in West African, South American, and Southeast Asian rainforests. Only a single acquisition of an angiosperm mitochondrial intron has been documented to date in Asian Gnetum mitogenomes. We wanted to develop a more comprehensive understanding of frequency and fragment length distribution of such events as well as their evolutionary history in this genus.ResultsWe sequenced and assembled mitogenomes from five Asian Gnetum species. These genomes vary remarkably in size and foreign DNA content. We identified 15 mitochondrion-derived and five plastid-derived (MTPT) foreign genes. Our phylogenetic analyses strongly indicate that these foreign genes were transferred from diverse eudicots—mostly from the Rubiaceae genus Coptosapelta and ten genera of Malpighiales. This indicates that Asian Gnetum has experienced multiple independent HGT events. Patterns of sequence evolution strongly suggest DNA-mediated transfer between mitochondria as the primary mechanism giving rise to these HGT events. Most Asian Gnetum species are lianas and often entwined with sympatric angiosperms. We therefore propose that close apposition of Gnetum and angiosperm stems presents opportunities for interspecific cell-to-cell contact through friction and wounding, leading to HGT.ConclusionsOur study reveals that multiple HGT events have resulted in massive amounts of angiosperm mitochondrial DNA integrated into Asian Gnetum mitogenomes. Gnetum and its neighboring angiosperms are often entwined with each other, possibly accounting for frequent HGT between these two phylogenetically remote lineages.

Environmental variation predicts patterns of genomic variation in an African tropical forest frog

Central African rainforests are predicted to be disproportionately affected by future climate change. How species will cope with these changes is unclear, but rapid environmental changes will likely impose strong selection pressures. Here we examined environmental drivers of genomic variation in the central African puddle frog (Phrynobatrachus auritus) to identify areas of elevated environmentally-associated turnover. We also compared current and future climate models to pinpoint areas of high genomic vulnerability where allele frequencies will have to shift the most in order to keep pace with future climate change. Neither physical landscape barriers nor the effects of past Pleistocene refugia influenced genomic differentiation. Alternatively, geographic distance and seasonal aspects of precipitation are the most important drivers of SNP allele frequency variation. Patterns of genomic differentiation coincided with key ecological gradients across the forest-savanna ecotone, montane areas, and a coastal to interior rainfall gradient. Areas of greatest vulnerability were found in the lower Sanaga basin, the southeastern region of Cameroon, and southwest Gabon. In contrast with past conservation efforts that have focused on hotspots of species richness or endemism, our findings highlight the importance of maintaining environmentally heterogeneous landscapes to preserve genomic variation and ongoing evolutionary processes in the face of climate change.

Disentangling the impact of nested sources of variability on species growth processes: A mixture of multilevel mixed model approach.

SummaryThe understanding of tree growth processes is crucial for promoting sustainable forest management strategies. This is a challenging task in highly biodiverse ecosystems where many tree species are observed on very few individuals and the small sample sizes hinder a good fit of species‐specific models. We propose the use of finite mixture of random coefficient regression models with multilevel nested random effects to infer guild specific fixed and random effects while evaluating the relative importance of the nested sources of variability on goodness‐of‐fit. This approach extends finite mixture of linear mixed model used for longitudinal or single group structured data contexts. A dedicated expectation–maximisation algorithm is introduced for parameter estimation. Simulations are performed for the evaluation of the misspecification of nested‐grouping structures. This work has been motivated by data collected biennially in Central African rainforests from 1986 to 2010. We show the accuracy of the proposed approach in successfully reproducing individual growth processes and classifying tree species into well‐differentiated clusters with clear ecological interpretations. Moreover, results confirm that interindividual variability appears as the most important factor to explain tropical tree species growth process variability from Central Africa forests.

Multidecadal Ethnoarchaeological Comparisons of Livelihoods and Wild Meat Availability and Consumption in a Central African Rainforest Foraging and Farming Community

We repurpose multidecadal ethnoarchaeological investigations of human hunting, prey availability, and socioeconomics in a rural Central African Republic village in the service of human ecology. Focusing on forest foragers in the village of Grima, initial 1999–2005 (Old Grima) data collection included documentation of hunting technology and offtakes, identification of wild meat bone assemblages, inventories of household material goods, and measurements of horticultural fields. Similar datasets were collected in 2021–2022 (New Grima) and longitudinal comparisons of prey remains and material wealth detected many significant differences. Old Grima house middens contained larger numbers of bones representing an array of wild meat taxa and inventories recorded diverse and abundant collections of material goods. The New Grima comparative data showed a reduction in the consumption of wild meat, increases in guns and especially metal cable snares, and marked declines in local wild meat (notably duiker) populations and forager material wealth paired with increases in debt. In 2022 the New Grima inhabitants were actively pursuing escargot for food and income and house middens were dominated by tortoise remains. All the data point to resource depression from overhunting and a community in jeopardy. The comparisons are also important because they include the transition from traditional nets and spears to more efficient metal cable snares and guns and provide information on the effects of hunting technology. The complexities of evaluating ecological perturbations and sustainability require multidisciplinary datasets and we propose ethnoarchaeology as a valuable tool to help identify subtleties in human food webs and biodiversity loss.

Phytochemical Composition and Medicinal Properties of Psidium guajava, Artocarpus heteorphyllus, Anona muricata and Passiflora edulis: A Critical Review

Artocarpus heterophyllus Lam, a part of the Moraceae family, is known by distinctive names in different districts over the globe. The jackfruit tree's significant alleviating impacts have made it a well-known choice for characteristic cures. Its bioactive compounds, counting lignans, flavones, and saponins, contribute to its momentous therapeutic properties, which incorporate anti-cancer, anti-ulcer, anti-hypertensive, and anti-aging impacts. As a result, the jackfruit tree holds awesome importance in conventional medication and characteristic mending hones. Guanabana, soursop, graviola, or Brazilian paw paw, scientifically known as A. muricata, is a plant native to Central America but can be found in abundance across Southeast Asia, South America, and the African rainforest.. This plant has appeared various advantageous properties counting anticancer, antiulcer, antidiabetic, antiprotozoal, antidiarrhea, antibacterial, antiviral, antihypertensive, and wound mending impacts. Psidium guajava includes a wealthy history of restorative employments, with all parts of the tree being esteemed for their helpful properties. From the takes off to the natural products, each component of Psidium guajava has been utilized for different wellbeing benefits throughout a long time. Its restorative centrality includes to the by and large significance of this tropical tree totally different societies and conventional hones. Energy natural products, which have a place to the sort Passiflora, comprise of around 450 species. Among them, Passiflora edulis is the foremost well-known and commonly utilized. Later thinks about have too highlighted its anti-inflammatory potential, especially within the frame of tea made from the imbued clears out. Passiflora alata and P. edulis have both found applications in various pharmaceutical arrangements and are broadly utilized within the nourishment industry. The anti-oxidant substances present in P. Edulis have sparked a growing interest in this plant. Even though it is important, no audit of this species has been included in the logical writing up to this point. The notable and recent literature on the botany, traditional uses, phytochemistry, pharmacological effects, and harmfulness of this ponder plant is surveyed and summarized here. This overview may prove beneficial for subsequent research aimed at misusing the beneficial attributes of this priceless, curative species.

Predictive mapping of tree species assemblages in an African montane rainforest

AbstractConservation of mountain ecosystems can benefit from knowledge of habitats and their distribution patterns. This benefit is particularly true for diverse ecosystems with high conservation values such as the “Afromontane” rainforests. We mapped the vegetation of one such forest: the rugged Bwindi Impenetrable Forest, Uganda—a World Heritage Site known for its many restricted‐range plants and animal taxa including several iconic species. Given variation in elevation, terrain and human impacts across Bwindi, we hypothesized that these factors influence the composition and distribution of tree species. To test this, detailed surveys were carried out using stratified random sampling. We established 289 georeferenced sample sites (each with 15 trees ≥20 cm dbh) ranging from 1320 to 2467 m a.s.l. and measured 4335 trees comprising 89 species that occurred in four or more sample sites. These data were analyzed against 21 digitally mapped biophysical variables using various analytical techniques including nonmetric multidimensional scaling (NMDS) and random forests. We identified six tree species assemblages with distinct compositions. Among the biophysical variables, elevation had the strongest correlation with the ordination (r2 = 0.5; p < 0.001). The “out‐of‐bag” (OOB) estimate of the error rate for the best final model was 50.7% meaning that nearly half of the variation was accounted for using a limited set of variables. We demonstrate that it is possible to predict the spatial pattern of such a forest based on sampling across a highly complex landscape. Such methods offer accurate mapping of composition that can guide conservation.

Microallopatric speciation in the relict dung beetle genus Grebennikovius (Coleoptera: Scarabaeidae) in the Eastern Arc Mountains

Abstract The Eastern Arc Mountains (EAMs) in Tanzania and Kenya are renowned for their exceptional species endemism often restricted to isolated mountain blocks. Forest fragmentation during the Pliocene–Pleistocene played a significant role in shaping the EAMs’ biodiversity by facilitating allopatric speciation between different mountains. However, only a few studies focused on species diversification within the same mountain block. In this article, we investigated the taxonomy and evolution of the dung beetle genus Grebennikovius, endemic to the Uluguru Mountains. Our goal was to unravel factors promoting allopatric speciation within a confined geographic area like the Ulugurus. We used an integrative taxonomic approach, combining phenotypic data and COI barcodes to delimit species and reconstructed a timetree of the genus. Molecular and morphological evidence consistently recovered 4 distinct Grebennikovius species, of which 3 are new to science: G. armiger n. sp., G. basilewskyi (Balthasar, 1960), G. lupanganus n. sp., and G. pafelo n. sp. Grebennikovius represents a rare case of microallopatry, with all species occurring in close proximity within different regions of the limited Uluguru forest (∼230 km2). We infer that speciation was driven by the interplay between climate fluctuations during the Miocene and mid-Pleistocene, Uluguru topography, and the stability of rainforest ecological conditions. The latter factor probably favored the loss of wings and a specialization for Uluguru microhabitats, reinforcing population isolation and divergence. This study highlights a unique instance of diversification resulting from small-scale speciation events, providing valuable insights into the evolution of Eastern African rainforest arthropods and underscoring the importance of microhabitats conservation.

Human-elephant conflict in the African rainforest landscape: crop-raiding situations and damage mitigation strategies in rural Gabon

While the conservation of forest elephants is a global concern, human-elephant conflict (HEC), especially crop-raiding by elephants, is a serious threat to both human livelihoods and conservation efforts. However, only a few studies have explored elephant crop-raiding and related damage mitigation strategies in Central Africa’s forest landscapes, which are characterized by low human and high animal densities and shifting cultivation practices. This study investigates HEC in rural Gabon, where human activities are limited, and local livelihoods are severely threatened by crop-raiding elephants. Through long-term ethnographic research and an in-depth analysis of damage mitigation practices by local people, the study unveils serious crop-raiding by elephants, leading to a significant change in the local lifestyle. Most households spend the majority of days in the field protecting crops, resulting in the village becoming almost empty. In addition to the physical burden of staying in poor living conditions, there is a considerable psychological burden for local people. Establishing effective elephant conservation systems requires understanding each local situation and evaluating the various costs to local people. To sustain livelihoods and address the challenge of HEC, it is crucial for local communities and various stakeholders to act collectively.

African rainforest moisture contribution to continental agricultural water consumption

Precipitation is essential for food production in Sub-Saharan Africa, where more than 80 % of agriculture is rainfed. Although ∼40 % of precipitation in certain regions is recycled moisture from Africa's tropical rainforest, there needs to be more knowledge about how this moisture supports the continent's agriculture. In this study, we quantify all moisture sources for agrarian precipitation (African agricultural precipitationshed), the estimates of African rainforest's moisture contribution to agricultural precipitation, and the evaporation from agricultural land across the continent. Applying a moisture tracking model (UTRACK) and a dynamic global vegetation model (LPJmL), we find that the Congo rainforest (>60 % tree cover) is a crucial moisture source for many agricultural regions. Although most of the rainforest acreage is in the DRC, many neighboring nations rely significantly on rainforest moisture for their rainfed agriculture, and even in remote places, rainforest moisture accounts for ∼10–20 % of agricultural water use. Given continuous deforestation and climate change, which impact rainforest areas and resilience, more robust governance for conserving the Congo rainforest is necessary to ensure future food production across multiple Sub-Saharan African countries.

Analysis of Sporulation in Bacillus cereus Biovar anthracis Which Contains an Insertion in the Gene for the Sporulation Factor σK.

Bacillus cereus biovar anthracis (Bcbva) is an untypical pathogen causing a fatal anthrax-like disease in a variety of wildlife species in African rainforest areas. In contrast to Bacillus anthracis and most species of the B. cereus group, all strains of the Bcbva cluster contain a 22 kb insertion in the sigK gene which encodes the essential late sporulation sigma factor σK. This insertion is excised during sporulation in a site-specific recombination process resulting in an intact sigK gene and a circular molecule. The sporulation kinetics of two strains each of Bcbva and B. anthracis were compared by the expression analysis of eight sporulation-associated genes, including sigK, using reverse transcriptase quantitative real-time PCR. In addition, morphological sporulation stages were analyzed and quantified by electron microscopy. Our results indicated that the necessary excision of the insertion in Bcbva neither delayed nor inhibited its sporulation. In two spontaneous mutants of Bcbva, the excision of the sigK insertion and sporulation were impeded due to mutations in the spo0A and spoVG regulator genes, respectively. The spo0A frameshift mutation was overcome by intragenic suppression in a revertant which was able to sporulate normally, despite an M171S amino acid exchange in the global regulator Spo0A. A screening of the NCBI database identified further strains of the B. cereus group which possess unrelated insertions in the sigK gene, and two strains containing almost identical insertions at the same gene position. Some of the sigK insertions encode putative prophages, whereas the Bcbva insertion encoded a type I restriction-modification system. The function of these insertions and if they are possibly essential for sporulation remains to be assessed.

Dynamic assessment of the impact of agricultural land use change and globalization on environmental quality in the tropical African Rainforest: evidence from the Congo Basin.

The rising human demand for food has increased the pursuit for more agricultural land to feed the ever-growing human population. Although agriculture constitutes the cornerstone of most economies and serves as a vital source of foreign earnings to others, experts suggest that it emits a substantial amount of greenhouse gases into the atmosphere, thereby enhancing global warming. Furthermore, with the growing pace of globalization, less developed countries are witnessing economic growth with detrimental impacts on the environment. Inspired by the need to protect tropical rainforests and basins, the current research aims to assess the dynamic impacts of agricultural land use change (LALUC) and globalization (LGLO) on environmental quality (LCO2) in the Congo Basin while controlling for economic growth (LGDP), biomass energy consumption (LBIO), and urbanization (LURBN). Based on panel data from 1980 to 2018, this study utilized second-generation econometric methods including the cross-sectional Im, Peseran Shin (CIPS), Westerlund bootstrapped co-integration test, autoregressive distributive lag/pooled mean group (ARDL/PMG), and the Dumitrescu Hurlin (D-H) panel causality estimates. The outcome reveals a long-run equilibrium co-integrating association among the estimated variables, and LALUC, LBIO, and LURBN were found to reduce LCO2, while LGDP and LGLO increase LCO2. These findings imply the inverted U-shaped relationship between LALUC, LBIO, and LURBN is beneficial for environmental quality in the Congo Basin. Based on the findings, environmental quality and economic growth can be achieved instantaneously in this region by engaging in large-scale production of biomass energy. Therefore, policymakers and governments should promote renewable energy use and convey foreign funds towards its enhancement, while investments in agriculture should prioritize environmentally benign practices such as agroforestry.

Contrasted spatial, demographic and genetic structures of a light-demanding African timber species, Cylicodiscus gabunensis Harms – Implications for a sustainable management of its populations

Most Central African rainforest canopies consist of light-demanding tree species that hold high commercial value but also suffer locally from regeneration deficits, raising concerns about the sustainability of logging. Regeneration is influenced by factors such as past perturbations (including human activity), mating systems, and seed/pollen dispersal processes that impact demographic, spatial, and genetic structures within populations. To gain a better understanding of these interactions, we studied the spatial distribution and trunk diameter structure of Cylicodiscus gabunensis (Fabaceae) - a wind-dispersed, insect-pollinated, timber species - in three plots ranging from 400 to 839 ha situated in various environmental contexts (e.g. forest types and elephant densities) across Central Africa. We also genotyped adults and juveniles using microsatellite markers to analyze the spatial genetic structure of each population and infer the selfing rate, seed and pollen dispersal capacities and selection gradients using the ‘neighborhood model’. The selfing rate was low (3 – 4 %), and seed dispersal distances (ds = 184 m) were much shorter than pollen dispersal distances (dp > 2 km). The three populations displayed contrasted spatial, demographic and genetic structures. One population showed no spatial aggregation or genetic structure, and a multimodal diameter structure indicating pulses of regeneration events. Two populations showed strong spatial aggregation and genetic structures. One exhibited a unimodal diameter structure indicating one ancient pulse of regeneration, while the other displayed a 'reverse J-shaped' diameter structure, typical of ongoing regeneration. In the latter, reproductive success appeared leptokurtic, three mother trees accounting for over 90 % of the regeneration and no tree below the minimum cutting diameter implemented by logging companies had offspring. The idiosyncratic nature of population characteristics observed in C. gabunensis suggests that, for sustainable management, a nuanced approach is needed. This involves protecting productive seed trees in areas where natural regeneration is occurring and actively supporting regeneration in areas exhibiting deficits, especially in contexts with low elephant densities.

Middle Stone Age at Equatorial Guinea: Technical and use-wear analysis of lithic bifacial points

Lithic industries during the Upper Pleistocene in Equatorial Guinea may be broadly included in the Central African Middle Stone Age (MSA) Lupemban tradition. However, these industries present certain particularities related to their raw materials, and stone-knapping sequences. In the case of bifacial tools, bifacial points are commonly found with a cortical reserved proximal portion that keeps the cortex covering the base and part of both faces. Bifacial points made on thin stone slabs that keep the cortex on the center of one or both faces are also commonly found. This knapping technique gives the idea of unfinished preform artifacts. The edges, however, suggest that both points and other bifacial artifacts were used for some tasks. A sample of these tools was taken from the open-air Mabewele I site to decide whether the MSA points from Equatorial Guinea were finished artifacts, in spite of the preservation of their cortex. Petrographic studies and macro and microscopic analyses of the use-wear traces and residues from retouched edges were also performed. The analysis clearly shows that the Mabewele I bifacial artifacts were used for plant processing, among other activities. The results confirmed the fact that cortical reserved-base points with cortex on one or both faces were intentionally manufactured, finished tools, rather than unfinished preforms. The petrographic analysis also shows the schistous nature of raw material and explains the shape and stepped edges of bifacial knives, extending our understanding of the unique technical characteristics of the MSA in Equatorial Guinea. It also provides new insights into some of the hunter-gatherer's subsistence strategies in the Central African tropical rainforest at the end of the Pleistocene.

Intraspecific variation in fruit production of African mahogany (Khaya anthotheca) in a semi‐deciduous East African rainforest

AbstractRestoring valuable timber trees is a necessary part of regaining many ecosystem services and products provided by degraded tropical forests. However, knowledge of seed production, a regeneration prerequisite, is limited for many tropical timber tree species. We studied the fruit production of African mahogany (Khaya anthotheca) in a semi‐deciduous rainforest in East Africa, to provide information for ecological restoration programs. First, we quantified population variability and synchrony in fruit production. Then, we assessed how reproductive status and output were influenced by tree size, neighbourhood crowding, exchangeable cations, liana presence, and crown exposure. We found fruit production at the population level was weakly synchronised, with high interannual variability at the population and individual levels. Tree size determined reproductive status. Individual quantity of fruit produced increased with tree size but decreased with neighbourhood crowding. Our results indicate that K. anthotheca does not meet the criteria for mast fruiting. Our findings suggest that reproductive output in mahogany is regulated by tree size and competition. In addition to active protection, thinning to reduce competition around seed trees may boost fruit production at the individual tree level to provide seed for forest enrichment.