African Rainforest Research Articles

Passive acoustic monitoring reveals behavioural response of African forest elephants to gunfire events

AbstractAfrican forest elephants (Loxodonta cyclotis) are a critically endangered and visually cryptic species that inhabits Central African rainforests. Using a 1250 sq‐km grid of 50 acoustic sensors in Republic of Congo, we investigated the landscape‐scale behavioural response of forest elephants to poaching events. We detected eight automatic weapon fire events over 1.5 years of recording (2017–2019). We examined detections of elephant vocalisations across grid sites within 10 km of the gunfire events in the 48 h surrounding the gunfire, and in paired 48‐h control periods free of gunfire. Fewer vocalisations were detected before gunfire events than during control periods, suggesting elephants show behavioural responses to poacher presence before any shots are fired. Immediately following the gunfire events, a significant increase in elephant calls was detected, which may indicate increased communication to facilitate group cohesion and movement. Elevated call levels dropped to lower‐than‐baseline rates after several hours, suggestive of a sustained response. These patterns indicate forest elephants respond to both poacher presence and to gunfire events themselves. As these patterns may reflect behaviours that mediate population processes, conservation strategies should account for the potential of poaching to impact populations via indirect effects on nontarget elephants in the area.

Transitional morphology and Afrotropical affinity of a bythinoplectine rove beetle from the early Eocene of India (Coleoptera: Staphylinidae: Pselaphinae)

Recently discovered Ypresian-age amber from Cambay, India, reveals an ancient arthropod assemblage on the Indian subcontinent during its collision with Asia. Despite the tectonic history of India, limited connections have been found between the Cambay palaeofauna and present-day Madagascan and mainland African faunas. Here, I describe a new fossil pselaphine rove beetle (Staphylinidae: Pselaphinae) recovered from the Cambay deposit that shows closest apparent phylogenetic affinity to modern Afrotropical genera. Yprezethinus grimaldii gen. et sp. nov. is placed in Bythinoplectini, subtribe Bythinoplectina. Based on antennal and maxillary palp morphology, Yprezethinus is a putative transitional stem lineage of the Zethinus-group of genera—an extant clade distributed across equatorial African rainforests. Although Yprezethinus shares with this clade the derived feature of ovoid antennal clubs formed by tight appression of the apical two segments, it differs from its putative extant relatives in its possession of the plesiomorphic complement of 11 antennomeres, without any fusions of segments. The fossil taxon signifies a biotic link between early Eocene India and continental Africa, and marks the Cenozoic emergence of a tropical leaf litter arthropod fauna approaching that of contemporary, ant-dominated rainforests.

Monkeypox virus preparation in Pakistan-Next viral zoonotic disease outbreak after COVID-19?

Monkeypox is a viral disease that often affects central and western African rainforests. But the illness has recently arisen in the World in imported African wild rats. Monkeypox exhibits symptoms that are remarkably similar to other types of smallpox, including flu-like symptoms, malaise, headache, back pain, fever, and the distinctive rash. Considering this therapeutic range, performing a differential diagnosis to exclude smallpox is critical. Monkeypox has no recognized treatment, but the smallpox vaccination can prevent the infection. Reducing contact with sick patients or animals and avoiding respiratory exposure to infected patients is vital for proper protection. ‎

Evolution of the Atlantic Intertropical Convergence Zone, and the South American and African Monsoons Over the Past 95‐Myr and Their Impact on the Tropical Rainforests

AbstractThe widening of the South Atlantic Basin led to the reorganization of regional atmospheric and oceanic circulations. However, the response of the Atlantic Intertropical Convergence Zone (ITCZ), and South American and African monsoons across paleoclimate states, especially under constant paleogeographic and climatic changes, has not been well understood. Here we report on paleoclimate simulations of the Cenomanian (∼95 Ma), early Eocene (∼55 Ma), and middle Miocene (∼14 Ma) using the Community Earth System Model version 1.2 to understand how the migration of the South American and African continents to their modern‐day positions, uplift of the Andes and East African Rift Zone, and the decline of atmospheric CO2 changed the Atlantic ITCZ, and the South American and African monsoons and rainforests. Our work demonstrates that the South Atlantic widening developed the Atlantic ITCZ. The South Atlantic widening and Andean orogeny led to a stronger South American monsoon. We find the orogeny of the East African Rift Zone is the primary mechanism that strengthened the East African monsoon, whereas the West African monsoon became weaker through time as West Africa migrated toward the subtropics and CO2 levels fell below 500 ppm. We utilize the Köppen‐Geiger Climate Classification as an indicator for maximum rainforest extent. We find that during the Cenomanian and early Eocene, a Pan‐African rainforest existed, while the Amazon rainforest was restricted toward the northwestern corner of South America. During the middle Miocene, the Pan‐African rainforest was reduced to near its modern‐day size, while the Amazon rainforest expanded eastward.

African mitochondrial haplogroup L7: a 100,000-year-old maternal human lineage discovered through reassessment and new sequencing

Archaeological and genomic evidence suggest that modern Homo sapiens have roamed the planet for some 300–500 thousand years. In contrast, global human mitochondrial (mtDNA) diversity coalesces to one African female ancestor (“Mitochondrial Eve”) some 145 thousand years ago, owing to the ¼ gene pool size of our matrilineally inherited haploid genome. Therefore, most of human prehistory was spent in Africa where early ancestors of Southern African Khoisan and Central African rainforest hunter-gatherers (RFHGs) segregated into smaller groups. Their subdivisions followed climatic oscillations, new modes of subsistence, local adaptations, and cultural-linguistic differences, all prior to their exodus out of Africa. Seven African mtDNA haplogroups (L0–L6) traditionally captured this ancient structure—these L haplogroups have formed the backbone of the mtDNA tree for nearly two decades. Here we describe L7, an eighth haplogroup that we estimate to be ~ 100 thousand years old and which has been previously misclassified in the literature. In addition, L7 has a phylogenetic sublineage L7a*, the oldest singleton branch in the human mtDNA tree (~ 80 thousand years). We found that L7 and its sister group L5 are both low-frequency relics centered around East Africa, but in different populations (L7: Sandawe; L5: Mbuti). Although three small subclades of African foragers hint at the population origins of L5'7, the majority of subclades are divided into Afro-Asiatic and eastern Bantu groups, indicative of more recent admixture. A regular re-estimation of the entire mtDNA haplotype tree is needed to ensure correct cladistic placement of new samples in the future.

Macrotermes termite mounds influence the spatial pattern of tree species in two African rainforest sites, in northern Congo. But were they really forests in the past?

AbstractTermite mounds have been poorly studied in tropical rainforest in contrast to those of savannahs where they create fertility hotspots and influence the spatial pattern of vegetation. An inventory of termite mounds and of 15 tree species with a diameter at breast height ≥ 10 cm was carried out in two 800-ha blocks, in two rainforest sites located in northern Congo. We used inhomogeneous and intertype K functions to study the spatial pattern of termite mounds and of tree species around mounds, respectively. We found that mounds in Loundoungou were over-dispersed within a radius of less than 70 m, while those in Mokabi were randomly spaced. Tree species within a 20-m radius around a mound were aggregated towards the mound, e.g. Entandrophragma cylindricum, randomly distributed, or even repulsed by the mound. The specific responses also differed in the two sites. These results suggest that (i) the mounds in Loundoungou were created by savannah termite species 3,000-2,000 years BP during the Late Holocene Rainforest Crisis and (ii) the mounds in Mokabi are characteristic of forest mounds. The impact of termite mounds on the spatial pattern of tree species is thus site-dependent, and these differences might be due to species seed dispersal strategies and to soil calcium concentrations.

The scarcity of fossils in the African rainforest. Archaeo-paleontological surveys and actualistic taphonomy in Equatorial Guinea

ABSTRACT The African rainforest is considered a ‘palaeontological desert’, exemplified with the virtual absence of ape fossils from the last 10 Ma. To overcome this deficiency of the fossil record, archaeo-palaeontological surveys have been undertaken in the rainforest of Equatorial Guinea. We have inventoried 225 outcrops and eluvial materials and the formation of ‘stone lines’ (of diverse genesis) predominate. Close to the Atlantic estuaries, there are short fluvial sedimentary sequences (sands and gravels), where remains of lithic industry and charcoal appear, but in no case macro vertebrate fossils. Given the intensity of the survey, the scarcity of sampling is ruled out as the cause of this ‘palaeontological desert’. Besides, biogenic, biostratinomic and fossildiagenetic factors have been explored by means of an actualistic approach. The rainforest ecosystem produces very low density tanatocenosis. Simultaneously, there is a low rate of sedimentation/erosion and the action of scavengers has not been detected, although the action of ants and termites may be determinant. Two fossildiagenetic factors can be inferred: lixiviation as a destructive cause and the existence of periods of intensive erosion. The search for palaeontological record should focus on protected sedimentary environments (rockshelters) or more confined ones (maars and small endorheic basins).

The status of arboreta in South Africa and the taxa they contain

Collections of living trees (hereafter arboreta) are important for conservation, research on species selection for forestry, and as sentinel sites for monitoring pests and diseases. Arboreta can also be the source of propagules for biological invasions. Between 2012 and 2022 a survey was undertaken to assess the status of arboreta in South Africa and the taxa present in such sites, the first such assessment since 1986. At least 172 arboreta have existed in South Africa, but 51 of these are no longer present, with the total number of arboreta peaking around 1980 and declining thereafter. Arboreta have been lost mostly because of conversion of sites to other land-uses, but in some cases because the specimens were felled or burnt down and not replaced. Most of the remaining 121 arboreta are on municipal or forestry land. The biggest challenge facing the extant arboreta is the financial burden of maintaining the collections. The extant arboreta house 2 309 taxa from 158 plant families; of these, 128 taxa (occurring variously in 88 arboreta) are listed as Vulnerable, Endangered, Critically Endangered or Extinct in the Wild under the 2020 IUCN Red List, and 400 taxa (occurring variously in 113 arboreta) have been listed as invasive somewhere in the world. Biogeographic regions that are relatively well represented include the East African Steppe, Sino-Japanese Region, West African Rainforest, North-Eastern Australia, and the Caribbean, making the arboreta valuable sources of germplasm for taxa from these regions. Arboreta are an important resource for South Africa, but a resource that appears to be shrinking. If the value of current arboreta for conservation, education, and research is to be fulfilled, they need to be formally catalogued, their species lists regularly updated, and measures put in place to ensure their sustainability.

The Global Atmosphere-aerosol Model ICON-A-HAM2.3-Initial Model Evaluation and Effects of Radiation Balance Tuning on Aerosol Optical Thickness.

The Hamburg Aerosol Module version 2.3 (HAM2.3) from the ECHAM6.3‐HAM2.3 global atmosphere‐aerosol model is coupled to the recently developed icosahedral nonhydrostatic ICON‐A (icon‐aes‐1.3.00) global atmosphere model to yield the new ICON‐A‐HAM2.3 atmosphere‐aerosol model. The ICON‐A and ECHAM6.3 host models use different dynamical cores, parameterizations of vertical mixing due to sub‐grid scale turbulence, and parameter settings for radiation balance tuning. Here, we study the role of the different host models for simulated aerosol optical thickness (AOT) and evaluate impacts of using HAM2.3 and the ECHAM6‐HAM2.3 two‐moment cloud microphysics scheme on several meteorological variables. Sensitivity runs show that a positive AOT bias over the subtropical oceans is remedied in ICON‐A‐HAM2.3 because of a different default setting of a parameter in the moist convection parameterization of the host models. The global mean AOT is biased low compared to MODIS satellite instrument retrievals in ICON‐A‐HAM2.3 and ECHAM6.3‐HAM2.3, but the bias is larger in ICON‐A‐HAM2.3 because negative AOT biases over the Amazon, the African rain forest, and the northern Indian Ocean are no longer compensated by high biases over the sub‐tropical oceans. ICON‐A‐HAM2.3 shows a moderate improvement with respect to AOT observations at AERONET sites. A multivariable bias score combining biases of several meteorological variables into a single number is larger in ICON‐A‐HAM2.3 compared to standard ICON‐A and standard ECHAM6.3. In the tropics, this multivariable bias is of similar magnitude in ICON‐A‐HAM2.3 and in ECHAM6.3‐HAM2.3. In the extra‐tropics, a smaller multivariable bias is found for ICON‐A‐HAM2.3 than for ECHAM6.3‐HAM2.3.

Intra-annual relationship between precipitation and forest disturbance in the African rainforest

Analysis of forest disturbance patterns in relation to precipitation seasonality is important for understanding African tropical forest dynamics under changing climate conditions and different levels of human activities. Newly available radar-based forest disturbance information now enables an investigation of the intra-annual relationship between precipitation and forest disturbance in a spatially and temporally explicit manner, especially in the tropics, where frequent cloud cover hinders the use of optical-based remote sensing products. In this study, we applied cross-correlation on monthly precipitation and forest disturbance time series for 2019 and 2020 at a 0.5° grid in the African rainforest. We used the magnitude of the correlation and time lag to assess the intra-annual relationship between precipitation and forest disturbance, and introduced accessibility proxies to analyse the spatial variation of the relationship. Results revealed that a significant negative correlation between forest disturbance and precipitation dominates the study region. We found that significant negative correlations appear on average closer to settlements with overall smaller variations in travel time to settlements compared to grid cells with non-significant and significant positive correlation. The magnitude of the negative correlation increases as the travel time to settlements increases, implying that forest disturbances in less accessible areas are more affected by precipitation seasonality and that in particular human-induced disturbance activities are predominantly carried out in the drier months. Few areas showed a significant positive correlation, mainly resulting from natural causes such as flooding. These new insights in the interaction between forest disturbance, precipitation and accessibility provide a step forward in understanding the complex interactions that underlie the complexity of forest loss patterns that we can increasingly capture with Earth Observation approaches. As such, they can support forest conservation and management in coping with climate change induced changes of precipitation patterns in African rainforest countries.

Rapid dung removal by beetles suggests higher duiker densities in Central African rainforests

AbstractFor many mammal species, converting dung density into population density requires accurate estimates of defaecation rate and dung survival time. The latter parameter probably varies seasonally. In Nki National Park, south-east Cameroon, we monitored 216 dung piles of the blue duiker Philantomba monticola and 373 of the red duiker group (Cephalophus spp.), major game animals in Central Africa, and estimated dung survival time across seasons. Mean survival time was 6.83 days in the major dry season and 1.21–1.81 in other seasons for the blue duiker, and 7.37 and 1.53–4.05 for red duikers, lower than the values conventionally used for density estimations in Central Africa (i.e. 18 days for the blue duiker and 21 days for red duikers). Overall, beetles removed half of the dung within 1 day of deposition. However, the proportion of dung piles that beetles removed was significantly lower in the major dry season, and other dung piles remained longer until they disappeared as a result of other factors. As shorter dung survival time results in higher estimates of population density, our findings imply that in forests with intense beetle activity, duiker densities are higher than those based on the conventional values of dung survival time. Duiker densities and dung survival time should be estimated simultaneously. To minimize the bias introduced by rapid removal of fresh dung by beetles, only fresh dung (< 3 hours old) should be monitored when estimating mean dung survival time.

Reproductive seasonality in the Baka Pygmies, environmental factors and climatic changes.

Reproductive seasonality is a phenomenon common to human and animal populations and driven by, among others, climatic variables. Given the currently changing climate and its impacts on both the environment and human lives, the question arises of its potential effects on reproductive seasonality. Few studies have specifically explored the seasonality of reproduction among hunter-gatherers and anyone investigated how current climate change might affect this phenomenon. In this study we addressed reproductive seasonality in the Baka Pygmy living in African rain forests. Since reproductive seasonality can be linked to weather patterns, we explore this possibility. However, climatic variables driving weather patterns have changed over the years, so we assessed whether this has influenced the Baka reproductive pattern. Based on 34 years of written birth records and oral questionnaires from 13 years of systematic fieldwork, we observed a bimodal birth pattern with two birth peaks at 6-month intervals. Our results demonstrate that precipitation at conception or at birth potentially has effects, respectively negative and positive on the monthly number of births; and temperature has a role in controlling other variables that do affect the reproductive pattern. Changing weather patterns appear to be affecting the reproductive seasonality in the Baka, suggesting that attention needs to be given to the influence of global climate change on forager societies.

Human behaviour and climate-linked fluctuations in the rainforests of West-Central Africa.

Africa, the cradle of human evolution, has one of the largest and most diverse rainforests in the world. The African rainforests contain evidence of human occupation as well as fluctuating climate during the Pleistocene; such evidence offers archaeologists and palaeoecologists the opportunity to understand how climatic fluctuations have influenced human behaviour. However, compared to the rainforests environments in Asia and South America, the human ecological history of those in West-Central Africa is poorly understood. This is because of comparatively fewer scientific programmes which synergize palaeoecological and archaeological data and thus could enhance the knowledge and allow for an evaluation of the impact of climatic fluctuations on human behaviour in the rainforests of West-Central Africa during the Pleistocene and Holocene periods. The goals of this paper are twofold, namely: (i) to provide a synthesis of the past climatic variability in the rainforests of West-Central Africa, and (ii) to demonstrate the influence of such variability on human behaviour during the Pleistocene to Holocene periods. It is hoped that this paper will stimulate Africanists to adopt an inclusive scientific anthropological and palaeoecological approach in understanding human-climate interactions in the West-Central African rainforests. This article is part of the theme issue 'Tropical forests in the deep human past'.

Ancient DNA and deep population structure in sub-Saharan African foragers

Multiple lines of genetic and archaeological evidence suggest that there were major demographic changes in the terminal Late Pleistocene epoch and early Holocene epoch of sub-Saharan Africa1–4. Inferences about this period are challenging to make because demographic shifts in the past 5,000 years have obscured the structures of more ancient populations3,5. Here we present genome-wide ancient DNA data for six individuals from eastern and south-central Africa spanning the past approximately 18,000 years (doubling the time depth of sub-Saharan African ancient DNA), increase the data quality for 15 previously published ancient individuals and analyse these alongside data from 13 other published ancient individuals. The ancestry of the individuals in our study area can be modelled as a geographically structured mixture of three highly divergent source populations, probably reflecting Pleistocene interactions around 80–20 thousand years ago, including deeply diverged eastern and southern African lineages, plus a previously unappreciated ubiquitous distribution of ancestry that occurs in highest proportion today in central African rainforest hunter-gatherers. Once established, this structure remained highly stable, with limited long-range gene flow. These results provide a new line of genetic evidence in support of hypotheses that have emerged from archaeological analyses but remain contested, suggesting increasing regionalization at the end of the Pleistocene epoch.

The impacts of human activity on mammals in a community forest near the Dja Biosphere Reserve in Cameroon

AbstractHuman activity in African tropical rainforests continues to threaten wild mammals. Many rural communities are dependent on hunting, yet there is a widespread lack of baseline data on ecology and the sustainability of hunting. We investigated the impacts of human activity on mammal species composition and distributions within a community forest surrounding a village in the buffer zone of the Dja Biosphere Reserve in south-east Cameroon. We conducted a camera-trap survey in August–November 2017 and detected 24 mammal species, including Critically Endangered western lowland gorilla Gorilla gorilla gorilla, Endangered central African chimpanzee Pan troglodytes troglodytes and Endangered tree pangolin Phataginus tricuspis. We used occupancy analysis to explore relationships between indicators of human activity (distance to a road and the Reserve), habitat quality (distance to the river and tree cover) and the distributions of species. We found that the local distribution of threatened mammals was not apparently limited by human activity, and proximity to the road did not negatively influence occupancy for any species. However, most of the Reserve's large species were not detected, including the African forest elephant Loxodonta cyclotis and the largest ungulates, and the occupancy of two species commonly hunted for wild meat was positively correlated with distance from the village, indicating hunting may be unsustainable. Our results show that the community forest provides habitat for threatened species outside the Reserve and in close proximity to people. However, effective conservation management will require continued monitoring and research to determine whether current rates of hunting are sustainable.

Sociogeographic correlates of typological variation in northwestern Bantu gender systems

Abstract This paper investigates the sociolinguistic factors that impact the typology and evolution of grammatical gender systems in northwestern Bantu, the most diverse area of the Bantu-speaking world. We base our analyses on a typological classification of 179 northwestern Bantu languages, focusing on various instances of semantic agreement and their role in the erosion of gender marking. In addition, we conduct in-depth analyses of the sociolinguistics and population history of the 17 languages of the sample with the most eroded gender systems. The sociohistorical factors identified to explain these highly eroded systems are then translated into a set of explanatory variables, which we use to conduct extensive quantitative analyses on the 179 language sample. These variables are population size, longitude, latitude, relationship with the Central African rainforest, and border with Ubangi/Central Sudanic languages. All these measures are relevant, with population size and bordering with Ubangi/Central Sudanic being the most robust factors in accounting for the distribution of gender restructuring. We conclude that fine-tuned variable design tailored to language and area-specific ecologies is crucial to the advancement of quantitative sociolinguistic typology.

From Patagonia to Indonesia: plant fossils highlight West Gondwanan legacy in the Malesian flora

Rainforests with the chinquapin Castanopsis and the yellowwood conifer Dacrycarpus occur today throughout Indonesia and the larger Malesian ecoregion, but they represent, in part, a history of survival stretching tens of millions of years and thousands of kilometers to the palaeo-Antarctic. Unlike New World and African tropical rainforests, the Malesian flora’s history is closely tied to tectonic introductions from exotic terranes, and thus, much palaeobotanical data about the origins of the Malesian rainforest comes from those terranes. For example, South America, Antarctica, and Australia remained adjacent until the Eocene final separation of Gondwana, and warm climates promoted high-latitude dispersals among those landmasses. Australia’s subsequent northward movement led to the late Oligocene Sahul-Sunda collision and the uplift of New Guinea, allowing the introductions into Malesia of survivor taxa that were once widespread in mesic Gondwanan rainforests. In Patagonian Argentina, the prolific Laguna del Hunco (52.2 Ma) site preserves abundant and well-preserved fossils of an unexpectedly large number of lineages whose living relatives characteristically associate in perhumid, lower montane “oak-laurel” rainforests of Malesia, especially in New Guinea. These taxa include the angiosperms Castanopsis (Fagaceae), Gymnostoma (rhu, Casuarinaceae), Alatonucula (extinct engelhardioid Juglandaceae), Eucalyptus (gums, Myrtaceae), Ceratopetalum (coachwood, Cunoniaceae), Lauraceae (laurel family), and Ripogonum (supplejack, Ripogonaceae); conifers in Cupressaceae (cypress family: Papuacedrus), Araucariaceae (dammars and relatives: Agathis and Araucaria Section Eutacta), and Podocarpaceae (yellowwoods: Dacrycarpus, Podocarpus, and a species similar to Phyllocladus); and the fern Todea (king fern, Osmundaceae). Many of these records are the only occurrences of the respective taxa in South America, living or fossil, vastly extending their past ranges and thus the biogeographic history of part of the Malesian mountain flora. The living-fossil taxa inhabit, and several dominate, critical watershed areas of high endemism and biodiversity in Malesia’s endangered tropical-montane rainforests. In Malesia itself, there have been very few Cenozoic palaeobotanical investigations for about a century or more. To remedy this situation and improve understanding of the evolution of the Malesian flora in situ, we have begun palaeobotanical fieldwork in collaboration with Professor Yahdi Zaim and ITB, along with international colleagues. So far, we have discovered several promising new fossil sites in the Eocene-Oligocene of West Sumatra (Sangkarewang and Sawahlunto formations) and South Kalimantan (Tanjung Formation), and I will report preliminary observations.

Diversity, Chemical Composition, and Domestication Potential of Allanblackia parviflora A. Chev. in West Africa

Allanblackia parviflora A. Chev. is an indigenous tree species which is found in West African rainforest zones. It is an underutilized fruit tree species that has been targeted for improvement as part of efforts to domesticate high-value indigenous multi-purpose trees for fruit and seed production in Africa. Allanblackia has several benefits, such as providing shade, timber, and medicine; however, the production of edible oil from its seeds is the economically most important use. There is evidence that the Allanblackia seed oil, which is used for cooking, the production of margarine and the manufacturing of ointments and soap, is being developed as a new agri-business in Ghana, Nigeria, Cameroon, and Tanzania. Despite the nutritional and socio-economic importance of A. parviflora, it is still at the early stages of its domestication process. Even though several researchers have explored the biology of this species, there is very limited scientific information available on its morphological and genetic diversity and silvicultural management in West Africa. Therefore, this systematic review presents an up-to-date overview on the uses, seed chemical composition, and morphological and genetic diversity of this fruit tree species, and proposes a way forward for future research towards improvement and domestication.

Spatial patterns of light-demanding tree species in the Yangambi rainforest (Democratic Republic of Congo).

Most Central African rainforests are characterized by a remarkable abundance of light‐demanding canopy species: long‐lived pioneers (LLP) and non‐pioneer light demanders (NPLD). A popular explanation is that these forests are still recovering from intense slash‐and‐burn farming activities, which abruptly ended in the 19th century. This “human disturbance” hypothesis has never been tested against spatial distribution patterns of these light demanders. Here, we focus on the 28 most abundant LLP and NPLD from 250 one‐ha plots distributed along eight parallel transects (~50 km) in the Yangambi forest. Four species of short‐lived pioneers (SLP) and a single abundant shade‐tolerant species (Gilbertiodendron dewevrei) were used as reference because they are known to be strongly aggregated in recently disturbed patches (SLP) or along watercourses (G. dewevrei). Results show that SLP species are strongly aggregated with clear spatial autocorrelation of their diameter. This confirms that they colonized the patch following a one‐time disturbance event. In contrast, LLP and NPLD species have random or weakly aggregated distribution, mostly without spatial autocorrelation of their diameter. This does not unambiguously confirm the “human disturbance” hypothesis. Alternatively, their abundance might be explained by their deciduousness, which gave them a competitive advantage during long‐term drying of the late Holocene. Additionally, a canonical correspondence analysis showed that the observed LLP and NPLD distributions are not explained by environmental variables, strongly contrasting with the results for the reference species G. dewevrei, which is clearly aggregated along watercourses. We conclude that the abundance of LLP and NPLD species in Yangambi cannot be unambiguously attributed to past human disturbances or environmental variables. An alternative explanation is that present‐day forest composition is a result of adaptation to late‐Holocene drying. However, results are inconclusive and additional data are needed to confirm this alternative hypothesis.

Revision of the African species ofMonanthotaxis(Annonaceae)

This taxonomic revision of the continental African species ofMonanthotaxis(Annonaceae) includes 79 species and one variety. Thirteen new species(M. aestuaria,M. bidaultii,M. confusa,M. glabra,M. hexamera,M. mcphersonii,M. quasilanceolata,M. sterilis,M. submontana,M. suffruticosa,M. ursus,M. vulcanicaandM. wieringae) are described and 5 new combinations (M. biglandulosa,M. kenyensis,M. ochroleuca,M. pynaertiiandM. seretii) aremade. ThegenusMonanthotaxisconsists of lianas or lianescent shrubs. It occurs throughout forests in tropical Africa and the highest species diversity is found in the Western Central African rain forests. A key for flowering material is provided, just like a synoptic key including 45 characters. Topics included in the revision are the history of the taxonomy ofMonanthotaxis, morphology, leafanatomy, floral biology, distribution and habitat, phylogeny and finally ethnobotany and phytochemistry. Each species is fully described including synonymy, notes on distribution, habitat &ecology, vernacular names, uses and a preliminary IUCN conservation status. Distribution maps are provided for all species, illustrations for 48 species and photographs of 22 species. An index of exsiccatae and an index of the scientific names are included at the end.