Northern Republic Research Articles

The extent of western lowland gorilla social relationships within and between groups.

The nature of western lowland gorilla social relationships within and between groups is largely understudied, partly due to the challenges of monitoring associations between individuals who live in neighboring groups. In this study, we examined the social relationships of four western lowland gorilla groups in the Ndoki landscape of northern Republic of Congo. To do so, we compiled all-occurrence social interaction and silverback nearest neighbor social networks from data collected during daily group follows conducted over several years. We observed a total of 5,923 dyadic all-occurrence social interactions (1,350 ± 489 per group, 138 intergroup interactions) and 54,989 dyadic silverback nearest neighbor associations (13,747 ± 3,963 observations per group, 105 nearest neighbor observations of intergroup partners during group scans). For all groups, we found that males were more social than females, younger individuals were more social than older gorillas, and slightly greater rates of social behaviors were observed during periods of higher fruit availability. While there was a considerable amount of interindividual variation in social behavior, the network of social interactions demonstrated a large extent of social relationships within and between groups. Additionally, we performed simulated network removals to assess the impact on social dynamics. Across all groups and the total population, the removal of blackback and immature individuals markedly decreased the number of intra- and intergroup relationships (>60% decrease). The documented extent of western lowland gorilla social relationships has direct implications for the conservation of species with multi-level social dynamics. Gaining clarity on the ways in which western lowland gorilla groups naturally occur in the wild, not only provides a greater understanding for their conservation, but also offers insights for managing their social dynamics within captive environments.

Descriptions of three new species of Lycaenidae (Lepidoptera: Papilionoidea) from Parc National de Nouabalé-Ndoki, Republic of Congo with additional notes on little-known species.

Three new species of Lycaenidae, Falcuna nouabaleensis sp. nov., Anthene sangha sp. nov. and Neurellipes smithi sp. nov. are described from material collected during recent African Natural History Research Trust expeditions to Parc National de Nouabalé-Ndoki in northern Republic of Congo. Several other interesting taxa were also sampled including the unknown male of Ornipholidotos ghesquierei Libert, 2005 and a short series of unidentified female Pilodeudorix Druce, 1891 specimens near P. catori (Bethune-Baker, 1903) which are all illustrated. The distribution of species in this area of Central Africa is discussed in relation to the biogeography of the interfluvial region between the Sangha and Congo Rivers.

New geological insights on the Palaeoproterozoic Sembé-Ouesso Basin in northern Congo-Brazzaville – Implications for the Kibaran orogeny, Neoproterozoic rifting and Pan-African overprint

The Palaeoproterozoic Sembé-Ouesso Basin (SOB) is the northeasternmost of six foreland subbasins of the Eburnean orogen; it covers an area of about 64,000 km2 in the northern Republic of Congo, southeast Cameroun and the Central African Republic. The structural architecture and tectono-metamorphic history of the SOB have been studied in the Republic of Congo by airborne geophysical interpretation, geological mapping, and petrography, analysis of illite crystallinity and K-Ar geochronology.The oldest tectono-metamorphic event (D1/M1), which caused the main structuring of the SOB, coincides in age with the last (1.0–1.07 Ga) stage of Kibaran orogeny. Metamorphic conditions decrease from greenschist facies in the east to upper diagenesis in the west. D1 deformation started with west-vergent folding followed by N-S sinistral transpression in discrete shear zones. The tectonic style characterises the SOB as foreland in the external zone of an eastern concealed orogen that either represents the continuation of the Kibaran Belt or forms a separate, as yet unidentified unit.Subsequent Neoproterozoic extension is marked by two conjugate N-S/NNE-SSW and E-W/NW-SE fault systems and a local pull-apart structure (D2). Coeval mafic magmas were emplaced in the faults of both systems. At regional scale, the extension can be linked to Tonian rifting in the central part of the Congo Basin and within the West Congo Belt.The influence of the Neoproterozoic (600 Ma) Central African orogeny is mainly restricted to the north-western part of the SOB where the Dja nappe was thrust from the north over the Palaeoproterozoic rocks (D3/M2). Elsewhere, the Pan-African event had no thermal and only minor structural effects on the SOB.

Early detection of human impacts using acoustic monitoring: An example with forest elephants.

The impacts of human activities and climate change on animal populations often take considerable time before they are reflected in typical measures of population health such as population size, demography, and landscape use. Earlier detection of such impacts could enhance the effectiveness of conservation strategies, particularly for species with slow population growth. Passive acoustic monitoring is increasingly used to estimate occupancy and population size, but this tool can also monitor subtle shifts in behavior that might be early indicators of changing impacts. Here we use data from an acoustic grid, monitoring 1250 km2 of forest in northern Republic of Congo, to study how forest elephants (Loxodonta cyclotis) assess risk associated with human impacts across a landscape that includes a national park as well as active and inactive logging concessions. By quantifying emerging patterns of behavior at the population level, arising from individual-based decisions, we gain an understanding of how elephants perceive their landscape along an axis of human disturbance. Forest elephants in relatively undisturbed forests are active nearly equally day and night. However, they become more nocturnal when exposed to a perceived risk such as poaching. We assessed elephant perception of risk by monitoring changes in the likelihood of nocturnal vocal activity relative to differing levels of human activity. We show that logging is perceived to be a risk on moderate time and small spatial scales, but with little effect on elephant density. However, risk avoidance persisted in areas with relatively easy access to poachers and in more open habitats where poaching has historically been concentrated. Increased nocturnal activity is a common response in many animals to human intrusion on the landscape. Provided a species is acoustically active, passive acoustic monitoring can measure changes in human impact at early stages of such change, informing management priorities.

A new species of Delorhachis Karsch, 1896 from Nouabalé-Ndoki National Park, Republic of Congo

ABSTRACT A new species of Delorhachis Karsch, 1896, Delorhachis nouabaleensis sp. n. is described from the Nouabalé-Ndoki National Park in northern Republic of Congo based on morphological and genetic evidence. This area is likely to have high levels of endemism due to the surrounding Sangha River Interval. http://www.zoobank.org/urn:lsid:zoobank.org:pub:CBAF262B-4616-4E45-9293-35DE836972D9

Disturbance sensitivity shapes patterns of tree species distribution in Afrotropical lowland rainforests more than climate or soil.

Understanding how tropical forests respond to abiotic environmental changes is critical for preserving biodiversity, mitigating climate change, and maintaining ecosystem services in the coming century. To evaluate the relative roles of the abiotic environment and human disturbance on Central African tree community composition, we employ tree inventory data, remotely sensed climatic data, and soil nutrient data collected from 30 1-ha plots distributed across a large-scale observational experiment in forests that had been differently impacted by logging and hunting in northern Republic of Congo. We show that the composition of Afrotropical plant communities at this scale responds to human disturbance more than to climate, with particular sensitivities to hunting and distance to the nearest village (a proxy for other human activities, including tree-cutting and gathering). These findings contrast neotropical predictions, highlighting the unique ecological, evolutionary, and anthropogenic history of Afrotropical forests.

Socioecological factors influencing intraspecific variation in ranging dynamics of western lowland gorillas (Gorilla gorilla gorilla) in Ndoki Forest.

Ranging dynamics are physical and behavioral representations of how different socioecological factors affect an organism's spatial decisions and space use strategies. Western lowland gorillas (Gorilla gorilla gorilla) are a model species to investigate the drivers of spatial dynamics based on both the natural variation in socioecological factors within the species and compared with their mountain gorilla counterparts. In this study, we evaluate the influences of resource seasonality and social dynamics on variation in home range size, utilization, and intergroup overlap among multiple gorilla groups over an 8-year study period in the northern Republic of Congo. This study shows that western lowland gorillas can have small home ranges comparable to mountain gorillas, rather than universally larger home ranges as previously supposed, and that home ranges are stable through time. The largest source of variation in space use was the degree of intergroup home range overlap. The study groups did not demonstrate intraspecific variation in range size nor changes in intergroup overlap with respect to seasonality of fruit resources, but all groups demonstrated expansion of monthly range and core area with group size, matching predictions of intragroup feeding competition. These findings highlight the potential impact of intergroup relationships on space use and prompt further research on the role of social dynamics in ranging strategies. In this study, we reveal a greater degree of variability and flexibility in gorilla ranging behavior than previously realized which is relevant to improving comparative studies and informing conservation strategies on behalf of these endangered primates.

Monitoring the Diameter growth of irregular trunk trees in the Celtis forest in northern Republic of Congo

Monitoring the Diameter growth of irregular trunk trees in the Celtis forest in northern Republic of Congo

Stepfamilies and cultural transmission dynamics in Congo Basin hunter-gatherers

Generally high rates of adult mortality coupled with cultural approval of divorce/remarriage mean that alternatives to the ‘nuclear model’ of the family can be common in contemporary hunter-gatherer communities. While many studies of hunter-gatherer societies have emphasised the flexible, cooperative nature of childcare, research has not specifically considered how step-parents navigate their unique roles in the lives of their own or their partner’s children. Additionally, research has only just begun to investigate the ways in which cooperative caretaking interacts with the dynamics of cultural evolution in hunter-gatherer societies. For instance, vertical cultural transmission (ie learning from parents) has repeatedly been shown as important among hunter-gatherers. Yet, the implications of alternative family forms for the dynamics of cultural transmission are unclear. For instance, step-parents may enhance the spread and longevity of novel cultural traits by moving from a social role associated with oblique cultural transmission to one associated with vertical transmission from the perspective of their stepchildren. In this paper, we 1) present a mathematical model of cultural transmission under conditions where step-parenting is more or less common but step-parents can transmit culture in the same way as parents versus other adults (eg through vertical versus oblique cultural transmission), and then 2) present a preliminary survey of the frequency of alternative families from two BaYaka communities in northern Republic of the Congo. Our modelling shows that remarriage and step-parenting can increase the frequency of a new cultural trait and its eventual mean frequency in a population. Validating the premise of the model, our data confirm that high rates of divorce, adult mortality and remarriage mean that many BaYaka children in our sample live with step-parents. We then discuss how our model and the demographic data can be interpreted considering the ethnographic reality of the study communities and the region, and how this provides the potential for step-parenting to facilitate cultural adaptation. We conclude that the integration of data on family diversity and demography with cultural evolutionary modelling can further our understanding of cultural transmission in hunter-gatherer societies and beyond.

Intergroup Cooperation in Shotgun Hunting Among BaYaka Foragers and Yambe Farmers from the Republic of the Congo

Whereas many evolutionary models emphasize within-group cooperation or between-group competition in explaining human large-scale cooperation, recent work highlights a critical role for intergroup cooperation in human adaptation. Here we investigate intergroup cooperation in the domain of shotgun hunting in northern Republic of the Congo. In the Congo Basin broadly, forest foragers maintain relationships with neighboring farmers based on systems of exchange regulated by norms and institutions such as fictive kinship. In this study, we examine how relationships between Yambe farmers and BaYaka foragers support stable intergroup cooperation in the domain of shotgun hunting. In the study village, shotgun hunting is based on a specialization-based exchange wherein Yambe farmers contribute shotguns and access to markets to buy cartridges and sell meat while BaYaka foragers contribute their specialized forest knowledge and skill. To understand how costs and benefits are distributed, we conducted structured interviews with 77 BaYaka hunters and 15 Yambe gun owners and accompanied hunters on nine hunting trips. We found that hunts are organized in a conventional manner within a fictive kinship structure, consistent with the presence of intercultural mechanisms to stabilize cooperation. However, because bushmeat demand is high, gun owners can gain significant cash profit, while compensating hunters only with cigarettes, alcohol, and a traditional hunter’s portion of meat. To level payoffs, hunters strategically hide kills or cartridges from gun owners to feed their own families. Our results illustrate how each group prioritizes different currencies (e.g., cash, meat, family, intergroup relations) and provide insights into how intergroup cooperation is stabilized in this setting. The example of this long-standing intergroup cooperative system is discussed in terms of its contemporary entwinement with logging, the bushmeat trade, and growing market intersection.

Ethnomedicinal Information on Plants Used for the Treatment of Bone Fractures, Wounds, and Sprains in the Northern Region of the Republic of Benin.

Medicinal plants are frequently used in African countries due to their importance in the treatment of various conditions. In the northern Republic of Benin, traditional healers are recognized as specialists in the treatment of fractures, wounds, and sprains. The present study was conducted to document the practices (diagnosis and materials) and traditional knowledge accumulated by healers in this region on their area of specialty. In addition, literature-based research was performed to support the usage of the most cited plants. Sixty traditional healers identified as "reference persons" from Atakora and Donga departments in the northern Republic of Benin, who specialized in the treatment of fractures, wounds, and sprains, were interviewed in their communities through a semi-structured questionnaire. Information about the practice, age of the healers, medicinal plants used in this treatment, methods of preparation, and administration were collected. Samples of the plant species were also collected, identified, and stored in the national herbarium at the University of Abomey-Calavi, the Republic of Benin. The study enabled the identification of thirty-four (34) species belonging to twenty-three (23) families. Ochna rhizomatosa and Ochna schweinfurthiana (21%) were the most quoted plants among the species, followed by Chasmanthera dependens (12.1%), Piliostigma thonningii (11.3%), and Combretum sericeum (8.1%). These plants were reported to strengthen bones, reduce inflammation, relieve pain, and promote healing in the northern part of the Republic of Benin. Besides their ability to treat fractures, wounds, and sprains, they are also used for multiple purposes in the West African subregions. According to the available literature, some of the plants will need to be investigated for their phytoconstituents and pharmacological activity to validate their ethnobotanical uses. These results confirm the need for documenting traditional knowledge since it represents an opportunity for exploring plant species with potentially good pharmacological effects, which have been barely investigated. Plants identified may constitute a significant source of bioactive compounds in the treatment of various ailments such as skin inflammation and musculoskeletal disorders. They can be further explored to justify their use in traditional Beninese medicine.

СОКРОВИЩА ФОНДА РЕДКИХ КНИГ И АРХИВНЫХ ДОКУМЕНТОВ НАЦИОНАЛЬНОЙ БИБЛИОТЕКИ РЕСПУБЛИКИ САХА (ЯКУТИЯ)

The article examines the owner's collections of northern scholars in the fund of the Scientific Research Center of Book Monuments of the National Library of the Republic of Sakha (Yakutia). The library has a collection of rare books and valuable documents, significant in number and content. The staff of the main book depository of the northern republic is carrying out a large-scale and socially significant in terms of goals and objectives systematic work to identify, study and popularize book monuments and archival documents. The paper provides a brief history of the formation of the center's fund, information from the biographies of the owners of private libraries: linguist and ethnographer Glafira Makarievna Vasilevich, scholar-northern scholar Claudia Aleksandrovna Novikova, the scientist-northern scholar Chuner Mikhailovich Taksami, historian-ethnographer Ilya Samuilovich Gurvich, ethnologist Ulla Johansen. The quantitative and qualitative characteristics of rare collections transferred to the National Library of the Republic of Sakha (Yakutia) are substantiated, the value of personal libraries as cultural phenomena — book monuments and information sources on languages, history, ethnography, folklore of the peoples of the North, Siberia and the Far East. The National Library of the Republic of Sakha (Yakutia) fulfills a high mission — it carries out a huge range of measures to preserve rare books and documents, and at the same time provides access to the intellectual and cultural heritage of Russian northern scholars. The article actualizes the problem of preserving and popularizing knowledge about culture, languages, folklore, ethnography of the peoples of the North, Siberia and the Far East in the context of the loss of traditional values of material and spiritual culture by the indigenous people of the North and the Arctic at the beginning of the 21st century. The authors consider the study of the richest funds of the National Library of the Republic of Sakha (Yakutia) in the process of a comprehensive analysis of the owner's collections of book monuments and the archival heritage of Russian northern scholars as a priority task of the historical and cultural sciences. The paper considers the main directions of the activities of the National Library of the Republic of Sakha (Yakutia) in the field of preserving the phenomena of the cultural heritage of the northern peoples; the activity of the Scientific Research Center of Book Monuments has been analyzed; the personal collections of northern scholars are described and systematized. As a general task, the postulate of the development of the concept of preservation for future generations of the values of the cultural heritage of the peoples of the North and the Arctic is put forward.

Combining offtake and participatory data to assess the sustainability of a hunting system in northern Congo

AbstractResearch suggests that bushmeat is hunted at unsustainable rates throughout much of the Congo basin, although accurately measuring hunting sustainability is challenging. Offtake data can contribute towards sustainability assessments, and when incorporated with information on hunters' strategies, can be used to monitor changes in hunting dynamics. We used a combination of (1) a long‐term, quantitative yet low‐resolution hunting offtake data set, (2) qualitative data acquired through participatory methods, and (3) a high‐resolution offtake survey, to examine the changes in a hunting system undergoing change due to new roads and associated socio‐economic developments in northern Republic of the Congo. Our results indicated that while the conclusions drawn from the different data sets were broadly the same (indicating wildlife depletion, particularly in one hunting zone), the results of the analysis of the participatory and the high‐resolution offtake data set provided an explanation for trends in the long‐term low‐resolution offtake data set, including the degree to which long‐term trends are due to changes in hunting strategy, or in underlying wildlife populations. We discuss how participatory hunter surveys can be used to distinguish between changes in prey populations and changes in hunting strategy in long‐term low‐resolution hunting offtake data sets, therefore, improving the effectiveness of long‐term offtake data sets to assess sustainability of hunting.

Linking Drone and Ground-Based Liana Measurements in a Congolese Forest

Lianas are abundant and diverse in tropical forests and impact forest dynamics. They occupy part of the canopy, forming a layer of leaves overtopping tree crowns. Yet, their interaction with trees has been mainly studied from the ground. With the emergence of drone-based sensing, very high-resolution data may be obtained on liana distribution above canopies. Here, we assessed the relationship between common liana ground measurements and drone-determined liana leaf coverage over tree crowns, tested if this relationship is mediated by liana functional composition, and compared the signature of liana patches and tree crowns in our drone images. Using drone platforms, we acquired very high resolution RGB and multispectral images and LiDAR data over two 9-ha permanent plots located in northern Republic of Congo and delineated liana leaf coverage and individual tree crowns from these data. During a concomitant ground survey, we focused on 275 trees infested or not by lianas, for which we measured all lianas ≥ 1 cm in diameter climbing on them (n= 615) and estimated their crown occupancy index (COI). We additionally measured or recorded the wood density and climbing mechanisms of most liana taxa. Contrary to recent findings, we found significant relationships between most ground-derived metrics and the top-of-view liana leaf coverage over tree crowns. Tree crown infestation by lianas was primarily explained by the load of liana climbing on them, and negatively impacted by tree height. Liana leaf coverage over individual tree crowns was best predicted by liana basal area and negatively mediated by liana wood density, with a higher leaf area to diameter ratio for light-wooded lianas. COI scores were concordant with drone assessments, but two thirds differed from those obtained from drone measurements. Finally, liana patches had a higher light reflectance and variance of spectral responses than tree crowns in all studied spectra. However, the large overlap between them challenges the autodetection of liana patches in canopies. Overall, we illustrate that the joint use of ground and drone-based data deepen our understanding of liana-infestation pathways and of their functional and spectral diversity. We expect drone data to soon transform the field of liana ecology.

Social ties in the Congo Basin: insights into tropical forest adaptation from BaYaka and their neighbours.

Investigating past and present human adaptation to the Congo Basin tropical forest can shed light on how climate and ecosystem variability have shaped human evolution. Here, we first review and synthesize genetic, palaeoclimatological, linguistic and historical data on the peopling of the Congo Basin. While forest fragmentation led to the increased genetic and geographical divergence of forest foragers, these groups maintained long-distance connectivity. The eventual expansion of Bantu speakers into the Congo Basin provided new opportunities for forging inter-group links, as evidenced by linguistic shifts and historical accounts. Building from our ethnographic work in the northern Republic of the Congo, we show how these inter-group links between forest forager communities as well as trade relationships with neighbouring farmers facilitate adaptation to ecoregions through knowledge exchange. While researchers tend to emphasize forager–farmer interactions that began in the Iron Age, we argue that foragers' cultivation of relational wealth with groups across the region played a major role in the initial occupation of the Congo Basin and, consequently, in cultural evolution among the ancestors of contemporary peoples.This article is part of the theme issue ‘Tropical forests in the deep human past’.

A Unified Structural Framework for Major Shear Zone in the Ntem-Chaillu-Ivindo Blocks: Case of Tectonic and Structural Evolution of the Ivindo Basement, Northern Republic of Congo, Congo Craton

A Unified Structural Framework for Major Shear Zone in the Ntem-Chaillu-Ivindo Blocks: Case of Tectonic and Structural Evolution of the Ivindo Basement, Northern Republic of Congo, Congo Craton

From town to national park: Understanding the long-term effects of hunting and logging on tree communities in Central Africa

Anthropogenic disturbances are changing the structure and composition of tropical forests worldwide. Multiple disturbances often occur simultaneously in forests. Hunting and logging, for example, are within-forest disturbances that impact vast areas of seemingly intact rainforests. Despite recent work on the individual effects of these disturbances, our understanding of how they interact to influence tree communities is still limited. In northern Republic of Congo, we explored the effects of hunting and logging on tree communities. Over an 8-year period, we monitored 12,552 tree stems (≥10 cm diameter-at-breast height) spread over 30 1-ha plots along a gradient of human disturbance to compare the tree diversity between hunted and logged forest, once-logged forest, and protected forest free of both disturbances. Tree density, species richness, and community composition were affected by both hunting and logging. Forest close to human settlements was richer, more heterogenous, and more dynamic in species composition across censuses. In hunted and logged forest, fast-growing secondary species with low shade tolerance replaced old growth species. Comparatively, the once-logged forest had the greatest stem density and intermediate species richness with an increased density of shade-bearing species over time. Both tree species spatial turnover and tree recruitment were greatly affected by proximity to human settlements. A shift towards abiotically dispersed trees and increasing seed predation by rodents near villages can partly explain the differences in tree recruitment across the forest types. The combination of hunting and logging seems to have a greater impact on tree communities than either single disturbance, especially with nearness to villages.

Wild bongo density estimation and population viability analysis improves conservation management

Bongo (Tragelaphus eurycerus eurycerus) are rare, mostly nocturnal forest antelopes in tropical Africa that are prized by trophy hunters for their large size, curved horns, and colorful pelage. Estimating bongo population size is difficult because of their low densities and forested habitat, and therefore management decisions have not previously been based on realistic models of population dynamics. In this study, we estimate bongo density and population size in a safari hunting concession in northern Republic of Congo using spatially explicit capture-recapture (SECR) models based on camera trap data. The SECR bongo population estimates were used to model population dynamics under different scenarios of regulated and unregulated harvest and catastrophic natural events. Bongo density in the safari hunting concession was 8.77 bongo 100 km−2 (4.78–15.58). Vortex modelling showed that trophy hunting quotas granted previously would, if achieved, have led to rapid local extinction of bongo. As a result of this study, quotas were reduced to three bongo per year, which is only sustainable if current optimal conditions are maintained.

Height–diameter allometry in African monodominant forest close to mixed forest

AbstractAfrican monodominant forests are frequently formed byGilbertiodendron dewevrei(De Wild.) J. Leonard and commonly found close to mixed forests. However, previous studies have ignored differences between these two forest types in height–diameter allometry, which is extremely important for aboveground biomass (AGB) estimates. This study aims to evaluate the performance of height–diameter models and their effects on height attributes and AGB estimations in African monodominant and mixed forests. Four 1-ha plots divided in 16 subplots (0.25 ha) were installed in each forest type in northern Republic of Congo. We measured diameter of all trees ≥ 10 cm diameter for each subplot and we measured the height of 264 trees over a large range of 7–64 m in two forest types. There was a significant difference in height–diameter allometry between two forest types and trees were taller and had greater AGB in monodominant forests than in mixed forests. Two height–diameter models from the literature generated the lowest error values when predicting tree height and AGB in mixed forests, whereas no model derived from the literature was appropriate for monodominant forests. The variation in height–diameter allometry between monodominant and mixed forests influences AGB estimates that have practical implications for carbon monitoring.

Cultural Components of Sex Differences in Color Preference.

Preferences for pink and blue were tested in children aged 4–11 years in three small‐scale societies: Shipibo villages in the Peruvian Amazon, kastom villages in the highlands of Tanna Island, Vanuatu, and BaYaka foragers in the northern Republic of Congo; and compared to children from an Australian global city (total N = 232). No sex differences were found in preference for pink in any of the three societies not influenced by global culture (ds − 0.31–0.23), in contrast to a female preference for pink in the global city (d = 1.24). Results suggest that the pairing of female and pink is a cultural phenomenon and is not driven by an essential preference for pink in girls.