References of "Huynen, Marie-Claude"
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See detailStructure and floristic composition of Kibira rainforest, Burundi
Hakizimana, Dismas; Huynen, Marie-Claude ULg; Hambuckers, Alain ULg

in Tropical Ecology (in press), 59(1),

This paper gives the results of the first census of trees in the 32.15 ha plot in order to provide tree species richness in Kibira rainforest (Burundi). All trees ≥ 10 cm dbh were permanently tagged and ... [more ▼]

This paper gives the results of the first census of trees in the 32.15 ha plot in order to provide tree species richness in Kibira rainforest (Burundi). All trees ≥ 10 cm dbh were permanently tagged and their girth measured. The forest structure pattern analysed were diameter at breast height (dbh), basal area, relative dominance, and relative density, Importance Value Index (IVI) and Family Importance Value (FIV). In total, 6504 trees representing 70 species, 67 genera and 37 families were recorded. Tree density was 202 stems/ha, with a basal area of 21.05m²/ha. Seventeen families were represented by a single species each, eleven families were represented by two species each, five families were represented by three species each, and four families were represented by four species each. The most important families in relation to FIV were Euphorbiaceae, Myrtaceae and Araliaceae. Macaranga kilimandscharica, Syzygium guineense and Polyscias fulva were the most important species in relation to IVI. Two tree species were found to be endemic to the Albertine Rift and one species probably endemic to the Albertine Rift. The Shannon-Weiner index (H') and eveness index (J') were respectively 3.18 and 0.75. This study provides a baseline for the management of Kibira National Park. As local communities still depend on forest resources, conservation awareness-raising and education actions have to focus in nearby villages, and growing some fast-growing native trees in the vicinity of the settlement, would be helpful for local communities, this would reduce their dependence on forest resources. [less ▲]

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See detailEcosystem services provided by a large endangered primate in a forest-savanna mosaic landscape
Trolliet, Franck ULg; Serckx, Adeline ULg; Forget, Pierre-Michel et al

in Biological Conservation (2016)

Forested landscapes are increasingly affected by human activities, but little is known about the role of large endangered frugivores as seed dispersers in such ecosystems. We investigated the role played ... [more ▼]

Forested landscapes are increasingly affected by human activities, but little is known about the role of large endangered frugivores as seed dispersers in such ecosystems. We investigated the role played by the bonobo (Pan paniscus) in a human-altered forest-savannamosaic in Democratic Republic of the Congo. The studied groups are part of a community-based conservation programme but live at the interface with human activities. We identified dispersed species via faecal analysis, classified them into a regeneration guild and a seed size category, determined the effect of gut transit on seed germination, and the habitat use of bonobos. Bonobos dispersed intact seeds of 77 species, 80.8% of which were large-seeded (≥10mmlong), ofwhich fewcan be dispersed by sympatric frugivores. They dispersed a majority (49%) of shade-bearers that thrive in forest understory with limited amount of light, all of whichwere large-seeded. Transit had an overall positive effect on seed germination. Bonobos used various habitat types, showing preferences for understorywith intermediate light availability and dominated by woody or herbaceous vegetation. This dispersal pattern probably enhances recruitment of shadebearers, and we thus hypothesized that those species benefited from directed dispersal by bonobos. This threatened frugivore provides unique dispersal services and likely plays a paramount functional role in the regeneration of late successional forests in this mosaic landscape. Management plans should pay particular attention to the role of large and rare frugivores in human-dominated regions as their disappearance could disrupt forest succession to a climax state. [less ▲]

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See detailEffect of hunting pressure and forest fragmentation on seed dispersal of Staudtia kamerunensis (Myristicaceae) in the Western Congolian forest-savanna mosaic
Trolliet, Franck ULg; Forget, Pierre-Michel; Huynen, Marie-Claude ULg et al

Conference (2015, June 22)

Numerous studies have investigated the impact of hunting and forest fragmentation on seed dispersal processes, but few of them in Africa. The African continent, however, holds the greatest abundance of ... [more ▼]

Numerous studies have investigated the impact of hunting and forest fragmentation on seed dispersal processes, but few of them in Africa. The African continent, however, holds the greatest abundance of large frugivores on Earth and is subject to increasing levels of hunting and forest fragmentation. Frugivory and seed dispersal in the pan-tropical family Myristicaceae has been well studied in the Neotropics, but remain barely known in Afro-tropical forests. Here we investigated how hunting, forest cover, and fruit availability influence the dispersal capacities of Staudtia kamerunensis in a mosaic composed of forest patches and savannas in D.R. Congo. We selected 34 fertile female S. kamerunensis trees distributed, at a landscape scale (300 km²), across 5 sites characterized by a gradient of hunting pressures and density of the study trees. The trees varied in size and surrounding forest cover (patch and corridors). We quantified the percentages of seed dispersal failure using litter trap and fruit remains during the entire 2013 fruiting season, and identified fruit eaters through focal observations. The most frequently observed frugivore was the White-thighed Hornbill (Bycanistes albotibialis). Our GLMM analyses show that increasing hunting pressure, decreasing abundance of B. albotibialis and decreasing forest cover near focal trees significantly increased dispersal failure. The limited forest cover of some patches, resulting from the highly fragmented feature of the landscape, and hunting pressure, are likely to impact negatively the abundance of B. albotibialis. Consequently, we suggest the dispersal system reached saturation because of a lack of effective seed dispersal away from parent trees. [less ▲]

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See detailChanges in Activity Patterns and Intergroup Relationships After a Significant Mortality Event in Commensal Long- Tailed Macaques (Macaca Fascicularis) in Bali, Indonesia
Brotcorne, Fany ULg; Fuentes, Agustin; Wandia, I Nengah et al

in International Journal of Primatology (2015), 36(3), 548566

Little is known regarding behavioral and social responses of free-ranging primates to demographic changes emerging from significant mortality events. Here, we report on the activity patterns and ... [more ▼]

Little is known regarding behavioral and social responses of free-ranging primates to demographic changes emerging from significant mortality events. Here, we report on the activity patterns and intergroup sociospatial relationships in a commensal population of long-tailed macaques (Macaca fascicularis) in Bali, Indonesia, that underwent a significant mortality event in summer 2012. During the period of interest, we noted heightened mortality in three of the five social groups present in this population, with adult females and juveniles experiencing higher mortality rates than adult and subadult males. Limited diagnostic data regarding pathogen identification and a lack of any conclusive etiology of the deaths prevent our ascertainment of the agent(s) responsible for the observed mortality, but given the characteristics of the event we assume it was caused by a transmissible disease outbreak. Comparing the pre- and postmortality event periods, we found significant differences in activity patterns, including a decreased proportion of affiliation in adult females. This result is likely indicative of enhanced social instability induced by the high mortality of adult females that constitute the stable core of macaque social structure. A higher social tension between groups after the mortality event was indicated by more frequent and intense agonistic intergroup encounters. Intergroup conflict success was inversely proportional to the rate of mortality a group suffered. Our results illustrate how changes in demographic structure caused by significant mortality events may have substantial consequences on behavior and social dynamics in primate groups and at the level of a population. [less ▲]

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See detailFood provioning influences ranging patterns in northern pigtailed macaques (Macaca leonina)
Huynen, Marie-Claude ULg; Savini, Tommaso ULg; Asensio, Norberto et al

in International Journal of Primatology (2015, January)

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See detailModelling the distribution of key tree species used by lion tamarins in the Brazilian Atlantic forest under a scenario of future climate change
Raghunathan, Poornima ULg; François, Louis ULg; Huynen, Marie-Claude ULg et al

in Regional Environmental Change (2015), 15

We used three IPCC climate change scenarios (A1B, A2 and B1) in a dynamic vegetation model (CARAIB), to determine the potential future distribution of 75 tree species used by two endemic primate species ... [more ▼]

We used three IPCC climate change scenarios (A1B, A2 and B1) in a dynamic vegetation model (CARAIB), to determine the potential future distribution of 75 tree species used by two endemic primate species from the Brazilian Atlantic Forest (BAF). Habitat conservation is a vital part of strategies to protect endangered species, and this is a new approach to understanding how key plant species needed for survival of golden lion tamarins (Leontopithecus rosalia) and golden-headed lion tamarins (L. chrysomelas) might be affected by climate change and what changes to their distribution are likely. The model accurately predicted the current distribution of BAF vegetation types, for 66 % of the individual tree species with 70 % agreement obtained for presence. In the simulation experiments for the future, 72 out of 75 tree species maintained more than 95 % of their original distribution and all species showed a range expansion. At the biome level, we note a substantial decrease in the sub-tropical forest area. There is some fragmentation of the savannah, which is encroached mostly by tropical seasonal forest. Where the current distribution shows a large sub-tropical forest biome, it has been replaced or encroached by tropical rainforest. The results suggested that the trees may benefit from an increase in temperature, if and only if soil water availability is not altered significantly, as was the case with climate simulations that were used. However, these results must be coupled with other information to maximise usefulness to conservation since BAF is already highly fragmented and subject to high anthropic pressure. © 2014 Springer-Verlag Berlin Heidelberg. [less ▲]

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See detailFeeding ecology of bonobos living in forest-savannah mosaics: diet seasonal variation and importance of fallback foods
Serckx, Adeline ULg; Kühl, Hjalmar; Beudels-Jamar, Roseline et al

in American Journal of Primatology (2015)

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See detailExploring the multiple functions of sleeping sites in Northern Pigtail macaques (Macaca leonina)
Jose Dominguez, Juan Manuel; Asensio, Norberto; Garcia Garcia, Carmen J et al

in International Journal of Primatology (2015), 36(4), 948-966

the seasonal variation, maximizing daily activities. Overall, predator avoidance and food efficiency were the main factors influencing the selection of sleeping sites. Our observations differ from those ... [more ▼]

the seasonal variation, maximizing daily activities. Overall, predator avoidance and food efficiency were the main factors influencing the selection of sleeping sites. Our observations differ from those found in a semiprovisioned group inhabiting the same Abstract Sleeping site selection in nonhuman primates may respond to various eco- logical factors, including predation avoidance, range defense, and foraging efficiency. We studied the sleeping sites used by a group of northern pigtailed macaques on 124 nights to test these hypotheses. The macaques used 57 different sleeping sites, of which 33 were used only once. They rarely used the same site on consecutive nights. These selection patterns are consistent with an antipredatory function, but may also be related to an antipathogenic strategy. Sleeping sites were located principally in the most heavily used areas of the home range and were generally away from areas of intergroup encounters. However, some of the most heavily used sleeping sites were in the area where intergroup encounters occurred, and intergroup encounters at sleeping sites always showed high levels of agonism, indicating possible intergroup competition over sleeping sites. On 77 % of nights, the study group selected the sleeping site nearest to either the last feeding area that day or to the first feeding area used the next morning, suggesting a foraging efficiency strategy. The mean distances from the sleeping site to the last and first feeding area were 227 m and 127 m, respectively, suggesting a multiple central place foraging strategy. The macaques entered sleeping sites a mean of 27 min before sunset and left 24 min after sunrise, and these times varied in line withstudy site, which used fewer sleeping sites and reused them much more often. This difference highlights the impact anthropogenic activities may have on sleeping site selection and the flexibility of sleeping patterns in a single species. Such flexibility may have helped the tree-to-ground evolutionary transition of sleep habits in primates [less ▲]

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See detailHabitat Use by White-Thighed Colobus in the Kikélé Sacred Forest: Activity Budget, Feeding Ecology and Selection of Sleeping Trees
Djègo-Djossou, Sylvie; Koné, I; Fandohan, A.B. et al

in Primate conservation (2015), 29

Abstract: Understanding habitat preference and use is an important aspect of primate ecology, and is essential for setting conservation strategies. This study examined the activity budget, feeding ecology ... [more ▼]

Abstract: Understanding habitat preference and use is an important aspect of primate ecology, and is essential for setting conservation strategies. This study examined the activity budget, feeding ecology and selection of sleeping trees of a population of white-thighed colobus (Colobus vellerosus). A group of 18 was followed during 72 days over a full annual cycle in the Kikélé Sacred Forest of the Bassila administrative region in central Benin (West Africa). Activity budget and diet were determined using scan sampling. The structure of the habitat and the physical characteristics of sleeping trees were determined using plot surveys. Resting, feeding, moving, social interactions and other activities accounted for 56.6%, 26.3%, 13.0%, 3.3%, and 0.7% of the activity budget, respectively. The group spent more time feeding and less time moving in the dry season compared to the rainy season. The diet was composed of 35 plant species belonging to 16 families, with items including leaves, fruits, seeds, buds, bark, flowers, gum, and inflorescences. Only three tree species were used as sleeping trees: Celtis integrifolia, Cola cordifolia, and Holoptelea grandis. Our findings suggest that the monkeys prefer tall (22.53 ± SD 3.76 m) and large-trunked (112.07 ± SD 14.23 cm) sleeping trees. The results of this study can be used for sound management of the white-thighed colobus in the study area and elsewhere. [less ▲]

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See detailNon-territorial Macaques Can Range Like Territorial Gibbons When Partially Provisioned With Food
José Dominguez, Juan Manuel; Huynen, Marie-Claude ULg; Garcia, Carmen J et al

in Biotropica (2015)

Human food supplementation can affect components of animal socioecology by altering the abundance and distribution of available food. We studied the effect of food supplementation by comparing the ranging ... [more ▼]

Human food supplementation can affect components of animal socioecology by altering the abundance and distribution of available food. We studied the effect of food supplementation by comparing the ranging patterns and intergroup interactions of two groups of northern pigtailed macaques (Macaca leonina), a non-territorial primate species. One group was partially reliant on food provisioning, whereas the other group foraged wild food. We also compared the macaques’ movement with that of a group of white-handed gibbons (Hylobates lar), a territorial species inhabiting the same site. Home range, core area, and daily path lengths were significantly smaller for the semi-provisioned group than for the wild-feeding group. In contrast to wild-feeding macaques, supplemented macaques showed higher fidelity to home range, core area, and particularly to the region where human food was most accessible and abundant. The rela- tionship of daily path length and home range indicated a low defendability index for wild-feeding macaques; the higher index for the semi-provisioned group was consistent with the territorial pattern found in gibbons. Semi-provisioned macaques showed further traits of territoriality with aggression during intergroup encounters. These findings indicate that human modification of food availability can sig- nificantly affect movement patterns and intergroup competition in macaques. The observed ranging dynamics related to food provision- ing may decrease the efficiency of macaques as seed dispersers and increase predation on their home range, and thus have important consequences for plant regeneration and animal diversity. [less ▲]

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See detailCharacterization of Nest Sites of Chimpanzees (Pan troglodytes schweinfurthii) in Kibira National Park, Burundi
Hakizimana, Dismas; Hambuckers, Alain ULg; Brotcorne, Fany ULg et al

in African Primates (2015), 10

Abstract: Kibira National Park is the only site in Burundi that harbors a large number of chimpanzees (Pan troglodytes schweinfurthii). While information on factors influencing the selection of nest sites ... [more ▼]

Abstract: Kibira National Park is the only site in Burundi that harbors a large number of chimpanzees (Pan troglodytes schweinfurthii). While information on factors influencing the selection of nest sites by chimpanzees is available for other locations of the species’ range, this information is lacking for Kibira National Park. This is mainly due to the political troubles that prevailed in the country from 1993 until 2007, making study there difficult. To better protect this chimpanzee population, it is crucial to survey nest sites to identify the tree species, physical characteristics of the trees and habitat type that chimpanzees preferentially use for nesting. Therefore, in this study, we investigated: 1) the tree species used by chimpanzees for building their nests; 2) nest tree availability in the study area; 3) whether chimpanzee selection of a nest tree is based on physical characteristics such as diameter at breast height, lowest branch height, tree size and crown height; and 4) whether chimpanzees choose their nest sites according to topography and canopy types. We collected data monthly along 16 transects of 3 km each, from September 2011 to February 2013 (18 months). However, data related to the measurements of nests and nest trees were collected for only the last 12 months, from March 2012 to February 2013. We identified tree species used for nesting, and measured physical characteristics of trees used as opposed to surrounding trees unused. The results showed that chimpanzees select certain tree species to build their nests. Among the 32 species of trees bearing nests, chimpanzees used 12 species significantly more frequently than expected and 11 species significantly less frequently than expected. In addition, trees bearing nests were significantly larger and taller than the surrounding trees and had higher lowest branch and bigger canopies. [less ▲]

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See detailAn ethnoprimatological approach of the human-macaque interactions at the Ubud Monkey Forest, Bali (Indonesia)
Brotcorne, Fany ULg; Fuentes, Agustin; Wandia, I Nengah et al

Conference (2014, September 24)

Macaque tourism, i.e. a tourist activity focusing on wild macaques as main attraction, is an example of the bourgeoning and diversified human-macaque interactions in Southeast Asia. Although both people ... [more ▼]

Macaque tourism, i.e. a tourist activity focusing on wild macaques as main attraction, is an example of the bourgeoning and diversified human-macaque interactions in Southeast Asia. Although both people and macaques can benefit from their interactions at tourist sites, this activity also raises several conservation and management issues which are essential to understand in order to promote a sustainable coexistence. Using an ethnoprimatological approach, we provide here an assessment of the effect of a long-term management regime at the very popular tourist Ubud Monkey Forest in Bali, Indonesia. Over a four-month period in 2013, we characterized the visitor-macaque interactions with ethological methods and we compared our data with those collected 12 years earlier by Fuentes and colleagues. In parallel, we conducted a questionnaire survey, interviewing 99 Balinese people to assess their attitudes towards macaques and the Monkey Forest. Our results confirmed that the management efforts to reduce the aggressiveness of macaques towards visitors have been effective. Indeed, we observed a considerable reduction of the frequency and intensity of agonistic interspecies interactions. However, the interactions between macaques and visitors frequently involved close physical contact, such as during provisioning. Men on the human side, and adult or subadult males on the macaque side, were the groups the most frequently involved in these types of interaction. A reinforcement of the management practices limiting close interspecies contact interactions by targeting the most exposed groups, is therefore necessary in order to reduce the risk of pathogen cross-species transmission. Our questionnaire survey revealed globally a high level of tolerance of local people towards macaques in Ubud. These positive attitudes were determined by the economic and cultural benefits derived from the macaque presence and tourism activity, as far as they compensate for the nuisances caused by macaques. Crop raiding in cultivated fields surrounding the Monkey Forest was still a source of tension which would require further management efforts including the development of open buffer zones. [less ▲]

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See detailModelling seed dispersal and tropical forest regeneration :application to Staudtia kamerunensis in the WWF Lake Tele-Tumba Landscape in DR Congo
Coos, William ULg; Dury, Marie ULg; Trolliet, Franck ULg et al

Poster (2014, June)

Unsustainable hunting and slash-and-burn farming in tropical forests can lead to the empty forest syndrome. It is characterized by the loss of key species essential in the maintenance and regeneration of ... [more ▼]

Unsustainable hunting and slash-and-burn farming in tropical forests can lead to the empty forest syndrome. It is characterized by the loss of key species essential in the maintenance and regeneration of the forest. Indeed the main mechanism of this regeneration is seed dispersal, which for tropical trees is usually driven by animals, and the alteration of this process through a reduction of the disperser population may have serious consequences on forest composition. Computer models are powerful tools to study these processes, not only towards a better understanding of the key mechanisms controlling tropical forest regeneration, but also with the aim of optimising forest management and exploitation to reach a better equilibrium between tropical tree species and their seed dispersers. This study describes a seed dispersal module ultimately developed to analyze the regeneration of the rainforest in the WWF Lake Tele – Lake Tumba Landscape in RD Congo (BIOSERF project funded by Belgian Science Policy). The module has been developed to upgrade the CARAIB dynamic vegetation model, which is used in the BIOSERF project. Data are derived from a field study in which we analyzed seed dispersal of a common tree species (Staudtia kamerunensis) and we determined the community of its main dispersers (largely dominated by the hornbill Bycanistes albotibialis). Additional data (density of S. kamerunensis, habitat use and retention time in the digestive tract of hornbills to simulate dispersal kernel) were obtained from literature and satellite images. Different simulations were performed to represent seed rain over time and a survival rate was applied to show the regeneration. The module was able to provide a percentage of recolonization of degraded places. In the end, this result was compared to field studies, which provide close percentage of recolonization [less ▲]

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See detailModelling the future range and productivity of African tree species. Perspectives and limits
Hambuckers, Alain ULg; Dury, Marie ULg; Tosso, Dji-ndé Félicien ULg et al

Poster (2014, June)

There remains a lack of information on the future of plant species in many parts of Africa under the threads of climate change with the exception of the mountainous areas. Models are valuables tools to ... [more ▼]

There remains a lack of information on the future of plant species in many parts of Africa under the threads of climate change with the exception of the mountainous areas. Models are valuables tools to examine this problem because they permit to extrapolate basic information as simple as species occurrence coming from a restricted number of localities to the entire continent. Niche-based models, like logistic regression or MaxEnt, easily allow fitting empirical relationships between environmental variables related to climate and possibly to soil properties. They produce probabilities of occurrence for the present with good accuracy (calibration phase). Projections for the future are made by switching the explanatory data set with future conditions. These models however are limited by the fact that it is difficult to integrate physiological response to increasing CO2 air concentration. Dynamic vegetation models (DVMs) are process-based models that simulate plant environment (soil water, light intensity at various heights, etc.) and plant physiology (transpiration, CO2 fixation, photosynthesis, respiration, carbon allocation, etc.) from climate variables, soil properties, and elevation. They could be run at various scales, from global to regional or even local scale, and simulate the growth of plant functional types (PFTs), of biological affinity groups (BAGs) or of species. A model like CARAIB is able to simulate PFTs and BAGs growth (occurrence and productivity) with rather good accuracy for Western Europe. For the future, the simulations confirm that the physiological effect of CO2 concentration change is dramatic but not easily foreseeable because it depends on overall fertility of the sites (Dury et al., iForest – Biogeosciences and Forestry, 4:82-99, 2011). From this conclusion, spatial and temporal variations of fertility would have to be introduced in modelling studies to reach more operational conclusions. Questions arising about the future of ecosystem services in tropical countries highlight particular plant species (BIOSERF project funded by the Belgian Science Policy: Sustainability of tropical forest biodiversity and services under climate and human pressure). In this study, we model a set of 11 selected African tree species including several Congolese species with logistic regression, MaxEnt and CARAIB models. The two niche-based-models rather properly simulate the ranges obtained with the alpha-hull polygon method. CARAIB correctly simulates the range of the evergreen species but not of the deciduous trees. We examine how physiological knowledge could be use to improve the model. IN particular, we conclude that bud dormancy breaking representation has to be upgraded in the model because this process is likely to control the range of the species. It should act in combination with the specific bioclimatic constants controlling the hydrological and thermal stress and the germination. Additionally, we examine the evolution of the ranges at the 2050 horizon using one of the most recent socio-economic scenarios. [less ▲]

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See detailThe Role of Anthropic, Ecological, and Social Factors in Sleeping Site Choice by Long‐Tailed Macaques (Macaca fascicularis)
Brotcorne, Fany ULg; Maslarov, Cindy; Wandia, I. Nengah et al

in American Journal of Primatology (2014)

When choosing their sleeping sites, primates make adaptive trade‐offs between various biotic and abiotic constraints. In human‐modified environments, anthropic factors may play a role. We assessed the ... [more ▼]

When choosing their sleeping sites, primates make adaptive trade‐offs between various biotic and abiotic constraints. In human‐modified environments, anthropic factors may play a role. We assessed the influence of ecological (predation), social (intergroup competition), and anthropic (proximity to human settlements) factors in sleeping site choice by long‐tailed macaques (Macaca fascicularis) occupying a habitat at the interface of natural forests and human‐modified zones in Bali Barat National Park, Indonesia. Over the course of 56 nights, we collected data relating to physical features of sleeping trees, patterns of the use of sleeping sites within the home range, pre‐sleep behavior, diurnal ranging patterns and availability of natural and human food. Overall, the macaques used 17 sleeping sites with 37 sleeping trees. When the monkeys slept in forest zones, they selected sleeping trees that had larger trunks but were not significantly taller than surrounding trees. Though the macaques rarely re‐used sleeping sites on consecutive nights, they frequently re‐used four sites over the study period. The group favored sleeping within the core area of its home range, despite the occurrence of frequent agonistic intergroup encounters there. Macaques preferentially selected sleeping trees located within or near human‐modified zones, especially when human food was abundant and natural food was scarce. These results partially support the hypothesis that long‐tailed macaques choose their sleeping sites to avoid predation; proximity to human settlements appears to be the primary factor influencing sleeping site choice in this primate species. Our results reflect the strong influence that anthropic factors have on primates, which subsist in increasingly human‐dominated landscapes. [less ▲]

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See detailNest grouping patterns of bonobos (Pan paniscus) in relation to fruit availability in a forest-savannah mosaic
Serckx, Adeline ULg; Huynen, Marie-Claude ULg; Bastin, Jean-François ULg et al

in PLoS ONE (2014)

A topic of major interest in socio-ecology is the comparison of chimpanzees and bonobos’ grouping patterns. Numerous studies have highlighted the impact of social and environmental factors on the ... [more ▼]

A topic of major interest in socio-ecology is the comparison of chimpanzees and bonobos’ grouping patterns. Numerous studies have highlighted the impact of social and environmental factors on the different evolution in group cohesion seen in these sister species. We are still lacking, however, key information about bonobo social traits across their habitat range, in order to make accurate inter-species comparisons. In this study we investigated bonobo social cohesiveness at nesting sites depending on fruit availability in the forest-savannah mosaic of western Democratic Republic of Congo (DRC), a bonobo habitat which has received little attention from researchers and is characterized by high food resource variation within years. We collected data on two bonobo communities. Nest counts at nesting sites were used as a proxy for night grouping patterns and were analysed with regard to fruit availability. We also modelled bonobo population density at the site in order to investigate yearly variation. We found that one community density varied across the three years of surveys, suggesting that this bonobo community has significant variability in use of its home range. This finding highlights the importance of forest connectivity, a likely prerequisite for the ability of bonobos to adapt their ranging patterns to fruit availability changes. We found no influence of overall fruit availability on bonobo cohesiveness. Only fruit availability at the nesting sites showed a positive influence, indicating that bonobos favour food ‘hot spots’ as sleeping sites. Our findings have confirmed the results obtained from previous studies carried out in the dense tropical forests of DRC. Nevertheless, in order to clarify the impact of environmental variability on bonobo social cohesiveness, we will need to make direct observations of the apes in the forest-savannah mosaic as well as make comparisons across the entirety of the bonobos’ range using systematic methodology. [less ▲]

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See detailModelling the Congo basin ecosystems with a dynamic vegetation model
Dury, Marie ULg; Hambuckers, Alain ULg; Trolliet, Franck ULg et al

Conference (2014, April)

The scarcity of field observations in some parts of the world makes difficult a deep understanding of some ecosystems such as humid tropical forests in Central Africa. Therefore, modelling tools are ... [more ▼]

The scarcity of field observations in some parts of the world makes difficult a deep understanding of some ecosystems such as humid tropical forests in Central Africa. Therefore, modelling tools are interesting alternatives to study those regions even if the lack of data often prevents sharp calibration and validation of the model projections. Dynamic vegetation models (DVMs) are process-based models that simulate shifts in potential vegetation and its associated biogeochemical and hydrological cycles in response to climate. Initially run at the global scale, DVMs can be run at any spatial scale provided that climate and soil data are available. In the framework of the BIOSERF project (“Sustainability of tropical forest biodiversity and services under climate and human pressure”), we use and adapt the CARAIB dynamic vegetation model (Dury et al., iForest - Biogeosciences and Forestry, 4:82-99, 2011) to study the Congo basin vegetation dynamics. The field campaigns have notably allowed the refinement of the vegetation representation from plant functional types (PFTs) to individual species through the collection of parameters such as the specific leaf area or the leaf C:N ratio of common tropical tree species and the location of their present-day occurrences from literature and available database. Here, we test the model ability to reproduce the present spatial and temporal variations of carbon stocks (e.g. biomass, soil carbon) and fluxes (e.g. gross and net primary productivities (GPP and NPP), net ecosystem production (NEP)) as well as the observed distribution of the studied species over the Congo basin. In the lack of abundant and long-term measurements, we compare model results with time series of remote sensing products (e.g. vegetation leaf area index (LAI), GPP and NPP). Several sensitivity tests are presented: we assess consecutively the impacts of the level at which the vegetation is simulated (PFTs or species), the spatial resolution and the initial land cover (potential or human-induced). First, we show simulations over the whole Congo basin at a 0.5◦ spatial resolution. Then, we present high-resolution simulations (1 km) carried out over different areas of the Congo basin, notably the DRC part of the WWF Lake Tele – Lake Tumba Landscape. Studied in the BIOSERF project, this area is characterized by a forest-savannah mosaic but also by swamp and flooded forest. In addition, forward transient projections of the model driven with the outputs of about thirty global cli- mate models (GCMs) from the new Coupled Model Intercomparison Project Phase 5 (CMIP5) will permit to outline the likely response of carbon pools to changing climate over the Congo basin during the 21th century. [less ▲]

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See detailModelling the Congo basin ecosystems with a dynamic vegetation model
Dury, Marie ULg; Hambuckers, Alain ULg; Trolliet, Franck ULg et al

Poster (2014, April)

The scarcity of field observations in some parts of the world makes difficult a deep understanding of some ecosystems such as humid tropical forests in Central Africa. Therefore, modelling tools are ... [more ▼]

The scarcity of field observations in some parts of the world makes difficult a deep understanding of some ecosystems such as humid tropical forests in Central Africa. Therefore, modelling tools are interesting alternatives to study those regions even if the lack of data often prevents sharp calibration and validation of the model projections. Dynamic vegetation models (DVMs) are process-based models that simulate shifts in potential vegetation and its associated biogeochemical and hydrological cycles in response to climate. Initially run at the global scale, DVMs can be run at any spatial scale provided that climate and soil data are available. In the framework of the BIOSERF project (“Sustainability of tropical forest biodiversity and services under climate and human pressure”), we use and adapt the CARAIB dynamic vegetation model (Dury et al., iForest - Biogeosciences and Forestry, 4:82-99, 2011) to study the Congo basin vegetation dynamics. The field campaigns have notably allowed the refinement of the vegetation representation from plant functional types (PFTs) to individual species through the collection of parameters such as the specific leaf area or the leaf C:N ratio of common tropical tree species and the location of their present-day occurrences from literature and available database. Here, we test the model ability to reproduce the present spatial and temporal variations of carbon stocks (e.g. biomass, soil carbon) and fluxes (e.g. gross and net primary productivities (GPP and NPP), net ecosystem production (NEP)) as well as the observed distribution of the studied species over the Congo basin. In the lack of abundant and long-term measurements, we compare model results with time series of remote sensing products (e.g. vegetation leaf area index (LAI), GPP and NPP). Several sensitivity tests are presented: we assess consecutively the impacts of the level at which the vegetation is simulated (PFTs or species), the spatial resolution and the initial land cover (potential or human-induced). First, we show simulations over the whole Congo basin at a 0.5◦ spatial resolution. Then, we present high-resolution simulations (1 km) carried out over different areas of the Congo basin, notably the DRC part of the WWF Lake Tele – Lake Tumba Landscape. Studied in the BIOSERF project, this area is characterized by a forest-savannah mosaic but also by swamp and flooded forest. In addition, forward transient projections of the model driven with the outputs of about thirty global cli- mate models (GCMs) from the new Coupled Model Intercomparison Project Phase 5 (CMIP5) will permit to outline the likely response of carbon pools to changing climate over the Congo basin during the 21th century. [less ▲]

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See detailDensity estimates and nesting-site selection in chimpanzees of the Nimba Mountains, Côte d'Ivoire and Guinea
Granier, Nicolas ULg; Hambuckers, Alain ULg; Matsuzawa, Tetsuro et al

in American Journal of Primatology (2014)

We investigated nesting behavior of non habituated chimpanzees populating the Nimba Mountains to document their abundance and their criterions of nesting-site selection. During a 19-month study we walked ... [more ▼]

We investigated nesting behavior of non habituated chimpanzees populating the Nimba Mountains to document their abundance and their criterions of nesting-site selection. During a 19-month study we walked 80 km of transects and recces each month, and recorded 764 nests (mean group size = 2.23 nests) along with characteristics of vegetation structure and composition, topography and seasonality. Population density estimated with two nest count methods ranged between 0.14 and 0.65 chimpanzee/km2. These values are lower than previous estimates, emphasizing the necessity of protecting remaining wild ape populations. Chimpanzees built nests in 108 tree species out of 437 identified, but 2.3% of total species comprised 52% of nests. Despite they preferred nesting in trees of 25-29 cm DBH and at a mean height of 8.02 m, we recorded an important proportion of terrestrial nests (8.2%) that may reflect a cultural trait of Nimba chimpanzees. A logistic model of nest presence formulated as a function of 12 habitat variables revealed preference for gallery and mountain forests rather than lowland forest, and old-growth forest rather than secondary forests. They nested more frequently in the study area during the dry season (December-April). The highest probability of observing nests was at 770 m altitude, particularly in steep locations (mean ground declivity = 15.54%). Several of the reported nest characteristics combined with the existence of 2 geographically separated clusters of nest, suggest that the study area constitutes the non-overlapping peripheral areas of 2 distinct communities. This nest-based study led us to findings on the behavioral ecology of Nimba chimpanzees, which constitute crucial knowledge to implement efficient and purpose-built conservation. [less ▲]

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