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See detailDynamic of seed dispersal by large frugivores in a forest-savanna mosaic subject to anthropic pressure in Western D.R. Congo
Trolliet, Franck ULiege; Serckx, Adeline ULiege; Huynen, Marie-Claude ULiege et al

Poster (2013, April 05)

The Western Congolian forest-savanna mosaic is an ecotone subject to anthropogenic as well as natural fragmentation. Its forests have thus a considerable proportion of edges. This vegetation structure is ... [more ▼]

The Western Congolian forest-savanna mosaic is an ecotone subject to anthropogenic as well as natural fragmentation. Its forests have thus a considerable proportion of edges. This vegetation structure is likely to impact animal and plant communities and its dynamics such as animal mediated seed dispersal. Synergetically, activities such as bush meat hunting deplete large frugivores populations and thus decrease recruitment potential of the plants they disperse. Indeed, zoochory is known to be of great importance for tropical forests and a number of studies proved that large-seeded tree species closely depend on large frugivores for their regeneration. In such a context, we aim to understand how forest edges affect the dynamics of seed dispersal. More precisely, we wonder if the interactions between large seeds and their dispersers and predators are affected when closer to edges and how this can impact plant regeneration capacity. Also, we wonder if the dispersal and regeneration of large-seeded tree species depend on a few disproportionally important frugivores species. Bonobos, Pan paniscus, are among the largest frugivores left in the area and thus likely to be disproportionally important seed dispersers, though, their role as seed dispersers has yet been little investigated. We thus focus on the qualitative role for seed dispersal of the potentially keystone and umbrella ape species, the bonobo. To answer those questions, we study the main steps characteristics of large-seeded tree species regeneration process; namely quantitative seed dispersal, seed deposition pattern, germination capacity after transit in frugivore’s gut and, seed and seedling fate. By studying five different tree species at varying distances from forest edge, we aim to drive an inter-species comparison and to highlight the effect of forest edge on the regeneration process. We first quantify the seed production for each tree species and then evaluate the quantitative capacity of seed dispersal. By combining direct focal observations and camera trapping, we are able to highlight variations in composition of dispersers community and their respective contribution to seed dispersal. A literature review on each disperser species’ seed retention time and habitat use will allow the computation of the seed dispersal kernels. We will also evaluate the effect of seed ingestion by the bonobo on its germination capacity: seeds will be collected from dung to evaluate the effect of seed ingestion on the rate and velocity of germination. Finally, we will study the predation pressure exerted on dispersed and non-dispersed seeds and seedlings by setting up two sets of seeds below the canopy of parent trees and away from any conspecific trees. One set will be dispersed unprotected to seed predators; another one will be enclosed in a cage and permit seeds to germinate, allowing us to evaluate the herbivores pressure on seedlings. [less ▲]

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See detailDispersal and regeneration capacity of large-seeded tree species in a forest-savanna mosaic in Western DR Congo
Trolliet, Franck ULiege; Huynen, Marie-Claude ULiege; Hambuckers, Alain ULiege

Poster (2012)

It is widely recognized that the Congo Basin is affected by numerous anthropogenic pressures. A number of studies proved that hunting and forest fragmentation diminish the diversity and abundance of large ... [more ▼]

It is widely recognized that the Congo Basin is affected by numerous anthropogenic pressures. A number of studies proved that hunting and forest fragmentation diminish the diversity and abundance of large vertebrates, more specifically, of large frugivores. The depletion of those animals can directly affect large-seeded tree species as large seeds closely depend on the community of large frugivorous vertebrates for their dispersal. Then, the disruption of animal mediated seed dispersal is thought to deeply impact the plant regeneration capacity. The forest-savanna mosaic situated in Western DR Congo is an ecotone characterized by naturally occurring forest fragments which are also subject to numerous anthropogenic pressures. Those are very likely to disrupt seed dispersal mechanisms and to alter forest regeneration processes. To date, few studies have considered the effect of such an ecosystem on plant-animal interaction dynamics such as seed dispersal, and none have been done in this region. This study will examine if the early stages of regeneration of the large-seeded tree species Anonidium mannii, namely the dispersal capacity and seedling establishment is affected by forest fragment size. We predict that the small fragment size will negatively affect the regeneration capacity of this species. To test this assumption, we will work along a gradient of forest fragment sizes to define the composition of the seed disperser communities. For each disperser assemblage, we will evaluate the quantitative capacity of seed dispersal by combining direct focal observations and camera trapping. A literature review on each disperser species seed retention time and habitat use will allow the computation of the seed dispersal kernels. We will also evaluate the effect of seed ingestion by a presumably important seed disperser, the bonobo, Pan paniscus, on its germination capacity. Seeds will be collected from dung to evaluate the effect of seed ingestion on the rate and velocity of germination. Finally, we will study the predation pressure exerted on dispersed and non-dispersed seeds and seedlings by setting up two sets of seeds below the canopy of parent trees and away from any conspecific trees. One set will be dispersed unprotected to seed predators; another one will be enclosed in a cage and permit seeds to germinate, allowing us to evaluate the herbivores pressure on seedlings. [less ▲]

Detailed reference viewed: 115 (17 ULiège)
See detailUne approche participative des interactions entre les hommes, femmes et la biodiversité de la forêt tropicale dans la région du lac Tumba, RDC
Halleux, C.; Dendoncker, N.; Huynen, Marie-Claude ULiege et al

Conference (2012)

L'objectif du projet BIOSERF est d'évaluer la durabilité d'un écosystème de forêt tropicale humide dans l'Ouest de la République démocratique du Congo sous des pressions démographiques, sociétales et ... [more ▼]

L'objectif du projet BIOSERF est d'évaluer la durabilité d'un écosystème de forêt tropicale humide dans l'Ouest de la République démocratique du Congo sous des pressions démographiques, sociétales et climatiques. Le projet se concentre sur les interactions entre la flore, la faune et la population humaine locale pour comprendre les processus modifiant la biodiversité et la disponibilité en services écosystémiques dans des zones tropicales humides. En collaboration étroite avec une ONG locale, il utilisera un modèle de végétation dynamique (CARAIB) qui sera associé à un modèle multi-agents, afin d'analyser l'utilisation de différents services écosystémiques comme par exemple la production de plantes médicinales, de bois et d'autres produits forestiers, ou de services liés à la création de réserves naturelles. Le modèle de végétation sera adapté pour prendre en compte les processus de régénération de plusieurs espèces de plantes, sélectionnées pour leur usage par les communautés humaines locales. Pour ce faire, une sélection de 5 espèces d'arbres utilisées fréquemment ou traditionnellement sera effectuée basée sur les résultats d'une enquête sociologique. Une étude combinée des communautés de disperseurs de graines permettra de prendre en compte leur rôle dans la régénération de la forêt. Le modèle multi-agents, quant à lui, devrait voir le jour lors d'un processus de modélisation d'accompagnement. Toutes les hypothèses de base de la modélisation peuvent être remises en cause durant le processus, au contact de la réalité du terrain. Cette méthode devrait permettre de mettre en débat les incertitudes liées à la notion de service écosystémique. A travers une approche post-normale, cette démarche de modélisation a pour vocation de faire dialoguer scientifiques, citoyens et décideurs et ceci afin d'améliorer la qualité du processus de prise de décision collective. La conception de différents scénarios permettra d'explorer différentes pistes de futurs possibles et/ou désirables. [less ▲]

Detailed reference viewed: 146 (19 ULiège)
See detailSustainability of tropical forest biodiversity and services under climate and human pressure (BIOSERF): tracking the regeneration of human-used plants through dispersal by the animal community
Huynen, Marie-Claude ULiege; Beudels, R.; Baert, A. et al

Conference (2011, June)

The objective of the BIOSERF project is to assess the sustainability of a tropical humid forest ecosystem and the local human communities in southern Congo under future climate, demographic and societal ... [more ▼]

The objective of the BIOSERF project is to assess the sustainability of a tropical humid forest ecosystem and the local human communities in southern Congo under future climate, demographic and societal changes. The project focuses on the interactions between flora, fauna and local human population to understand the processes affecting biodiversity and ecosystem services in tropical humid areas, with the objective of setting up mechanisms to preserve local biodiversity. In close collaboration with a local NGO, it will use a dynamic vegetation model (CARAIB) which will be integrated within an agent-based model, to analyze the impacts of different ecosystem services in a tropical humid area, e.g. the production of medicinal plants, of wood and other forest products, or the services provided by the building of natural reserves. The vegetation model will be upgraded to take into account the process of regeneration of several plant species, selected for their use by local human populations, through a quantitative and qualitative description of plant dispersal by the animal community. To do so, a selection of five tree species frequently or traditionally used will be made based on the results of a sociological survey. Observations (direct or through camera trapping) of a sample of the selected species will allow identifying the main dispersers and the pattern of seed shadow they generate. Integrated into the CARAIB model, these results will allow figuring how the evolution of the dispersal community under pressures of climate change, habitat loss and hunting, but also potentially placed under managed protection could affect the services available to the human community. [less ▲]

Detailed reference viewed: 62 (9 ULiège)
See detailA comparative study on the ecology of the black howler monkey living in limestone karst hills and in a riparian forest in Belize
Trolliet, Franck ULiege; Evans, Kayley; Kowalzik, Barbara et al

Conference (2010, October 11)

Detailed reference viewed: 17 (1 ULiège)
Full Text
See detailEcology of the Belizean black howler monkey (Alouatta pigra): a comparison between two populations living in a riparian forest and on coastal limestone hills
Trolliet, Franck ULiege

Master's dissertation (2010)

This study reports on the ecology of the Belizean black howler monkey (Alouatta pigra) in two different habitats. Monkey River is a riparian secondary forest whereas Runaway Creek Nature Reserve (RCNR) is ... [more ▼]

This study reports on the ecology of the Belizean black howler monkey (Alouatta pigra) in two different habitats. Monkey River is a riparian secondary forest whereas Runaway Creek Nature Reserve (RCNR) is a primary and mature forest situated in a limestone karst hills landscape. This type of ecosystem, neither the population inhabiting this reserve, has been studied before. We contrasted food availability, diet, group size and composition, population density, home range size and activity patterns between those two populations. We predicted the disturbed riparian forest to have higher food availability but a less diverse diet with a higher consumption of fruits. Thus, we predicted howlers to have higher population density, larger groups with more males and more infants, smaller home ranges with more overlapping. Also, we predicted activity budget to be biased toward a less active lifestyle with less travel but more inactivity, and more social interactions. Our results confirm some of those predictions as food availability is higher in Monkey River with food species accounting for 80% of the diet and all food species of howlers diet having a higher total relative basal area. This is likely to be associated with the higher population density (44.82ind/km² in Monkey River against 26in/km² in RCNR) and smaller average home range size (3.27 ha against 11.87 ha) with a higher proportion of overlapping (11.87% against 0%). Predictions on group size and composition are not confirmed as the difference in mean group size is not statistically significant and as many males per group are found in both habitats (one) but sex ratios (M:F) indicate the presence of more females in Monkey River (1:1.6 against 1:1.3). Also, more infants per group are found in RCNR (0.6 in Monkey River against 1 in RCNR). Those results are likely to be associated with different stage of population growth between the two habitats and more precisely of the hurricane Iris that have lowered the population in Monkey River and allowed more dispersal opportunities and, resulting effects of social factors such as infanticide. Nevertheless, our results indicate howler population to increase again in this disturbed forest. Howlers in RCNR have a more diverse diet (18 food sources in Monkey River against 23 in RCNR) which is likely to be due to higher diversity of plants present in the limestone karst hills. Diets in both habitats differ as only 19.5% of species are similar and species composition in both habitats are pretty different too, which confirms howlers having a flexible diet and being able to adapt their diet to the species found in the habitat. Both populations feed preferentially on leaves but howlers in the secondary forest spent more time feeding on fruits (20.46%) and less on flowers (6.46%) than in the primary forest (11% and 11.75% respectively), although those differences are not significant. Howlers in Monkey River are more active and travel significantly more (9.45% against 5.45%) which is likely to be due to the higher amount of fruits in the diet. Less time is spent in social interactions in Monkey River, which is likely to be due to the smaller number of infants per group. Finally, monkeys in the secondary forest spent significantly more time vocalizing than in the primary forest, which is likely to be due to the higher population density and level of overlap between neighboring groups. No overlap has been recorded in the limestone karst hills and percentage of vocalization is quite low. [less ▲]

Detailed reference viewed: 351 (1 ULiège)