Titel Deelnemers "The Enhancement of Secondary Succession by Western Lowland Gorillas (Gorilla gorilla gorilla) in a Moist Tropical Forest of Southeast Cameroon" "Charles-Albert Petre, Barbara Haurez, Nikki Tagg, Roseline Beudels-Jamar, Jean-Louis Doucet" "The Enhancement of Secondary Succession by Western Lowland Gorillas (Gorilla gorilla gorilla) in a Moist Tropical Forest of Southeast Cameroon." "Among animal seed dispersers in tropical ecosystems, the contribution of primates is recognized to be of paramount importance. However, the role played by the largest species of the Congo basin, the western lowland gorilla (Gorilla gorilla gorilla), has received little attention. Here, we provide the first long-term study describing all aspects of the ecology of seed dispersal by gorillas at a single site. Over three years of investigation in the forests of Mimpala, southeast Cameroon, we have identified 55 species whose seeds were found undamaged in 1030 faecal samples. On average, one faecal clump contained 2.4 seed species and 51.8 seeds. Gut passage, of a mean rate of 54.7h, does not affect viability of seeds and may even enhance germination success in some cases by separating the seed from the fruit pulp and/or by abrading the seed coat. As a result of habitat preference, seed deposition is biased towards open canopied environments, namely light gaps and young secondary forests. Monitoring of seedlings suggested that this directed-dispersal is an effective method of dispersal, as a significantly higher number of marked faeces still contained viable seedlings after one to two years in these habitats compared to the others. Quantitatively, this may be of benefit primarily to the tree genus Uapaca, as its seeds were found in almost half of all faecal clumps and its seedlings constituted the majority of the seedling cohort established in faeces. Furthermore, as a consequence of their heliophilous temperament, Uapaca seedlings were among those that developed the best at these seed deposition sites. We conclude that the western lowland gorilla may be a highly effective vector of secondary succession and its extirpation would likely have implications for forest dynamics." "The Influence of Transect Use by Local People and Reuse of Transects for Repeated Surveys on Nesting in Western Lowland Gorillas (Gorilla gorilla gorilla) and Central Chimpanzees (Pan troglodytes troglodytes) in Southeast Cameroon" "Nikki Tagg, Jacob Willie" "Seed dispersal effectiveness of the western lowland gorilla (Gorilla gorilla gorilla) in Gabon" "Barbara Haurez, Nikki Tagg, Charles-Albert Petre, Yves Brostaux, Armand Boubady, Jean-Louis Doucet" "The quantitative and qualitative aspects of seed dispersal by the western lowland gorilla (Gorilla gorilla gorilla) were investigated in Gabon. Fresh faeces were collected and washed to identify and count the seeds. Seed germinability after gut passage was estimated with trials in a nursery at the study site. To assess the impact of gut passage on germination success and delay, comparative trials were run with four treatments: (i) gut passed seeds cleaned of faeces, (ii) gut passed seeds within a faecal matrix, (iii) seeds from fresh fruits surrounded by pulp, and (iv) seeds from fresh fruits cleaned of pulp. The analysis of 180 faecal units resulted in the identification of 58 species of seed. Germination trials were realized for 55 species and the mean germination success reached 46%. The impact of gut passage was investigated for Santiria trimera and Chrysophyllum lacourtianum; both species displayed higher germination success after ingestion. This study shows that gorillas effectively disperse seeds of numerous plant species, many of which provide timber or nontimber forest products or are typical of Gabonese forests. Considering the high-quality of gorilla deposition sites, gorillas is thought to play a unique role in the dynamics of Central African forest." "Role of the western lowland gorilla (Gorilla gorilla gorilla) in seed dispersal in tropical forests and implications of its decline" "Charles-Albert Petre, Nikki Tagg, Barbara Haurez, Roseline Beudels-Jamar, Marie-Claude Huynen, Jean-Louis Doucet" "Patterns of seed dispersal significantly affect plant demography, dynamics and succession. In the tropics, the majority of tree species bear fruits that are adapted to animal-mediated dispersal. Amongst seed dispersers, the contribution of primates is widely recognized by ecologists as incomparable. However, in lowland Afrotropical forests, the specific role of the largest primate species, the western lowland gorilla (Gorilla gorilla gorilla Savage and Wyman, 1847), has been overlooked. This is of particular relevance as this species seems to fulfill important criteria for effective dispersal, both quantitatively and qualitatively. One trait makes it potentially unique as seed disperser; the regular deposition of seeds in open canopy environments where light will not be a limiting factor for subsequent seedling growth and survival. The magnitude of which this particular trait contributes to forest dynamics remains unexplored though it could be potentially important. It might no longer be the case, however, as the western lowland gorilla is critically endangered. The loss of the ecological services provided by large-bodied seed dispersers may have considerable impacts on the forests. Through dispersal limitation, population dynamics of plants in forests devoid of large frugivores will be strongly impacted. In the long-term, this may lead to shifts in plant community structure, composition and to reduced tree diversity. Currently, forests of the Congo basin face increasing level of deforestation and degradation, which puts already the ecosystem integrity in jeopardy. The additional threat that represents frugivorous wildlife depletion is therefore of forest management concern." "Role of the western lowland gorilla (Gorilla gorilla gorilla) in seed dispersal in tropical forests and implications of its decline" "Charles-Albert Petre, Nikki Tagg, Barbara Haurez, R. Beudels-Jamar, Marie-Claude Huynen, Jean-Louis Doucet" "Echocardiographic examination of a Western lowland gorilla (Gorilla gorilla gorilla)" "Blandine Houdellier, Laure Gatel, F Vercammen, Pascale Smets" "The Cross River Gorillas (Gorilla gorilla diehli) at Mawambi Hills, South-West Cameroon: Habitat Suitability and Vulnerability to Anthropogenic Disturbance" "Denis Ndeloh-Etiendem, Neba Funwi-Gabga, Nikki Tagg, Luc Hens, Eni K. Indah" "Only about 300 individuals of the Cross River gorilla (CRG; Gorilla gorilla diehli) survive today. The subspecies is endemic to approximately 12-14 sites at the Cameroon-Nigeria border, and is critically endangered. To understand survival prospects of the CRG at Mawambi Hills, Cameroon, a maximum entropy (MaxEnt) distribution model was used to predict the distribution of gorillas. Overall, 24% of the study area was predicted to be suitable for gorillas. The most important predictors of gorilla distribution were elevation as a surrogate for accessibility (52.4, distance to nearby villages which represents proximity to anthropogenic disturbance (22.7, and slope steepness as a proxy for security (19.4. Gorillas mainly occupied slopes of steep hills and avoided areas of human disturbance. To evaluate the spatial relationship between gorilla distribution and human activities, the predicted habitat suitability map was overlaid with a kernel density map of human activities. A positive correlation was found between locations of human activity and suitable habitat for gorillas (r = 0.5). This suggests that anthropogenic pressures in previously unused forest areas are increasing as a result of resource depletion at lower altitudes, consequently putting the gorillas at greater risk. Conservation management plans that seek to reduce human encroachment into habitats preferred by gorillas such as steep hills will probably contribute to gorilla survival. Copyright (c) 2013 S. Karger AG, Basel" "Feeding Ecology of Cross River Gorillas (Gorilla gorilla diehli) at Mawambi Hills: The Influence of Resource Seasonality" "Denis Ndeloh-Etiendem, Nikki Tagg" "Determining the composition of primate diet and identifying factors that affect food choice are important in understanding habitat requirements of primates and designing conservation plans. We studied the diet of Cross River gorillas (Gorilla gorilla diehli) in relation to availability of food resources, in a semideciduous lowland forest site (Mawambi Hills) in Cameroon, from November 2009 to September 2011. Based on 109 d of feeding trail data, 203 fecal samples, and 22 mo of phenological monitoring, we determined that gorillas consumed a total of 242 food items, including 240 plant items from 186 species and 55 taxonomic families. Mawambi gorillas diversified fruit consumption when fruit availability increased, and consumed more fibrous foods (pith, leaf, bark) during times of fruit scarcity, consistent with results of other gorilla studies. However, fruit availability was not related to rainfall, and the period of fruit scarcity was more pronounced at Mawambi than at other gorilla study sites, due to a single long dry season and extreme rainfall at the end of the rainy season that delayed fruit production and ripening. We found no relationship between the daily path length of the gorillas and fruit consumption. We found feeding habits of Mawambi gorillas to be notably similar to those of a population of Cross River gorillas at Afi Mountain, Nigeria, although subtle differences existed, possibly due to site-specific differences in forest composition and altitude. At both sites the liana Landolphia spp. was the single most important food species: the leaves are a staple and the fruits are consumed during periods of fruit scarcity. Snails and maggots were consumed but we observed no further faunivory. We suggest that tree leaves and lianas are important fallback food sources in the gorilla diet in seasonally dry forests." "Impacts of logging and hunting on western lowland gorilla ( Gorilla gorilla gorilla) populations and consequences for forest regeneration . A review" "Barbara Haurez, Charles-Albert Petre, Jean-Louis Doucet" "Timber exploitation is rapidly expanding throughout the Congo Basin. Forest areas assigned to timber harvesting have sharply expanded over the decades and logging concessions now largely overlap with the range of western lowland gorilla (Gorilla gorilla gorilla Savage Wyman, 1847). However this species, which is considered as critically endangered by IUCN, could play an essential role in maintaining the structure and composition of tropical rainforest notably through seed dispersal services. This is likely due to its frugivorous diet, high stomach capacity and ability to swallow seeds of variable sizes. Moreover gorillas have a long gut retention time of ingested food, travel long daily distances and deposit most ingested seeds in suitable habitats for plant development (such as logging gaps). Consequently, the preservation of the role of gorilla in forest regeneration is essential in the context of logged forest ecosystems. Timber harvesting has two major opposing impacts on gorilla populations: on the one hand, gorillas benefit from growth of herbaceous vegetation (e.g. Marantaceae and Zingiberaceae) following forest canopy opening, as such herbs provide both staple food and nest-building materials; on the other hand, gorilla populations suffer with the rise in hunting associated with logging activity, especially with road network installation. Considering the potential negative knock-on effects of logging concessions on the ecological function of western lowland gorilla, the implementation of timber harvesting methods that preserve gorilla populations is a considerable challenge for forest sustainability, as well as for gorilla’s conservation."