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Quantity and spatial distribution of seeds dispersed by a western lowland gorilla population in south-east Cameroon

Published online by Cambridge University Press:  02 March 2015

Charles-Albert Petre*
Affiliation:
Foresterie Tropicale, Gestion des Ressources Forestières, Département BIOSE, Gembloux Agro-Bio Tech, University of Liège, 2 Passage des Déportés, 5030 Gembloux, Belgium Conservation Biology Unit, Royal Belgian Institute of Natural Sciences, 29 Rue Vautier, 1000 Brussels, Belgium Projet Grands Singes Cameroon, Centre for Research and Conservation, Royal Zoological Society of Antwerp, 20–26 Koningin Astridplein, 2018 Antwerp, Belgium
Nikki Tagg
Affiliation:
Projet Grands Singes Cameroon, Centre for Research and Conservation, Royal Zoological Society of Antwerp, 20–26 Koningin Astridplein, 2018 Antwerp, Belgium
Roseline Beudels-Jamar
Affiliation:
Conservation Biology Unit, Royal Belgian Institute of Natural Sciences, 29 Rue Vautier, 1000 Brussels, Belgium
Barbara Haurez
Affiliation:
Foresterie Tropicale, Gestion des Ressources Forestières, Département BIOSE, Gembloux Agro-Bio Tech, University of Liège, 2 Passage des Déportés, 5030 Gembloux, Belgium École Régionale Post-Universitaire d’Aménagement et de Gestion Intégrés des Forêts et Territoires Tropicaux (ERAIFT), B.P. 15373 Kinshasa, Democratic Republic of Congo
Marcel Salah
Affiliation:
Projet Grands Singes Cameroon, Centre for Research and Conservation, Royal Zoological Society of Antwerp, 20–26 Koningin Astridplein, 2018 Antwerp, Belgium Ministry of Forestry and Wildlife, Boulevard du 20 mai, 34430 Yaoundé, Cameroon
Victoria Spetschinsky
Affiliation:
Foresterie Tropicale, Gestion des Ressources Forestières, Département BIOSE, Gembloux Agro-Bio Tech, University of Liège, 2 Passage des Déportés, 5030 Gembloux, Belgium
Jacob Willie
Affiliation:
Projet Grands Singes Cameroon, Centre for Research and Conservation, Royal Zoological Society of Antwerp, 20–26 Koningin Astridplein, 2018 Antwerp, Belgium
Jean-Louis Doucet
Affiliation:
Foresterie Tropicale, Gestion des Ressources Forestières, Département BIOSE, Gembloux Agro-Bio Tech, University of Liège, 2 Passage des Déportés, 5030 Gembloux, Belgium École Régionale Post-Universitaire d’Aménagement et de Gestion Intégrés des Forêts et Territoires Tropicaux (ERAIFT), B.P. 15373 Kinshasa, Democratic Republic of Congo
*
1Corresponding author. Email: capetre@doct.ulg.ac.be

Abstract:

Understanding the ecological function of large frugivores in tropical forests is important considering their central position in seed-dispersal networks. This study illustrates the seed-dispersal effectiveness of a western lowland gorilla (Gorilla gorilla gorilla) population in Cameroon by looking at the interaction of seed quantity, species regeneration traits and the environmental characteristics of the deposition sites (sleeping sites vs. feeding trails) in order to discuss the role of gorillas within the ecosystem. The analysis of 1030 faecal samples collected over a 3-y period (September 2009–August 2012) showed that gorillas dispersed a diverse array of species (58 spp. identified), with an average of 289 intact seeds (>5 mm) d−1 per individual. Seed damage during mouth and gut processing occurred for 12 spp., generally accounting for <5% of specific seed load. Germination trials suggested that germination success of passed seeds remained unchanged (N = 6 spp.) or improved (N = 5 spp.) after gut passage compared with hand-cleaned seeds, with one exception. Indicator species identification (IndVal method) and General Discriminant Analysis suggested that sleeping sites (N = 36), as a main type of seed deposition site, correspond to regenerating microhabitats and correspondingly degree of canopy openness is one variable discriminating significantly this type of deposition site with random locations in the forest (N = 36) used as a proxy for non-directed seed deposition on feeding trails. With a mean canopy openness of 19–27%, sleeping sites offer optimal light conditions for the seedling recruitment of non-pioneer light-demanding species, the seeds of which encompass 47.4% of the total seed load dispersed over the 3-y period. From this study, it is hypothesized that the gorilla performed directed-dispersal of some light-demanding plant species at sleeping sites, and hence, by being actively implicated in gap-phase dynamics, fulfils a valuable ecological function within its ecosystem.

Type
Research Article
Copyright
Copyright © Cambridge University Press 2015 

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References

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