Seed dispersal strategies and the threat of defaunation in a Congo forest

Abstract

Seed dispersal mode of plants and primary interactions with animals are studied in the evergreen Afrotropical forest of LuiKotale, at the south-western part of Salonga National Park (DR Congo). We first analysed seed dispersal strategies for (a) the plant species inventoried over a decade at the study site and (b) the tree community in 12 × 1 ha census plots. Our analyses of dispersal syndromes for 735 identified plant species show that 85 % produce fleshy fruits and rely on animals for primary seed dispersal. Trees depending on animals for primary dispersal dominate the tree community (95 %), while wind-dispersed and autochorous trees are rare in mixed tropical forests. A list of frugivorous vertebrate species of the ecosystem was established. Among the fruit-eating vertebrate species identified in the ecosystem, forest elephants and bonobos are threatened with extinction (IUCN, The IUCN red list of threatened species, 2012). Although most of the species listed previously are internationally and regionally protected, all the species we observed dispersing seeds are hunted, fished or trapped by humans in the area. With the exception of bush pigs, seed predators, mainly small-sized animals, are generally not targeted by hunters. As a consequence, we expect human pressure on key animal species to impact the plant community. We suggest defaunation to be considered as major conservation problem. Thus, not only for the sake of animal species but also for that of plant species conservation, anti-poaching measures should have priority in both “protected” and unprotected areas. Defaunation could bring a new impoverished era for plants in tropical forests.

Résumé

Dans la forêt tropicale humide de LuiKotale, au sud-ouest du parc national de la Salonga (RD Congo), nous avons analysé (a) l’ensemble des stratégies de dispersion des plantes inventoriées dans le site d’étude depuis une décennie, puis (b) des plantes recensées dans l’inventaire de la communauté d’arbres sur 12 parcelles de 1 ha. D’après l’analyse des syndromes de dispersion de 735 espèces de plantes identifiées, 85 % produisent des fruits adaptés pour la consommation par des animaux qui dispersent leurs graines. Les arbres dont la dispersion primaire est zoochore dominent la communauté (95 %), alors que les arbres autochores et dispersés par le vent sont rare. Nous avons identifié les espèces de vertébrés frugivores de l’écosystème, parmi lesquelles les éléphants de forêts et les bonobos qui sont menacés d’extinction (IUCN 2012). Bien que protégés internationalement, tous ces animaux sont chassés, pêchés ou piégés. Les prédateurs de graines, principalement des petits animaux (rongeurs et oiseaux), ne sont pas des espèces cibles pour la chasse à l’exception des potamochères. La pression humaine devrait affecter la communauté végétale par l’élimination d’espèces clefs de l’écosystème. La défaunation risque d’être la cause d’une nouvelle ère d’appauvrissement spécifique des plantes de forêt tropicale. Cette défaunation doit être considérée comme un problème majeur de conservation. Les mesures anti-braconnage doivent être une priorité dans les zones protégées et « non protégés » et ceci non pas seulement pour la conservation des espèces animal mais aussi pour la conservation des espèces végétales.

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Acknowledgments

We thank the Institut Congolais pour la Conservation de la Nature (ICCN) for granting permission to conduct research at Salonga National Park, and Lompole villagers for granting permission to access the forest of their ancestors. Research at LuiKotale was conducted under the auspices and with the financial support of the Max Planck-Society, the German Ministry of Education and Research, the Société Française d’Ecologie and the Conseil Régional de Bourgogne (France). The methods used to collect data in the field are in compliance with the requirements and guidelines of the ICCN, and adhere to the legal requirements of the host country, the Democratic Republic of Congo. We would like to thank the international and local staff of LK; Carmela Chateau-Smith and Doyle McKey for the English improvement; Ulrich Schliewen for fish identification and two anonymous reviewers for their detailed and helpful comments.

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Beaune, D., Bretagnolle, F., Bollache, L. et al. Seed dispersal strategies and the threat of defaunation in a Congo forest. Biodivers Conserv 22, 225–238 (2013). https://doi.org/10.1007/s10531-012-0416-x

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Keywords

  • Seed dispersal
  • Defaunation
  • Democratic Republic of the Congo
  • Forest ecology
  • Frugivores
  • Human pressure
  • Seed predators
  • Tropical rainforest
  • Zoochory