Declines of ebony and ivory are inextricably linked in an African rainforest
Vincent Deblauwe, Matthew Scott Luskin, Serge Désiré Assola, Olivier J. Hardy, Simon Jansen, Céline Loubières, Gaston Guy Mempong, Jean Mathurin Ntsihe, Gilbert Oum Ndjock, Eric Rostand Onguene, Luke L. Powell, Bonaventure Sonké, Thomas B. Smith
Abstract
Critically endangered African forest elephants preferentially eat fruits and disperse seeds of carbon-dense trees, including the highly valued and threatened African ebony. The illegal ivory trade has led to severe declines in elephant populations, but the long-term impacts on tree species are poorly understood. Using a comprehensive dataset including age-class, spatial, genetic, and experimental data, across a hunting pressure gradient, we show how paired declines in elephant and ebony populations are linked by a previously unrecognized mutualism in which elephant dung protects ebony seeds against seed predators. Disruption of this mutualism by poaching exacerbates seed predation by herbivores and was associated with a 68% reduction in small sapling recruitment. This threat to the survival of a valuable and iconic tree species raises concerns about the far-reaching consequences of forest elephant extermination.