Low functional redundancy among mammalian browsers in regulating an encroaching shrub (Solanum campylacanthum) in African savannah

Robert Mitchell Pringle, Jacob R. Goheen, Todd M. Palmer, Grace K. Charles, Elyse DeFranco, Rhianna Hohbein, Adam T. Ford, Corina E. Tarnita

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


Large herbivorous mammals play an important role in structuring African savannahs and are undergoing widespread population declines and local extinctions, with the largest species being the most vulnerable. The impact of these declines on key ecological processes hinges on the degree of functional redundancy within large-herbivore assemblages, a subject that has received little study. We experimentally quantified the effects of three browser species (elephant, impala and dik-dik) on individual- and population-level attributes of Solanum campylacanthum (Solanum incanum sensu lato), an encroaching woody shrub, using semi-permeable exclosures that selectively removed different-sized herbivores. After nearly 5 years, shrub abundance was lowest where all browser species were present and increased with each successive species deletion. Different browsers ate the same plant species in different ways, thereby exerting distinct suites of direct and indirect effects on plant performance and density. Not all of these effects were negative: elephants and impala also dispersed viable seeds and indirectly reduced seed predation by rodents and insects. We integrated these diffuse positive effects with the direct negative effects of folivory using a simple population model, which reinforced the conclusion that different browsers have complementary net effects on plant populations, and further suggested that under some conditions, these net effects may even differ in direction.

Original languageEnglish (US)
Article number20140390
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1785
StatePublished - Apr 30 2014

All Science Journal Classification (ASJC) codes

  • General Immunology and Microbiology
  • General Environmental Science
  • General Biochemistry, Genetics and Molecular Biology
  • General Agricultural and Biological Sciences


  • Biodiversity
  • Bush encroachment
  • Indirect effects
  • Invasive species
  • Megaherbivores
  • Seed dispersal


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