Forage nutritive quality in the Serengeti ecosystem: The roles of fire and herbivory

T. Michael Anderson, Mark E. Ritchie, Emilian Mayemba, Stephanie Eby, James B. Grace, Samuel J. McNaughton

Research output: Contribution to journalArticlepeer-review

88 Scopus citations


Fire and herbivory are important determinants of nutrient availability in savanna ecosystems. Fire and herbivory effects on the nutritive quality of savanna vegetation can occur directly, independent of changes in the plant community, or indirectly, via effects on the plant community. Indirect effects can be further subdivided into those occurring because of changes in plant species composition or plant abundance (i.e., quality versus quantity). We studied relationships between fire, herbivory, rainfall, soil fertility, and leaf nitrogen (N), phosphorus (P), and sodium (Na) at 30 sites inside and outside of Serengeti National Park. Using structural equation modeling, we asked whether fire and herbivory influences were largely direct or indirect and how their signs and strengths differed within the context of natural savanna processes. Herbivory was associated with enhanced leaf N and P through changes in plant biomass and community composition. Fire was associated with reduced leaf nutrient concentrations through changes in plant community composition. Additionally, fire had direct positive effects on Na and nonlinear direct effects on P that partially mitigated the indirect negative effects. Key mechanisms by which fire reduced plant nutritive quality were through reductions of Na-rich grasses and increased abundance of Themeda triandra, which had below-average leaf nutrients.

Original languageEnglish (US)
Pages (from-to)343-357
Number of pages15
JournalAmerican Naturalist
Issue number3
StatePublished - Sep 2007


  • Fire
  • Forage element concentration
  • Herbivory
  • Leaf nutrients
  • Plant community composition
  • Structural equation modeling

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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