Grazing herbivores reduce herbaceous biomass and fire activity across African savannas

Allison Tyler Karp, Sally E. Koerner, Gareth P. Hempson, Joel O. Abraham, T. Michael Anderson, William J. Bond, Deron E. Burkepile, Elizabeth N. Fillion, Jacob R. Goheen, Jennifer A. Guyton, Tyler R. Kartzinel, Duncan M. Kimuyu, Neha Mohanbabu, Todd M. Palmer, Lauren M. Porensky, Robert M. Pringle, Mark E. Ritchie, Melinda D. Smith, Dave I. Thompson, Truman P. YoungA. Carla Staver

Research output: Contribution to journalArticlepeer-review

Abstract

Fire and herbivory interact to alter ecosystems and carbon cycling. In savannas, herbivores can reduce fire activity by removing grass biomass, but the size of these effects and what regulates them remain uncertain. To examine grazing effects on fuels and fire regimes across African savannas, we combined data from herbivore exclosure experiments with remotely sensed data on fire activity and herbivore density. We show that, broadly across African savannas, grazing herbivores substantially reduce both herbaceous biomass and fire activity. The size of these effects was strongly associated with grazing herbivore densities, and surprisingly, was mostly consistent across different environments. A one-zebra increase in herbivore biomass density (~100 kg/km2 of metabolic biomass) resulted in a ~53 kg/ha reduction in standing herbaceous biomass and a ~0.43 percentage point reduction in burned area. Our results indicate that fire models can be improved by incorporating grazing effects on grass biomass.

Original languageEnglish (US)
Article numbere14450
JournalEcology letters
Volume27
Issue number6
DOIs
StatePublished - Jun 2024

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics

Keywords

  • burned area
  • fire
  • grazing
  • herbivore exclusion
  • megafauna
  • savanna

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