posted on 2025-08-19, 02:28authored byAllison 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. Young, A. Carla Staver
<p>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/km<sup>2</sup> 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.</p>
Funding
NSF: MSB-1802453
NSF: DEB-2224317
NSF: EAR-2204471
NSF: DEB-0516145
NSF: DEB-0841917
NSF: DEB-0516094
NSF: DEB-1712786
NSF: DEB-0709880
NSF: OISE-0852961
NSF: DEB-1355122
NSF: DEB-0444071
NSF: DEB-1930820
Division of Environmental Biology: 1547679
NSF: DEB-1930763
NSF: DEB-2018405
NSF: NSF-2132265
NSF: LTREB 97-07477
NSF: LTREB 03-16402
NSF: LTREB 08-16453
NSF: LTREB 12-56034
NSF: LTREB 19-31224
NSF: IOS-1656527
NSF: DEB-2225088
NSF: DEB-1145861
NSF: BSC-1461728
Sherwood Family Foundation*
Natural Sciences and Engineering Research Council
University of Florida
University of British Columbia
Princeton University
Smithsonian Institution
National Geographic Society: 4691-91
United States Fish and Wildlife Service: 98210-0-G563