Data from: Grazing herbivores reduce herbaceous biomass and fire activity across African savannas

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.火与草食动物取食相互作用，共同改变生态系统与碳循环。在稀树草原生态系统中，草食动物可通过移除草本生物量抑制火灾活动，但此类影响的强度及其调控机制仍不明确。为探究非洲稀树草原中放牧对可燃物载荷与火灾格局的影响，我们将草食动物排除实验（herbivore exclosure experiments）数据，与火灾活动及草食动物密度的遥感数据（remotely sensed data）相结合。研究结果显示，在非洲稀树草原整体范围内，放牧型草食动物可显著降低草本生物量与火灾活动水平。此类影响的强度与放牧型草食动物的密度密切相关，且出乎意料的是，其在不同环境中基本保持一致。当草食动物代谢生物量密度每增加约100千克/平方公里（相当于1头斑马的代谢生物量）时，现存草本生物量将减少约53千克/公顷，火烧面积将降低约0.43个百分点。本研究结果表明，在火灾模型中纳入放牧对草本生物量的影响，可有效提升模型性能。