Global response of fire activity to late Quaternary grazer extinctions

Fire activity varies substantially at global scales because of the influence of climate, but at broad spatiotemporal scales, the possible effects of herbivory on fire activity are unknown. Here, we used late Quaternary large-bodied herbivore extinctions as a global exclusion experiment to examine the responses of grassy ecosystem paleofire activity (through charcoal proxies) to continental differences in extinction severity. Grassy ecosystem fire activity increased in response to herbivore extinction, with larger increases on continents that suffered the largest losses of grazers; browser declines had no such effect. These shifts suggest that herbivory can have Earth system-scale effects on fire and that herbivore impacts should be explicitly considered when predicting changes in past and future global fire activity.

Automated summary

The study found that herbivore extinction leads to an increase in grassy ecosystem fire activity, especially in regions on continents with the most severe losses of grazers. Conversely, declines in browsers had no such effect. These shifts suggest that herbivory can have global effects on fire activity, and the impacts of herbivores should be explicitly considered when predicting changes in global fire activity in the past and future.