Fire and grazing modify grass community response to environmental determinants in savannas: Implications for sustainable use

•We investigated effects of recurring forest fires on herbaceous species composition.•Remotely sensed data was used to identify areas with different fire frequencies.•Species heterogeneity and abundance of preferred grass reduced with fire frequency.•Livestock grazing counteracted negative effect of high fire frequency on vegetation.•Fire frequency should be managed at low levels to sustain ecosystem processes.