Composition and structure of fescue prairie respond to burning and environmental conditions more than to grazing or burning plus grazing in the short-term

Burning and grazing are key processes in the natural disturbance regime of the Fescue Prairie. Burning, grazing and their interacting effects on plant species diversity (Hʼ), species richness, and heterogeneity in species composition were studied at two spatial scales for two years in a remnant Fescue Prairie near Saskatoon, Saskatchewan. Cattle distribution in relation to plant communities was also studied. At the plot scale (100 m²), burning increased Hʼ (P0.25; x=46%; S.E.±3.0) and temporal heterogeneity in species composition (P>0.21; x=42%; S.E.±3.8) were not affected by burning, grazing, or their interaction. Burning + grazing increased tiller densities in Elymus lanceolatus (68%) and those of Festuca hallii (11%) (P<0.001) compared to the control. Burning decreased total aboveground net primary production (ANPP) (P<0.001) (x=305 g m⁻²) compared to unburned treatments (x=500 g m⁻²; S.E.±30.8). Grazing and burning + grazing had no effect on total ANPP or graminoid ANPP (P≥0.36). At the scale of Kernen Prairie (130 ha), H' increased between 1996 (P