Short-term vegetation response to wildfire in the eastern Sierra Nevada: Implications for recovering an endangered ungulate

We studied short-term changes in vegetation for two years following a summer wildfire on the winter ranges of Sierra Nevada bighorn sheep (Ovis canadensis sierrae). Forbs dominated burned areas and shrubs dominated unburned areas. Green forage (new-growth of all forage classes) biomass rebounded quickly; within two years green forage biomass was equal in burned and unburned areas, although total forage biomass remained greater in unburned areas. Plants in the burn had slightly higher crude protein but equivalent digestibility and phenology as plants in unburned areas. This, in combination with the shift toward more forb biomass, likely increased forage quality in burned areas. Forage models developed from ground-based measures of biomass performed better than the NDVI and were able to capture changes in forage composition, emphasizing the importance of field sampling to model vegetation. Based on microhistological analyses of fecal pellets, Sierra Nevada bighorn sheep whose winter ranges were extensively burned consumed more forbs than those with less burned habitat. Visibility was greater in burned areas compared with unburned areas, suggesting that burns may decrease predation risk from stalking predators. In conclusion, wildfire may have beneficial effects for Sierra bighorn by increasing forb availability, forage quality and visibility.