US Department of Agriculture Forest Service
We assessed the effects of fire on the quality of herbaceous and browse forage for elk (Gervus e/aphus) and domestic sheep in the aspen (Populus tremu/oides) forest type. Selected forage species were sampled on burned and adjacent unburned areas during the summers of the first and second years after autumn prescribed burning of three sites in southeastern Idaho. These samples were analyzed for in vitro dry matter digestibility (IVDMD), crude protein, calcium, and phosphorus. This aspen type has a highly nutritious understory irrespective of burning. We found additional improvement in forage quality as a result of prescribed burning. In the middle of the first summer, aspen on the burned areas had higher crude protein and phosphorus contents, higher elk IVDMD, lower calcium contents, and lower calcium/phosphorus ratios than aspen had on the unburned areas. A month later, only crude protein levels of aspen remained higher on the burns. All of the shrubs analyzed in the first summer had higher crude protein levels on the burned areas. A year later, none of the shrubs or forbs on the burns had better forage quality than those under nearby unburned aspen. Pinegrass (Ga/amagrostis rubescens) on the burned areas in the second summer had more robust growth but lower IVDMD and crude protein values, likely due to more extensive flowering and seed production, than did pinegrass on unburned areas. Prescribed burning on these sites changed species composition from dense shrub motts to more palatable and nutritious forbs than were found on the unburned areas.
DeByle, N.V., Urness, P.J., & Blank, D.L. 1989. Forage quality in burned and unburned aspen communities. US Department of Agriculture Forest Service. Odgen, UT. 404.