| Patrick E. Clark, William C. Krueger, Larry D. Bryant, and David R. Thomas |
| Authors are range scientist, USDA Agricultural Research Service, Boise, Ida. 83712; professor, Department of Rangeland Resources, Oregon State University, Corvallis, Ore. 97331; range ecologist, USDA Forest Service, Washington , D.C. 20250; and professor, Department of Statistics, Oregon State University, Corvallis, Ore. 97331. At the time of the research, Clark was graduate research assistant, Department of Rangeland Resources, Oregon State University, Corvallis, Ore. 97331 and Bryant was wildlife biologist, USDA Forest Service, Pacific Northwest Research Station, La Grande, Ore. 97850. Research was funded by USDA Forest Service, Pacific Northwest Research Station, La Grande, Ore. and by Cooperative State Research Service. |
Abstract |
| The winter forage quality of bluebunch wheatgrass (Agropyron spicatum [Pursh] Scribn. & Smith) is generally inadequate for maintenance of wintering Rocky Mountain elk (Cervus elaphus nelsoni Bailey). Previous attempts to improve the winter forage quality of bluebunch wheatgrass by clipping and livestock grazing have achieved mixed results. We report crude protein (CP), in vitro dry matter digestibility (IVDMD), and dry matter (DM) yield responses of bluebunch wheatgrass to 3 phenological stage/defoliation intensity treatment combinations. The study was conducted in 1993 and 1994 at 2 sites in the Blue Mountains of northeastern Oregon. Bluebunch wheatgrass was hand clipped to a 7.6-cm stubble height in early June under 1 of 3 treatment combinations: 1) mid-boot/whole-plant clipped, 2) mid-boot/one-half of the plant’s basal area clipped, and 3) inflorescence emergence/whole-plant clipped. Early November levels of CP and IVDMD were greater under all 3 treatments compared to an unclipped control. Mean forage quality improvement over the control was greatest in the inflorescence emergence treatment with an improvement of 1.3 percentage points for CP and 5.8 percentage points for IVDMD. Dry matter yield of the control exceeded that of all clipping treatments. Increases in forage quality resulting from forage conditioning treatments may be important to the viability of elk populations wintering on rangelands where forage quality, rather than quantity, is limiting. |
| Key Words: Agropyron spicatum, Cervus elaphus, elk, forage conditioning, nutrition, phenology, winter range, elk |