Showing items related by title, author, creator and subject.

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  Defoliation Response of Bluebunch Wheatgrass and Crested Wheatgrass: Why We Cannot Graze These Two Species in the Same Manner

  Meays, Cindy L.; Laliberte, Andrea S.; Doescher, Paul S. (Society for Range Management, 2000-12-01)
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  Photosynthetic Characteristics of Crested Wheatgrass and Bluebunch Wheatgrass

  Nowak, R. S.; Caldwell, M. M. (Society for Range Management, 1986-09-01)

  Light and temperature dependencies for net photosynthesis and stomatal conductance were generally very similar between foliage on crested wheatgrass (Agropyron desertorum (Fisch. ex Link) Schult.) plants and that on bluebunch wheatgrass (A. spicatum (Pursh) Scribn. and Smith) plants. The similarity of these gas exchange characteristics between the 2 bunchgrass species was true for foliage on unclipped plants as well as on partially defoliated plants. However, light and temperature dependencies of senescing leaf blades that were exserted in late-spring were significantly different for unclipped plants of these 2 species. Photosynthetic rates and stomatal conductances of senescent late-season blades on bluebunch wheatgrass plants were greater than those on crested wheatgrass plants at light intensities greater than 0.8 mmol photons m-2 s-1 (photosynthetic photon flux density) and at all foliage temperatures between 18 degrees C and 41 degrees C. These greater photosynthetic rates and stomatal conductances do not mean that bluebunch wheatgrass tillers gained substantially more carbon or lost substantially more water than crested wheatgrass tillers. If both the photosynthetic area composition of tillers and the environmental conditions of the northern Utah study site were considered, carbon gain and water loss for individual bluebunch wheatgrass tillers would be very similar to those for individual crested wheatgrass tillers despite the significantly different responses to light and temperature during mid-summer.
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  Nutrition of Sheep Grazing Crested Wheatgrass Versus Crested Wheatgrass-Shrub Pastures During Winter

  Gade, A. E.; Provenza, F. D. (Society for Range Management, 1986-11-01)

  Grazing sheep on improved pastures during winter offers an economically attractive alternative to supplementation in sage-brush steppe ecosystems. We studied diet selection and nutrition of sheep grazing in crested wheatgrass (Agropyron desertorum) and crested wheatgrass-shrub (Kochia prostrata, Atriplex canescens, Purshia tridentata, Artemisia tridentata, Chrysothamnus nauseosus, Ceratoides lanata) pastures during early-January (period 1), mid-January (period 2), and late-January (period 3). Diet selection by esophageally fistulated sheep differed during each of the 3 periods because the amount of available forage changed with snow depth, trampling, and utilization. Sheep grazing crested wheatgrass (CW) pastures consumed diets that were about 55% mature grass and 45% green vegetative growth during periods 1 and 2, and 93% mature grass and 7% green vegetative growth during period 3. Sheep grazing crested wheatgrass-shrub (CWS) pastures consumed diets that were about one-half grass and one-half shrub during all periods. Organic matter intake (g kg BW ^ -.075), determined from total fecal output and in vitro digestibility estimates, were higher (P = 0.036) for sheep grazing CWS pastures than for sheep grazing CW pastures during periods 1 (38 vs. 28) and 3 (31 vs. 27), but were similar (P<0.10) during period 2 (28 vs. 26). Diets of sheep grazing CWS pastures contained more (P = 0.002) crude protein (%) than diets of sheep grazing CW pastures during periods 1 (9.0 vs. 5.8), 2 (7.3 vs. 6.6), and 3 (7.9 vs. 4.6). In vitro organic matter digestibilities (%) of diets of sheep in CW and CWS pastures were similar during period 1 (45 vs. 48), but higher (P = 0.001) for sheep grazing in CW pastures during periods 2 (46 vs. 29) and 3 (32 vs. 24). We stocked pastures heavily to accentuate differences between sheep diets in CW and CWS pastures during period 1-3; we believe results from period 1 best represent the potential nutritional benefits of shrubs on snowy winter ranges.