• Botanical composition of bison diets on tallgrass prairie in Oklahoma

      Coppedge, B. R.; Leslie, D. M.; Shaw, J. H. (Society for Range Management, 1998-07-01)
      Diets of bison (Bison bison L.) were examined using microhistological fecal analysis in a 2-yr study on a tallgrass prairie site in northcentral Oklahoma. Graminoids comprised at least 98% of the diet across all seasons. Bison showed strong feeding selectivity; grasses and sedges formed a significantly higher proportion of diets than was generally available in herbage on the landscape. Bison avoided forbs, which were less than or equal to 2% of the diet. Sedges were a large (17-44%) diet component in winter and spring but decreased substantially during summer and fall (11-16%). These changes in sedge use corresponded to seasonal variation in sedge availability. Our results confirm that bison are primarily grazers in prairie habitats, potentially having a significant role in shaping structure and function of tallgrass prairie.
    • Diet selection by sheep and goats on Mediterranean heath-woodland range

      Bartolomé, J.; Franch, J.; Plaixats, J.; Seligman, N. G. (Society for Range Management, 1998-07-01)
      The study determined the species components of the diets of small ruminants grazing mountain ranges of the Montseny Biosphere Reserve (Catalunya, NE Spain). Three mixed flocks of sheep and goats, led by shepherds, were monitored for a year. Animals grazed a mountain rangeland composed of Quercus ilex woodland and Calluna-Erica heathland during the day and were returned to their corrals every night. Diet selection was estimated using fecal analysis. Of the 111 species that were identified, 71 were common to both sheep and goat. Of these, 23 were represented in proportions of more than 1% of the annual diet. Even though goats and sheep grazed together, their diets were significantly different (p < 0.0001), the animal factor accounting for 18% to 60% of the total variation among the main diet components. Variation between seasons was also a major (5% to 56%) highly significant factor, while differences between flocks accounted for a significant, but relatively small part (3 % to 10% ) of the total variation in diet. The outstanding difference was the avoidance of the tree, Quercus ilex, by the sheep while the goats selected it throughout the year. Sheep selected graminoids throughout the year while goats tended to avoid them. For the rest there was substantial overlap in species composition between the diet of sheep and goats, especially when analysed over an entire cycle.
    • Nitrogen fertilization, botanical composition and biomass production on mixed-grass rangeland

      Samuel, M. J.; Hart, R. H. (Society for Range Management, 1998-07-01)
      Many studies have reported nitrogen (N) fertilization of rangeland, but few have reported changes in botanical composition, which may be as important as changes in forage production, or were continued for as long as 14 years. We determined frequency of occurrence of over 90 plant species in 1976-1988 under rates of 0, 22, or 34 kg N ha-1 applied in spring or fall to mixed-grass rangeland in southeast Wyoming; frequency of 23 species will be reported. We also determined total biomass production and production of major species and species groups in 1982-1988. Blue grama Bouteloua gracilis (H.B.K.) Griffiths] frequency decreased during years 5 through 7 because of the interaction of N and drought. The effects of long-term application of N decreased blue grama in year 12 and beyond. Nitrogen fertilization increased frequency of western wheatgrass [Pascopyrum smithii (Rydb.) A. Love] in all years except the driest year of the study. Needleleaf sedge [Carex eleocharis Bailey] decreased because grazing had been removed from the study area; this occurred sooner and to a greater extent on fertilized than on unfertilized plots. Fourteen other perennial species were quite variable in response to the 3 rates and the 2 seasons of application. Frequency of 6 annual species fluctuated greatly among years and treatments. Nitrogen fertilization did not increase average forage production enough to be profitable for cattle production.