• Diet selection and utilization by llama and sheep in a high altitude-arid rangeland of Bolivia

      Genin, D.; Villca, Z.; Abasto, P. (Society for Range Management, 1994-05-01)
      Botanical composition of llamas and sheep diets were quantified monthly during 1 year in the arid highlands of Bolivia to identify competition between these species for forage resources. Results indicated higher proportions of coarse bunchgrasses in llamas diets (48 to 75%) than in sheep (37 to 68%), while sheep consumed more soft herbs and grasses than llamas (25 to 45%, and 8 to 25%, respectively). Llamas had higher (P < 0.05) digestion coefficients than sheep for organic matter, dry matter, crude protein, and fiber fractions of the principle bunchgrass paja brava (Festuca orthophylla) during the vegetative phenological stage. Shrubs represented less than 20% of the diet components in both llamas and sheep. A canonical discriminant analysis showed that there was not a strong dietary overlap between these species, and suggested that mixed herds could allow a better utilization of the overall available forage.
    • Harvest date and fertilizer effects on native and interseeded wetland meadows

      Reece, P. E.; Nichols, J. T.; Brummer, J. E.; Engel, R. K.; Eskridge, K. M. (Society for Range Management, 1994-05-01)
      Studies of harvest date by fertilizer interactions on hay meadows are rare and none have been published for prairie meadows. Our objective was to evaluate the effects of initial harvest date (15 June, 15 July, and 15 August) and spring-applied N (0, 45, 90, and 135 kg ha-1) on first cutting and regrowth dry matter yield and forage quality from native and interseeded wetland meadow sites. Regrowth was harvested on all plots in late September. 'Garrison' creeping foxtail (Alopecurus arundinaceus Poir.) was interseeded on plots 4 years prior to application of treatments. Native vegetation was dominated by sedges (Carex spp.). Interseeded plots were dominated by Garrison creeping foxtail. Yield and quality on different dates and response to N were similar for vegetation types despite differences in duration of spring flooding between years. Harvest date by fertilizer interactions occurred for first cutting yield and crude protein concentration. Yield response to applied N ranged from 8.5 to 31.2 kg ha-1 kg-1 N. Fertilizer had no effect on digestibility and increased crude protein concentration only in herbage harvested on 15 June. Within levels of N, first cutting yield was about 60% of peak standing crop on 15 June and 90% on 15 July compared with 15 August. Greater plant growth rates and response to N after prolonged spring flooding compensated for initial differences between years by 15 July. Regrowth dry matter yield was not affected by spring-applied N and increased by about 43 kg ha-1 day-1 after initial harvest in both years. Sedge-dominated, prairie meadows are productive and provide predictable forage and wildlife habitat management alternatives.
    • Sixty-one years of secondary succession on rangelands of the Wyoming high plains

      Samuel, M. J.; Hart, R. H. (Society for Range Management, 1994-05-01)
      The slow and uncertain rate of recovery of plant communities after severe disturbance is a major problem on rangelands. Earlier studies sketched the outline of secondary succession on mixed-grass prairie, but were based on 1 or 2 years of observation on different areas disturbed at different times in the past, or several years of observation of a single area. To provide a more complete picture of succession over decades, we began observations in 1977 on 4 areas disturbed from 1 to 51 years previously, and on undisturbed areas of the same 2 soil types with and without grazing. Observations continued for 11 years. Secondary succession proceeded through the usual stages: annual forbs, perennial forbs and annual grasses, short-lived perennial grasses, and long-lived grasses. Western wheatgrass [Pascopyrum smithii (Rydb.) A Love] was an exception because it appeared much earlier and in much greater abundance than other long-lived perennial grasses. Blue grama [Bouteloua gracilis (H.B.K.) Lag ex. Steud.) may be another exception; total recovery of this grass may require centuries. Time of appearance in succession seemed to be related to availability of propagules and ease of establishment; persistence of species was related to competitive ability. Abundance of many species fluctuated widely from year to year, but fluctuations did not appear to be related to precipitation. After 61 years, secondary succession had not returned plant communities to the climax state.