• An Evaluation of Range Condition on One Range Site in the Andes of Central Peru

      Wilcox, B. P.; Bryant, F. C.; Fraga, V. B. (Society for Range Management, 1987-01-01)
      Little published information is available on the vegetation or its response to grazing in the high elevation (3,900-4,800m) grasslands of the Andes, known as the puna. The objective of this study was to evaluate grazing-induced vegetation changes on a major range site in the puna. Basal cover and diversity were compared on (1) rangelands managed by a cooperative of land holders (moderate grazing); (2) communal grazing land (heavy grazing); and (3) sacrifice or holding pastures (very heavy grazing). Basal cover was determined using point transects. With increased grazing pressure standing height of the vegetation was greatly reduced as was vegetation basal cover. Total cover of grasses was reduced while forb cover increased. Ability of a species to grow close to the soil surface probably enabled it to tolerate very heavy grazing. Species diversity as determined by Simpson's D, Shannon-Weaver's H', and species richness was highest on the community lands.
    • Grazing Effects on Water Relations of Caucasian Bluestem

      Svejcar, T.; Christiansen, S. (Society for Range Management, 1987-01-01)
      Caucasian bluestem [Bothriochloa caucasica (Trin.) C.E. Hubb.] is a warm-season grass introduced from Eurasia that is currently used for reseeding rangelands in the southern Great Plains. Although this species is thought to be grazing tolerant, no specific information is available concerning its response to grazing. This study was conducted to evaluate the effect of 2 levels of grazing on xylem water potential and total leaf conductance (gT) of Caucasian bluestem. During the grazing period (mid May to mid September) diurnal xylem water potential and gT measurements were made on 3 days in 1983 and 1984, and afternoon measurements were taken at weekly intervals in 1984. Soil moisture at 15, 45, and 75 cm depths was monitored in 1984. Heavily grazed plants exhibited consistently higher (less negative) xylem water potential, and generally higher gT than lightly grazed plants. Averaged over the season, heavy grazing increased mean afternoon xylem water potential and gT by 28 and 76%, respectively, compared to light grazing. Soil moisture was conserved with heavy grazing; treatment differences were greatest during July, which is generally the driest summer month in central Oklahoma. Thus, for Caucasian bluestem, leaves from heavily grazed swards were under less water stress than leaves from lightly grazed swards.
    • Grazing System Influences on Cattle Performance on Mountain Range

      Holechek, J. L.; Berry, T. J.; Vavra, M. (Society for Range Management, 1987-01-01)
      A 5-year study was conducted to evaluate the influences of rest-rotation, deferred-rotation, and season-long grazing systems on cattle diet botanical composition and quality and weight gains on mountain rangeland in northeastern Oregon. The grazing season in each year lasted from 20 June to 10 October. Esophageally fistulated animals were used to evaluate diet quality and botanical composition. All study pastures included forest, grassland, and meadow vegetation types. Each pasture had a north and southfacing slope divided by a riparian zone and creek. The grazing pressure for each system was similar. Grazing intensity was the same as National Forest Allotments in the area. There were no differences (P>.05) in weight gains among the 3 systems when data were pooled across years. Crude protein, in vitro organic matter digestibility, and acid detergent fiber percentages in fistula samples did not differ (P>.05) among systems for any year of study or for data pooled across years. Mid-season movements of cattle under the rest-rotation system had little influence on their diet and performance compared with cattle under the season-long system. Key forages in cattle diets were Idaho fescue (Festuca idahoensis), bluebunch wheatgrass (Agropyron spicatum), and common snowberry (Symphoricarpos albus). Cattle diet botanical composition under the 3 grazing systems did not differ (P>.05).
    • Influence of Clipping Frequency on Herbage Yield and Nutrient Content of Tall Wheatgrass

      Undersander, D. J.; Naylor, C. H. (Society for Range Management, 1987-01-01)
      Grazing or cutting frequency has been shown to affect yield and quality of many grasses, but similar data are lacking for tall wheatgrass [Agropyron elongatum (Host) Beauv. 'Jose']. The objective of the research was to determine the effect of frequency of clipping on tall wheatgrass. The study was conducted at the Texas Agricultural Experiment Station at Bushland, Texas, in 1979, 1980, 1981, and 1984 on a Pullman clay loam soil. Plots were irrigated as needed from February to the end of the growing season and fertilized with 112kg N/ha every 2 months for maximum yield and clipped either every week, 2 weeks, of 4 weeks at a 5-cm stubble height. Herbage yield was highest from spring harvests and declined over summer as is typical of cool-season grasses. The plots that were clipped every 4 weeks produced greater herbage yields than plots that were clipped 1 or 2 weeks, suggesting that rotational grazing would increase productivity. The nutrient content of the herbage was highest during summer when herbage yield was lowest. Plants clipped less frequently had the highest concentrations of phosphorus and potassium and the lowest concentrations of calcium and magnesium. The greatest differences in nutrient content occurred among years, which emphasizes the importance of continual herbage analysis to optimize mineral supplementation of grazing cattle.
    • The Woody Vegetation of Eastern Senegal

      Dickie, A.; Pieper, R. D.; Dickey, J. R. (Society for Range Management, 1987-01-01)
      The woody component of the vegetation of eastern Senegal was sampled using the point-centered quarter method. Data were evaluated using cluster, principal component, and multiple discriminant analysis (MDA) techniques. Sites were grouped into 8 ecologically significant groups. Six of these groups were considered woodland lateritic sites, and 2 drainage sediment sites. Species of the genus Combretum dominated all sites. The effect of livestock grazing on the botanical composition was inferred through the use of 4 environmental variables as discriminant factors in MDA. A floristic record of species composition and guidelines for management are embodied in the results of the analyses.