• Herbage dynamics on 2 Northern Great Plains range sites

      Heitschmidt, R. K.; Grings, E. E.; Haferkamp, M. R.; Karl, M. G. (Society for Range Management, 1995-05-01)
      Quantity and quality of forage produced are primary determinants of level of livestock production derived from grazing lands. Moreover, species composition of herbage is often considered a primary determinant of the ecological condition of rangelands. The broad objective of this study was to quantify the productivity, growth dynamics, and quality of herbage growing on 2 Northern Great Plains range sites and to concurrently relate magnitude and composition of production to the ecological condition of the sites. Using frequent harvest techniques, the 2-year study showed herbage production on the highly productive silty range site averaged 219 g m-2 as compared to 218 g m-2 on the supposedly less productive clay pan range site. The primary reason the clay pan site proved to be as productive as the silty site was attributed to the greater amounts of introduced annual grasses on the clay pan (148 g m-2) than the silty site (104 g m-2). The annual grass component on the clay pan was a near equal mix (71 vs 51 g m-2) of Japanese brome (Bromus japonicus Thunb.) and cheatgrass (B. tectorum L.) whereas the overwhelming dominant on the silty site was cheatgrass (73 g m-2). Western wheatgrass [Pascopyrum smithii Rydh. (Love)] was the dominant perennial grass on both sites averaging 49 g m-2 on the clay pan site and 57 g m-2 on the silty site. There were minimal differences between sites in terms of nutrient quality values (i.e., crude protein, acid detergent fiber, neutral detergent fiber) with results showing clearly that age of tissue was the major factor altering seasonal forage quality values. Range condition analyses revealed the clay pan site was in fair ecological condition and the silty site was in good condition. Study results demonstrate the need for land management agencies to continue to refine productivity estimates as well as adopt new techniques for assessing the ecological condition of rangelands.
    • Influence of an environmental gradient on physiology of singleleaf pinyon

      Jaindl, R. G.; Eddleman, L. E.; Doescher, P. S. (Society for Range Management, 1995-05-01)
      The acquisition of water and regulation of its loss are important to plant 'success' in arid environments. Species existing over a range of environmental conditions should respond physiologically to varying conditions to maximize water use efficiency and avoid low tissue water potentials. Seasonal and diurnal ecophysiological responses of singleleaf pinyon (Pinus monophylla Torr. and Frem.) were investigated along an environmental gradient involving elevation, moisture and temperature in Nevada. The gradient was represented by study sites in black sagebrush (Artemisia nova A. Nels), mountain big sagebrush (Artemisia tridentata ssp. vaseyana Nutt.), and mountain mahogany (Cercocarpus ledifolius Nutt.) communities. Xylem pressure potential, conductance, and transpiration were measured over 2 growing seasons. Xylem pressure potential and leaf conductance ranged from -3.0 to -0.7 MPa and 0.01 to 0.43 cm s-l, respectively, during the study. Carbon isotope discrimination (delta) of needles was determined in August 1990. Differences in delta values were not significant between sites at the lowest and highest elevations but were significant between the driest site (black sage) and the relatively wetter site (mountain mahogany). Leaf conductance was influenced by but not strongly correlated with predawn xylem pressure potentials, relative humidity, and temperature. Generally, there was little difference in water use characteristics of singleleaf pinyon along the environmental gradient in this study. Thus, it appears that singleleaf pinyon's ability to exist over a range of environmental conditions is not a function of variable ecophysiological responses but an opportunistic response to the availability of resources and conditions suitabie for erowth to occur.
    • Influence of temperature on germination of Japanese brome seed

      Haferkamp, M. R.; Palmquist, D.; Young, J. A.; MacNeil, M. D. (Society for Range Management, 1995-05-01)
      Japanese brome (Bromus japonicus Thunb.), an introduced annual grass, is now common in some northern mixed-prairie communities. This species has the potential to alter both the seasonality of standing crop and forage quality. We sought to gain a greater understanding of Japanese brome seed germination by subjecting seed to a series of 55 constant or alternating temperature regimes following 3 to 9 months of dry laboratory storage. Cold and moderate temperature regimes provided optimum germination conditions (defined as not lower than the maximum observed minus one-half its confidence interval at the 0.05 level of probability). Extremely cold or warm temperatures suppressed germination. Germination of afterripened seed over a wide range of temperature combinations, many of which occur during fall in the Northern Great Plains, should enhance establishment and perpetuation of Japanese brome on rangelands.
    • Livestock grazing impacts on interrill erosion in Pakistan

      Bari, F.; Wood, M. K.; Murray, L. (Society for Range Management, 1995-05-01)
      This study was conducted for 2 consecutive growing seasons in a temperate region of Pakistan to determine a residual phytomass level necessary to adequately protect the soil against accelerated interill erosion A rainfall simulator was used to apply rainfall to 48 (1 m square) circular plots arranged in a completely randomized experimental design, with 4 residual phytomass levels and 2 replications. The residual treatment with 3,024 kg ha-l phytomass resulted in the lowest erosion rates, and the treatment with 624 kg ha-l phytomass produced the highest erosion. Standing phytomass was the most important variable affecting erosion with foliar cover and basal cover also highly correlated to erosion.
    • New concepts for assessment of rangeland condition

      Adams, D. C.; Short, R. E.; Pfister, J. A.; Peterson, K. R.; Hudson, D. B. (Society for Range Management, 1995-05-01)
      Range condition score or classification does not tell us, in a general sense, much of what managers and the public want to know about rangelands. Range condition is not a reliable indicator, across all rangelands, of biodiversity, erosion potential, nutrient cycling, value for wildlife species, or productivity. Succession, the basis for the current concept of range condition is not an adequate yardstick for evaluation of rangelands. The Society for Range Management (SRM) established the Task Group on Unity in Concepts and Terminology which has developed new concepts tor evaluation of the status of rangelands. These concepts are based on the premise that the most important and basic physical resource on each ecological site is the soil. If sufficient soil is lost from an ecological site, the potential of the site is changed. The Task Group made three recommendations, which were adopted by the SRM: 1) evaluations of rangelands should be made from the basis of the same land unit classification, ecological site; 2) plant communities likely to occur on a site should be evaluated for protection of that site against accelerated erosion (Site Conservation Rating, [SCR]); and 3) selection of a Desired Plant Community (DPC) for an ecological site should be made considering both SCR and management objectives for that site.
    • Observation: Botanical and other characteristics in Arctic salt-affected coastal areas

      Bruce, L. B.; Panciera, M. T.; Gavlak, R. G.; Tilman, B. A.; Cadle, J. M. (Society for Range Management, 1995-05-01)
      This study was designed to provide information on cover, botanical composition, and frequency of major plant species in a brood-rearing area used by migratory geese south of Howe Island on the Sagavanirktok River Delta near Prudhoe Bay, Alaska. The area is split by the Endicott road and the information was also used to gain preliminary information concerning the effect of the road on goose and caribou activity. Transects on the east and west sides of the access road at the base of the Endicott causeway were established to evaluate occurrences of vegetation, goose fecal pellets, caribou tracks, and coastal debris. The point intercept method characterized plant cover, species frequency, and botanical composition. The recorded occurrence of fecal pellets and tracks on the transects were used as estimates of the presence of geese and caribou. Vegetative cover was 21% west and 38% east of the road near the Endicott causeway base in 1991. The 3 species most prominent west of the road were Carex sub-spathacea Wormsk., Salix spp., and Puccinellia phryganodes (Trin.) Scribn. & Merr. (botanical composition of 26, 23, and 21%, respectively). East of the road, Salix spp. (43%) dominated botanical composition followed by Carex aquatilis Wahlenb. (13%) and Dryas integrifolia M. Vahl (11%). The west and east sides differed botanically. Caribou tracks were observed in 60% of the transects on both sides of the road and goose fecal pellets were more prevalent on the west side (86%) than on the east side (48%). Geese pellets and caribou tracks occurred in different locations in the study area. Goose fecal pellets were from all goose species and may have included more than 1 year.
    • Technical Note: Physical factors that influence fecal analysis estimates of herbivore diets

      Bartolomé, J.; Franch, J.; Gutman, M.; Seligman, N. G. (Society for Range Management, 1995-05-01)
      Microhistological analysis of epidermal fragments in feces is often used to estimate the diet of herbivores but is not generally accepted as a consistently reliable method. Gross errors arise, especially when diets are composed of herbage components with widely different morphological and structural characteristics. The present study investigated the possibility of using such physical characteristics to improve the reliability of the method. Over a 7 day period, 4 rumen-fistulated beef cows were given a fixed diet composed of a shrub, a grass, and a forb component. On the last 2 days, samples of rumen content and feces were taken for analysis of epidermal fragment. Forbs were under-estimated, grasses over-estimated, and shrubs correctly estimated. Correction factors to estimate true diet composition were defined as the biomass represented by the specific epidermal fragments (epidermal weight index) and the degree of degradation to which the epidermis is subjected in the digestion process (epidermal erodibility factor). These factors account for characteristic physical features of the different dietary components and were measured directly or were derived from the calibration experiment. The utility of such factors depends on accurate determination of the component variables and may be overshadowed by sampling error and observer bias in the microhistological identification of epidermal fragments.