• Changes in shrub fecundity in fourwing saltbush browsed by cattle

      Cibils, A. F.; Swift, D. M.; Hart, R. H. (Society for Range Management, 2003-01-01)
      Shrub fecundity is critical to long term persistence of fourwing saltbush (Atriplex canescens (Pursh) Nutt.) populations at our research site on the shortgrass steppe in Colorado. We conducted a 2-year experiment to test hypotheses concerning the impact of cattle-browsing on fecundity-related variables in fourwing saltbush. Protection from cattle browsing was significantly associated with floral phenotype shifts toward femaleness, occurring mostly in monecious shrubs (1% and 13% of grazed and protected shrubs, respectively). Sex shifts observed at the individual shrub level did not translate into detectable alterations of sex ratios at the pasture level. Shrubs exhibiting no flowers were considerably more abundant in browsed pastures (26.5%) than in exclosures (1.5%). Nonflowering occurred as frequently in female (3.6%) as it did in male (1.8%) phenotypes. Percent utricle fill was not related to previous year's cattle browsing regime (39% and 44% in protected and grazed shrubs, respectively) but rather to crown volume of the fruiting female and to the gender of and distance to the nearest neighboring shrub. The influence of cattle-browsing on reproductive output of fourwing saltbush occurred mainly through its inhibition of flowering.
    • Comment: "Perspectives on water flow and the interpretations of FLIR images" J. Range Manage. 55:106-111 2002

      Beschta, R. L.; McIntosh, B. A.; Torgersen, C. E. (Society for Range Management, 2003-01-01)
      Reply by S.L. Larson, L.L. Larson, and P.A. Larson, p. 100-101.
    • Converting mesquite thickets to savanna through foliage modification with clopyralid

      Ansley, R. J.; Kramp, B. A.; Jones, D. L. (Society for Range Management, 2003-01-01)
      Honey mesquite (Prosopis glandulosa Torr.) is a problem plant in much of the southwestern USA because it reduces forage production for livestock, interferes with livestock handling and reduces off-site water yield. Aerial spraying a 1:1 mixture of clopyralid (3,6-dichloro-2-pyridinecarboxylic acid, mono-ethanolamine salt) and triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid, butyoxyethyl ester) at 0.28 kg ae ha-1 + 0.28 kg ae ha-1 usually achieves high above-ground (top-kill) and whole plant (root-kill) mortality, but limits multiple-use options of livestock and wildlife production because little mesquite foliage is left to provide screening cover for wildlife. In addition, most surviving plants resprout from basal meristems and will become multi-stemmed plants. Some managers treat mesquite in strips or blocks, leaving untreated areas for screening cover, but these areas become increasingly non-productive for livestock and wildlife forage. The objective of this study was to evaluate the potential of aerial sprays of clopyralid alone at 0.28 kg ha-1 to convert thickets of mature, multi-stemmed mesquite to savannas by reducing mesquite foliage amount to an intermediate level (by 50-70%), yet preserving apical dominance and limiting basal sprouting. The clopyralid treatment was compared to an untreated control and aerial sprays of 0.28 kg ha-1 clopyralid + 0.28 kg ha-1 triclopyr on 2 sites. The clopyralid treatment reduced foliage amount tree-1, canopy area tree-1, and stand-level mesquite cover by > 57% when compared untreated areas, and 73% of surviving trees maintained apical dominance. Apical dominance was maintained in > 70% of trees not totally top-killed if at least 20% of the original canopy survived and produced foliage following the spray year. Percent root-kill in the clopyralid-only treatment differed between sites (34 and 10%). The lower root-kill on one site was attributed to rainfall that occurred 2 days before and one day after spraying. The clopyralid+triclopyr treatment reduced foliage on original canopies by > 96% and mesquite cover by 82% on both sites. Root-kill was > 52% on both sites but only 37% of surviving plants maintained apical dominance. Results suggest that clopyralid at 0.28 kg ha-1 may be effective for converting mesquite thickets to savanna and may aid in multiple-use management.
    • Creating low-cost high-resolution digital elevation models

      Louhaichi, M.; Borman, M. M.; Johnson, A. L.; Johnson, D. E. (Society for Range Management, 2003-01-01)
      Ecologists and agronomists are interested in topography because it affects soil, plant, and hydrologic processes. Digital elevation models (DEMs) accurate to several centimeters of vertical elevation are needed but construction is time consuming and expensive when traditional surveying methods are used. Carrier-phase differential global positioning systems can map vertical changes in topography with root mean square errors (RMSE) of 2 to 9 cm, but equipment is expensive (20,000 to 100,000). Coarse-acquisition code differential global positioning systems (C/A code-DGPS) are much cheaper ( 8,000) and widely available but vertical errors are large with root mean square errors of 100 to 200 cm, which severely limits their usefulness in ecological studies. We combined a coarse-acquisition code differential global positioning system and a laser level (1,000) to map topographic change in fields, wetlands, and research plots. Our technique uses the coarse-acquisition code differential global positioning system for longitudinal and latitudinal (X or easting, Y or northing) position while the laser level provides vertical position (elevation) as measured from a ground control point or monument. Measuring elevation across a field scale area is a 2-step procedure. At each sample location the distance from the laser level to the ground is determined and entered as a comment in the differential global positioning systems data logger. In the office, sample locations are differentially corrected and elevation is calculated by subtracting the laser level-to-ground distance from the elevation of the laser. Data is then imported to geographic information system (GIS) software that interpolates between points. The differential global positioning system yields X, Y locations with a root mean square error of between 0.5 and 1.0 m. Elevations measured with our laser level had anaccuracy of better than 2 cm across its 230 m working radius. Our technique works best for areas up to approximately 40 ha on open, rolling terrain.
    • Date and plant community effects on elk sedge forage quality

      Clark, P. E. (Society for Range Management, 2003-01-01)
      Elk sedge (Carex geyeri Boott) is one of the most important livestock and big game forages in many areas of the western U.S. It is one of the most prominent forage species in the diets of cattle and elk utilizing forested rangelands. Despite its acknowledged ecological and economical importance, very little is known about the factors influencing the forage quality of elk sedge. Effects of sampling date, plant community, and their interaction on the neutral detergent fiber, acid detergent fiber, and crude protein levels of elk sedge are reported for samples collected at the Starkey Experimental Forest and Range and the Bridge Creek Wildlife Management Area, both in northeastern Oregon, during January, April, July, and October of 1997 and 1998. Neutral detergent fiber levels in elk sedge were lowest in mid-October (average = 71.3%) and highest in mid-July (average = 76.1%). Acid detergent fiber was lowest in elk sedge collected in mid-October (average = 37.3%) and highest in mid-July (average = 39.0%) and mid-January (average = 39.2%). Elk sedge from the Douglas-fir/ninebark community was lowest in acid detergent fiber (average= 38.1%). Crude protein was highest (average = 8.0%) in mid-July elk sedge samples and lowest (average = 5.7%) in mid-January samples. Elk sedge from the ponderosa pine/fescue community was lowest in crude protein (average = 5.9%). All forage quality parameters exhibited variability between years. Although sampling date and plant community effects were detected, the forage quality of elk sedge appeared relatively stable compared to other native forages. A more intensive spring sampling campaign is needed to characterize the relationship between elk sedge phenology and forage quality dynamics.
    • Diets of plains vizcacha, greater rhea and cattle in Argentina

      Pereira, J. A.; Quintana, R. D.; Monge, S. (Society for Range Management, 2003-01-01)
      Food habits of plains vizcacha (Lagostomus maximus), greater rhea (Rhea americana) and cattle (Bos taurus) in the Parana? River Delta, Argentina, were studied over 2 years using microhistological analysis of faeces. This was the first study of feeding habits of these herbivores grazing in common in a wetland of Argentina. Poaceae was the main diet component throughout the year for all 3 herbivores, with the exception of spring and summer, when greater rhea consumed a higher proportion of Prosopis nigra (Griseb.) pods. Botanical composition of plains vizcacha and cattle diets was generally similar for the same season but different from that of greater rhea. Panicum milioides Nees., Dichondra microcalyx (Hallier) Fabris. and P. nigra were the most consumed species for vizcacha, while P. nigra, Plantago myosuros Lam., Solanum sp. L., Spilanthes stolonifera (H. et A.) Baker and D. microcalyx dominated the greater rhea diet. The species most consumed by cattle were Luziola peruviana Gmel. and P. milioides. Similarities between the diets of plains vizcacha and cattle seem to support the ranchers' view that vizcachas compete with domestic herbivores for forage. However, high overlap in food habits would result in competition only if forage is scarce. Greater rhea and cattle have different foraging patterns and hunting of greater rhea is not justified solely on the basis of forage competition with cattle.
    • Diffuse knapweed and bluebunch wheatgrass seedling growth under stress

      Kiemnec, G.; Larson, L. L.; Grammon, A. (Society for Range Management, 2003-01-01)
      Growth characteristics of diffuse knapweed (Centaurea diffusa Lam.) and bluebunch wheatgrass (Pseudoroegneria spicata (Pursch) Scribn. Smith) seedlings were evaluated in 2 temperature regimes, 10 and 16 degrees C, and 2 moisture regimes, -0.01 and -0.03 MPa, in an environmental chamber. In cool, wet conditions, root penetration was greater for diffuse knapweed roots than bluebunch wheatgrass roots, but penetration was equal in warm, dry conditions. Root lengths for both species were equal in cool, wet conditions; but, bluebunch wheatgrass root length was greater in warm, dry conditions. Leaf area of diffuse knapweed was greater than bluebunch wheatgrass in warm, dry conditions. Drier, but not cooler, conditions favored diffuse knapweed leaf area over bluebunch wheatgrass leaf area. Root:shoot ratios for bluebunch wheatgrass were greater than diffuse knapweed in all environmental conditions. Results suggest that bluebunch wheatgrass should be more competitive than diffuse knapweed for nutrients and water at lower depths in warmer, drier conditions. Diffuse knapweed should be more competitive for nutrients and water in wetter conditions.
    • Female-biased herbivory in fourwing saltbush browsed by cattle

      Cibils, A. F.; Swift, D. M.; Hart, R. H. (Society for Range Management, 2003-01-01)
      Female fourwing saltbush (Atriplex canescens Pursh [Nutt.]) shrubs are more abundant in exclosures than in adjacent grazed pastures at our research site on the shortgrass steppe in Colorado. We hypothesized that female shrubs at this site were being browsed more heavily by cattle than were male shrubs. We conducted a series of 2-year experiments (1997 and 1998) with cattle to measure levels of cattle utilization of male and female shrubs. Overall, utilization of marked leaders was 43.5% in January, 19.7% in April, and 33.4% in September. Percent utilization of marked leaders was consistently and significantly higher on female shrubs both in January (females: 46.5%, males: 40.2%), and September (females: 36.9%, males: 29.9%). In April, differences in utilization of shrub sexes were not significant (females: 20.3%, males: 19.2%). The female-bias in cattle herbivory increased significantly with increasing overall utilization of shrubs. Gender-biased herbivory may have promoted higher mortality among female shrubs, leading to the sex ratio alteration previously observed at this site.
    • In vivo digestibility of kleingrass from fecal nitrogen excretion

      Ferri, C. M.; Stritzler, N. P.; Brizuela, M. A.; Petruzzi, H. J. (Society for Range Management, 2003-01-01)
      It was proposed that the digestibility of organic matter (OMD) can be estimated from the relationship between total fecal nitrogen (TFN, as a % of organic matter intake (OMI) and fecal nitrogen concentration (FNc) through the equation: OMD = 1 - TFN/FNc. Two assumptions are critical to this equation, total fecal nitrogen (as a % of OMI) is a constant and does not change within a range of diet crude protein and fecal nitrogen concentration is proportional to digestibility of organic matter. The objective of this study was to test if total fecal nitrogen (as a % if OMI) remains constant over 3 feeding levels, and if fecal nitrogen concentration decreases with decreasing organic matter digestibility of maturing forages. Total fecal nitrogen did not change (P = 0.94) with feeding level, but increased (P < 0.05) with evaluation period. The fecal nitrogen concentration correlated (r = 0.60, P < 0.001) to digestibility of organic matter. The results show that digestibility of organic matter cannot be estimated from total fecal nitrogen, unless time of year is considered.
    • Lessons in developing successful invasive weed control programs

      Anderson, G. L.; Delfosse, E. S.; Spencer, N. R.; Prosser, C. W.; Richard, R. D. (Society for Range Management, 2003-01-01)
      The development of successful regional or national invasive weed control programs is often hampered by the way the problem is approached. Typically weed control programs are developed and evaluated solely from the perspective of the biological sciences. While this is appropriate from a local or landscape perspective, it will probably not produce the desired results when addressing widespread well-established infestations that impact large regions. The "Ecological Area-wide Management (TEAM) of Leafy Spurge" program was the first U.S. Department of Agriculture (USDA), Agricultural Research Service (ARS) area wide invasive weed program. The 5-year program, funded by the ARS and conducted cooperatively with the USDA Animal and Plant Health Inspection Service, focused on the control of leafy spurge (Euphorbia esula L.) in North Dakota and South Dakota, Montana and Wyoming. Now in its final year (2001), the TEAM Leafy Spurge program has made significant progress in controlling leafy spurge, increasing public awareness of the problem and demonstrating the effectiveness of biologically-based integrated pest management. While this is a significant accomplishment, the lessons learned over the course of the project clearly demonstrate that the success of regional weed control programs depends on more than a persistent, marked reduction in the pest population. Effective regional weed control programs need to focus not only on biological issues, but also on the ecological, scientific, economic, social and legal factors that influence the effectiveness of the program. Therefore, the implementation and subsequent evaluation of a weed control program must include all the principal factors that will ultimately determine success and sustainability. This manuscript outlines the history of leafy spurge on the North American continent, the situation currently facing weed managers, and an evaluation of the TEAM Leafy Spurge program's success for each factor listed above. The final analysis indicates that successful biologically-based leafy spurge control is on the horizon, especially when weed managers understand the number of problem areas that must be addressed to achieve a sustained reduction of a weed population. The amount of time it will take to be realized depends on our commitment to solving the problem and our willingness to work together as a cohesive team.
    • Prescribed fire effects on erosion parameters in a perennial grassland

      O'Dea, M. E.; Guertin, D. P. (Society for Range Management, 2003-01-01)
      A 2-year field experiment was undertaken to quantify the interacting effects of a late-spring prescribed burn and summer rainfall on seasonal runoff and erosion in a southern Arizona grassland. Six blocks with walled subplots (n = 24) were installed on a hillslope to measure changes to plant, soil, and hydrologic variables in response to treatments. Increased bulk density, erosion, and runoff volumes; and lowered plant cover and water intake rates were observed within the burned plots following the first summer season. In the second year, higher bulk density, runoff volumes, and erosion measures were again observed within the burned plots, as well as lower plant cover, aggregate stability, and water intake rates. The results of this study indicate that following late-spring burning, semi-desert grasslands are susceptible to greater summer runoff and erosion compared to unburned grasslands.
    • Understory species response to Utah juniper litter

      Horman, C. S.; Anderson, V. J. (Society for Range Management, 2003-01-01)
      A greenhouse study was conducted to determine the effects of litter leachate and litter depth of Utah juniper [Juniperus osteosperma (Torr.) Little] on seedling emergence and emergence rate of 8 common herbaceous understory species. Species tested were: ‘Secar’ bluebunch wheatgrass [Pseudoroegnaria spicata (Pursh) A. Love], bottlebrush squirreltail [Elymus elymoides (Raf.) Swezey], cheatgrass (Bromus tectorum L.), ‘Paiute’ orchardgrass (Dactylis glomerata L.), ‘Appar’ Lewis flax (Linum lewisii Pursh), ‘Delar’ small burnet (Sanguisorba minor Scop.), antelope bitterbrush [Purhsia tridentata (Pursh) DC.], and mountain big sagebrush [Artemisia tridentata spp. vaseyana (Rydb.) J. Boivin]. Three water treatments (distilled water, 1%, and 10% litter leachates) and 3 litter depths (0, 3, and 5 cm) were tested. Leachates decreased seedling emergence of orchardgrass and small burnet. Emergence rate was unaffected by leachate treatments. Seedling emergence of all species tested decreased significantly with increasing litter depth. Emergence rate was initially slower in pots with litter, but after 2 weeks no differences were found.
    • Vegetation of chained and non-chained seedlings after wildfire in Utah

      Ott, J. E.; McArthur, E. D.; Roundy, B. A. (Society for Range Management, 2003-01-01)
      After wildfires in 1996 in the sagebrush (Artemisia spp.) and pinyon-juniper (Pinus spp.–Juniperus spp.) zones of west-central Utah, the USDI-BLM attempted to reduce soil erosion and cheatgrass proliferation (Bromus tectorum L.) through rehabilitation treatments. We compared the vegetation of aerially seeded, chained treatments with aerially seeded but non-chained treatments for 3 years following seeding. Vegetation cover increased significantly in both treatments between the first and second year, concurrent with above-average precipitation. By the second year, seeded grasses, primarily crested wheatgrass [Agropyron cristatum (L.) Gaertn.] and intermediate wheatgrass [Elymus hispidus (Opiz) Meld. and Elymus elongatus (Host) Runem.], dominated the chained treatment while cheatgrass dominated the non-chained treatment. Seeded grass establishment in non-chained areas was highest beneath dead trees on steep northeast-facing slopes. The first year following the fires, frequency of most annual species and some native perennial species was higher in the non-chained than chained treatment. Native species richness and diversity declined in both treatments between the first and third year following the fires due to the loss of early-seral native annuals and probably because of climatic factors and competition from seeded grasses and cheatgrass. This study reaffirmed the utility of aerial seeding followed by chaining as a rehabilitation technique for rapid establishment of standard plant materials and suppression of cheatgrass, although the implications for soil protection were less clear. Maintenance of native biodiversity on public lands will require greater development and use of native plant materials for wildfire rehabilitation. Planning for future rehabilitation needs is important in light of continuing wildfire risks.