• Water balance in pure stand of Lehmann lovegrass

      Frasier, G. W.; Cox, J. R. (Society for Range Management, 1994-09-01)
      Lehmann lovegrass (Eragrostis lehmanniana Nees), an introduced warm season grass, has invaded grasslands in southern Arizona, in many areas replacing the native warm-season grasses. A water balance evaluation in a pure stand of Lehmann lovegrass showed that more soil water was used through evapotranspiration than occurred as precipitation during 2 years of a 3-year study period. During the winter season, an appreciable amount of water was used by Lehmann lovegrass or lost by evaporation from the soil surface. The remaining available soil water was used in the spring dry period. In the dry early spring the soil water contents (to depths of 120 cm) were less than the traditional wilting point tension of -1.5 MPa. The invasion of Lehmann lovegrass into grasslands of southern Arizona is partially related to its ability to utilize soil water during parts of the year when the native species are dormant and also to extract water from the soil profile to very low water contents.
    • Variation of BLM employee attitudes toward environmental conditions on rangelands

      Richards, R. T.; Huntsinger, L. (Society for Range Management, 1994-09-01)
      Using survey data collected as part of a comprehensive reevaluation of the Vale Rangeland Rehabilitation Project in eastern Oregon, this exploratory study examined variation in attitudes of Bureau of Land Management (BLM) employees toward rangeland environmental conditions. Almost one-half of the BLM employees surveyed believed the loss of streamside vegetation (48%) and streambank erosion (42%) were widespread problems on Vale rangelands. Approximately a quarter of the respondents believed rangeland soil loss (24%) and overgrazing (26%) were problems, while only a tenth believed water pollution (10%) was a problem on many or most areas. A composite scale of these attitude toward environmental conditions on rangelands was developed and assessed. The composite scale was regressed on respondents' regional affiliation, length of service, and ideological attitudes towards government role in natural resource management. In contrast to findings from studies for USFS employees, attitudes toward range environmental conditions were not determined by regional affiliation or length of service (P > 0.05). Rather, BLM employee attitudes toward range environmental conditions were found to vary by the interaction of length of service in the agency and attitude toward government's role in regulating water quality (P < 0.05) and managing livestock grazing (P < 0.01). As length of service increases, core beliefs, professional norms, or client constituencies may not polarize employee attitudes but rather moderate them over time. The accumulation of environmental knowledge may also tend to influence environmental attitudes so that ideological attitudes may have a weaker effect as time passes and expertise expands.
    • Understanding cause/effect relationships in stocking rate change over time

      Rowan, R. C.; White, L. D.; Conner, J. R. (Society for Range Management, 1994-09-01)
      Decisions made by Texas ranchers over a 10 year period (1980-1990) concerning stocking rate levels were dominated by perceptions about weather. A regression model explained 64% of the variability in stocking rate change over time, with the rainfall/drought variable explaining the majority of variability. As ranchers' perception of a positive rainfall effect increased, so did stocking rates, and vice versa. Although the presence or absence of rainfall cannot be managed per se, proactive stocking decisions should include a strategy for adjusting stocking levels in response to changing environmental conditions. Other factors with significant (alpha = 0.05), albeit trivial, path coefficients on stocking rate change were age, grazing rights (owned vs. leased), traditional stocking rate factors, traditional grazing program factors, and weed/brush information factors. Older ranchers (> 65 years) and ranchers who leased all of their rangeland tended to decrease stocking rates over time. Rangeland operators indicated they considered "improved livestock performance" as the most important benefit from initiating a grazing program. Evidence also suggested that ranchers who rely on their neighbors for advice about weed/brush decisions are not benefitting from the latest technology information. Adoption of economic factors (cost/benefits) for selection of weed/brush technology did not have a significant impact on stocking rates over the 10 year period.
    • Toxic alkaloid levels in tall larkspur (Delphinium barbeyi) in western Colorado

      Pfister, J. A.; Manners, G. D.; Gardner, D. R.; Ralphs, M. H. (Society for Range Management, 1994-09-01)
      Consumption of tall larkspur (Delphinium barbeyi L. Huth.) can be fatal to cattle grazing mountain rangeland during summer. Tall larkspur contains many alkaloids, but virtually all the toxicity is caused by methyl succidimido anthranoyl lycoctonine-type (MSAL) diterpenoid alkaloids. We measured the concentration of MSAL alkaloids (% of dry matter) in tall larkspur in various phenological stages during 1990, 1991, and 1992 near Yampa, Colorado. The site represented tall larkspur-infested rangelands on the western slope of the Rocky Mountains. Toxic alkaloid concentrations were greatest (0.4 to 0.6%) early in the growing season (bud stage). Toxic alkaloid concentrations were generally static during the flower and pod stages, or increased during the pod stage. Immature leaves had greater MSAL alkaloid concentrations early in the growing season compared to flowering parts. Alkaloid concentrations in pods were greater than in leaves (P<0.05; pod stage), as pod concentrations increased to 0.4% late in the growing season. In 2 of 3 years, plant parts did not differ in MSAL alkaloid concentrations, although weather conditions differed each year. Concentrations of toxic alkaloids did not seem to influence amounts of tall larkspur consumed by grazing cattle on the same sampling dates. Many livestock producers defer grazing of tall larkspur ranges until the plant is in the pod stage because of a general belief that toxicity is greatly reduced. Our results suggest that grazing tall larkspur ranges during the pod stage may exacerbate cattle losses if MSAL alkaloid concentrations do not decrease, yet consumption by cattle increases.
    • Technical Note: Mechanical despining of plains pricklypear

      Mueller, D. M.; Forwood, J. R. (Society for Range Management, 1994-09-01)
      Plains pricklypear cactus (Opuntia polyacantha L.) is abundant on the Central Great Plains, producing dry matter yields from 1,500 to 2,000 kg/ha. Although pricklypear is high in energy and palatable, long sharp spines make it, and vegetation immediately surrounding it, unavailable to livestock. The possibility of simultaneously controlling and feeding plains pricklypear led to development of machinery for harvesting and despining cactus. The mechanical despiner described here adequately removed spines from pads during periods of low relative humidity. Softening of cactus spines due to high relative humidity resulted in failure of the despiner to adequately remove spines. Cattle readily ate despined cactus in the winter when green forage was unavailable.
    • Tannin and in vitro digestibility of tropical browse: predictive equations

      Conklin, N. L. (Society for Range Management, 1994-09-01)
      Summative equations to predict digestibility of tropical browse species for cattle were tested by comparison to in vitro digestibility. Four equations were used for the comparison: first the 2 Van Soest equations, 1 using sulfuric acid lignin and the other using permanganate lignin, neither of which have a correction for tannins. And second, the 2 Horvath equations, each using 1 of the 2 above mentioned lignin values and both include a value for tannin content. The Van Soest equation using permanganate lignin and the Horvath equation using sulfuric acid lignin predicted the in vitro digestibilities of the leaf species quite well (r = 0.89 for both). The same Horvath equation predicted the digestibility of the high tannin species better than the Van Soest equation (r = 0.93 versus 0.84). For initial evaluation and ranking of browse species suitable for future research efforts, either equation suitable.
    • Regional differences among Texas rangeland operators

      Rowan, R. C.; White, L. D. (Society for Range Management, 1994-09-01)
      Based on a 1990 mail survey of Texas beef cattle producers owning and/or operating rangeland, 54% are older than 56 years, but nearly 95% had completed a high school education. Seventy-five percent of total family income came from livestock production, off-ranch employment, and off-ranch investments. Percent of total income from off-ranch investments, off-ranch employment, livestock production, and wildlife production varied with location (vegetation/resource management region). As ranch location progressed from east (humid) to west (arid) ranches became larger, the proportion of livestock income increased, and rancher's reliance on off-ranch employment decreased. Leasing additional rangeland increased the percentage of livestock income and probably increased labor responsibilities which precluded the opportunity (or need) to work off of the ranch. Number of years of ranching experience, rancher age, and the type of animal enterprises also influenced percentages of family income from various sources. More brush control using mechanical, herbicide, and fire techniques was planned when ranchers perceived that more than 49% of their rangeland needed treatment. Less mechanical control and more herbicide use was planned for weed control when ranchers perceived that more than 50% of the area needed treatment.
    • Preliminary response of Sandhills prairie to fire and bison grazing

      Pfeiffer, K. E.; Steuter, A. A. (Society for Range Management, 1994-09-01)
      This research determined the preliminary response of sandhills prairie to spring and summer prescribed burns, and their interaction with bison (Bison bison) grazing. Changes in species composition and standing crop were determined for paired (caged/uncaged) plots established in burned and unburned areas during the 1991 and 1992 growing seasons. End of season standing crop of both rhizomatous grasses and bunchgrasses was increased by spring burning on sands range sites. Summer burning did not affect rhizomatous grass standing crop, but dramatically reduced bunchgrass standing crop. On burned areas, bison grazing reduced bunchgrass standing crop by 56%, while reducing rhizomatous grass standing crop by only 18%. Forbs generally appeared unaffected by bison grazing and were affected variously by burning. The current bunchgrass composition of Nebraska Sandhills prairie appears dependent on fire exclusion. With fire, a replacement of bunchgrass with rhizomatous grasses may increase available forage, but also increase the risk of wind erosion, particularly on choppy sands range sites.
    • Perceptions vs. recommendations: A rangeland decision-making dilemma

      Rowan, R. C.; Ladewig, H. W.; White, L. D. (Society for Range Management, 1994-09-01)
      This paper analyzes subjective perceptions of Texas ranchers concerning management decision-making to obtain insight for improving technology transfer. Correlations among variables from a 1990 mail questionnaire were transformed by principal component analysis into a small number of "new" variables representing unobservable patterns of behavioral similarities. Two principal components explained variability in rancher's perceptions for each of the areas of interest: stocking rate factors, grazing program benefits, and weed/brush treatment techniques. Stocking rate and grazing program components were each characterized by traditional and nontraditional factors. Ranchers perceived the primary benefit from instituting a grazing program to be improved livestock performance (traditional grazing component 1). Some modification of ranchers' perceptions about the primary benefits of grazing programs is indicated. Weed/brush decision-making was characterized by information-source and economic factors. The information-source component was defined by the importance of advice from neighbors and fear of treatment methods. Because these tend to be negative perceptions, both of these variables have the potential for restricting adoption of weed/brush technology.
    • Observation: Cattle diets on excellent and good condition Chihuahuan desert rangelands

      Smith, G.; Holechek, J. L.; Cardenas, M. (Society for Range Management, 1994-09-01)
      Information is limited on the influence of range condition on cattle diets in the Chihuahuan desert. Botanical composition of cattle diets on Chihuahuan desert ranges in excellent and good condition was studied by microhistological analysis. Cattle feces were analyzed seasonally from fall 1991 through fall 1992. Excellent condition and good condition ranges supported 86% and 72% of the climax vegetation, respectively. Key species in cattle diets on the excellent condition range were black grama (Bouteloua eripoda Torr.) and threeawns (Aristida spp.). On the good condition range the key species were dropseeds (Sporobolus spp.), threeawns and black grama. Total grass and black grama content of cattle diets were greater on the excellent condition range. Seasonal trends occurred in cattle diets on good condition but not on excellent condition range. Low availability of forbs and shrubs explained the high diets similarities among seasons on the excellent condition range. Cattle on good condition range readily used forbs and shrubs when green grass was unavailable. Nitrogen and phosphorus analyses of fecal samples indicated diets were nutritionally superior on the good compared to the excellent condition range. Our research and other studies show consumption of forbs and shrubs permits cattle to maximize their nutritional welfare when grasses are dormant. The excellent condition range in our study had a different(P<0.05) mean grass standing crop (999 kg/ha) across periods compared to on the good condition range (659 kg/ha). Based on our research and other studies excellent condition Chihuahuan desert range maximizes forage quantity for cattle but good condition range appears better from a nutritional standpoint in the spring and early summer. Our research and other studies indicate Chihuahuan desert ranges dominated by black grama are most effectively used in winter while ranges with a high dropseed component are best suited for use in summer and early fall.
    • Individual variation of in vitro dry matter digestibility in moose

      Pehrson, Å.; Faber, W. E. (Society for Range Management, 1994-09-01)
      The in vitro technique for estimating relative digestion rates in ruminants on various forages has created conflicting results in a number of investigations. Some studies show both inter- and intraspecific variation in the ability of inocula to digest the same substrate, while the results of other studies do not verify this potential source of error. This study was designed to compare variation in in vitro dry matter digestibility (IVDMD) using inocula from 8 different moose. Further, samples were taken from 3 different parts of the rumen, cranial sac, ventral sac, and ventral blind sac, in order to look for potential variation in inoculum quality within the rumen. The moose were collected on 3 consecutive days in October 1990. Current year growth of Scots pine (Pinus sylvestris L.) collected immediately before the experiment was used as substrate. The results showed considerable differences between inocula from different animals in digestion of the substrate. Sex or age of inoculum donor did not account for the variability, and site of origin from within the rumen had a significant impact on IVDMD only in 1 animal. A botanical analysis of the rumen contents from the moose showed considerably variation in the proportion of pine and dwarf shrubs (Ericaceae), the main food types consumed. These feeding differences were not reflected in the IVDMD results.
    • Effect of forage seeding on early growth and survival of lodgepole pine

      Powell, G. W.; Pitt, M. D.; Wikeem, B. M. (Society for Range Management, 1994-09-01)
      Smooth bromegrass (Bromus inermis Leys.), orchardgrass (Dactylis glomerata L.), alsike clover (Trifolium hybridum L.), and a mixture by mass of 40% orchardgrass, 40% alsike clover, and 20% white clover (Trifolium repens L.), were sown at 0.5, 1.5, 3.0, 6.0, and 12.0 kg/ha on a forest clear-cut in the southern interior of British Columbia. The seeding treatments were monitored for 3 growing seasons following planting to determine their influence on the growth, survival and damage of planted one-year old lodgepole pine (Pinus contorta var. latifolia Engelm.) seedlings. Competing vegetation reduced lodgepole pine diameter by up to 38% (P < 0.004) and heights by up to 30% (P < 0.005). Lodgepole pine basal diameters (P < 0.002), height (P < 0.02) and survival (P < 0.03) decreased linearly with increasing forage seeding rate. Lodgepole pines planted with smooth bromegrass had up to 59% larger (P < 0.01) diameters and were up to 33% taller (P < 0.06) than those planted with orchardgrass at equal seeding rates by mass. Lodgepole pine cumulative mortality was 2 to 5 times greater (P < 0.0001) on plots sown to alsike clover compared to plots sown with smooth bromegrass or orchardgrass. Rodent damage peaked between the first and second growing seasons at 24% of the lodgepole pine seedlings; rodent damage was similar (P > 0.05) among the treatments and controls, and conifer survival was independent (P > 0.05) of rodent damage.
    • Economic feasibility of controlling tall larkspur on rangelands

      Nielsen, D. B.; Ralphs, M. H.; Evans, J. O.; Call, C. A. (Society for Range Management, 1994-09-01)
      Larkspur (Delphinium spp.) poisoning of cattle poses a serious economic problem on many western rangelands. Losses varied from 1.5% to 12.3% of the grazing cattle over a 15-year period on the Manti Canyon grazing allotment. Three herbicides and different application methods were compared for control of tall larkspur. The 3 herbicides were: glyphosate [N-(phosphonmethyl) glycine]; picloram (4-amino-3,5,6- trichloro-2-pyridine carboxylic acid); and metsulfuron 2[[[[(4-methyoxy-6-methly-1,3,5-triaxin-2-yl) amino] carbonyl] amino] sulfonyl] benzoic acid. A boom type sprayer and a carpeted roller applicator were tested for the selective herbicides. Spot treatment and backpack sprayers were tested for the nonselective herbicide (metsulfuron). The internal rate of return was used to evaluate the economic feasibility of each alternative control method. A treatment was considered economically feasible if the internal rate of return was equal to or higher than the cost of borrowing money. Each treatment was evaluated for an assumed cattle death loss of 4.5% and 2.25%. A 10-year life was considered for each treatment. All of the herbicides and application methods tested were economically feasible. The internal rates of return varied from 14.23% to 133.38%. An internal rate of return above 100% occurs when the benefits in a single year exceeds the total cost of control. The cost of herbicides have increased considerably over the past few years, but they can still be used economically if treatment results in death loss reductions described in this study.
    • Changes in pinyon-juniper woodlands in western Utah's Pine Valley between 1933-1989

      Yorks, T. P.; West, N. E.; Capels, K. M. (Society for Range Management, 1994-09-01)
      Changes in woodland vegetation integrate the consequences of livestock grazing intensity, the alteration of fire regimes, and possible climate alterution, as well as other factors. Quantitative measurements of these changes, if taken over sufficient intervals, can allow evaluation of conservation management strategies. In 1933, vegetation along a 37-km transect in southern Pine Valley, Utah was described from circular 19-m2 plots located every 42 m. The major intermediate management treatment has been reduction of grazing pressure by introduced animals, although a fraction of the area was chained and burned in 1977. During a period climatically and phenologically similar to the original study, we reexamined representative segments of this transect by a more detailed updating of the original "square-foot-density" method. Significantly greater shrub and perennial grass covers (more than threefold increases) were found in 1989, even where overall dominance is still by pinyon-juniper [Pinus monophylla (Torrey & Fremont) and Juniperus osteosperma (Torrey) Little]. This change is more obvious on steeper slopes away from roads and water, where both human and livestock disturbances would be expected to be minimized. Except in the chained portion, the observed shifts in dominance/diversity are contrary to widely accepted expectations.
    • Airborne synthetic aperture radar analysis of rangeland revegetation of a mixed prairie

      Smith, A. M.; Major, D. J.; Hill, M. J.; Willms, W. D.; Brisco, B.; Lindwall, C. W.; Brown, R. J. (Society for Range Management, 1994-09-01)
      Microwave radar is a potentially useful tool for monitoring the condition of the rangeland. A study was conducted in a mixed prairie community at the Agriculture Canada Research Substation at Onefour, Alberta in 1991 to examine the effects of historical management on synthetic aperture radar (SAR) data obtained from 2 aircraft flights, 24 May 1991 and 1 August 1991. Ground-truthing expeditions were conducted on the same days to obtain estimates of vegetation amounts, species distribution and soil moisture. A former grazing experiment established in 1955 and abandoned 20 years ago enabled comparison of 3 grazing treatments, continuous, rotation and free choice superimposed on native range, crested wheatgrass (Agropyron cristatum (L.) Gaertn.) and Russian wildrye (Elymus junceus Fish.). The ground data and imagery were integrated in a Geographic Resource Analysis Support System (GRASS). Fields that had been cultivated and seeded to Russian wildrye had higher radar backscatter than native range. The radar backscatter from crested wheatgrass fields was similar to native range in May but higher than native range in August. Radar backscatter was positively correlated with number of years since seeding with Russian wildrye. Generally there was little difference in radar backscatter with grazing treatment. Correlation analyses between radar digital number extracted from the ground truth sites and vegetation and soil parameters revealed, depending upon swath mode, significant relationships between radar backscatter and the amount of certain grass species, radar backscatter and canopy moisture, and radar backscatter and soil moisture in May. A significant negative correlation was observed between radar backscatter from the August images, in both swath modes, and percent ground cover. The results of this study indicated a role for SAR imagery in evaluating range characteristics.