• Runoff and erosion in intercanopy zones of pinyon-juniper woodlands

      Wilcox, B. P. (Society for Range Management, 1994-07-01)
      In semiarid pinyon-juniper environments, the principal mechanisms of redistribution of water, sediments, nutrients, and contaminants are runoff and erosion. To study the phenomena underlying these mechanisms, we established six 30-m2 plots, in intercanopy zones, for monitoring over a 2-yr period (1991-1993). Two of the plots were severely disturbed; 4 were undisturbed. We measured the most runoff from these plots during mid summer (generated by intense thunderstorms) and late winter (from snowmelt and/or rain-on-snow). Runoff accounted for 10 to 28% of the water budget over the 2-yr period—a higher proportion than that observed in most other pinyon-juniper woodlands, which is probably explained by the smaller scale as well as the higher elevation of our study area. Runoff accounted for 16% of the summer water budget the first year, with above-average precipitation (and thereby higher soil moisture content) and 3% the second year, when precipitation was about average. Winter runoff was substantial both years as measured on the small scale of our study (no winter runoff was observed in the nearby stream channel). Interestingly, even though precipitation was lower the first winter, runoff was higher. This may be because snowmelt set in about 20 days earlier that year—while the soils were still thoroughly frozen, inhibiting infiltration. Differences between disturbed and undisturbed plots were most evident in the summer: both runoff and erosion were substantially higher from the disturbed plots. On the basis of our observations during this study, we suggest that the following hypotheses proposed about runoff and erosion in other semiarid landscapes are also true of pinyon-juniper woodlands: (1) Runoff amounts vary with scale: runoff decreases as the size of the contributing ares increases and provides wore opportunities for infiltration. (2) The infiltration capacity of soils is dynamic; it is closely tied to soil moisture content and/or sod frost conditions and is a major determinant of runoff amounts. (3) Soil erodibility follows an annual cycle; it is highest at the end of the freeze-thaw period of late winter and lowest at the end of the summer rainy season, when soils have been compacted by repeated rainfall.
    • Defoliation of a northern wheatgrass community: Above- and belowground phytomass productivity

      Zhang, J.; Romo, J. T. (Society for Range Management, 1994-07-01)
      A defoliation study was conducted on a fair condition, clayey range site that is potentially dominated by northern wheatgrass (Agropyron dasystachyum (Hook.) Scribn.) in south-central Saskatchewan. Vegetation was subjected to a factorial experiment with an initial defoliation in early-May, June, July, or August and repeated at 2- or 6-week intervals until mid-September in the same plots for 3 years. An undefoliated control was also included. Herbage removed, residual live, dead, total and root phytomass were measured. Defoliation reduced all yield components, with the exception of herbage removed. Residual live grass was reduced 37, 57, and 46%, respectively, in first second, and third years; the sedge and forb components of live residual phytomass generally were not affected by defoliation. Compared to control, dead phytomass was reduced 77% in the first year, 67% in the second, and 52% in the third year across treatments. Total herbage yield across defoliation treatments ranged from 68 to 93% of control Total live phytomass (herbage removed + residual live phytomass) in defoliated plots equaled control Herbage removal was greatest when initially defoliated in early July and thereafter at 2-week intervals. When defoliated at 6-week intervals residual live and dead phytomass were generally greater than when herbage was removed biweekly. Yields were higher when the first defoliation was delayed and repeated at 6-week intervals. Generally, root phytomass was not different among defoliation treatments, but total belowground phytomass was reduced 30% in the 0-30-cm depth after 3 year of defoliation. This northern mixed prairie ecosystem is sensitive to herbage removal. Maximum forage yield can be obtained if grazing is deferred until after peak growth in July.
    • Extended grazing systems for improving economic returns from Nebraska sandhills cow/calf operations

      Adams, D. C.; Clark, R. T.; Coady, S. A.; Lamb, J. B.; Nielsen, M. K. (Society for Range Management, 1994-07-01)
      Three winter treatments were cross classified with 2 spring treatments to create 6 feeding and grazing systems utilizing Nebraska sandhills range and subirrigated meadow forage. Systems were evaluated with multiparous crossbred beef cows over 4 years (240 head beginning year 1). Systems were: 1) owing range during winter; 2) grazing subirrigated meadow during winter; and 3) fur feed of meadow bay during winter; in combination with either: a) full feed of subirrigated meadow hay during May, or b) grazing subirrigated meadow during May. From June through November all cows grazed range. The feeding and grazing systems were compared with selected linear contrasts and evaluated with respect to variable input prices. Some differences in cow body weight and body condition occurred but differences were considered small. Throughout the study, cows on all systems generally maintained a body condition score of about 5 (1 to 9 scale) year long. Inputs of hay were reduced by grazing range or subirrigated meadow during winter and during May without affecting pregnancy rate. Weaning weight of calves was increased 5.0 kg by grazing meadow during May compared to feeding hay during May. When opportunity costs were included in the analysis, the most profitable system involved grazing subirrigated meadow during winter and during May. Grazing subirrigated meadow during May enhanced the profitability of all wintering systems.
    • Cattle grazing white locoweed in New Mexico: Influence of grazing pressure and phenological growth stage

      Ralphs, M. H.; Graham, D.; James, L. F. (Society for Range Management, 1994-07-01)
      Locoweed poisoning generally occurs in early spring when other forage is dormant or in short supply and locoweed is the main green plant available to grazing livestock. The objective of this study was to estimate the amount of white locoweed (Oxytropis Sericea Nut. ex T&G) consumed by cattle, and to determine if cattle graze locoweed because it is relatively palatable, or if they are forced to graze it because of decreasing availability of other forage. Three grazing trials were conducted that corresponded to the vegetative, flower, and pod phenological growth stages of white locoweed. Four cows were used in Trial 1 (vegetative growth stage), and 7 cows were used in Trials 2 (flower stage) and 3 (pod stage). Pastures were fenced for the 10-day grazing trials, so that forage became limited and grazing pressure increased as the trials progressed. Acceptance of white locoweed at the beginning of each trial, when there was adequate forage, would indicate preference. Rejection of white locoweed at the beginning of the trials, followed by increasing consumption as the trials progressed would indicate that grazing pressure was forcing the cows to select white locoweed. White locoweed was readily accepted by 1 cow in the vegetative trial, and by 2 cows in the flower trial (these cows were termed "loco-eaters"). The remainder of the cows (termed "normal") rejected white locoweed in the vegetative and flower trials until the availability of new growth cool n grasses decreased, after which they started to select white locoweed. AD cows rejected white locoweed at the beginning of the pod trial but consumed it as availability of other plants decreased. Regression analysis showed that grazing pressure was positively associated with ingestion of white locoweed (r2 = .46 to .88) by the "normal" cows.
    • Government policy effects on cattle and wildlife ranching profits in Zimbabwe

      Kreuter, U. P.; Workman, J. P. (Society for Range Management, 1994-07-01)
      The profitability of alternative range-based production systems is frequently affected by government policies. Moreover, the comparative profitability of wild and domestic animal production systems on African semi-arid savannas has not been well analyzed. This paper presents a simple method for analyzing government policy effects on ranch profits and reports application of the method to 30 commercial cattle, 7 wildlife, and 13 mixed ranches in Zimbabwe. Ranches were selected in 4 contiguous woodland savanna areas with abundant wildlife and in 2 adjacent open savanna areas with sparse wildlife. Financial profits were calculated from 1989/90 ranch data and economic profits were estimated from the opportunity costs of inputs and outputs. A policy analysis matrix was used to estimate financial-economic profit-differences. Cattle ranches in the 2 areas with sparse wildlife were the most profitable group studied. Profits were lower (but similar) for cattle and mixed ranches in the areas with abundant wildlife. The financial profit was higher than economic profit for all ranch types, thus creating production disincentives. However, currency over valuation and implicit taxes on exported beef created greater production disincentives for cattle than wildlife producers. While the policy interventions negated the government's stated objectives of increasing foreign currency earnings and being self sufficient in beef production, they did appear to have beneficial range management consequences by encouraging fewer cattle on historically overstocked cattle ranches.
    • Influence of duration of exposure to field conditions on viability of fecal samples for NIRS analysis

      Leite, E. R.; Stuth, J. W. (Society for Range Management, 1994-07-01)
      This experiment was conducted to address the issue of spectral integrity of pelleted feces exposed to environmental conditions at different times of the year in near infrared reflectance spectroscopy analysis using goats as the representative herbivore. Both dietary crude protein and digestible organic matter were predicted. Results indicated that fecal samples collected with up to 7 days of exposure provided similar estimates of diet crude protein and digestible organic matter from samples collected immediately after defecation Goat feces response to environmental conditions provided useful information as to how collection of many wild herbivores' fecal material could be efficiently sampled for future near infrared reflectance spectroscopy analyses.
    • Protein supplementation of stocker cattle in the Northern Great Plains

      Grings, E. E.; Adams, D. C.; Short, R. E. (Society for Range Management, 1994-07-01)
      A comparison of the response of varying classes of growing beef cattle to protein supplementation was conducted on Northern Great Plains rangeland during the summer and early fall. Response was evaluated in 2 experiments, conducted in 1988 and 1989, by measuring organic matter intake and body weight gain in 13-month-old (spring-born steers) and 7-month-old steers (fall-born steers), which received either a 26% crude protein supplement or no supplement. Weight gain was also monitored in 7-month old heifers (fall-born heifers). In experiment 1, spring-born steers were fed 1.28 kg and fall-born steers and heifers 1.64 kg of protein supplement every other day. During experiment 2, spring-born steers were fed supplement at a rate of 1 kg and fall-born steers and heifers at 1.8 kg every other day. Intake of forage organic matter for steers was not affected (P > 0.10) by supplementation in either experiment. In experiment 1, total organic matter intake tended to be increased by protein supplementation in June but not in August (date X supplementation level interaction, P = 0.08). Forage organic matter digestibility was greater (P < 0.01) in June than in August during experiment 1 and in August than September in experiment 2. In experiment 1, this difference was greater for fall-born steers than spring-born steers. In experiment 1, supplementation increased (P < 0.01 average daily gain of cattle from 0.63 to 0.78 kg/day. In experiment 2, daily pin of cattle was increased (P < 0.01) from 0.62 0.82 kg/day with protein supplementation. Also, in experiment 2, cattle receiving supplement were 18 kg heavier (P < 0.05) at the end of the grazing season than unsupplemented controls. Protein supplementation increased weight pins of growing cattle in the late summer in the Northern Great Plains. The advantage was most consistent for fall-born steers with higher relative protein requirements.
    • Storms influence cattle to graze larkspur: an observation

      Ralphs, M. H.; Jensen, D. T.; Pfister, J. A.; Nielsen, D. B.; James, L. F. (Society for Range Management, 1994-07-01)
      Livestock producers report cattle deaths from larkspur (Delphinium spp.) poisoning increase during stormy periods. In controlled grazing studies, we observed cattle increase larkspur consumption during stormy weather. Periods of "gluttonous" larkspur consumption generally coincided with storms during a 1990 grazing study. Cattle consumed larkspur almost exclusively for 20-30 min periods during storms, as opposed to intermittent grazing of larkspur flowers, pods, and leaves. In 1991 weather parameters were measured and correlated with larkspur consumption. Larkspur consumption was negatively correlated with decreasing temperature and barometric pressure (r = -0.45 and -0.60 respectively); and positively correlated with increasing relative humidity, leaf wetness, and precipitation (r = 0.45, 0.74, and 0.27, respectively). Understanding consumption patterns of cattle grazing larkspur will aid in developing management strategies to reduce cattle deaths.
    • Preferences of mule deer for 16 grasses found on Intermountain winter ranges

      Austin, D. D.; Stevens, R.; Jorgensen, K. R.; Urness, P. J. (Society for Range Management, 1994-07-01)
      In rangeland revegetation, selection of forages palatable to the primary grazer is crucial Five tame mule deer were used in the spring and fall to determine forage preferences for 16 grasses commonly found on seeded foothill rangelands. Trials were conducted within a planted enclosure. Cheatgrass (Bromus tectorum L.) was the most preferred species in spring, and also preferred in fall. Other preferred species included 'Paiute' orchardgrass (Dactylis glomerata L.), 'Luna' pubescent wheatgrass (Agropyron trichophorum link.), and fairway wheatgrass (Agropyron cristatum [L.] Gaertn). The least preferred grasses were three species of wildrye, 'Vinall' and 'Boisoisky' Russian wildrye (Psathyrostachys juncea Fisch.) and 'Magnar' basin wildrye (Elymus cinereus Scrib. and Merr.). Results showed a wide range of preferences for grasses.
    • Vegetative response to burning on Wyoming mountain-shrub big game ranges

      Cook, J. G.; Hershey, T. J.; Irwin, L. L. (Society for Range Management, 1994-07-01)
      Information on vegetative productivity and nutritive responses to burning in mesic, high elevation big sagebrush (Artemisia tridentata Nutt.) communities is limited. We investigated the effects of 2 wildfires and 3 prescribed fires on current year's production of herbs and selected shrubs for 3 years post-burn, and forage quality for 2 years post-burn in high elevation big sagebrush habitats in southcentral Wyoming. Production of perennial herbs on burned sites averaged twice that on controls, while production of annual herbs varied little 2-3 years post-burn. Burn-induced mortality of Saskatoon serviceberry (Amelanchier alnifolia (Nutt) Nutt. ex Roem.) was less than or equal to 15%, but a 6-fold increase in twig production more than compensated for plant losses. Mortality of true mountain mahogany (Cercocarpus montanus Raf.) and antelope bitterbrush (Purshia tridentata (Pursh) DC) averaged 25% and 55%, respectively, but these losses generally were compensated by increases in browse production. Crude protein content of herbs from late spring through early far was significantly higher on burns for 2 years post-burn. These results suggest well-managed prescribed burning programs have potential to improve May through September diets of large herbivores in southcentral Wyoming mountain-shrub communities.