• Impact of leafy spurge on post-Conservation Reserve Program land

      Hirsch, S. A.; Leitch, J. A. (Society for Range Management, 1998-11-01)
      Leafy spurge (Euphorbia esula L.), a noxious weed infests some of the 1.2 million hectares of Conservation Reserve Program (CRP) land in North Dakota. Once established a leafy spurge monoculture will reduce expected CRP benefits and impact returns to some post-CRP land uses. The study estimated statewide direct economic impacts of about 351,000 on post-CRP land maintained in vegetative cover, 1.118 million on post-CRP grazing land, and negligible (assumed 0) on post-CRP cropland, for a total of 1.469 million. Total annual direct and secondary economic impacts to North Dakota's economy were estimated to be 4.665 million, which would support about 57 jobs.
    • Impact of locoweed poisoning on grazing steer weight gains

      Ralphs, M. H.; Graham, D.; Duff, G.; Stegelmeier, B. L.; James, L. F. (Society for Range Management, 2000-01-01)
      Emaciation is one of the clinical signs of locoweed poisoning but few studies have documented impacts of locoweed poisoning on weight gains. Stocker steers (British X Continental cross, 200-210 kg) were grazed on locoweed-infested, short-grass prairie in 1996 and 1997 in northeast New Mexico. Each year, half the steers were averted to locoweed to allow them to graze locoweed-infested pastures without eating locoweed. They did not graze locoweed and steadily gained weight (0.50 kg/day in 1996 and 0.71 kg/day in 1997). The other group of steers were allowed to graze locoweed under natural grazing conditions and became intoxicated. Weight gains were not affected for the first 3 weeks, but thereafter the steers lost weight in both years. In 1996, non-averted steers consumed locoweed for a season average of 20% of bites. They were severely intoxicated and did not begin gaining weight for 50 days after they stopped eating locoweed. Steers in the 1997 trial consumed less locoweed (11% of bites) than those in 1996 and they recovered more rapidly. Seasonal weight gains were 21 to 30 kg less for locoed steers than control steers in 1996 and 1997, respectively. Locoweed poisoning will cause weight loss, and severely intoxicated cattle require a lengthy recover period after they cease grazing locoweed before weight gains resume. Stocker cattle should not be placed on locoweed-infested rangelands until green grass is abundant and locoweed begins to mature.
    • Impact of Native Grasses and Cheatgrass (Bromus tectorum) on Great Basin Forb Seedling Growth

      Parkinson, Hilary; Zabinski, Cathy; Shaw, Nancy (Society for Range Management, 2013-03-01)
      Re-establishing native communities that resist exotic weed invasion and provide diverse habitat for wildlife are high priorities for restoration in sagebrush ecosystems. Native forbs are an important component of healthy rangelands in this system, but they are rarely included in seedings. Understanding competitive interactions between forb and grass seedlings is required to devise seeding strategies that can enhance establishment of diverse native species assemblages in degraded sagebrush communities. We conducted a greenhouse experiment to examine seedling biomass and relative growth rate of common native forb species when grown alone or in the presence of a native bunchgrass or an exotic annual grass. Forb species included bigseed biscuitroot (Lomatium macrocarpum [Nutt. ex Torr. A. Gray] J.M. Coult. Rose), sulphur-flower buckwheat (Eriogonum umbellatum Torr.), hoary aster (Machaeranthera canescens [Pursh] Gray), royal penstemon (Penstemon speciosus Douglas ex Lindl.), and Munro’s globemallow (Sphaeralcea munroana [Douglas ex Lindl.] Spach ex Gray); and neighboring grass species included bottlebrush squirreltail (Elymus elymoides [Raf.] Swezey), Sandberg bluegrass (Poa secunda J. Presl); and cheatgrass (Bromus tectorum L.). Forbs and grasses were harvested after 6, 9, or 12 wk of growth for biomass determination and calculation of relative growth rates (RGR) of forbs. Neither bunchgrass reduced biomass of any forb. RGR was reduced for royal penstemon when grown with either native grass and for Munro’s globemallow when grown with bottlebrush squirreltail. Although only assessed qualitatively, forbs with vertically oriented root morphologies exhibited no reduction in RGR when grown with native grasses, compared to forbs with dense lateral branching, similar to the root morphology of native grasses. Biomass of forbs was reduced by 50% to 91% and RGR by 37% to 80% when grown with cheatgrass. Understanding native forb interactions with native grasses and cheatgrass will aid land managers in selecting effective seed mixes and making better use of costly seed.
    • Impact of plant toxins on fetal and neonatal development: A review

      Panter, K. E.; Keeler, R. F.; James, L. F.; Bunch, T. D. (Society for Range Management, 1992-01-01)
      Many poisonous plants grazed by livestock on ranges and pastures in the western USA are fetotoxic causing fetrl malformations, embryonic or fetal death, abortion, or early parturition. Decreased incidence of plant-induced livestock malformations may be accomplished through grazing management strategies. To develop these strategies one must understand some basic principles of toxicology and teratology such as susceptible livestock species, type of compound and concentration in the plant and its disposition in the animal, dose response, and the susceptible gestational period. Much of this information is known for certain plants; however, additional information will enhance our ability to control livestock losses from these plants. Certain criteria may be established to maximize grazing management methods to minimize teratogenic effects of poisonous plants. When the suspect plant grows in a restricted habitat, poses a hazard only at certain growth stages or when the susceptible period of pregnancy is relatively short, minor adjustments in management methods can be considerably successful in reducing incidence of malformations and subsequent financial loss.
    • Impact of poisonous plant on the livestock industry

      James, L. F.; Nielsen, D. B.; Panter, K. E. (Society for Range Management, 1992-01-01)
      Livestock poisoning by plants is one of the serious causes of economic loss to the livestock industry. Losses can be classified as either direct or indirect. Direct losses include deaths, weight loss, abortions, lengthened calving intervals, decreased efficiency and other effects on the animals. Losses from death and some reproductive losses in the 17 western states are estimated at 340,000,000. In addition to these are the indirect losses such as fencing, herding, supplemental feeding, medical costs, management alterations, and loss of forage which are associated with efforts to prevent or minimize poisoning of livestock by plants. Nearly all plant communities include poisonous plants, thus, most grazing animals are exposed to intoxication. However, the presence of these plants does not cause poisoning. Poisoning is usually associated with management errors, lack of forage due to range conditions, drought, and other events that would cause Livestock to consume vegetation normally unacceptable. Often a sequence of events, such as storm, frost, cold, and other occurrences can influence an animal to where it will eat too much of a toxic plant too fast.
    • Impact of prescribed burning on vegetation and bird abundance at Matagorda Island, Texas

      Van’t Hul, J. T; Lutz, R. S.; Mathews, N. E. (Society for Range Management, 1997-07-01)
      We measured the impact of prescribed summer and winter burns on vegetation characteristics and spring abundance of birds in a Spartina/Paspalum grassland at Matagorda Island National Wildlife Refuge and State Natural Area, Texas, 1993-94. We burned 8 (4 summer burn, 4 winter burn), 122-ha plots. We estimated bird abundance by surveying once a week from March through May at 12-16 fixed-radius point count stations in each plot. We measured forb and grass foliar cover, litter depth, visual obstruction, and woody and residual stem density at each point count station 6-10 months after burning and 18-22 months after burning and found few differences in vegetation between summer and winter burns. Litter depth, visual obstruction, and woody stem density values were greater on control plots 6 to 10 months post-burn. By 18 to 22 months post-burn, only litter depth and visual obstruction remained higher on control plots than on either burn treatment. At 6 to 10 months after burning, wrens were more abundant on control plots and sparrows were more abundant on the burned plots. By 18 to 22 months post-burn, wren abundance had increased on the burned plots, but was still highest on control plots. Sparrow abundance remained highest on burned plots 18-22 months after burning. Precipitation was higher in 1993 than 1994; we believe blackbirds responded more to annual precipitation differences than to burning treatment. In this coastal island grassland, wren abundance was highest on unburned plots and sparrow abundance was highest on burned plots. We suggest that land managers could burn at > 2 year intervals in this grassland without negatively impacting most resident bird species.
    • Impact of Presowing Seed Treatments, Temperature and Seed Coats on Germination of Velvet Bundleflower

      Haferkamp, M. R.; Kissock, D. C.; Webster, R. D. (Society for Range Management, 1984-03-01)
      Seeds with both smooth and rough, apparently scarified, seed coats occur in harvested samples of velvet bundleflower (Desmanthus velutinus Scheele.). To determine the degree of scarification, germination responses of rough and smooth seeds were investigated at 4 night/day temperature regimes, 5/15 degrees C, 10/20 degrees C, 15/25 degrees C, and 20/30 degrees C with a 12-hour photoperiod during the high temperature and with 3 seed treatments, cutting, acid scarification and hot water soak. Rough seed coats appear to be caused by peeling of the cuticular layer on the seed surface. Moisture was imbibed more rapidly by smooth seeds, and total germination of smooth seeds was 31% without treatment, 4 times greater than rough seed germination. Treatments increased germination of smooth seeds two- to four- fold and rough seeds over 10-fold. After treatment, rough seeds germinated significantly (P<.05) better than smooth seeds at all temperature regimes except 5/15 degrees C. Cut and scarified seeds generally germinated more rapidly than water-treated seeds, but total germination was similar for all treatments at warmer temperatures. Germination was only 31% at 5/15 degrees C.
    • Impact of Range Goats on Infiltration Rates in Southwestern Utah

      Gifford, G. F.; Provenza, F. D.; Malechek, J. C. (Society for Range Management, 1983-03-01)
      Three levels of goat browsing on a blackbrush site in southwestern Utah had no significant impact on infiltration rates. The probable reason for these results was the presence of a vesicular soil crust, which is unstable when wet and therefore masks any browsing impacts.
    • Impact of Small Mammal on the Vegetation of Reclaimed Land in the Northern Great Plains

      Hingtgen, T. M.; Clark, W. R. (Society for Range Management, 1984-09-01)
    • Impact of SO2 Exposure on the Response of Agropyron smithii to Defoliation

      Lauenroth, W. K.; Detling, J. K.; Milchunas, D. G.; Dodd, J. L. (Society for Range Management, 1985-01-01)
      Agropyron smithii populations exposed to 3 controlled SO2 concentrations were defoliated either once or twice during the growing season at a light and a heavy intensity. The intensity and frequency of defoliation were most influential in determining growth and tillering responses. Defoliating twice, at either intensity, had a large negative impact on plant growth whereas compensatory growth occurred after defoliating once at either intensity. Sulfur dioxide alone had no significant effect on biomass or the number of tillers, even though sulfur accumulated approximately in proportion to exposure concentration. Sulfur dioxide exposure with the additional influence of defoliation affected both the regrowth of A. smithii in terms of biomass and tiller numbers and forage sulfur concentration. Decreased plant growth in response to SO2 plus defoliation was dependent on defoliation frequency, whereas the effect of SO2 plus defoliation on plant sulfur concentration was positive and negative and depended on a complex interaction of SO2 concentration and defoliation frequency and intensity. The results are discussed in relation to the short- and long-term compensatory growth potential of a system simultaneously exposed to grazing and air pollution and the potential effect on consumers.
    • Impact of Stocking Rate and Rainfall on Sheep Performance in a Desert Steppe

      WangHan, Zhongwu; Jiao, Shuying; Han, Guodong; Zhao, Mengli; Willms, Walter D.; Hao, Xiying; Wang, Jian’an; Din, Haijun; Havstad, Kris M. (Society for Range Management, 2011-05-01)
      Livestock performance is a critical indicator of grassland production systems and is influenced strongly by precipitation and stocking rates. However, these relationships require further investigation in the arid Desert Steppe region of northeastern China. We employed a randomized complete block design with three replications and four grazing treatments (nongrazed exclosure [Control]), lightly grazed [LG], moderately grazed [MG], and heavily grazed [HG]) by sheep in a continuously grazed system (June to November), to test the effect of stocking rate on sheep performance. The planned stocking rates were 0, 0.15, 0.30, and 0.45 sheep ha-1 mo-1, for the control, LG, MG, and HG treatments, respectively. However, actual stocking rates were calculated for each paddock in each year based on a 50-kg sheep equivalent (SE). Annual net primary production (ANPP) was determined at peak standing crop in August 2004 to 2008. Live weight gain was determined for the summer and fall periods, as well as the total grazing period, in each year. ANPP decreased with increasing stocking rate, and daily live weight gain per head decreased linearly with increasing stocking rates over the total grazing period but in a quadratic manner over the summer period with a plateau at the lower rates. Maximum sheep production per unit area over the total grazing season occurred at about 2 SE ha-1 for about a 5-mo grazing period, but individual gains per sheep were predicted to decline after about 1 SE ha-1 presumably because of forage limitations. However, in order to achieve stable annual production, we recommend that the Desert Steppe be grazed at about 0.77 SE ha-1 for a 5-mo period (0.15 SE ha-1 mo-1). This estimate is based on published grazing strategies that consider an average ANPP with a recommended utilization rate of 30%.
    • Impact of Various Range Improvement Practices on Watershed Protection Cover and Annual Production Within the Colorado River Basin

      Hessary, I. K.; Gifford, G. F. (Society for Range Management, 1979-03-01)
      During 1976 a study of annual production and cover (litter + rock + vegetation) on various range improvement practices was conducted in Utah, Colorado, New Mexico, and Arizona. The range improvement practices studied included gully plugs, contour furrowing, pitting, pinyon-juniper chaining, and various sagebrush control treatments. Results from studies of annual production on treated vs untreated sites indicated that: (a) about 33% of the contour furrowed sites had significant increases in annual production. Best responses were found on loam and clay loam soils, while soils of sandy loam or clay texture indicated a poor response to treatment. Soils classified as typical ustifluvents and ustollic haplargids were most favorable in terms of increased production; (b) annual production on pinyon-juniper chainings was significantly increased across a variety of soil types (growth of trees excluded). The greatest increases in production were measured on sites with loam soils classified as typic haplustolls; (c) neither of the two pitting treatments on a clay and a sandy clay loam site indicated increased annual production; (d) less than 50% of the various sagebrush treatments indicated increased annual production. There appears to be a general trend for best responses on loam soils, though significant decreases in production were also indicated on this type of soil; (e) plowing was the least successful sagebrush treatment studied. Best cover responses on the various range improvement practices were found on contour furrowing treatments on sandy clay loam and loam textured soils and on typic torriorthent or ustic torriorthent soil types. Though significant cover increases due to chaining of pinyon and juniper were noted on 57% of the treatments, on a variety of soil textures and soil types, the increases were uniformly small (tree cover included) and no clear pattern emerged with either soil texture or soil type. Only about 20% of the various sagebrush treatments showed significant increases in cover; 10% indicated decreased cover, and there was no impact on cover on the remaining 70% of the treatments. Pitting treatments in this study had no impact on cover. Age of contour furrow treatments made little difference as to whether there was a significant increase or decrease in either production or cover. Cover data from pinyon-juniper chainings indicate either that significant increases in cover (if they occur) are slightly more dramatic on more recent teatments, or that treatments approximately 11 years old represent conditions most ideal for enhanced cover. The former interpretation is probably more nearly correct. Production data suggests that pinyon-juniper sites chained since 1964 are not as favorable in terms of increased production as those chained prior to 1964. Age of sagebrush treatment had no impact on significant changes in cover; however, a general trend indicated that production increases are slightly higher for more recent sagebrush ripping and sagebrush chaining treatments than for older ones.
    • Impact of Wildfire on Three Perennial Grasses in South-Central Washington

      Uresk, D. W.; Cline, J. F.; Rickard, W. H. (Society for Range Management, 1976-07-01)
      In a south-central Washington sagebrush-bluebunch wheatgrass community, bluebunch wheatgrass responded to burning by increased vegetative and reproductive performance. Burning decreased the vegetative and reproductive vigor of Cusick bluegrass and Thurber needlegrass.
    • Impact on Associated Vegetation of Controlling Tall Larkspur

      Cronin, E. H. (Society for Range Management, 1976-05-01)
      Herbicide treatments that effectively control tall larkspur also convert the tall-forb community to a grass-dominated community. The composition of the grass community is determined more by the grazing system imposed on the treated area than by the herbicide treatments. Early grazing reduces mountain brome and increases letterman needlegrass. With protection from grazing, the converted grass community can produce abundant high-quality forage and watershed cover superior to that of the former larkspur-dominated tall-forb community.
    • Impacts of big game on private land in south-western Montana: landowner perceptions

      Lacey, J. R.; Jamtgaard, K.; Riggle, L.; Hayes, T. (Society for Range Management, 1993-01-01)
      Increasing populations of big game animals are a problem for private landowners in some parts of western North America. Influence of bit game costs, hunting-related income, noneconomic benefits, size of private land holding, and proportion of total income from agriculture upon landowner management goals as well as perception of damage to forage resources were studied in 1989-1990 using a mail survey of 858 randomly selected southwestern Montana landowners. They reported that elk (Cervus canadensis) populations increased, did not change, or decreased on 71%, 25%, or 4% of their private lands, respectively. Similar trends were reported for mule deer (Odocoileus hemionus), whitetail deer (Odocoileus virginia), and antelope (Antilocapra americana). More than 50% of the respondents thought that bit tame damaged forage and crop yields, while less than 2% of the respondents thought that bit game was beneficial to forage and crop yields. Big Same consumed a mean of 511 AUMs per private landowner, which contributed to the mean big game cost of 6,353 per landowner. Respondents desiring fewer elk, deer, and antelope outnumbered those desiring more by a 4-to-1 margin. As costs of big game increased and as dependency on agricultural income for livelihood increased, respondents desired fewer big game animals and perceived the impact of big game to be more harmful to forage and crop yields. Landowner attitudes toward big game were not significantly affected by economic returns from big game. Although owners with larger land holdings were more likely to allow hunters access to hunt big game, owners of large- and of small-sized ranches generally regarded big game populations similarly. Results from this survey should be useful in forming natural resource policy.
    • Impacts of Black-tailed Jackrabbits at Peak Population Densities on Sagebrush-Steppe Vegetation

      Anderson, J. E.; Shumar, M. L. (Society for Range Management, 1986-03-01)
      In the northern Great Basin, populations of black-tailed jackrabbits (Lepus californicus) are cyclic, reaching high densities at approximately 10-year intervals. This project examined impacts of jackrabbits during a peak in their cycle on sagebrush-steppe vegetation in southeastern Idaho. Total vascular plant cover was significantly lower on plots open to jackrabbit herbivory than on exclosure plots, but in no case was cover of a specific species significantly reduced on open plots. The most severe impacts were on shrubs during winter; most aboveground tissues of both winterfat (Ceratoides lanata) and green rabbitbrush (Chrysothamnus viscidiflorus) plants were completely eaten by spring. However, these impacts were largely ameliorated by compensatory growth during the following growing season, and there was no difference in total biomass for either species between the open and protected plots by July. New growth of winterfat plants that had been browsed the previous winter was significantly greater than that of protected plants. Thus, although the cumulative effects of herbivory reduced total plant cover, no single species was irreparably impacted. Over a year, jackrabbits exert feeding pressure on nearly all of the important species in these communities; therefore, these hares do not appear to apply differential grazing pressure that would alter the course of vegetation development on northern Great Basin rangelands.
    • Impacts of Cattle on Streambanks in Northeastern Oregon

      Kauffman, J. B.; Krueger, W. C.; Vavra, M. (Society for Range Management, 1983-11-01)
      Impacts of a late season livestock grazing strategy on streambank erosion, morphology, and undercutting were studied for 2 years along Catherine Creek in northeastern Oregon. Streambank loss, disturbance, and undercutting were compared between grazing treatments, vegetation type, and stream-meander position. No significant differences were found among vegetation types or stream-meander location. Significantly greater streambank erosion and disturbance occurred in grazed areas than in exclosed areas during the 1978 and 1979 grazing periods. Over-winter erosion was not significantly different among treatments. However, erosion related to livestock grazing and trampling was enough to create significantly greater annual streambank losses when compared to ungrazed areas.
    • Impacts of defoliation on tiller production and survival in northern wheatgrass

      Zhang, J.; Romo, J. T. (Society for Range Management, 1995-03-01)
      Although northern wheatgrass (Agropyron dasystachyum (Hook.) Scribn.) is a dominant or co-dominant species that decreases under grazing in northern Mixed Prairie, little is known about its response to herbage removal at different times during the growing season. The objective of this research was to determine the effects of defoliation on the tiller production and survival of this native perennial on a clayey range site in mixed prairie 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. On average defoliation enhanced tillering (71%) and survival relative to the control, and tiller recruitment was greatest during June and September 1989. Generally tiller survival decreased as the date of emergence in the growing season was delayed. Numbers of tillers emerging was positively correlated with soil water (r = 0.77). Some tillers of northern wheatgrass lived 5 years. The 2- and 6-week intervals of defoliation had little influence on tiller survival, but initiating defoliation near the time of tiller emergence reduced survival whereas delaying defoliation until August increased their survival. Increased tillering may be an adaptive feature enabling northern wheatgrass to tolerate defoliation by re-establishing lost photosynthetic area and maintaining or even increasing basal area. Thus, once released from grazing it may rapidly increase phytomass production in a relatively short time. Delaying grazing until August will maximize tiller survival of northern wheatgrass.
    • Impacts of differing grazing rates on canopy structure and species composition in hulunber meadow steppe

      Yan, R.; Xin, X.; Yan, Y.; Wang, X.; Zhang, B.; Yang, G.; Liu, S.; Deng, Y.; Li, L. (Society for Range Management, 2015-01)
      In this study, the impacts of cattle grazing with differing grazing rates on species composition, canopy structural traits, standing crop of canopy biomass, and plant species diversity were examined in a meadow steppe of the Hulunber grasslands, Northeastern China. Six stocking-rate treatments (0, 0.23, 0.34, 0.46, 0.69, and 0.92 AU.ha-1) with three replicates were established, and observations were conducted from 2009 to 2011. Our findings demonstrate that short-term grazing substantially altered the species composition and relative dominance, standing crop of aboveground biomass, and canopy structural traits, whereas no significant changes in species diversity and evenness occurred in response to different-rated grazing in this meadow steppe, which has a long-term evolutionary grazing history and high-resources availabilities. We found that perennial graminoid significantly decreased, while forbs and annuals increased at the same time, with increasing grazing intensity and duration; canopy height and coverage decreased substantially with increasing stocking rates, whereas significant changes in plant density occurred only at heavy grazing in the second and third years; and significant negative linear relations were found between the standing crop of biomass and grazing intensity in each individual year or for 3 years on average. Significantly highest species richness and canopy dominance occurred only at the intermediate grazing rate in the third year, and intermediate grazing intensity also maintained a highly constant standing crop of canopy biomass in the 3 years, all being in accordance with the intermediate disturbance hypothesis. Our findings imply that monitoring changes in species composition, canopy traits, and standing crop of biomass in grassland communities can provide important references for assessing current grazing management scenarios and conducting timely adaptive practices to maintain the long-term ability of grassland systems to perform their ecological functions. © 2015 Published by Elsevier Inc. on behalf of Society for Range Management.
    • Impacts of Federal Land Livestock Reductions on Nevada's Economy

      Pearce, Rob; Henderson, Don; Harris, Tom; Tetz, Tim (Society for Range Management, 1999-08-01)