• Tracked vehicle effects on vegetation and soil characteristics

      Prosser, C. W.; Sedivec, K. K.; Barker, W. T. (Society for Range Management, 2000-11-01)
      A 3-year experiment to evaluate tracked vehicle effects on vegetation and soil characteristics was established on the Gilbert C.Grafton South State Military Reservation (CGS) in North Dakota. Study objectives were to evaluate the effects of 3 tracked vehicle use intensity treatments on plant species cover and frequency, and soil compaction. The 3 treatments evaluated include heavy use (74 passes), moderate use (37 passes) and no use. The moderate use treatment represents a typical use of 1 battalion unit at CGS with the heavy use treatment classified as 2 battalion units. This land area comprised a 50 by 150 meter block subdivided into three, 50 by 50 meter blocks. Each 50 by 50 meter block was subdivided into three, 16.7 by 50 meter blocks with each block treated with 1 of the 3 treatments. Soil bulk density increased (P < 0.05) on the moderate and heavy use treatments in the 0 to 15, 30 to 45, and 45 to 60 cm soil depths. Kentucky blue-grass (Poa pratensis L.) cover (P < 0.05) decreased in 1996 on both the moderate and heavy use treatments but was not (P >0.05) different among all treatments in 1997. The tracked vehicle use on the heavy and moderate treatments did not change species composition or litter amounts after 2 years; however, bulk density and bare ground increased on both treatments in 1996 and 1997.
    • Fire history of the Rochelle Hills Thunder Basin National Grasslands

      Perryman, B. L.; Laycock, W. A. (Society for Range Management, 2000-11-01)
      A fire scar chronology was constructed from ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and Rocky Mountain juniper (Juniperus scopulorum Sarg.) trees within the 70 km2 Rochelle Hills Area of the Thunder Basin National Grasslands, in north-east Wyoming. A total of 65 fire scars occurred in 48 crossdated samples, and a master fire chronology was constructed for the period 1565 to 1988. No trees recorded more than 3 fires and most (26 of 42) recorded only one. For this reason, fire frequency intervals were considered as fire-free intervals in the Rochelle Hills Area. The Weibull Median Probability Interval (WMPI) for the entire period of record was 7.4; 7.9 for the non-suppression period (1565 to 1939); and 6.7 for the suppression period (1940 to 1988). Infrequent occurrence of multiple scars, rough topography, and low potential substrates suggest that understory fuel loads were limited in amount and spatial consistency during most fire years. Position of scars within annual growth rings suggests that most fires (80%) occurred during the latter stages of the growing season or during the dormant period.
    • Food aversion learning to eliminate cattle consumption of pine needles

      Pfister, J. A. (Society for Range Management, 2000-11-01)
      Conditioned food aversions are a potentially useful tool to eliminate consumption of some toxic plants by livestock. This study examined consumption of pine needles (Pinus ponderosa Lawson) in South Dakota and Oregon by pregnant cattle. Averted cattle were conditioned to avoid green pine needles using a gastrointestinal emetic, lithium chloride; control (non-averted) animals were not treated. Averted and non-averted cattle were offered green pine needles during pen trials, and they were also grazed in pastures with abundant pine needles in 2 winter trials during 1997 and 1998. Averted cattle ate no green needles in pen trials in Oregon and South Dakota in either year; whereas, control cattle always ate some green needles during those tests. The 1997 South Dakota field trial was inconclusive: the averted cattle ate no needles and the control cattle ate almost no needles while grazing. In the 1998 Oregon field study, the averted cows began eating pine litter after 4 days in the pasture, and the aversion to green needles extinguished rapidly thereafter. In Oregon, controls ate more than 50% of their diet as pine needles, and particularly selected green needles from recently cut trees or branches. When the trial ended after 16 days, the controls and averted cattle were both eating about the same amount of green pine needles and dry needle litter even though they grazed in different pastures. Although averted to green needles, cattle did not appear to generalize the aversion from green needles to dry needle litter. Conditioning permanent aversions may require averting cattle to all forms of pine needles (i.e., green and dry) likely to be encountered in a pasture.
    • Red deer and cattle diet composition in La Pampa, Argentina

      Pordomingo, A. J.; Rucci, T. (Society for Range Management, 2000-11-01)
      Presence of 2 large herbivores in the same rangeland makes assessment of proper stocking rates and management practices rather complex. This study evaluated composition and overlap of red deer and cattle diets in a semiarid, temperate rangeland of La Pampa province, Argentina. Deer and cattle diets were estimated by microhistological analysis of feces. Fifteen samples were collected for cattle and deer during fall, winter, spring, andsummer of 1994/95 (Period 1) and the same seasons of 1996/97 (Period 2). Red deer and cattle diets were different (P < 0.01) within each sampling season. Diets were also different (P < 0.01) among sampling seasons within each animal species. Red deer were better shrub users than cattle. Deer consumed more than 4 times the amount of shrubs than cattle during all seasons. Shrubs accounted for 28 to 50% of deer diets in most seasons, and from 6 to 12% in cattle diets. Forbs were a variable component of diets. However, red deer harvested more forbs than cattle in most sampling seasons (P < 0.05). Cattle were better grass users than red deer. Cows consumed more (P < 0.05) perennial graminoids in all seasons, and based their diet on cool-season perennial grasses. A trend for red deer to behave as an intermediate feeder, compared with cattle could be suggested. In the environment of our study, deer and cattle diet overlap varied greatly depending on availability of palatable fractions of forbs, shrubs, and grasses. Forb and shrub regrowth would reduce the diet overlap.
    • Lichen polysaccharides and their relation to reindeer/caribou nutrition

      Svihus, B.; Holand, Ø. (Society for Range Management, 2000-11-01)
      Samples of Cetraria islandica, Cetraria nivalis, Cladina stellaris,Cladina arbuscula, Cladina rangiferina and Stereocaulon paschalewere collected at 3 sites in 2 mountain areas in Norway. Alectoria ochroleuca was collected at 3 sites in 1 of the mountain areas. Lichens contained between 83 and 93% fiber, measured by the dietary fiber analysis, with Cladina spp. containing significantly more fiber than the other lichen species. The fiber consisted mainly of mannose, galactose, and glucose, but the relative content of each monosaccharide differed between species. Fibers from Cetraria spp.and Alectoria ochroleuca contained significantly more glucose than those from Cladina spp. and Stereocaulon paschale, while Cladina spp. and Stereocaulon paschale contained significantly more mannose and galactose. The higher glucose content in Cetraria spp. And Alectoria ochroleuca was reflected in a high lichenan content in these species, while the Cladina spp. and Stereocaulon paschale contained no lichenan. Solubility of the fiber fraction in hot water was strongly correlated to lichenan content, and great differences existed between species. Less than 5% of the dietary fiber was soluble in lichens of the Cladina genus, while more than 50% of the fiber was soluble in Cetraria islandica and Alectoria ochroleuca. Twenty-one percent of the dietary fiber was soluble in Cetraria nivalis. In vitro gas production experiments using rumen inocula from reindeer revealed a higher gas production rate the first 5 hours of incubation in Cetraria islandica, Cetraria nivalis, and in Alectoria ochroleuca compared to Cladina spp. and Stereocaulon paschale. Maximum production rate was observed at about 13 hours and dropped rapidly thereafter. No systematical differences in gas production rate between lichens species were observed after the initial phase. Differences in gas production rate in the initial phase resulted in higher total gas production in Cetraria islandica, Cetraria nivalis and in Alectoria ochroleuca compared to Cladina spp. and Stereocaulon paschale the first 9 hours of incubation. Total gas production after 52 hours of incubation did not vary between species. Gas production characteristics indicate that the amount of readily fermentable fraction was greater, whereas the amount slowly fermentable fraction was lower in lichens of the Cetraria genus and in Alectoria ochroleuca compared to Cladina spp. and Stereocaulon paschale. The water-soluble fraction is easy available for rumen micro-organisms and the results indicate a close relationship between high gas production in the initial phase and high proportion of water soluble fibers and/or lichenan content. Content, composition, and solubility of the fiber fraction could thus be potentially important factors determining nutritive value of the lichen for reindeer/caribou.
    • Close-range vertical photography for measuring cover changes in perennial grasslands

      Bennett, L. T.; Judd, T. S.; Adams, M. A. (Society for Range Management, 2000-11-01)
      We describe a method of close-range vertical photography and digital image analysis for measuring changes in total projective cover in perennial tussock grasslands of semi-arid Australia. Repeated photographs of permanent plots (1 m2) were classified using supervised image analysis, providing a clear and objective record of the effects of single-burns on grass cover relative to controls. Computer simulations of the photographic set-up indicated that errors due to camera perspective were consistently less than 4% across a range of cover classes. Other errors, including misclassification error, were not quantified because simplified laboratory tasks indicated that conventional field methods, such as point sampling and visual estimation, provided unreliable estimates of grass cover and were therefore not suitable benchmarks for assessing the photographic method. However, the presented data indicate that the photographic method was sufficiently accurate and precise to measure treatment effects over time and to elucidate relationships between independent growth parameters across a range of cover conditions. In addition, the photographic method was inexpensive, involved minimal field time, and utilised commercial software to classify images. It has the clear advantage over more traditional methods of providing outputs that are readily archived for retrospective studies.
    • Protocol for monitoring standing crop in grasslands using visual obstruction

      Benkobi, L.; Uresk, D. W.; Schenbeck, G.; King, R. M. (Society for Range Management, 2000-11-01)
      Assessment of standing crop on grasslands using a visual obstruction technique provides valuable information to help plan livestock grazing management and indicate the status of wildlife habitat. The objectives of this study were to: (1) develop a simple regression model using easily measured visual obstruction to estimate standing crop on sandy lowland range sites in the Nebraska Sandhills, (2) provide sampling and monitoring suggestions in the use of visual obstruction on this grassland type, and (3) compare the visual obstruction technique to the standard clip and weigh procedure. Visual obstruction precisely predicted average standing crop dry weights for the sandy lowland range sites (r2=0.88). A prediction accuracy of ± 295 kg ha-1was found using a test data set. Two sampling options (A and B) were evaluated using a 2-stage sampling protocol. Option A (1 transect/quarter section) provided more precise estimates applicable to extensive grasslands than option B. However, option A was not applicable to a section (259 ha) or a few sections. Option B (3 transects/section) provided estimates applicable to each section and to the entire area, but it required more intensive sampling than option A to attain the same precision. The visual obstruction technique provided more precise estimates of standing crop than the standard clip and weigh technique when clipping and weighing up to 6 plots per transect. When 7 or more clipped and weighed plots per transect were sampled, standing crop estimates were more precise than using visual obstruction readings. However, since 20 visual obstruction readings/transect (25 minutes) can be sampled in about half the time spent clipping and weighing 6 plots/transect (45 minutes), visual obstruction in combination with a previously estimated regression model provides a simple, reliable, and cost effective alternative to the clip and weigh technique. Regression models should be developed for other grassland types following the methodology described in this paper.
    • Technical note: Use of digital surface model for hardwood rangeland monitoring

      Gong, P.; Biging, G. S.; Standiford, R. (Society for Range Management, 2000-11-01)
      We built digital surface models (DSM) that contain 3D surface morphological information of the entire landscape using digital photogrammetry and aerial photographs. Changes in landscape components such as crown closure and tree height in hardwood rangeland were estimated using DSM. In comparison with manual interpretation results, errors of crown closure and tree hieght estimation using DSM were less than 0.7% and 1.5 m, respectively. This technique can be used for rangeland management, monitoring and ecological studies.
    • Predictive equations for biomass and fuel characteristics of Argentine shrubs

      Hierro, J. L.; Branch, L. C.; Villarreal, D.; Clark, K. L. (Society for Range Management, 2000-11-01)
      Predictive equations for estimating shrub biomass in semi-arid scrub ecosystems are essential for evaluating shrub encroachment, conducting ecosystem-level studies of net primary productivity (NPP) and nutrient cycling, and examining effects of different fire regimes. In this study, we developed predictive equations to estimate total aboveground biomass and biomass of foliage and stems of the 8most common shrubs in the semi-arid scrub (Monte) of central Argentina. We also examined the relationship between shrub size and proportions of these components for the dominant species, Larrea divaricata Cavanilles (creosotebush), and determined fuel characteristics (dead-to-live ratio, bulk density) of the 8 shrub species. Regression analyses were used to examine the relationships between aboveground biomass and 5 field measurements (diameter of the longest stem, shrub height, maximum crown width, crown width at right angles to maximum crown width, and crown volume). A natural log-log model based on a single variable best described this relationship in most cases. The easiest field measurement for 6 of the 8 species was diameter of the longest stem, and this measure was often the best predictor of shrub biomass. As L. divaricata increased in size, the proportional biomass of large stems increased, and bio-mass of foliage and small stems decreased. This pattern suggests productivity may decrease with shrub age. The mass of dead materialwas low in most shrub species. Bulk densities were comparable to those of shrubs in other semi-arid ecosystems. Equations developed here will allow rapid and accurate estimation of shrub biomass in the Monte of Argentina.
    • Response of incomplete Tifton 9 bahiagrass stands to renovation

      Gates, R. N. (Society for Range Management, 2000-11-01)
      Establishment of warm-season grasses from seed is often impeded by slow germination and emergence, and low seedling vigor. Stand development can be further retarded by unfavorable soil moisture resulting from high temperatures and erratic precipitation. Management of poorly established stands of warm-season grasses has received limited research attention. Two- or 3-year old, poorly established stands (basal occupation < 61%) of ‘Tifton 9’ bahiagrass (Paspalum notatum Flügge var. saure) at a dry upland site and at a moist lowland site were reseeded (5.6 kgh a-1) in April of 2 different years either without tillage or after rototilling or light disking and compared to a non-seeded control. Our objective was to determine whether any combination of tillage and/or seeding would enhance stand coverage. At the upland site, basal occupation of the control increased from an initial 61 to 80%. No benefit was derived from interseeding, and both tillage treatments resulted in a stand reduction (P < 0.05) after 1 year. At the lowland site, basal occupation increased froman initial 28 to 59% for the control. Similar responses were observed with renovation treatments, but none were greater (P >0.05) than the control. Bahiagrass stands with at least a few plants per m2 should be managed to minimize weed encroachment, but introducing additional seed, with or without tillage, offered no benefit.
    • Grassland fire effects on corroded barbed wire

      Engle, D. M.; Weir, J. R. (Society for Range Management, 2000-11-01)
      Fire effects on rangeland ecosystems have been studied extensively. Few studies have investigated effects of fire on rangeland developments. Only 1 study has investigated the effects of fire on barbed wire with an intact coating of corrosion-resistant zinc and no studies have investigated wire that has lost the protective coating. A common perception is that grass fire causes older wire to break more easily and become more brittle. In the present study, we determined the influence of grassland fire on wire that was 20 and 30-years old and had sufficient loss of the zinc coating to have undergone corrosion of the underlying steel. We found that regardless of age, wire subjected to grass fire did not differ (P > 0.05) in breaking strength, elongation, or ductility from the same wire that was not subjected to fire. We conclude that the problems experienced when repairing breaks in old barbed wireare not a result of fire, but rather brittle and weak wire resulting from exposure to the corrosive elements of the environment.
    • Sward quality affected by different grazing pressures on dairy systems

      Mosquera-Losada, M. R.; Gonzalez-Rodríguez, A.; Rigueiro-Rodriguez, A. (Society for Range Management, 2000-11-01)
      The objective of the experiment was to examine the effects of different stocking densities (3.7, 4.6, and 5.5 cows ha- l) on tiller density, botanical composition, and chemical (crude protein [CP], acid detergent fiber [ADF], Ca, P, K, and Mg) quality of pasture and the seasonal (before flowering [spring], after flowering [summer], and autumn) distribution of these parameters. Percentages of sown [perennial ryegrass (Lolium perenne L. cv ‘Brigantia’) and white clover (Trifolium repens L. cv ‘Huia’)] and volunteer species were not significantly affected by stocking density, although as stocking density increased, tiller density also increased. This effect was more pronounced for volunteer species than sown species. Density was significantly higher before flowering than after flowering or autumn. Stocking density affected the chemical quality of herbage with ADF, CP, P, K, and Mg higher at high stocking density. The Ca/P relationship was lower at high stocking density, but the K/(Ca+Mg) relationship was not significantly affected by stocking density. Chemical quality of the pasture was higher before flowering than after flowering or autumn. The Ca/P ratio exceeded the upper limit recommended for dairy cows, but no osteomalacia was found in the presen texperiment. Low values of the K/(Ca+Mg) ratio were found in the spring. Therefore, on these pasture types it is advisable to use concentrates high in Mg or Mg supplements in the spring in order to avoid hypomagnesemia.
    • Suppression of grasshoppers in the Great Plains through grazing management

      Onsager, J. A. (Society for Range Management, 2000-11-01)
      It was hypothesized that grazing management could mitigate grasshopper outbreaks on native rangeland in the northern Great Plains. Key practices would require deliberate variation in timing and intensity of grazing events, preservation of canopy during critical periods of grasshopper development, and reductions in areas of bare soil. The twice-over rotational grazing system appeared compatible with those requirements. Grasshopper population trends were monitored during 1993–1995 and 1997–1998 on commercial native rangeland under twice-over rotational grazing vs traditional season-long grazing. A ubiquitous pest grasshopper, Melanoplus sanguinipes (Fabricius), occurred at every sample site during each year in numbers sufficient to provide life history parameters for comparison between treatments. Under rotational grazing, the nymphs developed significantly slower and their stage-specific survival rates were significantly lower and less variable. Consequently, significantly fewer adults were produced signifi-cantly later in the season under rotational grazing.Seasonal presence of all grasshopper species combined averaged 3.3X higher under season-long grazing than under rotation-al grazing. Local outbreaks that generated 18 and 27 adult grasshoppers per m2 under season-long grazing in 1997 and 1998, respectively, did not occur under rotational grazing. The outbreaks consumed 91% and 168%, respectively, as much forage as had been allocated for livestock, as opposed to 10% and 23%, respectively, under rotational grazing. Of 9 important grasshopper species, none were significantly more abundant at rotational sites than at season-long sites. Three species that were primary contributors to outbreaks under season-long grazing remained innocuous under rotational grazing. It therefore appears that outbreak suppression through grazing management is feasible in the northern Great Plains.
    • Long-term effects of fire on sage grouse habitat

      Nelle, P. J.; Reese, K. P.; Connelly, J. W. (Society for Range Management, 2000-11-01)
      This study documented the long–term (> 10 years) impact offire on sage grouse (Centrocercus urophasianus Bonaparte) nesting and brood–rearing habitats on the Upper Snake River Plainin southeastern Idaho. The habitat of the study area is primarily mountain big sagebrush (Artemisia tridentata vaseyana Rydb.)—grassland. Twenty different-aged burns were sampled from 1996 to 1997, ranging from wildfires which burned during the 1960s to prescribed fires set during the 1990s. Canopy coverage and height of vegetation, and relative abundance of invertebrates, were estimated at burned and unburned sites within burns. Fourteen years after burning, sagebrush had not returned to pre-burn conditions. No difference was detected in forb abundance between different-aged burns. Relative abundance of ants and beetles was significantly greater in the 1-year old burn category but had returned to unburned levels by 3–5 years postburn. No benefits for sage grouse occurred as a result of burning sagegrouse nesting and brood-rearing habitats. Burning created along-term negative impact on nesting habitat because sagebrush required over 20 years of postburn growth for percent canopy cover to become sufficient for nesting.
    • Impacts of western juniper on plant community composition and structure

      Miller, R. F.; Svejcar, T. J.; Rose, J. A. (Society for Range Management, 2000-11-01)
      Western juniper (Juniperus occidentalis Hook.) has been actively invading shrub steppe communities during the past 120 years. The majority of these stands are still in transition, from early open juniper shrub steppe communities to closed juniper woodlands. In addition, juniper expansion has been occurring across a broad array of soils and topographic positions. Despite the high degree of spatial and developmental heterogeneity, juniper woodlands are frequently treated generically in resource inventories, management, and wildlife habitat assessments. Our goal was to evaluate the impact of western juniper encroachment and dominance on plant community composition and structure across several plant associations. This study was conducted in southeastern Oregon and northeastern California on low sage-brush (Artemisia arbuscula Nutt.), mountain big sagebrush (A . tridentata spp. vaseyana (RYBD. )Beetle), and aspen (Populus tremuloides Michx.) alliances. Stages of woodland development across plant associations were categorized into 1 of 4 successional phases (early, mid, late, and closed) based on tree growth and stand structural characteristics. Plant cover by species group, species diversity and richness, bareground cover, soil characteristics, elevation, aspect, and slope were measured in 108, 60 x 46m macroplots. Twinspan was used to sort plant communities. Regression analysis was used to evaluate the relationship of tree canopy cover to shrub and herbaceous cover. Herbaceous and bareground cover were compared between early and closed stands within plant communities. Woodland structure at stand closure was different among associations varying from 19% cover and 64 trees ha-1 in a low sagebrush community to 90% cover and 1,731 trees ha-1 in an aspen community. Increase in juniper dominance had little impact on low sagebrush and an inconsistent effect on bitterbrush (Purshia tridentata Pursh.). In the mountain big sagebrush alliance, sagebrush cover declined to approximately 80% of maximum potential as juniper increased to about 50% of maximum canopy cover. Aspen (Populus tremuloides Michx.) also declined as juniper dominance increased. Herbaceous cover and species diversity declined and bare ground increased with increasing juniper dominance in the mountain big sagebrush/Thurber needlegrass association. However, herbaceous cover on the deeper soils characterized by Idaho fescue did not decrease with increasing juniper dominance. To determine the effect of juniper dominance or woodland management on community composition and structure, plant community and stage of stand development should be identified.
    • Stubble height as a tool for management of riparian areas

      Clary, W. P.; Leininger, W. C. (Society for Range Management, 2000-11-01)
      Stubble height, a measure of the herbaceous vegetation remaining after grazing, has been widely used in recent years to gage the impacts of grazing use in riparian areas. Stubble height is a short-term management guide that should only be applied to help attain long-term ecological objectives; it should not be thought of as a long-term management objective. Maintaining a minimum stubble height helps preserve forage plant vigor, retain sufficient forage to reduce cattle browsing of willows (Salix spp.), stabilize sediments, indirectly limit streambank trampling, maintain cattle gains, and provide an easily communicated management criterion. Based on limited specific research of riparian system response and on knowledge of the characteristics of how cattle graze, a 10-cm residual stubble height is recommended by the authors as a starting point for improved riparian grazing management. Monitoring should then be conduted to determine if an adjustment is needed. In some situations, 7 cm or even less stubble height may provide for adequate riparian ecosystem function, particularly when streambanks are dry and stable or possibly at high elevations where vegetation is naturally of low stature. In other situations, 15-20 cm of stubble height may be required to reduce browsing of willows or limit trampling impact to vulnerable streambanks. The recommended criterion would apply to streamside and nearby meadow sites with hydrophilic or potentially hydrophilic vegetation, but not directly to dry meadows or even to all wet meadows. Stubble height may have little application where the streambanks are stabilized by coarse substrates, or the channels are deeply incised. The effects of residual stubble height in riparian functions have received limited direect experimental examination. Consequently, much of the information in this review was derived from studies indirectly related to the questions raised and, to some extent, from observations of experienced professionals. The authors have identified areas of scientific investigation needed to improve our understanding of the effects of stubble height on riparian function and grazing management.