• A Direct Approach for Quantifying Stream Shading

      Clark, Patrick E.; Johnson, Douglas E.; Hardegree, Stuart P. (Society for Range Management, 2008-05-01)
      Management and regulatory standards for stream shading have been established to mitigate excessive stream temperature. Existing shade assessment tools, however, are inadequate for monitoring extensive stream networks. Our objectives were to develop and evaluate an efficient, low-cost field technique for sampling stream-surface shading using digital images and to evaluate the efficiencies and effectiveness of eight different digital image analysis techniques for shade assessments. We developed a quadrat-based technique and associated field equipment to directly photograph stream-surface shading. Sampling at random points (pixels) within the resultant digital images was the most accurate, efficient, and robust image analysis technique. An approach pairing the photographic field technique and the random point-sampling image analysis technique should enable managers to conduct ground-based assessments of stream shading over extensive stream networks. This approach may also provide an efficient means of collecting ground truth samples for even broader scale, remote sensing-based stream- shade assessments. 
    • Broad-Scale Assessment of Rangeland Health, Grand Staircase-Escalante National Monument, USA

      Miller, Mark E. (Society for Range Management, 2008-05-01)
      Over a 3-yr period, the qualitative assessment protocol ‘‘Interpreting Indicators of Rangeland Health’’ was used to evaluate the status of three ecosystem attributes (soil/site stability, hydrologic function, and biotic integrity) at over 500 locations in and adjacent to Grand Staircase-Escalante National Monument (Utah). Objectives were to provide data and interpretations to support the development of site-specific management strategies and to investigate broad-scale patterns in the status of different rangeland ecological sites. Quantitative data on ground cover, plant community composition, and soil stability were collected to aid the evaluation of qualitative attributes and improve consistency of the assessment process. Ecological sites with potential vegetation dominated by varieties of big sagebrush (Artemisia tridentata Nuttall) had the highest frequencies (46.7%-75.0%) of assessments with low ratings (moderate or greater departure from expected reference conditions) for all three ecosystem attributes. In contrast, sites with potential vegetation characterized by Utah juniper ( Juniperus osteosperma [Torrey] Little) and/ or Colorado pinyon (Pinus edulis Engelmann) had low frequencies (0.0%-7.8%) of assessments with low ratings for all attributes. Several interacting factors likely contributed to the development of patterns among ecological sites, including 1) potential primary production and thus long-term exposure to production-oriented land uses such as livestock grazing; 2) the presence of unpalatable woody plants capable of increasing and becoming persistent site dominants due to selective herbivory, absence of fire, or succession; 3) soil texture through effects on hydrologic responses to livestock grazing, trampling, and other disturbances; and 4) past management that resulted in high livestock use of ecological sites with sensitive fine-loamy soils following treatments designed to increase forage availability. This case study illustrates an extensive application of an assessment technique that is receiving increasing use worldwide, and results contribute to an understanding of factors contributing to patterns and processes of rangeland degradation. 
    • Evaluation of NEXRAD Radar Precipitation Products for Natural Resource Applications

      Hardegree, Staurt P.; Van Vactor, Steven S.; Levinson, David H.; Winstral, Adam H. (Society for Range Management, 2008-05-01)
      Timing and amount of precipitation are principal drivers of most rangeland processes, but the availability of rainfall-gauge data over extensive rangelands, particularly in the western United States, is limited. The National Weather Service (NWS), Department of Defense, and Federal Aviation Administration operate a network of Doppler radar stations that produce hourly rainfall estimates, at approximately 16-km2 resolution, with nominal coverage of 96% of the conterminous United States. Internal utilization of these data by the three agencies is primarily for the detection and modeling of extreme weather events. The usefulness of these data for external hydrologic and natural resource applications is limited by a lack of tools for decoding and georeferencing digital precipitation data products. We modified NWS source code to produce decoding and georeferencing tools and used them to evaluate radar precipitation data for the Boise (CBX) radar relative to gauges in the Snake River Plain of southwestern Idaho for the period January 1998 to May 2004. The relationship between radar and gauge precipitation estimates changed after a revision of radar-processing protocols in 2002 and 2003. Cumulative radar precipitation estimates made prior to November 2002 underestimated gauge readings by 50%-60%. Subsequent radar data overestimated cumulative gauge precipitation by 20%-40%. The radar, however, detected precipitation during significantly fewer hours than were detected by the gauge network both before and after programming changes. Additional modification of NWS precipitation- processing procedures might improve accessibility and utility of these data for rangeland management and natural resource modeling applications. Currently available data can still be very useful for estimating high-intensity events that greatly affect processes such as soil erosion and flooding. 
    • Exotic Plant Species Diversity: Influence of Roads and Prescribed Fire in Arizona Ponderosa Pine Forests

      Fowler, James F.; Sieg, Carolyn Hull; Dickson, Brett G.; Saab, Victoria (Society for Range Management, 2008-05-01)
      Many studies have investigated the ecological effects of roads and roadsides as both habitat and dispersal corridors for exotic plant species. Several of these compared roadside exotic species richness and abundance with adjacent interior habitats, but we found no studies of individual exotic species’ abundance between the two habitats in the context of prescribed fire. We measured exotic species richness and individual species’ abundance along roadsides and in adjacent interior habitat (> 150 m) before and after prescribed fire at three ponderosa pine (Pinus ponderosa Douglas ex Lawson C. Lawson) sites in northern Arizona. Eighteen of the 20 exotic plant species found in this study have been and continue to be intentionally introduced or are known agricultural seed contaminants. Roadsides had significantly higher exotic species richness than adjacent forest interior habitats, but only one site showed a significant (decreasing) fire effect on species richness. Four exotic plant species had significantly higher densities along roadsides at two of the three sites, and four species had no significant difference in abundance between habitats at any site supporting an individualistic species response hypothesis. Most exotic species showed no significant change in density post-prescribed fire suggesting that low-intensity prescribed fire may have minimal effect on exotic species diversity. Variability in total exotic species richness, composition, species’ constancies, and species’ densities between the three regionally similar sites suggests differing degrees and effectiveness of past management practices and policies such as intentional seeding. 
    • Fuels Reduction in a Western Coniferous Forest: Effects on Quantity and Quality of Forage for Elk

      Long, Ryan A.; Rachlow, Janet L.; Kie, John G.; Vavra, Martin (Society for Range Management, 2008-05-01)
      Use of mechanical thinning and prescribed fire to reduce fuels in dry forest ecosystems has become increasingly common in western North America. Nevertheless, few studies have quantified effects of fuels reduction treatments on wildlife. We evaluated effects of fuels reduction on quantity and quality of forage available to elk (Cervus elaphus) in northeastern Oregon. From 2001 to 2003, 26 stands of true fir (Abies spp.) and Douglas-fir (Pseudotsuga menziesii [Mirbel] Franco) were thinned and burned, whereas 27 similar stands were left untreated to serve as experimental controls. We estimated percentage of cover, percentage of in vitro dry-matter digestibility (digestibility), and percentage of nitrogen (%N) of 16 important forage species and genera in treatment and control stands during spring (May-June) and summer (July-August) of 2005 and 2006. Quantity and quality of forage were lower in summer than spring in both stand types. In contrast, total cover of forage was higher in treatment than in control stands during spring, whereas the opposite was true during summer. For graminoids, %N was higher in control than in treatment stands whereas digestibility did not differ between stand types. For forbs, neither index of forage quality differed between stand types. When treatment stands were separated by years since burning, %N and digestibility of forbs and %N of graminoids increased from 2 to 5 yr following treatment, and by the fifth year after burning had exceeded maximum values observed in control stands in both seasons. As a result of the interacting effects of fuels reduction and season on forage characteristics, treated stands provided better foraging opportunities for elk during spring, whereas control stands provided better foraging opportunities during summer. Consequently, maintaining a mosaic of burned and unburned (late successional) habitat may be of greater benefit to elk than burning a large proportion of a landscape. 
    • Intake of Water Containing Condensed Tannin by Cattle and Sheep

      Kronberg, Scott L. (Society for Range Management, 2008-05-01)
      Ingestion of small amounts of condensed tannin (CT) by ruminants can prevent bloat, improve nitrogen retention, and reduce excretion of urea, a precursor of ammonia and the greenhouse gas nitrous oxide. Because grasses and many forbs don’t contain CT, it is desirable to find a reliable way to have ruminant livestock ingest small amounts of CT when they consume high-quality forage. Putting CT in their drinking water may be a reliable approach, but only if all animals drink enough to meet their requirements for water. Therefore, objectives of this study were to determine the amount of variation in intake of water containing different amounts of CT when this was the only water available, and if cattle and sheep would drink water with CT in it if offered tap water simultaneously. Animals were penned or pastured individually, fed twice daily (first cattle and sheep trial) or grazed (second cattle trial) and had ad libitum access to tannin water, tap water, or both. Liquid intake was measured daily. Steers drank tannin solutions (mean daily intake 49.7-58.3 kg), but variation in intake among steers was higher than for tap water (SD were 44%-58% greater for the two most concentrated tannin solutions). At the highest concentration of tannin, steers ingested 2.3% of their daily feed intake in CT. During most of the preference trial, steers preferred water over tannin water when offered both simultaneously (P < 0.002), but drank some tannin water each day. Sheep drank tannin solutions, but individual variation in tannin solution intakes were greater than for tap water. Placing CT in water of cattle and sheep may be a useful way to put small amounts of CT in them. However, they will likely drink less tannin water if normal water is available. 
    • Invasion of Broom Snakeweed (Gutierrezia sarothrae) Following Disturbance: Evaluating Change in a State-and-Transition Model

      Thacker, Eric T.; Ralph, Michael H.; Call, Christopher A.; Benson, Brock; Green, Shane (Society for Range Management, 2008-05-01)
      Broom snakeweed (Gutierrezia sarothrae [Pursh] Britt. Rusby) is an aggressive native invasive species that thrives after disturbance in semiarid rangelands of the western United States. A 5-yr (2002-2006) study was initiated following grazing and fire disturbances on an Upland Gravelly Loam ecological site in the sagebrush steppe of northern Utah, to evaluate broom snakeweed invasion in different plant communities. The study site originally had two plant communities: a sagebrush/ bunchgrass community that received alternate-year, fall cattle grazing, and was dominated by bluebunch wheatgrass (Elymus spicatus) and an open stand of Wyoming big sagebrush (Artemisia tridentata subsp. wyomingensis), and a sagebrush community that received continuous, annual, spring cattle grazing that removed the bunchgrasses, leaving a dense stand of Wyoming big sagebrush with an understory of Sandberg bluegrass (Poa secunda). Portions of these two plant communities were burned in a wildfire in 2001, removing the sagebrush, and creating two additional communities. The burned portion of the sagebrush/bunchgrass community became a bluebunch wheatgrass-dominated community, and the burned portion of the sagebrush community became a snakeweed-dominated community. Foliar cover, aboveground biomass, and sagebrush and snakeweed densities were compared among the four communities. Mature snakeweed plants that existed in the sagebrush/bunchgrass community were eliminated in 2003, because of drought conditions. Snakeweed was eliminated in the bluebunch wheatgrass community by the wildfire in 2001, and there was no reestablishment. Snakeweed density and cover remained constant in the sagebrush community. Snakeweed cover increased from 2% to 31% in the snakeweed community, despite the presence of Sandberg bluegrass. The data were used to evaluate and update the current Upland Gravelly Loam (Wyoming big sagebrush) ecological site description in the Great Salt Lake Major Land Resource Area and its state-and-transition model to reflect vegetation changes associated with snakeweed invasion. 
    • Organic Matter Turnover in Light Fraction and Whole Soil Under Silvopastoral Land Use in Semiarid Northeast Brazil

      Wick, Barbara; Tiessen, Holm (Society for Range Management, 2008-05-01)
      Trees in silvopastoral systems can accumulate carbon (C) and nutrients under their canopies. Most studies measure only net changes in organic matter and nutrients without evaluating turnover of soil organic matter. Here, the change in vegetation cover from caatinga, a semideciduous thorn forest (principally C3 metabolism) to buffel grass (Cenchrus ciliaris L.) pasture (C4 metabolism) was used to quantify in situ input and turnover rates of organic carbon 14 yr after land-use changes. The accretion of C under new pasture and loss of original caatinga C was studied for whole soil (WS) and light fraction (LF). The effects of two tree species preserved during selective clearing and one species planted after complete clearing of caatinga were evaluated. All trees prevented organic matter mineralization that occurred in surrounding cleared pasture. The C mineralization under pasture was twice as high (66% loss) in LF as in WS (34% loss) over 14 yr. The C4-C was similar under and outside the remnant and planted tree canopies, i.e., the input of new C4-C did not compensate for the loss of old C3-C that occurred following caatinga clearing and pasture establishment. The organic matter in this tropical, semiarid region mineralized rapidly with C half lives between 9 and 16 yr for LF and between 11 and 28 yr for WS. The 13C data indicate that elevated C contents under preserved (WS and LF) and planted (LF) trees, relative to the pasture outside the tree canopies, largely represent C3-C inherited from the caatinga. In this silvopastoral system, derived from land-use changes from dry forest, the islands of fertility and organic matter under the trees were not built up and represent preserved, rather than new, C inputs. 
    • Prescribed Fire Effects on Deciduous Oak Woodland Stand Structure, Northern Diablo Range, California

      Fry, Danny L. (Society for Range Management, 2008-05-01)
      Despite the increasing use of fire in managing oak woodlands, little information exists on quantitative changes to stand structure from prescribed burning. Fire damage and recovery in a mixed deciduous oak woodland were recorded after a prescribed fire on the northern Diablo Range, Santa Clara County, California. Blue oak (Quercus douglasii Hook. Arn.), valley oak (Q. lobata Nee), and black oak (Q. kelloggii Newb.) trees were monitored for 4 yr to determine the effects of a late spring burn on stand structural characteristics. Fire-caused mortality was low; 4 yr after the low intensity ground fire only four oaks died (1.9%). There were significant differences in mean percent tree crown scorch and mean trunk char height between plots that burned under different fire intensities, but not between tree size classes. Although overall tree damage was low, crown resprouts developed on 80% of the trees and were found as shortly as 2 wk after the fire. Recovery was vigorous; both valley oaks and blue oaks produced crown resprouts on trees with 100% crown scorch. Classification tree analysis identified aspect (mostly southern exposures) and tree size related to the presence of crown resprouting. Crown damage was also an important factor; trees with greater than 40% of their crown scorched resprouted. Fire-induced trunk scars occurred on a small number of trees (9.1%) but was disproportionately higher for black oak compared to blue and valley oak. Stand structural characteristics (species composition, tree density, basal area, and crown closure) were not substantially altered by the event but rather maintained. Prescribed fire might be a viable tool in reducing fuels and maintaining oak woodlands; however, further investigations that include relationships of regeneration with repeated fire are needed. 
    • Soil Depth and Climatic Effects on Desert Vegetation Dynamics

      Khumalo, Godfrey; Holechek, Jerry; Thomas, Milt; Molinar, Francisco (Society for Range Management, 2008-05-01)
      Soil depth effects on honey mesquite (Prosopis glandulosa Torr) cover and density and perennial grass standing crop were evaluated over an 11-yr period (1995-2005) on two lightly stocked and two conservatively stocked pastures on the Chihuahuan Desert Rangeland Research Center in south-central New Mexico. These four adjoining pastures have similar size, vegetation, and soils. Soils in these study pastures are primarily light sandy loams varying from a few centimeters to 1 m or more in depth underlain by a calcium carbonate layer. Deep soils had lower perennial grass standing crop and higher honey mesquite cover and density than did shallow soils at both the beginning (1995-1997) and ending (2003-2005) periods of study. Average perennial grass standing crop across the four study pastures dropped 82% between 1995-1997 and 2003-2005 because of drought during the last 5 yr of study. Honey mesquite canopy cover and perennial grass standing crop did not differ between light and conservative grazing treatments at the beginning or end of our study. Honey mesquite canopy cover did not change from 1995-1997 to 2003-2005 but honey mesquite density was higher in 2003-2005 than in 1995-1997. Our study shows that both soil depth and climatic fluctuations have a major influence on vegetation dynamics in desert and semiarid areas. 
    • The Effect of Targeted Grazing and Biological Control on Yellow Starthistle (Centaurea solstitialis) in Canyon Grasslands of Idaho

      Wallace, John M.; Wilsom, Linda M.; Launchbaugh, Karen L. (Society for Range Management, 2008-05-01)
      Yellow starthistle (Centaurea solstitialis L.) is an invasive weed of significant importance on rangelands in the western United States. Field experiments were conducted in 2003 and 2004 to determine the effect of targeted grazing on yellow starthistle growth and bud production, and on the efficacy of four established biological control seed-head-feeding insects, which included three species of weevils and one fly species. We tested sheep and cattle grazing at three yellow starthistle growth stages—rosette, bolting, and late bud—at a site where all four biocontrol agents were established. The timing of grazing had a greater impact on yellow starthistle growth and bud production than the type of grazing animal. In comparison to the control, grazing at the rosette and bolting stage resulted in shorter plants both years of the study, but increased the number of buds following grazing at the bolting stage and at the rosette stage in 2003. Negligible seed production across treatments, in 2003, precluded detection of treatment effects. However, in 2004, grazing at the rosette and bolting stages resulted in a greater number of seeds per plant compared to the control and the late bud stage, which were similar. Results indicated that the timing of grazing did not negatively impact biocontrol efficacy. Eustenopus villosus adult injury and total insect larval damage were similar to control plants following each grazing treatment both years, indicating potential compatibility between targeted grazing and biocontrol for integrated management of yellow starthistle. 
    • Vigilance in Cattle: The Influence of Predation, Social Interactions, and Environmental Factors

      Kluever, Bryan M.; Breck, Stewart W.; Howery, Larry D.; Krausman, Paul R.; Bergman, David L. (Society for Range Management, 2008-05-01)
      Vigilant behavior in wild ungulates is critical to guard against predation. However, few studies have examined vigilant behavior in domesticated ungulates. Considering the expansion of large predator populations, understanding vigilant behavior and factors that influence it will help with the management of livestock. We observed adult female cattle (Bos taurus L.) in open-range conditions where large predators (wolves [Canis lupus L.] and mountain lions [Puma concolor (L.).]) were common threats during summers of 2005 and 2006 in eastern Arizona. This study was designed to determine 1) to what extent cattle exhibit vigilant behavior compared to published data on wild ungulates, 2) whether predation events influence vigilance rates of cattle, and 3) whether social and environmental factors affect vigilance of cattle. Cattle exhibited vigilant behavior (3% +/- 0.19%) during peak foraging periods, but at a lower rate than wild ungulates. Cows with calves were more than twice as vigilant (4.5% +/- 0.46%) as those without calves (2.0% +/- 0.27%). Single cattle and groups of two to five exhibited higher vigilance rates (4.2% +/- 0.79%) than groups of six to 20 (2.5% +/- 0.32%) and groups of > 20 (3.0% +/- 0.41%). Cattle in groups of > 20 increased vigilance as visual obstruction increased. Mother cows whose calves were preyed upon (n = 5) exhibited a 3% to 48% increase in vigilance within 3 d after their calves were killed; this rate returned to near baseline levels after 10 d. Conversely, mother cows reduced foraging after their calves were killed from 88.5% +/- 1.69% to 43.5% +/- 11.4%; foraging rate also returned to near baseline levels after 10 d. Cattle exhibit vigilance at lower levels compared to wild ungulates, but this behavior appears to be at least partially an antipredatory behavior. Our findings provide support that predators can influence cattle behavior. 
    • Water Balance of a Stock-Watering Pond in the Flint Hills of Kansas

      Duesterhaus, J. L.; Ham, J. M.; Owensby, C. E.; Murphy, J. T. (Society for Range Management, 2008-05-01)
      Small ponds are often the main source of drinking water for grazing livestock. The hydrology of these ponds must be understood so impoundments can be located, designed, and managed to avoid water shortages during dry weather. A study was conducted to measure the water balance of a stock-watering pond in the Flint Hills region of east-central Kansas from June 2005 to October 2006. The 0.35-ha pond supplied water to 250-kg yearling steers in a 65-ha pasture of native tallgrass prairie. Evaporation, depth change, and cattle consumption were measured continuously using meteorological sensors, depth recorders, and water meters. Seepage, transpiration, and inflow were measured periodically or modeled. Evaporation was also predicted from weather data using forms of the Penman and Priestley-Taylor models. Evaporation accounted for 64% of the total water loss annually, while seepage, cattle consumption, and transpiration accounted for 31%, 3%, and 2%, respectively. The greatest water loss was observed in July, with total monthly losses over 358 mm and peak daily losses sometimes exceeding 18 mm d-1. Cattle consumption averaged 30 L day-1 animal-1 with peak usage of 46 L day-1 animal-1. On average, the Priestley-Taylor and Penman evaporation models estimated monthly evaporation to 3% and 5%, respectively. Thus, evaporation, the main form of loss, can be predicted with simple models using data from weather station networks. Inflows from runoff proved difficult to predict and were highly dependent on antecedent soil water content. Results showed that losses from ponds can be measured or predicted with reasonable accuracy. These data could be incorporated into catchment-scale hydrology models to provide site-specific designs for stock-watering ponds and livestock-watering strategies.