• Vegetational Responses Following Control of Sand Shinnery Oak with Tebuthiuron

      Jacoby, P. W.; Slosser, J. E.; Meadors, C. H. (Society for Range Management, 1983-07-01)
      Tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thia-diazol-2-yl]-N,N′-dimethylurea} pellets were applied aerially in April 1979 at rates of 0.5 and 1.0 kg ai./ha to rangelands supporting a uniform stand of sand shinnery oak (Quercus havardii Rydb.) near Andrews, Texas. Tebuthiuron pellets were applied at 1.1 kg ai/ha to a second location near Jayton, Texas, in March 1980. Sand shinnery oak was significantly reduced (P is lesser than or equal to 0.05) in treated plots at both locations. Yields of annual and perennial grasses were significantly greater (P is lesser than or equal to 0.05) and those of forbs significantly less (P is less than or equal to 0.05) on tebuthiuron-treated plots at Andrews. Untreated plots at Andrews had more bare soil than those treated with tebuthiuron after 18 and 30 months. Grass yields at the Jayton site were greater, although no significant (P is less than or equal to 0.05) differences occurred with forb yields.
    • Unbiased Systematic Sampling Plans for the Line Intercept Method Vegetation, Forest Floor

      Butler, S. A.; McDonald, L. L. (Society for Range Management, 1983-07-01)
      Experimentors have been using cost-efficient systematically located transects in the line intercept method for some time with little support from mathematical statistics. In this paper, it is shown that for rectangular regions the usual line intercept estimators for cover, density, and other attributes are unbiased for certain systematic sampling plans. The estimators are approximately unbiased for "large" irregularly shaped study regions.
    • Some Factors Affecting Twig Growth in Blackbrush

      Provenza, F. D.; Malechek, J. C.; Urness, P. J.; Bowns, J. E. (Society for Range Management, 1983-07-01)
      Domestic goat browsing was used to stimulate twig production by blackbrush. Precipitation, soil depth and stoniness, branch location, and the number of years of browsing and rest from browsing affected twig production (P<0.05). As precipitation doubled, production increased by a factor of 1.9. Twig production by plants growing on deep soils (71 cm) was 1.9 times that by plants growing on shallow soils (39 cm). Older branches growing on the outer edges of blackbrush plants (terminal branches) produced 4.6 times more current season's twigs than sprouts and young branches (basal branches) growing within the shrub canopy. Heavily browsed plants increased twig production by a factor of 3.6 relative to control plants, and production remained at this level, even after 4 consecutive years of browsing. Annual twig production declined with rest from browsing. However, plants that were browsed and subsequently rested for 2 years yielded an aggregate 1.6 times more available forage than plants that were browsed on a yearly basis. This was due to an accumulation of twigs ranging in age from 1 to 3 years.
    • Soil Characteristics Related to Production on Subclover-Grass Range

      Jones, M. B.; Williams, W. A.; Vaughn, C. E. (Society for Range Management, 1983-07-01)
      In northwestern California moisture is usually not limiting for range production during the annual winter-spring growing season. It is, therefore, important to understand how other site factors, both physical and chemical, affect range production. Ridge regression analysis and simple correlations were used to evaluate range production as related to site slope and elevation; soil depth, texture, bulk density, water holding capacity, and pH; and several chemical measures of soil fertility including available P and S, exchangeable cations, total N and S, and organic matter. Subclover (Trifolium subterraneum L.) - grass production was measured at 17 typical range sites for 4 fertilizer treatments: P0S0, P300S0, P0S90, P300S90 (subscripts = kg/ha). When no fertilizer was applied, soil pH and available P appeared to be the 2 variables most closely related to yield. Forage production increased when P and S fertilizers were applied. When P was applied, exchangeable soil K was the most important variable related to yield; and when S was applied, available P was the variable most closely related to production. When P and S were applied together, available P and K were most closely related to yield. While there was generally a striking response to applied S, our measures of available soil S were poorly related to production.
    • Seed Germination Characteristics of Two Woody Legumes (Retama and Twisted Acacia) from South Texas

      Everitt, J. H. (Society for Range Management, 1983-07-01)
      The seed germination characteristics of retama (Parkinsonia aculeata) and twisted acacia (Acacia schaffneri) were investigated in relation to temperature and light regimes, substrate salinity, pH, osmotic potential, seed age, and seedling emergence. Seed germination of both species is restricted by impermeable seed coats. Soaking seeds of both species in concentrated sulfuric acid for 45 min increased germination. Retama seed germination was greater than or equal to 87% at continuous temperatures of 15 to 35 degrees C and at alternating temperatures of 10-20, 15-25, and 20-30 degrees C, while twisted acacia seed germination was greater than or equal to 58% at constant temperatures of 15 to 30 degrees C and at alternating temperatures of 10-20, 15-25, and 20-30 degrees C. Light was not required for germination, and no dormancy mechanisms were observed. Viability of twisted acacia and retama seeds was not reduced after storage at room conditions for 2 years. Germination and radicle length were sensitive to osmotic potentials of polyethylene glycol solutions of 0.4 MPa and no germination occurred at 1.4 MPa. Germination of both species was only mildly depressed in aqueous solutions of 10 g/l NaCl; however, radicle elongation of both species was reduced at 5 g/l NaCl and severely inhibited at 10 g/l NaCl. The osmotic potentials of the NaCl solutions had little effect on germination, but they may have contributed to reduced radicle growth. Percent germination and seedling radicle length of both species were relatively tolerant of pH extreme. Twisted acacia seedling emergence was highest when the seeds were left exposed on the soil surface, whereas optimum retama seedling emergence occurred when seeds were covered with 1 to 7 cm of soil.
    • Seasonal Variation of Monoterpenoids in Big Sagebrush (Artemisia tridentata)

      Cedarleaf, J. D.; Welch, B. L.; Brotherson, J. D. (Society for Range Management, 1983-07-01)
      Monthly monoterpenoid content was determined for 16 big sagebrush (Artemisia tridentata) plants grown on a uniform garden. These 16 plants were selected at random from 4 accessions of basin big sagebrush (A.t. ssp. tridentata)-4 plants per accession. A composite sample was taken for a fifth accession of mountain big sagebrush (A.t. vaseyana). Monoterpenoid content varied seasonally with the lowest content occurring during May (0.97% of dry matter). Highest monoterpenoid content occurred during July (4.18%) followed by August (3.36%) and September (2.73%). Dove Creek (2.61% of dry matter) and Marysvale (2.64%) basin big sagebrush accessions contained significantly higher pooled levels of monoterpenoids than the Indianola (1.73%) and Loa (1.55%) big sagebrush accessions. The composite samples of the Indian Peaks mountain big sagebrush accession, an accession significantly preferred over the Marysvale and Loa accessions, contained an overall monoterpenoid level of 2.82%. Adverse relationships between monoterpenoid content and the consumption of big sagebrush by wintering mule deer seem weak.
    • Response of Soft Chess (Bromus mollis) and Slender Oat (Avena barbata) to Simulated Drought Cycles

      Ewing, A. L.; Menke, J. W. (Society for Range Management, 1983-07-01)
      Herbage production in the California annual grassland has been correlated with seasonal weather, particularly fall and spring rainfall patterns. To further examine the relationship between herbage production and rainfall pattern, 3 soil water regimes (-1, -7, -15 bars) simulating expected rainfall and drought events in annual rangelands were applied in seminatural annual grassland communities. Soft chess (Bromus mollis) tillers grew longest under the -7 bar water regime treatments while total plant growth was greatest under the -1 bar treatment. Tiller length and total growth of slender oat (Avena barbata) were greatest under the -1 bar treatment. Vegetative growth of slender oat was less sensitive to season-long soil water regimes than soft chess. The two species required different soil water conditions for maximum spring growth; soft chess put on spring growth most rapidly in the -7 bar treatment while slender oat grew fastest in the -1 bar treatment. Periodic water stress during the growing season did not reduce spring herbage production. Maximum growth and herbage production occurred only when soil water was available after March 15. Withholding water after March 15 reduced herbage production by 46%.
    • Predicting Soluble Nitrogen and Fibrous Fractions in Crested Wheatgrass with Near-Infrared-Reflectance Spectroscopy

      Park, Y. W.; Anderson, M. J.; Asay, K. H.; Mahoney, A. W. (Society for Range Management, 1983-07-01)
      A near-infrared-reflectance (IR) spectroscopic method was evaluated for potential usage in predicting soluble N, total N and some fibrous fractions in crested wheatgrass, Agropyron cristatum (L.) Gaertn., A. desertorum (Fisch. ex Link), et al. The correlation coefficients (r) between IR and total N, soluble N in 0.15N NaCl (N Sal), soluble N in 10% Burroughs Mineral Mixture solution (NBMM), neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) for 84 samples were 0.95, 0.90, 0.70, 0.90, 0.82, and 0.72, respectively. The IR technique provided a closer estimation of total N and N Sal than of NBMM in the calibration data. The mean solubility of N Sal was higher than that of NBMM. High variation occurred between the duplicate determinations of NBMM. The predictions on 30 unknown samples by the equation developed using 84 calibration samples for mean, SED (standard error of difference), and r were: total N, 1.01, 0.04, 0.98; N Sal, 0.43, 0.04, 0.90; NDF, 64.1, 0.96, 0.93, ADF, 36.2, 1.01, 0.91; and ADL, 5.24, 0.53, 0.62. Predictions of fibrous fractions were highly satisfactory even though the correlations were low. Correlations between chemical determinations of total N and N Sal, NBMM, NDF, ADF, ADL were 0.89, 0.53, -0.13, -0.33, -0.08, respectively. Significant differences (P<0.01) were found among crested wheatgrass species for all nitrogenous and fibrous fractions measured. Differences among clonal lines within species were also significant (P<0.05 or 0.01) for all determinations indicating that opportunities are available to improve the nutritional value of crested wheatgrass through selection.
    • Nutrient and Sediment Discharge from Southern Plains Grasslands

      Smith, S. J.; Menzel, R. J.; Rhoades, E. D.; Williams, J. R.; Eck, H. V. (Society for Range Management, 1983-07-01)
      Amounts of nitrogen, phosphorus, and sediment were measured in runoff from grassland watersheds in the Blackland Prairies, High Plains, Reddish Prairies, and Rolling Red Plains land resource areas of Oklahoma and Texas. Periods of study were 3 to 5 years and included treatments involving fertilization, cultivation, and burning. Overall nutrient concentrations generally ranged from 2 to 10 mg/l for nitrogen and 0.3 to 2 mg/l for phosphorus. In most cases, less than half the nutrients existed as soluble forms in the runoff water. Typically, annual sediment losses were less than 0.5 metric tons/ha. Corresponding losses for nitrogen and phosphorus were less than 5 and 2 kg/ha, respectively. In the case of nitrate, more was received in precipitation than was lost in runoff. Total nitrogen and phosphorus losses were strongly correlated with sediment losses. Preliminary results using predictive techniques to estimate nutrient and sediment discharge from the watersheds were encouraging. With proper management, the likelihood of any adverse environmental effects due to nutrient and sediment discharge from Southern Plains grasslands appears slight.
    • Nonstructural Carbohydrate and Crude Protein in Pinegrass Storage Tissues

      Stout, D. G.; Suzuki, M.; Brooke, B. (Society for Range Management, 1983-07-01)
      Nonstructural carbohydrates in storage tissues of pinegrass (Calamagrostis rubescens Buckl.) consist of sucrose, glucose, fructosan, and starch. The predominant polymer is a long-chain fructosan. An acid-extractable structural carbohydrate appeared to be xylan. Total nonstructural carbohydrates (TNC) of rhizome plus root tissue decreased during May, reached a minimum value during late May to early June, increased until late June, remained constant until late August, and then increased until November. The TNC level of crown tissue was low during May and early June and reached a peak during July and again in the fall. The crude protein concentration of rhizome plus root tissues was relatively constant throughout the season. Rhizome plus roots accumulated the largest amounts of TNC and crude protein.
    • Nebraska Sedge (Carex nebraskensis Dewey): Observations on Shoot Life History and Management

      Ratliff, R. D. (Society for Range Management, 1983-07-01)
      Nebraska sedge (Carex nebraskensis Dewey), a valuable and distinct species, can withstand a high degree of defoliation by livestock without being seriously damaged. To understand this species better and learn how it can withstand defoliation, shoot life history is being studied on a site in the Sierra National Forest, California. Initial results of the study (overwinter 1979-1980 and the 1980 growing season) indicate that (1) Nebraska sedge shoots live for more than one year; (2) a high proportion of vegetative shoots overwinter; (3) overwintering shoots have cores of live leaf tissue which can develop rapidly in spring; and (4) about half of the shoots surviving winter become reproductive and die. In addition, Nebraska sedge is now recognized as a culmless species. That helps account for its withstanding defoliation. Reproduction appears to be mainly vegetative, and a management goal of producing an abundance of healthy rhizomes is suggested.
    • Mule Deer Preference and Monoterpenoids (Essential Oils)

      Welch, B. L.; McArthur, E. D.; Davis, J. N. (Society for Range Management, 1983-07-01)
      Wild wintering mule deer browsed on a uniform shrub garden near Helper, Utah. On this garden, 21 accessions from 5 Artemisia taxa were selected to test the relationship between deer preference for these accessions and the amount of monoterpenoids present in the accessions. Deer preferences were determined by measuring removal of current year's growth. Samples of current year's growth (leaves and stems with terminal buds) were collected at the time preference measurements were taken to determine monoterpenoid content. Deer use ranged from zero to 83% of the current year's growth. Total monoterpenoid content among accessions varied from 0.75 to 3.62% of dry matter. Coefficients of determination, preference versus monoterpenoid levels (total and individual) ranged from 0 to 18%. The monoterpenoid content of various accessions of Artemisia taxa was not significantly related to deer preference.
    • Mastication Effects on Cattle Diet Determined by Microhistological Analysis

      Gross, B. D.; Mahgoub, E.; Holechek, J. L. (Society for Range Management, 1983-07-01)
      This study examined the influence of mastication on the composition of several hand compounded diets fed to esophageally fistulated cattle. Microhistological analysis was used to determine diet sample botanical composition. Mastication had no effect on diet botanical composition. However, considerable variation existed between observers. The use of observers demonstrating high accuracy with hand compounded mixtures and replication of observers are possible ways to maintain accuracy when microhistological analysis is used to evaluate herbivore diets.
    • Interception of Rainfall by Tarbush

      Tromble, J. M. (Society for Range Management, 1983-07-01)
      The objective of this study was to determine the interception by tarbush of artificially applied rainfall. Twelve tarbush shrubs were collected near Las Cruces in southern New Mexico to obtain a representative sample of shrub size classes. Simulated rainfall was applied at the rate of 6 cm/hr for 30 min. Canopy cover of the tarbush community was determined from 10 line intercept transects 30.48 m long. A stepwise regression analysis using the minimum R2 improvement technique was used to examine the effects of plant parameters on interception. The "best" one variable model was shrub green weight, which accounted for 75% of the variability of the intercepted rainfall. Extrapolating the calculated interception of artifically applied rainfall to the native stand of tarbush with 15.2% canopy cover indicated that 0.5 mm of rainfall would be intercepted from a 30 mm rainfall event. Disregarding rainfall events of less than 3.0 mm, an average of 8.5 mm of rainfall would be intercepted by the tarbush community or 6.7% of the average rainfall from May through October.
    • Impact of Feral Herbivores on Mamane Forests of Mauna Kea, Hawaii: Bark Stripping and Diameter Class Structure Sophora chrysophylla

      Scowcroft, P. G.; Sakai, H. F. (Society for Range Management, 1983-07-01)
      Management of feral and Mouflon sheep and feral goats within the Mauna Kea Forest Reserve/Game Management area has been criticized as inadequate to prevent the adverse environmental impact which these introduced herbivores have on native components of the scrub forest ecosystem. This study determined the intensity of bark stripping of mamane (Sophora chrysophylla), a small endemic leguminous tree, by these animals and assessed the impact of their browsing on the size class structure of mamane stands. In all but one of the 4 areas sampled, a high proportion of mamane trees bore bark stripping wounds. Differences in the amount of stripping between elevations in a given area, and between areas, were attributed to differences in browsing pressure, which in turn was dependent on the frequency of human disturbance and the behavioral traits of the herbivores. Tree size class distributions revealed that browsing has suppressed mamane reproduction in some areas. Suppression appeared to be the greatest in the most heavily browsed areas.
    • Herbicidal Control of Common Broomweed

      Boyd, W. E.; Herndon, E. B.; Sosebee, R. E. (Society for Range Management, 1983-07-01)
      Common broomweed (Amphiachyris dracunculoides) infests Texas rangelands during the fall, winter, or spring in years with abundant soil water. Herbicidal control of common broomweed was studied in the Rolling Plains of Texas in 1977, a wet year. Dicamba and picloram plus 2,4,5-T effectively controiled broomweed at rates ranging from 0.14 to 1.1 kg a.i./ha. Tebuthiuron produced less consistent control and 2,4-D was ineffective at rates from 0.14 to 1.1 kg/ha. Broomweed production was reduced and grass production increased regardless of whether dicamba or picloram plus 2,4,5-T were applied in early December, late January, or mid-May. Grass production increased 1.5 fold following broomweed control. Compared to untreated plots, neither soil water content nor soil temperature were affected by broomweed reduction, but photosynthetic active radiation reaching more desirable forage was significantly increased by broomweed control.
    • Habitat Differences Between Basin and Wyoming Big Sagebrush in Contiguous Populations

      Barker, J. R.; McKell, C. M. (Society for Range Management, 1983-07-01)
      Basin and Wyoming big sagebrush plants growing in contiguous populations were studied to identify potential habitat differences in plant water and soil relationships. At 3 study sites, basin big sagebrush plants were growing in and adjacent to a drainage, while Wyoming big sagebrush plants occupied areas adjacent to the basin big sagebrush populations. Soil- and leaf-water potentials and leaf-transpiration resistances were measured from May to October 1980 to identify differences between basin and Wyoming big sagebrush plant-water relationships. Soil identification and plant tissue analyses were conducted to help characterize edaphic differences between the subspecies. The results of these studies showed that basin big sagebrush plants grew in a more mesic and fertile habitat than did Wyoming big sagebrush plants. Understanding the environmental differences of these two big sagebrush subspecies is important in effectively managing basin and Wyoming big sagebrush ranges.
    • Gains of Steers and Calves Grazing Crested Wheatgrass

      Hart, R. H.; Balla, E. F.; Waggoner, J. W. (Society for Range Management, 1983-07-01)
      Efficient utilization of pasture requires proper class of livestock, stocking rate, and season of use. Crested wheatgrass was grazed with steers in spring for 3 years at two stocking rates and with calves in fall for 2 years at 2 stocking rates to evaluate alternate uses. Differences in forage production and lengths of grazing season over years produced grazing pressures of 47-79 steer days or 53-73 calf days per metric tonne of forage produced. Steer gains of 0.85-1.20 kg/day were unaffected by grazing pressure, but lighter steers gained faster. Implantation of 36 mg of Ralgro per steer increased daily gains by 13%. Calf gains were 0.15-0.24 kg/day, and decreased with increasing grazing pressure according to the function ADG=0.45-0.0041 (calf days/tonne forage); r2=0.95. Such grazing pressure-gain response functions facilitate comparisons between seasons of use and class of livestock, as well as those between stocking rates, and help range managers make management decisions. Maximum steer gains in spring per hectare and tonne of forage were over 3 and 6 times, respectively, the gains of calves in fall.
    • Forage Standing Crop and Animal Diets Under Rotational vs. Continuous Grazing

      Sharrow, S. H. (Society for Range Management, 1983-07-01)
      Effects of 5-paddock rotational grazing and continuous grazing were monitored in 1977 and 1978 on an annual grass-subclover (Trifolium subterraneum) pasture. More forage was available to livestock under rotational grazing than under continuous grazing during the midspring through late spring period. However, grazing management had little effect upon forage intake by Romney ewes and their lambs during this period. Live weight gains of ewes and lambs were higher under rotational compared with continuous grazing in the spring, perhaps due to an observed increase in subclover, a highly nutritious feed, in diets of sheep grazing rotationally. In contrast to the spring green-feed period, live weight gains of ewes under rotational grazing were lower than those under continuous grazing during the summer dry-feed period. Poor ewe performance on rotationally grazed pasture during the summer period apparently reflects reduced opportunity for dietary selectivity and, therefore, a lower quality diet compared with that available to ewes on continuously grazed pasture.