• Population Dynamics After Wildfires in Sagebrush Grasslands

      Young, J. A.; Evans, R. A. (Society for Range Management, 1978-07-01)
      Population dynamics of herbaceous and shrub species were investigated in big sagebrush/Thurber needlegrass communities burned in wildfires. The sites burned are representative of extensive areas of degraded rangelands in the central Great Basin. Herbaceous succession after wildfires in these communities is dominated by the dynamics of populations of the alien annual grass downy brome. Downy brome caryopses are greatly reduced by most large wildfires, but the plants originating from surviving downy brome caryopses respond dynamically to the released environmental potential. The response may include hybridization and recombination. The result is a purge of native annual species from the community and the failure of seedlings of native perennial grass species to become established. Root and crown sprouting of the native shrubs, green rabbitbrush and horsebrush, occurs after the wildfire has killed the dominant big sagebrush. Green rabbitbrush sprouts produce abundant achenes, which readily germinate and grow. The reestablishment of downy brome dominance predisposes the vegetation to recurring wildfires and cyclic environmental degradation.
    • Response of Birds, Small Mammals, and Vegetation to Burning Sacaton Grasslands in Southeastern Arizona

      Bock, C. E.; Bock, J. H. (Society for Range Management, 1978-07-01)
      We studied the impact of fire on an ungrazed sacaton grassland community at The Research Ranch in southeastern Arizona. Two summer burns were followed through two post-fire growing seasons. A winter burn was studied through one post-fire growing season. Burning reduced the height and extent of sacaton grass (Sporobolus wrightii) itself, and stimulated growth of other grasses and forbs. Summer fires created more bare ground and encouraged a greater number and variety of annuals than the winter fire. The fires had the effect of reducing total small-mammal populations and greatly increasing bird populations. These results were more dramatic on the areas which burned in early summer than on the winter-burned plot. Raptors and most game birds, particularly mourning doves, were most abundant on one-year-old burns. Seed-eating birds (Fringillidae) preferred burned over unburned areas. Cotton rat (Sigmodon hispidus) populations were greatly reduced by the fires, while populations of seed-eating pocket mice (Perognathus) and kangaroo rats (Dipodomys) increased, especially on the summer burns. Sacaton grasslands recover rapidly even from summer burning, at least in the absence of livestock. Results of this study suggest that fire is beneficial to the indigenous plants and wildlife of sacaton communities, as long as a mosaic of different aged stands is maintained.
    • Response of Fourwing Saltbush to Periods of Protection

      Pieper, R. D.; Donart, G. B. (Society for Range Management, 1978-07-01)
      Fourwing saltbush plants produced less leader growth after 4 years of continuous cattle browsing than after 3 years of continuous browsing followed by 1 year of protection. Plants in pastures used in a rotation grazing system produced as much leader growth as protected plants.
    • Revegetation Trials on a Saltgrass Meadow

      Ludwig, J. R.; McGinnies, W. J. (Society for Range Management, 1978-07-01)
      Saltgrass (Distichlis stricta (Torr.) Rydb.) meadows may be converted to productive pasture if the low-value saltgrass is removed and productive forage plants established. Field planting trials were conducted in 1975 and 1976 to determine the effects of nitrogen fertilizer, chemical soil amendments, mulch, and furrows on establishment of crested wheatgrass (Agropyron desertorum (Fisch. ex Link) Schult.), tall wheatgrass (A. elongatum (Host) Beauv.), Russian wildrye (Elymus junceus Fisch.), and smooth brome (Bromus inermis Leyss.). In 1975, alternate-furrow planting produced thinner stands than nonfurrowed planting, but in 1976, yields of the 1975 planting were similar from both treatments. Nitrogen fertilizer did not improve stand establishment or yield. All species became established, but tall wheatgrass appeared to be least able to withstand the droughty conditions encountered in late 1975 and all of 1976. In the 1976 planting, a straw mulch increased seedling height and vigor but did not increase the number of seedlings or stand ratings. Because of its combined high seedling vigor and good drought tolerance, crested wheatgrass produced significantly better stands than did the other three species in the 1976 planting.
    • Runoff Water Quality from Varying Land Uses in Southeastern Arizona

      Schreiber, H. A.; Renard, K. G. (Society for Range Management, 1978-07-01)
      Surface runoff waters from three kinds of activity on rangeland were examined for suspended solids and some indicator chemical constituents. We compared ungrazed brush-covered rangeland with recently subdivided rangeland, originally and still partly brush-covered, but whose surface was disturbed by man's urbanizing influence. Water quality indicators showed the urbanized watersheds had poorer water quality. Comparisons between the two brush-covered watersheds and a third-grass-covered and grazed-were made only on the runoff water's dissolved constituents. Despite the grazing activity, the waters were of better quality. A contrast in the geology between the grass and brush areas suggested that mineral sources affected qualitative changes in the dissolved solids. Calcareous soils produced waters higher in Ca and total dissolved solids and lower in other cations. Phosphate in runoff averaged higher from the grass-covered, noncalcareous area than from the brush-covered calcareous watershed. We hypothesize now that the phosphate originated from soil sources, rather than from grazing activity. Nitrate levels were comparable in runoff from all the nonurban areas, but increased in runoff from the semiurban area. Thus, the nonagricultural complex of activities associated with a housing development was more detrimental to water quality than those from undisturbed or grazed rangelands.
    • Soil Water Use and Recharge in a Fertilized Mixed Prairie Plant Community

      Wight, J. R.; Black, A. L. (Society for Range Management, 1978-07-01)
      Nitrogen fertilization on a mixed prairie, upland range site increased soil water extraction, overwinter recharge, and water- and precipitation-use efficiency. Overwinter recharge was inversely related to soil water content in the fall.
    • The Estimation of Winter Forage and Its Use by Moose on Clearcuts in Northcentral Newfoundland

      Parker, G. R.; Morton, L. D. (Society for Range Management, 1978-07-01)
      This study was designed to evaluate the effect of clearcutting on moose (Alces alces americana) populations in northcentral Newfoundland. Fourteen logged areas of various size and age were sampled for potential standing forage and current use. Balsam fir (Abies balsamea), white birch (Betula papyrifera), pin-cherry (Prunus pensylvanica), and willow (Salix spp.) were the most common forage species. Moose browsed most heavily upon pin-cherry, followed by birch and willow. Balsam fir was only lightly used. The most efficient sized plot for measuring browse production was found to be 6 m2. Available browse on balsam fir trees ≤5 m in height was measured by linear correlation with the product of stem diameter and height. Most winter browse was in cuts 8 to 10 years of age. The greatest use was in cuts 40 to 50 ha in size. A forest management plan which encourages a heterogeneous pattern of 40 to 50 ha block cuts and mature forest cover is suggested to be most compatible with the management of moose in northcentral Newfoundland.
    • The Influence of Ammonium Nitrate on the Control of Mesquite Resprouts with 2,4,5 T Ester

      Arnold, J. D.; Burzlaff, D. F. (Society for Range Management, 1978-07-01)
      The influence of ammonium nitrate on the phytotoxicity of 2,4,5-T ester, nitrogen concentration, and niacin concentration of honey mesquite was studied. Fertilizer was applied to individual 3-year-old resprouts in the fall of 1973 and 2,4,5-T ester was applied to the individual 3-year-old resprouts on 3 dates in 1974. There was no conclusive evidence that N fertilizer affected the percentage of root-kill of mesquite when sprayed with 2,4,5-T ester. Ammonium nitrate had no effect on the nitrogen or the niacin levels in honey mesquite.
    • Vegetative Differences Among Active and Abandoned Towns of Black-tailed Prairie Dogs (Cynomys ludovicianus)

      Klatt, L. E.; Hein, D. (Society for Range Management, 1978-07-01)
      Vegetational differences were studied among one active prairie dog (Cynomys ludovicianus) town and three towns which had been abandoned 1, 2, and 5 years, respectively. Blue grama (Bouteloua gracilis) and buffalograss (Buchloe dactyloides) were dominant on all four study areas. Percent cover of total vegetation, grasses, and increaser and invader species declined with length of abandonment. Percent cover of the only decreaser, western wheatgrass (Agropyron smithii), was similar on the abandoned towns and lowest on the active town. Composition of vegetation on the four study areas did not indicate that the usual stages of secondary succession on short grass prairie had occurred on the abandoned prairie dog towns. Most changes in vegetation following abandonment of 5 years or less by prairie dogs were apparently relatively minor and would not benefit cattle grazing significantly.