• Denitrification and Bacterial Numbers in Riparian Soils of a Wyoming Mountain Watershed

      Hussey, M. R.; Skinner, Q. D.; Adams, J. C.; Harvey, A. J. (Society for Range Management, 1985-11-01)
      The presence and activity of denitrifying bacteria as well as bacteria capable of reducing sulfate in 1 upland and 5 riparian soils of a mountain watershed in Wyoming were studied. Bacteria were enumerated from soil samples collected during summer along transects placed perpendicular to stream flow. Samples were taken at 3 depths within each plant community. Subsamples were frozen and later utilized to determine denitrification potential. Higher counts of total heterotrophic aerobic bacteria, sulfate-reducing bacteria, denitrifying bacteria, and denitrification potential existed in the upper 5 to 15 cm of soil than at 30 cm. Soils located close to the stream's edge tended to have more bacterial activity than those further from the stream, indicating that these soils may be important areas for nitrate and sulfate reduction. Soil organic matter and water content decreased with depth in all plant communities, and those closer to the stream contained more organic matter and water than those further from the stream.
    • Precipitation, Soils and Herbage Production on Southeast Wyoming Range Sites

      Hart, R. H.; Samuel, M. J. (Society for Range Management, 1985-11-01)
      Herbage production and precipitation were determined at 13 locations in 483 ha of mixed grass range 1975-1979; production was determined at all locations 1982-1983, but precipitation was measured only at the main weather station. Vegetation and herbage production were more uniform on sites with similar subsoil than on sites with similar surface soil, the usual basis for site classification. Within any year, herbage production on similar sites was not correlated with spatial distribution of precipitation. Across years 1975-1979 and 1982-1983, herbage production on sites with sandy subsoil was correlated with March-April weather station precipitation (r2=0.866**) and March-April plus May-August precipitation (R2=0.95**). Herbage production on sites with loamy subsoil was not significantly correlated with precipitation in March-April (r2=0.32) or any other period.
    • The Role of Fourwing Saltbush in Mined Land Reclamation: A Viewpoint

      Booth, D. T. (Society for Range Management, 1985-11-01)
      Ease of establishment by direct seeding has resulted in fourwing saltbush [Atriplex canescens (Pursh) Nutt.] becoming the principal, sometimes the only, shrub on certain revegetated mined lands in Wyoming. To prevent dense stands that might exclude other shrub species, the Wyoming Department of Environmental Quality-Land Quality Division, now limits the amount of fourwing saltbush that can be included in a reclamation seed mix. There is evidence that fourwing saltbush may aid, rather than hinder, the establishment of other shrubs. A thesis is developed for fourwing's role as a pioneer species that creates ecosystem diversity, auguments the invasion of late-succession plants, and declines in density as succession progresses. The shrub is recommended as a means to direct succession toward successful reclamation. Mine managers are cautioned that the rate of natural invasion of climax species into seeded stands of fourwing saltbush is not known.