• Heated substrate and smoke: influence on seed emergence and plant growth

      Blank, R. R.; Young, J. A. (Society for Range Management, 1998-09-01)
      Combustion products of burning vegetation can increase seed germination of many species of fire-prone plant communities. We tested the influence of heating sagebrush (Artemisia tridentata Nutt.) subcanopy soil, aqueous extracts of artificially burned soil, and sagebrush smoke on the emergence of several range plant species of the sagebrush-steppe. In addition, test seeds were exposed to sagebrush smoke and aqueous slurries of artificially burned sagebrush subcanopy soil to determine their effect on plant growth. As compared to the control, substrates previously heated from 250 to 750 degrees C significantly (P less than or equal to 0.05) increased the emergence of Thurber's needlegrass [Achnatherum thurberianum (Piper) Barkworth] and needle-and-thread [Hesperostipa comata (Trin. & Rupr.) Barkworth]. Sagebrush smoke and aqueous slurries of artificially burned soil significantly increased the emergence of Sierra Nevada needlegrass [Achnatherum occidentalis (Thurber) Barkworth], Indian ricegrass [Achnatherum hymenoides (Roemer & Schultes) Barkworth], and antelope bitterbrush [Purshia tridentata (Pursh) DC.]. Rates of new leaf production and leaf elongation following treatment of seeds with the smoke of burning sagebrush were significantly greater for cheatgrass (Bromus tectorum L.), basin wildrye [Leymus cinereus (Sribner & Merr.) A. Löve], Idaho fescue (Festuca idahoensis Elmer ), Sierra Nevada needlegrass, and needle-and-thread as compared to the control. After 83 days of growth, smoke-treated seeds of basin wildrye and needle-and-thread produced significantly greater plant mass than their controls. Smoke treatment of certain seeds before sowing is potentially useful for range plant seedings.
    • Variations in nutritional quality and biomass production of semiarid grasslands

      Corona, M. E. P.; de Aldana, B. R. V.; Criado, B. G.; Ciudad, A. G. (Society for Range Management, 1998-09-01)
      The effect of the growing season and topographic zone on biomass production, protein content, cell content (CC), lignin, cellulose, hemicellulose, digestibility (DMD), and mineral element concentrations (P, K, Ca, Mg, Na, Mn, Fe, Cu, Zn) were studied in herbage samples collected from semiarid grasslands in Central Western Spain. Protein and mineral contents decreased as the growing season progressed whereas fibre properties tended to increase. Topographic gradient significantly affected peak biomass production, fibre properties, protein and mineral contents. Stepwise multiple regression showed that the prediction of biomass production on these areas was related to cellulose, Na, Fe, and Mg contents in the grassland community whereas fibre properties were mainly predicted by Ca, Na, and Cu. Principal component analysis indicated that the temporal evolution (component II) of the organic variables determined pasture quality whereas most of the variation in mineral content was related to the topographical gradient (component I). Some organic and inorganic parameters may cause deficiencies in cattle grazing en the upper and middle zones, mostly at the end of the growing season. The data suggest that information about the temporal and spatial variations of the production and nutritional quality of semiarid grassland is necessary for making correct management.