• Establishment of Diffuse and Spotted Knapweed from Seed on Disturbed Ground in British Columbia, Canada

      Roze, L. D.; Frazer, B. D.; McLean, A. (Society for Range Management, 1984-11-01)
      The rangeland weeds diffuse and spotted knapweed (Centaurea diffusa L. and C. maculosa L.) were sown at densities of 208 to 1,504 seeds/m2 on disturbed rangeland in Westwold, British Columbia, in 25 × 25-cm plots. Both species established well to the rosettes stage at the lowest sowing densities, but only 5% of the diffuse knapweed rosettes bolted in the second year compared to 45% of the spotted knapweed rosettes. Intraspecific competition appeared to decrease the number of spotted knapweed rosettes bolting at the higher sowing densities.
    • Natural Establishment of Aspen from Seed on a Phosphate Mine Dump

      Williams, B. D.; Johnston, R. S. (Society for Range Management, 1984-11-01)
      The natural reproduction of aspen (Populus tremuloides Michx.) from seed was discovered on a phosphate mine dump in southeastern Idaho. Aspen seedlings were found growing on areas that were essentially bare except for scattered plantings of containerized shrubs and trees. Aspen survival and growth was monitored for 4 growing seasons. Seedling density varied from 2 to 10 per m2, seedling heights varied from 16 to 81 cm, and survival rate was 73% at the end of 4 growing seasons. No changes in the number of seedlings were noted after the second growing season.