An ecological study of Atriplex nuttallii in the Big Horn Basin of Wyoming.

摘要

An ecological study of Atriplex nuttallii was initiated in the Big Horn Basin of Wyoming in 1960.;Nuttall's saltbush was found to be capable of starting growth in early February and regrowth was possible during September and early October in years when temperatures were mild. Flowering could begin in early April and seed set usually occurred in July and August.;Germination and viability of Nuttall's saltbush seed was very low, however, due to the large quantities of seeds which were produced per plant, nature had enough viable seeds to maintain and reproduce the species. Increased germination was not obtained by treating Nuttall's saltbush seeds with different pH solutions of sodium hydroxide.;Forbs and grasses averaged only 3 percent of the ground cover, while Nuttall's saltbush averaged 15 percent on the 40 acres studied. Percentage ground cover was not found to be correlated with soil pH, clay content of the soil, or soluble salt concentrations of the soil. There was no one class of soil texture found which was necessary for the growth of Nuttall's saltbush.;Nuttall's saltbush was growing in several different soil types derived primarily from shales deposited during the late Cretaceous and early Tertiary time periods, and where summer temperatures were hot and the winters cold. Precipitation was presumably one of the major factors which limited the area where Nuttall's saltbush was found.;This degree of grazing for a three-year period seemingly reduced the cover of saltbush about 6 percent, compared with a none-use area.