The effect of cheatgrass (Bromus tectorum) competition and browsing on Wyoming big sagebrush (Artemisia tridentata wyomingensis) in southeastern Utah. Eddington, Daniel^*,1, Roundy, Bruce², Davis, James ³, ¹ 139 East 400 North # 9, Provo, UT, USA² Brigham Young Universtiy 401 WIDB, Provo, UT, USA³ 735 North 500 East, Provo, UT, USA

ABSTRACT- This study was to determine if competition from annuals, primarily cheatgrass (Bromus tectorum), is restricting Wyoming big sagebrush (Artemisia tridentata wyomingensis) reproduction, seedling establishment, annual growth, and flower production. A second objective was to determine if browsing had a significant effect on sagebrush recovery after competition by annuals was eliminated or greatly reduced. Seven paired sites, each 100 feet by 100 feet, were selected in the San Juan management unit in Utah. Each paired plot had one plot that was sprayed with Plateau (imazapic, AC 263,222) herbicide at a rate of six ounces per acre. The responses for seedling establishment were measured in spring and fall of 2003 and 2004 by sampling cover, frequency, and shrub density. Annual leader growth and flower production were indicators for change in sagebrush due to sprayed and unsprayed plots. Larger growth was found in leader growth, the number of seed heads and seedling establishment in the plots which were sprayed with Plateau. Reduced competition from cheatgrass in the understory provided greater soil moisture for sagebrush production and seedling establishment.

KEY WORDS: Bromus tectorum, Artemisia tridentata wyomingensis, Plateau, imazapic, AC 263,222