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Wyoming big sagebrush recovery and understory response with tebuthiuron control

TitleWyoming big sagebrush recovery and understory response with tebuthiuron control
Publication TypeJournal Article
Year of Publication2005
AuthorsMcDaniel, KC, Torell, LA, Ochoa, CG
JournalRangeland Ecology and Management

Field data collected over a 20-year period at 8 sites in northwestern New Mexico was used to determine Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis Beetle and Young) recovery following control with tebuthiuron (N-[5-(1,1-
dimethylethyl)-1,3,4-thiadiazol-2-yl]-N-N9-dimethylurea) and to relate understory perennial grass yield to overstory canopy cover. Tebuthiuron killed between 80% and 95% of mature Wyoming big sagebrush plants within 18 months of chemical
treatment, but through recruitment plant numbers equaled or exceeded pretreatment density (plants/m2) at 3 of the 8 sites and were increasing at other locations near the study’s end. Wyoming big sagebrush canopy cover averaged ,2% the first 10 years
after herbicide treatment but had returned to near pretreatment levels (.15%) at 2 sites, to between 5% and 10% at 4 sites, and to less than 3% at the remaining 2 sites. Treatment life was projected to exceed 35 years for 6 of the 8 study sites. Higher rates of tebuthiuron generally extended treatment life. Annual average perennial grass yield increased on treated areas relative to untreated rangeland at all study sites over the 20-year study period. Grass yield was highly variable between years, with
pronounced increases when weather and environmental conditions were favorable for grass growth. A nonlinear S-shaped curve best described overstory–understory relationships and also defined the time path of Wyoming big sagebrush recovery, which
differed by study site.