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Abstract
The objectives of this study were to determine tebuthiuron’s (1) effectiveness at low application rates in thinning dense, high elevation stands of mountain big sagebrush, (2) impact on understory herbaceous plants and soil microflora, and (3) movement and stability in soil. Four study sites were established in the Fish Lake National Forest and adjacent Bureau of Land Management holdings. Tebuthiuron pellets were applied at one site in 1994, a second site in 1995, and two sites in 1996 at rates ranging from 0.2 to 0.7 pounds of active ingredient (AI) per acre (0.18 to 0.63 kg AI per ha). Data from the two sites treated in 1996 show that sagebrush canopy cover was reduced in annual increments from pretreatment levels of about 23 percent to11 percent (0.3 AI treatment), 6 percent (0.5 AI), and 4 percent (0.7 AI) by 1999 (control plots were 26 percent by 1999). Understory vegetation increased slightly or had no change over time depending on treatment and climatic factors. Tebuthiuron treatments at these rates did not have long-term adverse effects on soil microflora. Tebuthiuron was mobile and its concentration remained twice as high in the zero to 15 cm soil samples as compared to deeper soil samples (>15 to 30 cm). Overall, tebuthiuron levels dropped about six fold from the second to third year after application (to 0.1 ppm). The preliminary conclusion is that tebuthiuron applied at these low concentrations can maintain mountain big sagebrush cover at meaningful levels without damage to the understory and soil micoflora.
Parent Publication
Citation
Wachocki, Barbara A.; Sondossi, Mohammad; Sanderson, Stewart C.; Webb, Bruce L.; McArthur, E. Durant. 2001. Impact of tebuthiuron on biodiversity of high elevation mountain big sagebrush communities. In: McArthur, E. Durant; Fairbanks, Daniel J., comps. Shrubland ecosystem genetics and biodiversity: proceedings; 2000 June 13-15; Provo, UT. Proc. RMRS-P-21. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 216-223.
